The D-R model is distinctive in a way that this is temperature
dependant phenomenon (Dada
From figure 9, the values of D–
evaluated to be 7.0x10-7
mol
2.0x10-7
mol2
k-1
J-2
at 298K, 313K and 323K respectively with
the R2
values of 0.9931, 0.9993 and 0.9922 respectively.
The values of theoretical isotherm saturation capacity ‘Q
were evaluated to be 3.542g.g
at 298K, 313K and 323K respectivel
Thermodynamic Studies
The thermodynamic parameters such as standard Entropy
change ∆So
(J.mol−1
K−1
),standard Enthalpy change
∆Ho
(kJ.mol-1
) and standard Gibbs Free Energy Change
∆Go
(kJ.mol-1
) were calculated by using following equations
(Zhonghui et al. 2014).
∆ = −
=
.
−
.
From the Van’t Hoff graph of Log K
the standard entropy change ∆S
change were determined.
International Journal of Current Research, Vol. 7, Issue, 12, pp.23542-23550, December, 201
versus Qe at 25o
C, 40o
C and 50o
C
……………………. (8)
……………………… (9)
represents the equilibrium adsorbate amount
represents theoretical saturation capacity of the
represents the D–R isotherm constant
) and ε is the Dubinin–Radushkevich isotherm
R model is distinctive in a way that this is temperature
dependant phenomenon (Dada et al. 2012).
–R isotherm constant ‘Kad’ were
mol2
k-1
J-2
, 3.0x10-7
mol2
k-1
J-2
and
at 298K, 313K and 323K respectively with
values of 0.9931, 0.9993 and 0.9922 respectively.
The values of theoretical isotherm saturation capacity ‘Qs’
were evaluated to be 3.542g.g-1
, 25.68mg.g-1
and 21.73mg.g-1
at 298K, 313K and 323K respectively.
The thermodynamic parameters such as standard Entropy
),standard Enthalpy change
) and standard Gibbs Free Energy Change
) were calculated by using following equations
…………………. (11)
…………………. (12)
From the Van’t Hoff graph of Log Kd versus T-1
, the values of
∆So
and standard enthalpy ∆Ho
2015](https://image.slidesharecdn.com/820a1938-8e0b-420d-9389-2f4b175f5a52-151230192142/85/Muhammad-Saad-Published-Paper-5-320.jpg)
Muhammad Saad Published Paper
- 1. SYNTHESIS AND CHARACTERIZATION OF S APPROACH AND THEIR EFFICACY FOR THE TREATMENT OF DYES ASSISTED SIMULATED Muhammad Saad, Department of Chemistry, University of Karachi, Pakistan ARTICLE INFO ABSTRACT The current studies emphasises the synthesis of SnO adopting sol gel method. These treatment of tartrazine (TR) dye assisted simulated waste water under the influence of variable conditions to achieve best adsorption capacity. The effect of adsorbent amount, adsorbate concentration, stay time and pH Freundlich, Dubinin Radushkevich and Temkin were also employed to check the feasibility of the adsorption process. Adsorption capacities ‘K 323K respectively. found to be 3113.32 J. mole process was affirmed by equations to determine rate constant and order of the reaction like pseudo first order and pseudo second order, intraparticles diffusion model, Boyd’s kinetics model and Elovich model. The adsorption data rep mode to be diffusion. techniques. the challenges posed by them in the environment and public health. Copyright ©2015Muhammad Saad et al. This is an open access article distributed under the Creative Commons Att use, distribution, and reproduction in any medium, provided the original work is properly cited. INTRODUCTION In recent era, the requirement of new materials applications are critical. Nanomaterials (NM) are one of the successful choices for such applications. They consist of dimensions of the order of nanometer (10-9 m). Their catalytic, optical, electronic and other physical properties are being use in many applications. In twenty first century, the technology advances in days. Due to increasing wealth and covetousness of human being the requirement of new materials and their applications are essential. The scientific community tries to develop new material with innovative applications (Irena 2006). Their catalytic, optical, electronic and other physical properties make them one of the most attractive research topics now a day. The physical properties of nano materials are strongly dependent on their size therefore the morphology describes their physical properties. *Corresponding author: Dr. Hajira Tahir, Department