Free Essay

Will Tv Succumb to the Internet

In: Business and Management

Submitted By praptishah
Words 5899
Pages 24
Environ Sci Pollut Res
DOI 10.1007/s11356-014-2974-9


Determination of lead(II) sorption capacity of hazelnut shell and activated carbon obtained from hazelnut shell activated with ZnCl2
Aziz Şencan & Mustafa Karaboyacı & Mehmet Kılıç

Received: 26 November 2013 / Accepted: 23 April 2014
# Springer-Verlag Berlin Heidelberg 2014

Abstract This study aimed to determine the Pb+2 adsorption capacities of hazelnut shell and activated carbon obtained from hazelnut shell. It also aimed to determine the effect of
ZnCl2 in the activation process. The hazelnut was pyrolyzed at
250 and 700 °C. For determining the capture speed of the adsorbents, the pseudo-first- and second-order kinetic studies were performed. The Freundlich and Langmuir isotherm models were used to determine adsorption equilibrium. The surface characterization of hazelnut shell and activated carbon was determined by Brunauer-Emmett-Teller (BET) analysis and FTIR spectrum. Pb+2 adsorption capacity of obtaining activated carbon was determined by ICP-OES analysis. The raw hazelnut shell’s BET surface area is 5.92 m2/g and the surface area of activated carbons which is pyrolyzed at 250 and 700 °C were determined (270.2 and 686.7 m2/g, respectively. The surface area of hazelnut shell, which pyrolyzed at
700 °C after being activated with ZnCl2, was determined to be
736.49 m2/g. Results show that physical adsorption process is dominant for the activated carbon pyrolysis at 700 °C but the chemical adsorption is dominant for the activated carbon pyrolysis at lower degrees and for raw hazelnut shell.

Keywords Activated carbon . Heavy metals . Lead(II) .
Kinetic . Isotherm . Hazelnut

Responsible editor: Philippe Garrigues
A. Şencan (*) : M. Karaboyacı
Department of Chemical Engineering, Süleyman Demirel University,
32260 Isparta, Turkey e-mail:
M. Kılıç
Department of Environmental Engineering, Süleyman Demirel
University, Isparta, Turkey

In the last two centuries, along with the mankind’s increasing industrial activities, elements and metals have been used intensively. Therefore, it can be said that the heavy metal contamination is also known for this period of time. Because of the increasing industrial development and the usage of metals for various activities of humanity, the environmental health is being seriously threatened. In terms of the environment, the metals especially like Cd, Cr, Pb, and Hg, because of their tendency to accumulate, have toxic and inhibition effects on living organisms (Forster and Wase 1997). Lead has acute and chronic effects on people. Especially, it damages the liver and the stomach in a short time and the brain and the kidney in a long period of time (Tchobannoglous et al. 2002). That is why developing new methods to control the environmental metal contamination and sending the heavy metals out of water supplies is needed.
One ion’s or molecule’s accumulation in another phase’s surface or its gaps is called adsorption. The material that accumulates is called as adsorbate, and the solid that adsorbs is called adsorbent. The liquid’s concentration in one solid’s micro cracks on its surface or pores is called as capillary adsorption. Adsorption phenomena depend on the materials which will be adsorbed, concentration in the solution. Beside this, the agents like temperature, pH, amount of adsorbent material, and mixing speed are the factors that effect the adsorption (Öztürk 2006).
Activated carbons are composites which have an outstanding inner surface area and volume of pores, and generally contain 87–97 % of carbon which has nonuniformed surface form. And the rest of it may contain hydrogen, oxygen, sulfur, and nitrogen. There may be useless materials in activated carbon at the rate of 5 to 20, but these materials should be abducted before usage. This process is called as decreasing the content of ash and in usage as adsorbents and this content

Environ Sci Pollut Res

should be taken in 0.1–0.2 % rate (Choma et al. 1987).
Activated carbons are used in various industries for different goals. Because it is a good adsorbent, it is used in wide areas like purification and refinement of the activated carbon gases, treatment of water and wastewater, carbon contribution to metal industry, making protective wearing in the defense industry, making bombs for silencing the explosive and electronic systems in weapon industry, and also in the health sector. As a result, the activated carbon that we use for different goals in our daily life is an indispensable material (Stoeckli and Kraehenbuehl 1984). Activated carbon in liquid or gas phase is used for the adsorption of various materials. It can adsorb a lot of different molecules in it is inner surface
(Jaroniec and Choma 1986). In an ideal formed activated carbon, the pores are almost 0.2–1.0 cm3/g. The surface area is 400–1,000 m2/g, and this value may be exceeded in production for special goals (Morgan and Fink 1997; Küçükgül
2004). Activated carbons are porous adsorbents and are used in several industrial processes. These carbons have often been used in the adsorption of pollutants present in gas or liquid phases in order to control environmental pollution, to remove organic compounds, or to remove toxic metallic species (AlOthman et al. 2012).
In this study, heavy metal adsorption capacities of the hazelnut shell’s and activated carbon’s, which is obtained from hazelnut shell, were firstly determined. And then, by making studies about increasing the activated carbon surface area, changes of the adsorption capacity were observed. For extension of the surface area, the thermal procedures are applied first. For this extension, chemical activation is achieved with zinc chloride and made some studies on determining the obtained sorbents’ potential of adsorbing the Pb+2 ion. In the literature, different activated carbons were obtained from different biomasses and the contaminant adsorption capacities were determined for the obtained activated carbons
(Imamoglu and Tekir 2008; Acharya et al. 2009; Demirbas et al. 2009). In addition to this, Pb+2 ion adsorption studies are not too much for the activated carbon derived from hazelnut shells. The dominant mechanism for the adsorption phenomena was determined by utilizing the FTIR spectra. Also, there is no study in the literature about the raw hazelnut shell and activated carbon, which was obtained from hazelnut shell, by different methods, surface bonds and the effects of carbonization on the surface bonds, and contribution of that bond in the adsorption process.

contaminations on them by being washed with a great amount of distilled water before being used in the study. Then they were incubated for 48 h in 60 °C. After the drying process, by being treated in the grinder robot; these hazelnut shell is minimized to the required piece size. For the homogenization of this piece sizes, the material which is sieved in a sieve that has biomass 300 and 180-μm pore size and stayed together between two sieves. Hazelnut shells were waited in desiccator before being used in the study and therefore, it is ensured that it is not effected by the moisture of the occasion in a possible way. All the chemicals used in the study are in analytical purity.
As a stock in a concentration of 1,000 mg/L, Pb+2 solution is arranged by using Pb(NO3)2, and the Pb+2 solution which is used in adsorption experiments is used by being diluted from this stock solution. For arranging the solution pH values to the desired value, the NaOH and HCl solutions which have molarities between 0.1 and 3.0 M are used. For determining the biomass, heavy metal adsorption capacity, the filtrate’s heavy metal concentration was determined by using spectrophotometric methods with ICP-OES device. For chemical activation process, 20 % of ZnCl2 solution was used.
Converting hazelnut shells to the activated carbon
Thermal activation
The hazelnut shell is transformed into activated carbon by pyrolysis in two different temperatures, 250 and 700 °C. The hazelnut shell which is brought for the certain piece size is placed into a steel capsule. For sending away the oxygen from the stage, a great deal of azote gas is given into the capsule.
The capsule, which is cooked immediately, was left in the ash oven for pyrolysis. During the activated carbon’s pyrolysis, three different rates of temperature enhancement are determined and provided the ash oven to be in 250 and 700 °C
(beginning temperature is 100 °C). These rates are 1, 2.5, and
5 °C/min. These rate, which gives the highest adsorption efficiency used in activated carbon’s Pb+2 adsorption in three speeds, is used in other studies. The obtained activated carbon samples, to remove the remnants from its structure, are washed with a great amount of distilled water and left to be dry in 60 °C in the oven for 24 h. The samples were especially left in the desiccator in the adsorption studies to avoid being effected by the stage moisture.
Chemical activation

Materials and method
The hazelnut shell which is used in the study is obtained from
Ünye in Turkey. These hazelnut shells purified from

ZnCl2 is used to acquire activated carbon with chemical activation. At the beginning, raw hazelnut shell is poured into
ZnCl2 solution (20 %). The mixing rate is 60 g hazelnut shell/
1 l solution. This mixing is stirred for 24 h at room temperature and filtered through filter paper to remove its water then

Environ Sci Pollut Res

left to be dry. The sample was pyrolyzed in two different temperatures after it is dried. Pyrolyzed samples are washed with 5 % (w/w) HCl solution. To remove the acid residue from the stage, it is washed with distilled water until its pH value was 7. Washed samples were dried and ground, and then put in desiccator until its usage.
The surface characterization of activated carbon

Kinetic studies

For the surface characterization of hazelnut shell and the activated carbon obtained from hazelnut shell, BrunauerEmmett-Teller (BET) surface area measurements and IR spectrums have been made. BET surface area is made by
Micromeritics device. IR spectrums were made with Fourier
Rotative Pelkin Elmer BX spectrometer.
Adsorption studies
To determine the raw hazelnut shell and its adsorption performance, optimum pH, kinetic, and isotherm determination studies were made for every single activated carbon sample. There were some adsorption tests done in different pH values to determine the pH value’s effect on adsorption capacity. For the Pb+2 adsorption experiments, pH values were taken between 1 and 6. The reason why these values were taken is that after the pH is 6, lead hydroxide occurs in solution (there is a
0.5 unit difference between the values). After arranging the beginning pH value of the heavy metal solution which has
100 mg/L beginning concentration to the stated values, 50mg-weighting sorbent was added to the solutions and this mixture was shaken in orbital incubator for 1 h under the conditions of 150 rpm and 20 °C. To see if there is settling in terms of metal ions during adsorption process, other control samples, which do not have sorbent in it but with pH values rearranged to the intended value, were shaken in the same time with the other mixings. There are two grains of all samples, and all the adsorption experiments were retaken when the samples are not close to each other. This situation is taken into consideration in all adsorption experiments. After the shaking process, sorbents left the solution by floating and the metal morality in this filtrate was determined by using the ICP device.
After calculating the pH value which obtains the maximum sorption capacity, the heavy metal concentration in the filtrate was determined. By calculating their adsorption capacities, we tried to determine the optimum pH value with the following equation: qe ¼

ðC o −C e Þ

L), Ce represents the metal ion concentration left on the permeate (mg/L), m represents the dry weight of the biomass in the mix (g), and the V represents the volume of the mixing (L).
Adsorption capacities were calculated with the adaptation of the equation used in the adsorption experiments in this study. ð1Þ

In this equation; qe represents the amount of metal ions which adsorbed on biomass on equilibrium time (mg/g), C0 represent the solution’s beginning metal ion concentration (mg/

After a certain time in adsorption process, the amount of heavy metal which is adsorbed by the sorbent will not change.
So the adsorption process will reach to the dynamical equilibrium. This period of time which passes over when the metal concentration’s decreasing pattern stops is determined at the equilibrium time. To determine this period of time, by rearranging the beginning pH value of the heavy metal solution which has 100 mg/L of concentration to the optimum pH value which is determined in the former process, they are placed into the vials with the volume of 50 mL. These mixings, which are made by adding 50-mg-weighting biomass into them, were exposed to be shaken in the orbital incubator under conditions of 150 rpm and 20 °C in the following period of time: 5, 10, 15, 30, 60, 90, and 120 min.
At the end of these periods of time, the mix is filtered to remove the sorbent from the suspension, by using sieve paper with 1 μm pore size. The metal concentrations were calculated in obtaining the filtrate.
Experimental data were adapted to the pseudo-first-order kinetic model in the way as follows: qt ¼ qe ð1−expð−k 1 t ÞÞ


In this equation, qt represents the amount of metal ion adsorbed in any t time (mg/g), qe represents the amount of metal ion adsorbed during the equilibrium time (mg/g), and k1 represents the pseudo-first-order kinetic constant (min−1).
Pseudo-second-order kinetic model is as follows: qt ¼

qe 2 k 2 t
1 þ qe k 2 t


In this equation, qt represents the amount of metal ion adsorbed in any t time (mg/g), qe represents the amount of metal ion adsorbed during the equilibrium time (mg/g) k2
(g/mg.min.) and the pseudo-second-order kinetic constant
(min−1), and t represents the time (min). Nonlinear regression method is used in solving the equations with the aid of the
Microsoft Office Excel program. The same solution is used in determining the isotherm model constants.