of Chemistry, University of Karachi, Pakistan. ISSN: 0975-833X Available online at http://www.journal Vol. Article History: Received 25th September, 2015 Received in revised form 07th October, 2015 Accepted 09th November, 2015 Published online 21st December, 2015 Key words: Nanocomposites; Tartrazine dye, Adsorption isotherms, Thermodynamics, Kinetic model. Citation: Muhammad Saad, Dr. Hajira Tahir and Fakhra Shaheen bottom up approach and their efficacy for the treatment of dyes assisted simulated waste wate 7, (12), 23542-23550. RESEARCH ARTICLE SYNTHESIS AND CHARACTERIZATION OF SnO-CoO NANOCOMPOSITES BY BOTTOM UP APPROACH AND THEIR EFFICACY FOR THE TREATMENT OF DYES ASSISTED SIMULATED WASTE WATER Muhammad Saad, *Dr. Hajira Tahir and Fakhra Shaheen Department of Chemistry, University of Karachi, Pakistan ABSTRACT The current studies emphasises the synthesis of SnO-CoO nanocomposites by bottom up approach adopting sol gel method. These nano particles were effectively employed as nano adsorbent for the treatment of tartrazine (TR) dye assisted simulated waste water under the influence of variable conditions to achieve best adsorption capacity. The effect of adsorbent amount, adsorbate centration, stay time and pHpzc were studied. Adsorption isotherm models of Langmuir, Freundlich, Dubinin Radushkevich and Temkin were also employed to check the feasibility of the adsorption process. Adsorption capacities ‘KF’ of the adsorbent were determ 323K respectively. Thermodynamic studies were conducted and the values of found to be 3113.32 J. mole-1 and 56.712 J.mole-1 K-1 respectively. The spontaneity of adsorption process was affirmed by ∆Go values. The experimental data was also fitted to various kinetic equations to determine rate constant and order of the reaction like pseudo first order and pseudo second order, intraparticles diffusion model, Boyd’s kinetics model and Elovich model. The adsorption data represent pseudo second order kinetics is followed with the major mode mass transfer mode to be diffusion. The surface morphology of nanocomposites was stud techniques. Such recycling methods effectively implemented at industrial scale and the challenges posed by them in the environment and public health. is an open access article distributed under the Creative Commons Attribution License, which use, distribution, and reproduction in any medium, provided the original work is properly cited. In recent era, the requirement of new materials and their applications are critical. Nanomaterials (NM) are one of the successful choices for such applications. They consist of m). Their catalytic, optical, electronic and other physical properties are being used in many applications. In twenty first century, the technology advances in days. Due to increasing wealth and covetousness of human being the requirement of new materials and their applications are essential. The scientific community tries to material with innovative applications (Irena et al., 2006). Their catalytic, optical, electronic and other physical properties make them one of the most attractive research topics now a day. The physical properties of nano materials are on their size therefore the morphology Department of Chemistry, University of Karachi, Pakistan. Altering the synthesis method, reagents, capping agent and the pH govern the morphology of the nanoparticles (Baolin 2004). Metal nanoparticles are also photostable and do not undergo photo bleaching. This property allows them to be utilized as ideal colour groups for colorimetric sensor design (Yingju et al., 2009). Nanomaterials have much improved physical properties than their parent macro substances therefore they are now being employed in sensors which have much improved sensitivity than their example nanoparticles modified electrodes have been used for sensitive and selective determination of 17β et al., 2011), hydroquinone (Bin et al., 2005, Abdollah et al., 2007), hypox 2005), thiocyanate (Guang-Feng cresyl blue (Mao-Guo et al., 2005). oxide and Cobalt oxide nanocomposites were synthesized by bottomup approach by sol-gel method in which a