Environ Sci Pollut Res
Fig. 1 The change of sorbent’s sorption capacity with pH
(conditions: 100 mg L−1 initial concentration, 300–180 μm particle size, 1 g L−1 adsorbent dosage, 150 rpm, 60 min agitation time, and 20 °C)

Isotherm study
There were isotherm experiments made to determine the equilibrium situation of sorbent’s process of adsorbing the heavy metal. For this particular purpose, 25, 50, 75, 100, 125, and
150 mg dry weight biomass was added to 50 mL of the solution which has 100 mg/L heavy metal concentration; the formed mixing was shaken off in the orbital incubator under
20 °C until the equilibrium time which is determined after the kinetic studies. After adsorption was done, mixtures were filtered and their Pb+2 concentrations were determined. These obtained experimental data were analyzed due to the nonlinear regression analyses; the Freundlich and Langmuir isotherms parameters were calculated, and the isotherm model which

Fig. 2 Distribution of the lead ions in aqueous solution according to pH value

shows compliance to the adsorption phenomenon is determined. Parameters that belong to the nonlinear Freundlich isotherm model are determined through Eq. 4: qe ¼ K F C e ð1=nÞ


In this equation, qe represents the amount of metal ion adsorbed in the equilibrium time (mg/g); KF represents the proportional adsorption capacity, a parameter that belongs to the isotherm; n represents the adsorption density; and Ce represents the materials concentration which stays in the solution in equilibrium time (mg/L).

Environ Sci Pollut Res
Fig. 3 Pseudo-first- and secondorder kinetical graphics of the sorption process made with nutshell (conditions: 100 mg L−1 initial concentration, pH 5, 300–
180 μm particle size, 1 g L−1 adsorbent dosage, 150 rpm, and
20 °C)

Parameters that belong to nonlinear Langmuir isotherm are as follows: qe ¼

qm a L C e
1 þ aL C e


In this equation, qe represents the amount of metal ion adsorbed in the equilibrium time (mg/g), qm represents the maximum monolayer adsorption capacity (mg/g), aL represents the isotherm fix which states the adsorption energy
(L/mg), and Ce represents the materials concentration which stays in the solution in equilibrium time (mg/L).

Results and discussion
The effect of pH value on the adsorption
In the sorption studies, the crucial parameter is the pH. pH has an important effect on metal ion’s resolution and ionizing of the functional groups on the activated carbon’s surface. This
Table 1 Sorbents’ first- and second-order kinetic model constants and regression numbers qe Raw
250 °C
700 °C
Zn+700 °C










effect has a great place on the sorption phenomenon
(Nomanbhay and Palanisamy 2005). The change in pH and sorbent, sorption capacity in the study is given in Fig. 1.
It is clearly seen that the occasion pH is an active parameter on sorption incident. pH studies were made between the pH values of 1 and 6, and because there is a residue in the solution when the pH is over 6, there was no study over this value
(Fig. 2). It is observed that between pH values 1 and 3, sorption capacity is comparatively too low and over pH 4, the capacity gets much better. When comparing the hazelnut shell pyrolysis at 250 °C and the values at 700 °C, it is seen that the sorption capacity of the activated carbon has increased
40 %. Towards these data, we can say that especially the raw hazelnut shell is positively charged in low pH values. In low pH values, hydrogen ions protonate activated carbon grains and make them positively charged. The intense existence of the H+ ions in occasion makes a competition with the positively charged heavy metal ions and that makes the adsorption of the heavy metal with the electrostatic forces impossible
(Nomanbhay and Palanisamy 2005; Al-Qodah 2006). The reason why sorption is powerful, especially after pH 4, may be the ionization of the carboxyl groups in the activated carbon. Carboxylic acid’s pKa is about 4.2. Carboxylic acid, above these pH values ionizes. Therefore the carboxyl which has conjugation becomes a negatively charged ion. That is how it generates a familiarity through the positively charged ions in the water. When looking at the activated carbon’s IR spectrum (Fig. 5), the existence of the carboxyl groups is seen.
Strains seen in 1,100 and 1,000 cm−1 show the existence of carboxyl (Dikman 1985). Also, when the pH increases, H+ concentrations will be neutralized with the OH− ions in the solution and concentration will be decreased, so the heavy

Environ Sci Pollut Res
Fig. 4 Langmuir and Freundlich isotherm constants (conditions:
100 mg L−1 initial concentration, pH 5, 300–180 μm particle size,
150 rpm, 90 min agitation time, and 20 °C)

metal ions will not be compatible and the electrostatic forces and sorption will come forward. As a result of the studies, the ideal pH value for sorbents is determined as 5 and that is the basis for the next studies. Özcan et al. (2009) with the
Phaseolus vulgaris L. biomass determined the ideal pH value as 5 in lead adsorption studies. They also state that the hydrogen ion competes with the adsorbent at low pH values. Beside this, they emphasize that there are metal pellets in the solution when there is pH value over than intended.

Kinetic studies
Adsorption kinetics expresses the capture speed of the pollutant in the solution by activated carbon. Determination of this speed level is needed for the design of processes based on adsorption. In this process, hydraulic retention time depends on kinetical data. There are some tests need to be done to determine the kinetical data in a good way (Ho and McKay
1999). Obtained results after the experimental studies are shown in Fig. 3 with a graphic.
When the graphic is examined, it is seen that the sorption process is made quickly. In the first 15 min, 62 % of the sorption were done. At the end of 90 min, it is seen that sorption is done. Pehlivan et al. (2009) studied on lead
Table 2 Pb(II) adsorption’s Langmuir and Freundlich constants

250 °C
700 °C
Zn+700 °C

Langmuir n 0.11






outgoing Pb+2 in aqueous solutions with their hazelnut shell and established that the hazelnut shell removes the 90 % of the
Pb+2 away the aqueous solution.
For the kinetical analyses of the obtained data, by investigating pseudo-first- and pseudo-second-order equations to see if they are good for this or not, we determined kinetic constants. In this calculation process, nonlinear regression method is used. Data obtained through calculation is shown in Table 1.
In Table 1, when looking at the R2 values by pyrolysis raw sorbent at 250 °C, it is expressed as second-order kinetic, sorbents which were pyrolyzed at 700 °C and activated with
ZnCl2 sorption process is more compliable with pseudo-first order-kinetic model. Ho and McKay (1999), stated that the pseudo-second-order kinetic mechanism which gives high regression in all time periods may be the chemisorption which includes electron change and share between the adsorbate and the adsorbent. Data obtained through the study are the indicators that in the sorption process, chemical incidents are not dominant because of incompliance. When looking at the IR spectrums of both sorbents, sorbents could not make a C≡C adsorption as a result of combustion. That is why it may be said that the physical capture is more dominant is sorption process. Isotherm studies
Adsorption isotherm is an essential data source for practical design and fundamental understanding of the carbonaceous adsorbents. The parameters obtained from different isotherm models are important for the optimization of the adsorption mechanism pathways and expression of the surface properties of adsorbents (Foo and Hameed 2012). An adsorption process depends on the surface area, pore size distribution, and surface chemistry of the adsorbents (Mahapatra et al. 2012). In this study, adsorption capacities of activated carbons obtained at

Environ Sci Pollut Res

Fig. 5 Raw nutshell’s IR spectrums taken before and after the adsorption (above is raw, bottom is the Pb(II) adsorbed sorbent’s spectrum)

different activation temperatures and activated with ZnCl2 sorbents were investigated. Several adsorption isotherm equations are available, and two important isotherms are selected in this study.

Langmuir and Freundlich isotherms
Results obtained from the sorbents’ isotherm studies on raw hazelnut shell and modification of it are shown in Fig. 4.

Fig. 6 250 °C pyrolyzed nutshell and the Pb(II) adsorption, before and after IR spectrums (above is raw, bottom is Pb(II) adsorped sorbent’s spectrum)

Environ Sci Pollut Res

Fig. 7 Before and after IR spectrums of nutshell pyrolyzed at 700 °C with its adsorption with Pb(II) (above is raw, bottom is Pb(II) adsorbed sorbent’s spectrum) Fig. 8 Before Pb(II) adsorption IR spectrum of nutshell pyrolyzed at 700 °C

Environ Sci Pollut Res

Fig. 9 After Pb(II) adsorption IR spectrum of nutshell pyrolyzed at 700 °C

Langmuir and Freundlich isotherm constants and R2 values showing the compliance of sorption incident with this model obtained from nonlinear analyses of the data are also given in
Table 2.
On Table 2, when looking at the R2 values, it is seen that adsorption incidents of the raw and sorbents pyrolyzed at
250 °C show compliance with the Langmuir isotherm model, but the adsorption equilibrium of sorbents pyrolyzed at 700 °C and activated with ZnCl2 is compliable with the Freundlich isotherm model. Explanation of isotherm data with Langmuir isotherm model is the indicator that the sorption incident is monolayer and that is why chemical incidents are dominant in capturing. Therefore, it may be thought that the raw hazelnut shell and the sorbents pyrolyzed at 250 °C are the dominant chemical incidents in capturing the Pb+2 ion. Also, the capturing areas on sorbents surfaces are homogenous in terms of capturing energy. Bulut and Tez (2007), in their study of adsorption with hazelnut shell and Pb+2, stated that the sorption incident at 318 K temperature complies with the
Langmuir isotherm model. Sorption process of 700 °C pyrolyzed sorbents is compliable with Freundlich model. The compliance of the adsorption incident with Freundlich isotherm model is the indicator that there is multilayered capture at the surface of sorbent and their capturing areas are distributed heterogeneously on sorbents’ surface.

Adsorbent’s Pb+2 adsorption mechanism
To determine the surface characterization and adsorption mechanism, FTIR spectrums are used in the study. For this particular purpose, by getting the before and after spectrums of sorbent’s hazelnut shell, the changes in chemical bonds were investigated. The spectrums are shown in Figs. 4 and 5.
Tangjuank et al. (2009), made cadmium adsorptions by the activated carbons obtained from cashew. They stated that they observed (O–H) bonds belong to hydrogen protons adsorbed to oxygen in 3,200–3,600 cm−1 of raw hazelnut shell. In our
FTIR spectrum obtained from raw hazelnut shell, there is also a bond in this area. This bond belongs to O–H alcoholic groups adsorbed to alcoholic groups and cellulosic in a hazelnut shell. They stated there are bonds in between 2,800 and
2,900 cm−1 for the methyl and methylene on C–H vibrations.
We may express the bonds in these methyl and methylene groups as C–H strains. Tangjuank et al. (2009) interpreted these bonds at 1,630 cm−1 as bonds belonging to C=C vibrations. The bonds that we observed at this point are the ones belonging to C=C vibrations and C–O strains. Bonds about
1,100 cm−1 are the C–O bonds that belong to alcohol and ether. When we investigate the FTIR spectrum taken after adsorption in 3,200–3,600, 1,600, and 1,100 cm−1 areas, we may see a decrease in these bonds. This shows that the lead

Environ Sci Pollut Res

adsorbed to the construct via electrons not compliable with oxygen and therefore O–H and C–O bonds seen in this territory got weak and lost their permeability. Also the hazelnut shell’s BET surface area is measured as 5.92 m2/g. This number is so low. So it may be said that in the hazelnut shell’s capture of Pb+2 ions; chemisorption are dominant.
When investigating the IR spectrum obtained in pyrolysis at 250 °C, it is seen that the hazelnut shell is not carbonized enough (Fig. 6). Because there are still bonds belonging to O–
H vibrations seen between 2,800 and 3,200 cm−1. Also, there is an IR spectrum seen on the C–O bonds that belong to strains about 1,600 cm−1, and they are all already seen in 1,100 cm−1 alcohol and ester groups. When investigating the spectrum obtained after adsorption, there is a decrease in permeability in between 3,000 and 3,300 cm−1. The O–H groups on hazelnut shell are lignocellulose materials responsible for adsorption.
Because of the metal ion on the negative sides on O (oxygen)
O–H bonds gets weakened and therefore, there will be a decrease in the permeability in this area. Obtained sorbent’s
BET surface area is determined as 270.2 m2/g. Demirbas et al.
(2009) performed a study about obtaining activated carbon from hazelnut shells and hazelnut shells carbonized by airdried method. The obtained product BET surface area were determined 441 m2/g. The reason for the difference may be caused from carbonization method.
As seen in Fig. 7, after the pyrolysis at 700 °C IR spectra, all the observation seen on functional groups are gone. And this may mean that carbonization achieves exactly in pyrolysis. There is no significant change in the IR spectrum taken after adsorption. The decrease in permeability near
2,100 cm−1 exists with the interaction by C≡C bonds metal ion. Boonamnuayvitayaa et al. (2004) established that these bonds belong to C≡C groups, in IR bonds they obtained from coffee leftover. Sorbent’s BET surface area is established as
686.7 m2/g.
The before and after the adsorption IR spectrum of the sorbent’s pyrolysis at 700 °C is quite similar to the spectrum of hazelnut shell pyrolysis at 700 °C (Figs. 8 and 9). After the pyrolysis at 700 °C, raw hazelnut shell and all the functional groups seen on sorbents which are pyrolysis at 250 °C are lost.
Hazelnut shells are composed of 30 % hemicellulose, 27 % cellulose, and 43 % lignin (Demirbas 2002). Hemicellulose is composed of amorphous chains of monosaccharides, whereas cellulose is composed of linear chains of glucose, which tend to form intermolecular hydrogen bonds and make the structure crystalline, and linens are polymers of aromatic compounds.
Researchers have defined the decomposition temperature ranges for each of these components by studying the pyrolysis products of lignocellulosic biomass and agreed on the decomposition regions of lignocellulosic biomass as follows: 200–
320 °C for hemicellulose, 200–400 °C for cellulose, and the entire pyrolysis range for lignin (Seo et al. 2010). In the view of these findings, pyrolysis of lignocellulosic biomass at