specific concentration of precursor was reduced by NaOH in solution form to prepare particles of metals. The metals particl then mixed and separated from the solution. The obtained Available online at http://www.journalcra.com International Journal of Current Research Vol. 7, Issue, 12, pp.23542-23550, December, 2015 INTERNATIONAL OF CURRENT RESEARCH Dr. Hajira Tahir and Fakhra Shaheen, 2015. “Synthesis and characterization their efficacy for the treatment of dyes assisted simulated waste water”, International Journal of Current Research z O NANOCOMPOSITES BY BOTTOM UP APPROACH AND THEIR EFFICACY FOR THE TREATMENT OF DYES ASSISTED SIMULATED Fakhra Shaheen Department of Chemistry, University of Karachi, Pakistan CoO nanocomposites by bottom up approach nano particles were effectively employed as nano adsorbent for the treatment of tartrazine (TR) dye assisted simulated waste water under the influence of variable conditions to achieve best adsorption capacity. The effect of adsorbent amount, adsorbate were studied. Adsorption isotherm models of Langmuir, Freundlich, Dubinin Radushkevich and Temkin were also employed to check the feasibility of the ’ of the adsorbent were determined at 298K, 313K and Thermodynamic studies were conducted and the values of ∆Ho and ∆So were respectively. The spontaneity of adsorption imental data was also fitted to various kinetic equations to determine rate constant and order of the reaction like pseudo first order and pseudo second order, intraparticles diffusion model, Boyd’s kinetics model and Elovich model. The resent pseudo second order kinetics is followed with the major mode mass transfer The surface morphology of nanocomposites was studied by SEM and FTIR Such recycling methods effectively implemented at industrial scale and therefore assess the challenges posed by them in the environment and public health. ribution License, which permits unrestricted Altering the synthesis method, reagents, capping agent and the pH govern the morphology of the nanoparticles (Baolin et al., Metal nanoparticles are also photostable and do not undergo photo bleaching. This property allows them to be al colour groups for colorimetric sensor design 2009). Nanomaterials have much improved physical properties than their parent macro substances therefore they are now being employed in sensors which have much improved sensitivity than their parent electrodes. For example nanoparticles modified electrodes have been used for sensitive and selective determination of 17β-estradiol (Lihua 2011), hydroquinone (Bin et al., 2005), H2O2 (Chunbu 2007), hypoxanthine (Xiaoli et al., Feng et al., 2004), and brilliant 2005). In the present studies, Tin oxide and Cobalt oxide nanocomposites were synthesized by gel method in which a specific concentration of precursor was reduced by NaOH in solution form to prepare particles of metals. The metals particles were then mixed and separated from the solution. The obtained INTERNATIONAL JOURNAL OF CURRENT RESEARCH characterization of SnO-CoO Nanocomposites by International Journal of Current Research,
- 2. precipitate was then kept at 120o C for 15hours in air oven. The precipitate was then kept at about 400o C for 4 hours. Then the nanocomposites were ground in a piston mortar for further homogeneity. They were utilized for the purification of effluent. Dyes are natural or synthetic compounds and they can be used to colour various materials, and have wide industrial applications .They are available in widest ranges for different applications like acids dyes for wool and nylon, direct dyes for cotton, etc. (NIIR board 2004). Due to increasing demands for textile products, dyes and its intermediates have also increased demand, therefore their emissions in effluent water is much increased in recent past. Certain kinds of dyes can be toxic, carcinogenic or mutagenic and can pose as a hazard to health. Therefore the effluent water must be efficiently treated to minimize the dye and colorants. Nanocomposites have efficiently been employed to treat toxic effluent. The super paramagnetic Poly(acrylic acid) Coated-Fe3O4, Hydrolyzed