temperatures above 600 °C will probably result in the collapse of the structure due to the complete decomposition of lignin, which provides a backbone for biomass-derived carbonaceous products, and the required open network will not be attained.
Considering our FTIR spectrums, there is a collapse in the lignocellulosic backbone. Because of that, it may be said that the physical adsorption is dominant here. The sorbent’s BET surface area which is obtained with this method is calculated as 736.49 m2/g.

As a result of these studies, hazelnut shell’s surface area is increased from 5.92 to 736.49 m2/g by thermal and chemical treatments. Because the sorbent’s surface area increased, there is more chance to capture Pb+2 ion. When looking at the FTIR spectrums in adsorption mechanism, the captures of Pb+2 chemical adsorption in raw and sorbents pyrolyzed at
250 °C is active, and it is seen that in an adsorption incident with sorbents pyrolyzed at 700 °C, physical sorption is active.
When looking at the kinetically and isothermal data, it is seen that when pyrolysis temperature is increased, the adsorption incident is shifting from chemical adsorption to physical adsorption. Acknowledgments This project was funded by Süleyman Demirel
University Scientific Research Project Foundation Fund (project no:
2148-D-10). The financial assistance from the Research Project Foundation Fund on “Determination of lead(II) sorption capacity of hazelnut shell and activated carbon obtained from hazelnut shell with different methods” is thankfully acknowledged by the authors.

Acharya J, Sahu JN, Mohanty CR, Meikap BC (2009) Removal of lead(II) from wastewater by activated carbon developed from
Tamarind wood by zinc chloride activation. Chem Eng J 149:249–
Al-Othman ZA, Ali R, Naushad M (2012) Hexavalent chromium removal from aqueous medium by activated carbon prepared from peanut shell: adsorption kinetics, equilibrium and thermodynamic studies.
Chem Eng J 184:238–247
Al-Qodah Z (2006) Biosorption of heavy metal ions from aqueous solutions by activated sludge. Desalination 196:164–176
Boonamnuayvitayaa V, Sae-ungb S, Tanthapanichakoon W (2004)
Preparation of activated carbons from coffee residue for the adsorption of formaldehyde. Separation and Purification Technology 42: 2:
15: 159-168
Bulut Y, Tez Z (2007) Adsorption studies on ground shells of hazelnut and almond. J Hazard Mater 149:35–41
Choma J, Jaroniec M, Piotrowska J (1987) On the mesopore correction of adsorption data used for characterizing microporous structure of activated carbons. Mater Chem Phys 18(4):409–421
Demirbas A (2002) Fuel characteristics of olive husk and walnut, hazelnut, sunflower, and almond shells. Energy Sources 24:215–221

Environ Sci Pollut Res
Demirbas E, Dizge N, Sulak MT, Kobya M (2009) Adsorption kinetics and equilibrium of copper from aqueous solutions using hazelnut shell activated carbon. Chem Eng J 148:480–487
Dikman E (1985) Enstrümental Analiz. Çağlayan Kitapevi, İstanbul
Foo KY, Hameed BH (2012) Preparation, characterization and evaluation of adsorptive properties of orange peel based activated carbon via microwave induced K2CO3 activation. Bioresour Technol 104:679–
Forster CF, Wase DAJ (1997) Biosorbents for metal ions, biosorption of heavy metals: an introduction. CRC Press, London
Ho YS, McKay G (1999) Pseudo second-order model for sorption processes. Process Biochem 34:451–465
Imamoglu M, Tekir O (2008) Removal of copper (II) and lead (II) ions from aqueous solutions by adsorption on activated carbon from a new precursor hazelnut husks. Desalination 2(28):108–113
Jaroniec M, Choma J (1986) Characterization of heterogeneity of activated carbons by utilizing the benzene adsorption data. Mater Chem
Phys 15:521–536
Küçükgül EY (2004) Production of the commercial activated carbon and determination of the properties. DEÜ Mühendislik Fakültesi Fen ve
Mühendislik Dergisi 6(3):41–56
Mahapatra K, Ramteke DS, Paliwal LJ (2012) Production of activated carbon from sludge of food processing industry under controlled pyrolysis and its application for methylene blue removal. J Anal
Appl Pyrolysis 95:79–86
Morgan I, Fink CE (1997) Activated carbon production. Ind Eng Chem
Res 2:219

Nomanbhay SM, Palanisamy K (2005) Removal of heavy metal from industrial wastewater using chitosan-coated oil palm shell charcoal.
Electron J Biotechnol 8:43–53
Özcan A, Tunalı S, Akar T, Özcan A (2009) Biosorption of lead(II) ions onto waste biomass of Phaseolus vulgaris L.: estimation of the equilibrium, kinetic and thermodynamic parameters. Desalination
Öztürk N (2006) Kafes yapılı sistemlerde çeşitli organik sıvıların kırmızıaltı spektroskopisi ile incelenmesi. Dissertation, Universty of Süleyman Demirel
Pehlivan E, Çetin S, Yanık BH (2009) Equilibrium studies for the sorption of zinc and copper from aqueous solutions using sugar beet pulp and fly ash. J Hazard Mater 135(1–3):193–199
Seo DK, Park SS, Hwang J, Yu TU (2010) Study of the pyrolysis of biomass using thermo-gravimetric analysis (TGA) and concentration measurements of the evolved species. J Anal Appl Pyrolysis
Stoeckli HF, Kraehenbuehl F (1984) The external surface of microporous carbons, derived from adsorption and immersion studies. Carbon
Tangjuank S, Insuk N, Tontrakoon J, Udeye V (2009) Adsorption of lead(II) and cadmium(II) ions from aqueous solutions by adsorption on activated carbon prepared from cashew nut shells. World
Academy of Science. Eng Technol 52:1–7
Tchobannoglous G, Burton F L, Stensel H D (2002) Wastewater engineering: treatment and reuse. McGraw-Hill Science/Engineering/
Math; 4th edt., USA…...

Similar Documents

Premium Essay

Internet vs Tv Advertising

..."DIFFERENCE BETWEEN INTERNET ADVERTISEMENT AND TV ADVERTISEMENT IN BUILDING STRONG BRANDS" WHAT IS A BRAND? According to Rita Clifton, CEO of Interbrand Newell and Sorrell - a leading specialist brand consultancy firm - a brand is: "A mixture of tangible and intangible attributes, symbolized in a trademark, which, if properly managed, creates influence and generates value" This definition truly captures the essence of a brand, and highlights the importance of brand management. Branding is about creating 'value', both for customers, and for the company. This value stems from the products and services that companies create and bring to the market, but extends further to encompass added values derived from factors such as the brand-customer relationship, the brand's emotional benefits and its self-expressive benefits. Other common descriptions of a brand include - a 'relationship', a 'reputation', a 'set of expectations', and a 'promise'. It is a company's promise to consistently deliver a specific set of features, benefits, and services to customers. Brands are richly endowed entities. They start life as ideas, making their way into planning and strategy documents, yet ultimately reside as consumer perceptions. For some companies, brands are their most valuable asset. The space a brand occupies inside a customer's head can create a 'mental' patent, which grows out of the cumulative memory and the experiences customers have of products or services. As...

Words: 2427 - Pages: 10

Free Essay

Will Tv Succumb to the Internet

...| Case Study 1 | Will TV Succumb to the Internet? | | | 1/27/2013 | CISK 511 | Case Study: Will TV Succumb to the Internet? Problem: Cable/Satellite Provides have adopted a business model of expanding select programing services online while remain competitive with an increasingly digitized world. The very technology they have embraced poses a threat to the future of mainstream TV as more and more household have cut the cord and terminated standard TV service in favor of Internet programing. Challenge: Recommend the best course of action to take for cable/satellite providers to expand their online product offerings without cannibalizing revenues from traditional TV programming Facts: * High-speed internet connections, powerful computers, and portable software devices have become widespread in use and ease of access. It’s changed the way people obtain songs, videos, TV shows and books. File sharing and DVR service have increased the ease which TV shows and music can be uploaded to the internet and shared with others for free. Although these TV shows and music files are illegal to share, current laws against those who supply and download these digital files have near zero effect on users because the laws are hardly enforced. * YouTube, which was started in 2005, is the most popular video-sharing website in the world. Over 150,000, unauthorized video clips of copyrighted television programs appeared on YouTube. *, a website......

Words: 2017 - Pages: 9

Free Essay

Direct Tv

...retroceder en 4 velocidades. Los suscriptores de Directv también pueden grabar sus programas favoritos desde la internet solo suscribiéndose a Mi Directv. Otra ventaja que tienen es la variedad de programación. Sistemas Esta área está encargada de dar soporte técnico al área de facturación y recaudación de la compañía principalmente. IMAGINAR EL FUTURO Directv Perú fácilmente también en tu PC portátil y celular. Directv Movil + Internet wimax Directv Movil + IPAD El servicio se dará con un modem antena USB con un software integrado que decodificara los canales de paga como HBO, Laptv, Discovery Channel, Espn , etc que vendría incluido en el paquete de internet y puedes verlo en el celular o en las computadoras. Se podría vender separado. Este modem mantendría la ventaja de grabaciones atraves de memorias expandibles. Directv Clásico Directv Pre pago Análisis del entorno Coopetitivo Clientes Debido a los cambios tecnológicos que se están desarrollando, los clientes van adoptando nuevas tecnologías de manera que su actitud y deseo satisfagan sus nuevas necesidades. Lo importante para nosotros es desarrollar alta capacidad de respuesta ante estas exigencias. Queremos lograr que esta nueva experiencia televisiva se disfrute en todo el Perú a menor precio, diversificando la forma de brindar el servicio apoyándonos también en internet. Hemos identificado que el mercado de televisión y el mercado de computadoras se han incrementado......

Words: 3034 - Pages: 13

Premium Essay

The Tv

...The TV Those endless days, the same routines, the same people, the same complications at work, nothing new is meeting you. Life has become a routine, and suddenly you see no point with it. You stay home one day, watching some television, and discover that life is just in front of you. You see the same person over and over again in different TV-shows, and realise it could be you. Maybe life isn’t so bad and routine marked after all. The story The TV is written by Ben Loory and published in the newspaper The New Yorker in April 2010. The story is about a man that stays home from work one day, because he is sick, and like most of us would do when we are sick, he lays on the couch all day and watches television. When suddenly he finds a show he wants to watch, and he wonders. The main character seems so familiar, and the show is so long. Afterwards he takes a shower, and realises, the show was about him, he was the main character. The story starts in medias res, which is a common characteristic for short stories. An omniscient third-person narrator tells the story. “In the morning, the man awakens confused… He feels as if he were forgetting something..” P. 2, l 47, the narrator knows how our main character thinks and feels, which works really well because, the main character has so many different thoughts and feelings about seeing him self in the television, so it makes it easier to understand the story. The name on our main character is not stated, and somehow it......

Words: 1021 - Pages: 5

Free Essay

The Tv

...The TV By Ben Loory “The TV” is a short story written by Ben Loory, and his story was published in the April 12, 2010. First I will look at the course of events in this story. The story “The TV” is about a man, who stays home one day suddenly from his work. On this day he discovers that there is a special TV channel about himself or his life - but it could be his other self he had. After that the man becomes very engrossed with the TV show. In time he saw reflections of himself of the man's world in the TV show. At one point, he discovers that he chews on his lips on TV, so he starts trying to stop chewing her lips in his really life - not in the TV show, causing his other self to stop chewing his lips. And yet, his other self is different, better. He reads intellectual books, asks his boss for a raise, hosts corporate meetings and his “real self” begins to feel jealous. The author also used religious words in this story, such as the word "God," when he says: "My God.” This could symbolizes that he thinks that he is his God, because he is different, but there are still some who are like him, but maybe he has not felt. If we are looking at the author, he use third-person narrator, because he called the man for “the man.” Authors of novels and composers of papers use “he,” “she,” or “it” when referring to a person, place, thing, or idea. The reader gets not a name for the man in the story, but only one fact of the man, and it is that he has the name “the man”. The......