Polyacrylamide Grafted Xanthan Gum and Incorporated Nanosilica, Fe3O4-Cu2O-PANI, Magnetic Multi- Walled Carbon Nanotubes-Fe3C, graphite oxide-magnetic chitosan, CaO-Fe2O3, sodium alginate-coated Fe3O4, chitosan- MgO, Ag/Kaolin, Polyaniline zirconium (IV) silicophosphate (PANI-ZSP) nanocomposites have been effectively used for the treatment of methylene blue, methyl violet, congo red, methyl orange, acid Red, reactive Black 5, malachite green and acid Cyanine 5R dyes (Chunjiao et al., 2013; Sumita et al., 2014; Juan et al., 2014; Wojciech et al., 2014; Hamid et al., 2013; Nikolina et al., 2013; Sushanta et al., 2014; Mittal et al., 2014, yuvaraj et al., 2014; Saeedeh et al., 2013a ; Vinod et al., 2014). There are several methods reported for the preparation of nanoparticles, including attrition, pyrolysis, radiolysis and sol- gel. Sol-gel method is one of the most widely used methods to prepare nanomaterials due to facile procedure and instrumentation (Saeedeh et al., 2013a ; Saeedeh et al., 2013b ; Mirjalili et al., 2010; Ferav et al., 2013; Nirasttisai et al., 2010). The precursor in sol-gel method is a chemical solution which upon chemical reaction forms discrete particles as a result of hydrolysis and poly condensation of metal alkoxides and metal chlorides. MATERIALS AND METHODS Cobalt chloride (CoCl2.6H2O), Tin Chloride (SnCl2.2H2O), Sodium Hydroxide (NaOH), tartrazine dye (TR) were used in the experimental work. All the materials were of analytical grade and were used as received. Distilled deionized water was used throughout the experimental work. Synthesis Of SnO-CoO Nano-Composites The nanocomposites of SnO-CoO were prepared by sol-gel method. About 16.9g of tin chloride dihydrate (SnCl2.2H2O) was dissolved in 300mL deionized distilled water under constant stirring which was followed by the addition of 3.0g of NaOH pallets. Similarly, 17.8g of Cobalt chloride hexahydrate (CoCl2.6H2O) were dissolved in 300mL of deionized distilled water under stirring which was followed by the addition of 3.0g of NaOH pallets. The solutions were mixed under stirring and the obtained precipitates were kept at 120 °C for 15 hours. The slurry was cooled at room temperature and then washed with ethanol several times after that it was dried and then calcinated at 400°C. Finally SnO-CoO nanocomposites were obtained and they were stored in desiccators for the desired work (Gajendiran et al., 2014). Adsorption Experiments Adsorption experiments were proceeded by utilizing nanocomposites acting as adsorbent. To check the feasibility of adsorption process, laboratory batch mode of studies was conducted. Batch samples were agitated at 200 rpm to facilitate good contact between the dye and the adsorbent. The suspensions were filtered after agitation. The filtrate was tested to determine residual concentration of dye by (T80 UV/VIS) spectrophotometer. Parameters which influence the extent of adsorption such as adsorbate concentration, adsorbent dosage and agitation time were also investigated. Effect of Variation in Dye Concentration A series of concentration of dye about 10, 20, 30, 40 and 50ppm was prepared by standard addition method. Then optimum amount of 0.1g of nanosorbent was added into 50 mL of each specified concentration of the dye. After specific time the suspension was filtered to evaluate the dye concentration. Optimization Of Amount Of Adsorbent For the determination of amount of adsorbent at which maximum adsorption takes place, 50mL of 20ppm dye solution was taken in a series of Erlenmeyer flask in which amount of 0.1, 0.2, 0.3 and 0.4g were added. The samples were put in shaking incubator for 1hr at 200rpm. The suspensions were then filtered and the absorbances after addition of adsorbent were determined. The optimum amount of adsorbent was evaluated by the decrease in the absorbance of the dye solution. Effect of Variation in Adsorbent Stay Period A series of dye solutions with a concentration of 20ppm of dye adding 0.3g amount of adsorbent was agitated at different time intervals of 5 to 60 minutes. After filtration, the optimized stay time for the adsorbent was evaluated by taking the absorbance after suitable time intervals. The stay time for the maximum adsorption was taken as optimized stay time. pH AT ZERO POINT CHARGE (pHzpc) pHzpc is abbreviated as pH at zero point charge. pHzpc is the pH at which the surface has an overall neutral charge. Above this pH value, species have overall negative charge and below this, species have an overall positive charge. The pH at the point of zero charge of SnO-CoO nanocomposite was measured by using the pH drift method. The pH of 0.005 mol.dm-3 NaCl solutions was adjusted between 2.18 to 11.80 by adding required amount of 0.1 M HCl or NaOH. Then 0.3 g of adsorbent was added in 25 mL of solution in Erlenmeyer flask 23543 Muhammad Saad et al. Synthesis and characterization of SnO-CoO nanocomposites by bottom up approach and their efficacy for the treatment of dyes assisted simulated waste water
- 3. and left at room temperature in dark for 24 and 48 hrs. The graphs of pH drawn were used to determine the points at which the initial and final pH values were equal (Hajira Final pH of the solutions was recorded and results wer plotted. RESULTS AND DISCUSSION Characterization Of Nanocomposites The characterization of the prepared nanocomposites was done by Fourier Transformed Infrared Spectroscopy and Scanning Electron Microscopy. I-Fourier Transformed Infrared Spectroscopy The FTIR spectrum of SnO-CoO nanocomposites showed prominent absorption peaks at 669cm-1 , 1620cm 1 as shown in Figure 1. Figure 1. FTIR spectrum of SnO-CoO nanocomposites The region between 500cm-1 to 670cm-1 contain many peaks that relates to the stretching and bridging vibrations of oxygen and the hetero atoms (Manigandan et al., 2013 et al., 2013). The absorption peaks at 3374cm are mainly due to the vibration of surface OH adsorbed surface water molecules (Vijayaprasath A very small peak observed at 2372 cm-1 impurity. Scanning Electron Microscopy Scanning electron microscope (SEM) is one of the best characterization techniques for the nanoparticles analyses. The scanning electron microscopy was performed on model 6380, JEOL, Japan. The Scanning Electron Micrograph of the prepared nanocomposites is shown in Figure 2. The scanning electron micrograph indicates that the particles are quite homogenous in nature and the size ranging from 50 100nm. The prepared nanocomposites were used in the whole experimentation. 23544 International Journal of Current Research, and left at room temperature in dark for 24 and 48 hrs. The graphs of pH drawn were used to determine the points at which the initial and final pH values were equal (Hajira et al. 2014). Final pH of the solutions was recorded and results were The characterization of the prepared nanocomposites was done by Fourier Transformed Infrared Spectroscopy and Scanning Fourier Transformed Infrared Spectroscopy CoO nanocomposites showed , 1620cm-1 and 3373cm- CoO nanocomposites contain many peaks that relates to the stretching and bridging vibrations of oxygen 2013; Vijayaprasath ). The absorption peaks at 3374cm-1 and 1620 cm-1 are mainly due to the vibration of surface OH- group or adsorbed surface water molecules (Vijayaprasath et al., 2013). 1 is due to some Scanning electron microscope (SEM) is one of the best the nanoparticles analyses. The scanning electron microscopy was performed on model 6380, JEOL, Japan. The Scanning Electron Micrograph of the prepared nanocomposites is shown in Figure 2. The scanning electron micrograph indicates that the particles quite homogenous in nature and the size ranging from 50 - 100nm. The prepared nanocomposites were used in the whole Figure 2.SEM image of the nanocomposites Adsorption Experiments Variation In Dye Concentration In experiment, varying the concentration of the dye from 10 to 50ppm aided in determining the optimum concentration of the dye. Approximately 0.1g of adsorbent was added in each flask containing 20ppm of dye solution and shaken for the specified period of time. The concentration of dye was observed by spectrophotometer. Kd was also calculated with respect to concentration as shown in the Figure 3. Figure 