Words: 574 - Pages: 3

Free Essay

Will Tv Suvvumb to the Internet?

...Case # 2 Will TV Succumb to The Internet Introduction: The case study of “Will TV Succumb to the Internet” explains how the Internet has transformed how viewers watch television programs and other videos. There are now several online outlets in which viewers can watch whatever TV show/movie they desire. YouTube was one of the first online outlets by allowing users to provide video clips, and even entire TV shows, for anybody to watch. However, this was considered copyright infringement, and a 2008 lawsuit made it much more difficult to put clips on YouTube without proper authorization. Web sites offering streaming video of TV shows have since revolutionized the way in which viewers watch TV shows and movies. High-powered companies such as Hulu and Netflix have caused a number of U.S. households to get rid of their cable, satellite, or high-speed television services altogether. The number of U.S. households to follow this trend is predicted to double in the upcoming years. However, these companies providing online video-streaming have experienced growing pains regarding revenue. They have had to charge users a higher fee for their services because the main source of revenue, advertising, is not generating enough money to satisfy all of the content suppliers. Regarding advertising, there have also been complaints about the number of ads shown while viewing online TV shows. This could cause these unhappy customers to rebel and go back to subscribing to their basic cable......

Words: 1103 - Pages: 5

Premium Essay

Will Tv Succumb to the Internet? Case Study

...ways P&G could use collaboration to foster innovation? Will TV Succumb to the Internet? CASE STUDY Will TV Succumb to the Internet? CASE STUDY T T he Internet has transformed the music industry. Sales of CDs in retail music stores have been steadily declining while sales of songs downloaded through the Internet to iPods and other portable music players are skyrocket- ing. Moreover, the music industry is still contending with millions of people illegally downloading songs for free. Will the television industry experience a similar fate? Widespread use of high-speed Internet access, powerful PCs with high-resolution display screens, iPhones, iPads, other mobile handhelds, and leading- edge file-sharing services have made downloading of video content from movies and television shows faster and easier than ever. Free and often illegal downloads of some TV shows are abundant. But the Internet is also providing new ways for television studios to distribute and sell their content, and they are trying to take advantage of that opportunity. YouTube, which started up in February 2005, quickly became the most popular video-sharing Web site in the world. Even though YouTube’s original mis- sion was to provide an outlet for amateur filmmakers, clips of copyrighted Hollywood movies and television shows soon proliferated on the YouTube Web site. It is difficult to gauge how much proprietary content from TV shows winds up on YouTube without the studios’ permission. Viacom......

Words: 5332 - Pages: 22

Free Essay

Android Internet Tv

...ĐẠI HỌC QUỐC GIA THÀNH PHỐ HỒ CHÍ MINH TRƯỜNG ĐẠI HỌC KHOA HỌC TỰ NHIÊN KHOA ĐIỆN TỬ - VIỄN THÔNG SVTH: NGUYỄN HỒNG THẮNG MSSV: 0820156 INTERNET TV TRÊN NỀN TẢNG ANDROID KHÓA LUẬN TỐT NGHIỆP CỬ NHÂN NGÀNH ĐIỆN TỬ - VIỄN THÔNG CHUYÊN NGÀNH: MÁY TÍNH VÀ HỆ THỐNG NHÚNG NGƯỜI HƯỚNG DẪN KHOA HỌC TS. HUỲNH HỮU THUẬN CN. TRẦN HOÀNG ĐẠT THÀNH PHỐ HỒ CHÍ MINH, NĂM 2012 NHẬN XÉT CỦA GIÁO VIÊN HƯỚNG DẪN .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .......................................................................

Words: 15886 - Pages: 64

Premium Essay

Will Tv Succumb to the Internet?

...Is there a difference between training and learning? Two definitions - training and learning I define 'training': Training is the conscious and planned process of transferring knowledge, skills and attitudes to others. The concept of transfer here is critical, as is the element of planning. I define 'learning': Learning is the processing and assimilation of what we hear, see or experience that alters or improves our knowledge, skills and attitudes. The combination of knowledge, skills and attitudes is behaviour. If someone trains us, or we learn something new or different, it is our behaviour that is affected. If our behaviour is changed, we have learnt something. Training is active - it is conscious and planned - it does not just happen. What is the best way to learn? Should someone train us or should we go off and try to learn something new by ourselves? In recent years, self-directed learning has gained increased attention. Some people felt that it was better for some people to 'discover' something rather than be taught. I believe both learning and training are important. In this informal learning article*, I explained that about 70% of learning was informal. Informal learning is very helpful. I probably have a bias, but I believe organisations should have a planned approach to the development of their people. If training needs are identified, they should be addressed in a timely manner. A well planned training event can do this, particularly if the trainer can identify......

Words: 471 - Pages: 2

Premium Essay

Will Tv Succumb to Th

...Study: Will TV Succumb to the Internet? Akankah TV mengalah ke Internet? Internet telah mengubah musik industri. Penjualan CD di toko musik retail terus menurun sedangkan penjualan lagu yang diunduh melalui internet untuk iPod dan pemutar musik portabel lainnya meroket tinggi. Selain itu, industri musik masih bersaing dengan jutaan orang secara ilegal mengunduh lagu gratis. Akankah industri televisi mengalami nasib yang serupa? Internet sebagai media komunikasi Internet sebagai media komunikasi, merupakan fungsi internet yang paling banyak digunakan dimana setiap pengguna internet dapat berkomunikasi dengan pengguna lainnya di seluruh dunia. Kemudahan memperoleh informasi yang ada di internet dapat membuat orang-orang tahu apa saja yang terjadi. Biasanya kita harus duduk di depan televisi untuk menonton pemrograman. Namun waktu telah berubah, dan kita memiliki beberapa pilihan untuk menonton televisi, diantaranya televisi kabel dan televisi streaming. TV online atau TV internet Pada dasarnya TV online ini adalah dimana semua acara TV dapat Anda lihat secara online dengan menggunakan jaringan internet. Dengan demikian maka Anda tidak membutuhkan perangkat listrik ataupun pesawat televisi biasa untuk dapat menonton tayangan pada tv online. Untuk dapat menyaksikan TV Online yang dibutuhkan adalah PC ataupun laptop. Penggunaannya: televisi online akan mudah diakses dengan koneksi Internet yang berkecepatan tinggi. Semakin besar kecepatan koneksi Internet, maka......

Words: 1598 - Pages: 7

Premium Essay

Case Study Will Tv Succumb to Internet Q1-3

...whereby TV shows and movies can be watched without any charges by Internet users. In terms of customers forces, problem that has merged towards the television industry is that customers find it easier and more convenient for them to watch their favourite shows online. Rather than having to follow the television programme schedule, customers can easily watch any shows via the Internet at anytime they wish. Another problem would be the loss of revenue of the television industry as people might cut their TV cable and turn to watching online because it is indeed lower to them in the sense of money. Obviously, most people do not want to pay an extra sum of money for TV programmes that they can watch for free. 2. Describe the impact of disruptive technology on the companies discuss in this case. In the case study, the two companies that were affected by the advancement of technology is the music company and the cable company. The music company face declining number of CD sales since the introduction of the Internet. This is because a lot of music can be downloaded for free from the internet. Not only that, another problem faced by the music company is regarding the copyright issue. Most videos or music posted in the web page such as Youtube and Facebook are unauthorized clips, making it a big problem to the music industry. The cable companies face a similar problem with the music company. Most of the cable subscribers have moved on to the internet to watch their favourite......

Words: 499 - Pages: 2

Free Essay

The Internet

...THE INTERNET  The internet is the largest computer network in the world, connecting millions of computers.  A network is a group of two or more computer systems linked together. Types of Computer Networks  Local Area Network (LAN) - two or more connected computers sharing certain resources in a relatively small geographic location.  Wide Area Network (WAN) -two or more LANs. The computers are farther apart and are linked by telephone lines or radio waves. -The internet is the largest Wide Area Network (WAN) in existence. Servers and Clients  Server -a computer that "serves" many different computers in a network by running specialized software and storing information.  Client -communicates with the server to get the information it requires. Peer-to-Peer (P2P) Network  each computer acts as both a server and a client. The World Wide Web (WWW)  The internet is the physical network of computers all over the world.  The World Wide Web is a virtual network of web sites connected by hyperlinks (or "links"). Web sites are stored on servers on the internet, so the World Wide Web is a part of the internet. HTML  The backbone of the World Wide Web is made of HTML files, which are specially-formatted documents that can contain links, as well as images and other media. URL  To get to a web page, you can type the URL (Uniform Resource Locator) in a browser.  The URL, also known as the web address, tells the browser exactly where to find the......

Words: 3555 - Pages: 15

Premium Essay

Tv Obesity

...Couch-Potato Conundrum: TV leads to obesity In contemporary society, the most consumed medium in almost every household across the world is television. People spend a considerable amount of time watching television. Some studies indicate that in an average 65-year lifespan, an individual spends 9 years watching television (Jenvey 811). It is then not surprising to realize that the average person spends 22 hours each week watching television (Jenvey 811). An average American household has 2.24 TVs with an estimated 6 million videos rented daily (Jensen 811). The consequences of spending such a considerable amount of time watching television are weight gain and obesity. The global obesity pandemic costs the world billions in medical expenses to counteract the medical conditions and diseases resultant from obesity and having a high body mass index (BMI). These diseases include diabetes, cardiovascular complications and conditions, high blood pressure, high cholesterol levels, back pain, some cancers and even infertility. Coupled with the psychological burden of being obese, there is clearly a need to mitigate obesity (Jenvey 810). One means of reducing the prevalence of obesity is by regulating the amount of time spent watching TV in every household. Spending high amounts of time watching television encourages the onset of obesity in viewers because it encourages unhealthy dietary habits, sedentary behavior and leads to slow metabolic rates. When watching TV programs and......

Words: 1350 - Pages: 6

Free Essay

The Tv

...The Impact of personal finance and behavior on television The impact of our personal finance has been affected by our society, culture, economy, moral and ethics behavior all our life’s with the use of the television. Television has a very important part of our lives as humans. It how we get our latest new, deals, entertainment even communication. But how does the television impact our personal finance? Without the television there would not be any TV ads and what do TV ads do try and get customer to buy new products. Industries spend millions, even billions of dollars to win our hearts and minds, and to influence our choices towards their products and ideas. According to the A.C. Nielsen Co., the average American watches more than 4 hours of TV each day (or 28 hours/week, or 2 months of nonstop TV-watching per year). In a 65-year life, that person will have spent 9 years glued to the tube. The number of TV commercials seen by the by age 65 is 2 million. (Norman Herp) But why are commercial ads use and are important? One reason they give us as costumer’s information we may not know on product we want to buy. Like when Toyota is having a new car deal or when Macys is having a one day sale. How the new IPhone is 5g and the day it comes out. All the television commercials give us information on item we think we may need or have an interest in. But the way some of the television ads are advertised can have a negative way of influencing our decision making. The media......

Words: 1011 - Pages: 5

Premium Essay


...THE ADVANTAGES AND DISADVANTAGES OF INTERNET There are many technological innovations that have led to this world being called a world of machines. The most jaw dropping innovation is internet. Even though in our everyday busy life we may not take a second and be thankful for this creative innovation but we would not deny that is has changed our life immensely. Internet links computer to computer and like this was not enough, it has spread like cancer cells in every new technology available e.g. – mobiles, laptops, TV etc. We are surrounded by technology every second of the day. The most important question as of now we can ask ourselves is weather the benefits of internet outweigh the disadvantages or has the nightmare just begun. To a great degree, of course, internet has made our lives a lot laid-back and stress free. A businessman can check his bank balance at a mere flick of the button whilst his wife can cook delicious food by taking the recipe sitting in the front of the computer screen. Their teenage daughter can buy expensive clothes through internet and their son can contact his friends all round the world over the internet. Nobody requires move. More seriously, however, internet has resulted in massive progress in majority fields of the life from medicine to business, from art to education. It serves as a package for everyone regardless of their age and class. Internet has become a necessity. Moreover, the slog of work has been occupied over by laptops, leaving...

Words: 532 - Pages: 3