3. Variation in dye concentration Effect Of Amount of Adsorbent The amount of nanocomposites was varied from 0.1g to 0.4g in a system containing 50mL of solution of the tartrazine dye. The optimum amount of adsorbent was evaluated as 0.3g as it shows the greatest removal tendency of the dye from the solution as shown in Figure 4. Moreover it also revealed that the distribution coefficient gets decreased by increase in the amount of the nanocomposite. International Journal of Current Research, Vol. 7, Issue, 12, pp.23542-23550, December, SEM image of the nanocomposites Variation In Dye Concentration In experiment, varying the concentration of the dye from 10 to 50ppm aided in determining the optimum concentration of the Approximately 0.1g of adsorbent was added in each flask containing 20ppm of dye solution and shaken for the specified of time. The concentration of dye was observed by was also calculated with respect to concentration as shown in the Figure 3. Variation in dye concentration Effect Of Amount of Adsorbent The amount of nanocomposites was varied from 0.1g to 0.4g in a system containing 50mL of solution of the tartrazine dye. The optimum amount of adsorbent was evaluated as 0.3g as it shows the greatest removal tendency of the dye from the in Figure 4. Moreover it also revealed that the distribution coefficient gets decreased by increase in the , 2015
- 4. Figure 4. Effect of amount of adsorbent on dye removal and K Variation Of Adsorbent Stay Period The optimum stay period was evaluated by shaking flasks containing the optimum concentration and optimum amount of nanocomposite for variable intervals of time from 5 to 60 minutes. The optimum stay time for the removal of dye was determined to be 60 minutes. Moreover it is evident from Figure 5 that the distribution coefficient is directly proportional to shaking time period. Figure 5. Variation in shaking period Isotherms Studies Isotherms are algebraic functions that express relationship between the adsorbed materials with adsorbent (Kumar 2013). Studies were made on Freundlich isotherm, Temkin isotherm, Langmuir isotherm, and Dubinin isotherm and values of respective constants were evaluated. Freundlich Isotherm The isotherm supposes an assorted facade of adsorbent with irregular distribution of heat of adsorption over the adsorbent surface and is applicable for mono and multilayered adsorption process (Srivastava et al., 2015).This isotherm is used to study the adsorption of dye onto the surface of nanocomposites (Dada et al., 2012). The Freundlich model can be expressed as: 23545 Muhammad Saad et al. Synthesis and characterization of SnO efficacy for the treatment of dyes assisted simulated waste water Effect of amount of adsorbent on dye removal and Kd The optimum stay period was evaluated by shaking flasks containing the optimum concentration and optimum amount of intervals of time from 5 to 60 minutes. The optimum stay time for the removal of dye was determined to be 60 minutes. Moreover it is evident from Figure 5 that the distribution coefficient is directly proportional ation in shaking period Isotherms are algebraic functions that express relationship between the adsorbed materials with adsorbent (Kumar et al., Studies were made on Freundlich isotherm, Temkin Dubinin-Radushkevich isotherm and values of respective constants were evaluated. The isotherm supposes an assorted facade of adsorbent with irregular distribution of heat of adsorption over the adsorbent surface and is applicable for mono and multilayered adsorption 2015).This isotherm is used to study dsorption of dye onto the surface of nanocomposites 2012). The Freundlich model can be expressed as: Where, KF is a constant that shows the adsorbent capacity. ‘n’ is the constant that shows surface and ‘KF’ were evaluated via linear plotting log Q Ce. Figure 6. Freundlich isotherms at The values related to the surface homogeneity ‘n’ were determined to be 1.0154gL-1 , 1.1061gL 298K, 313K and 323K respectively. The adsorption capacities were determined to be 1.3298mg 1.6211mg0.0959 L0.9041 g-1 and 1.7033mg 313K and 323K respectively. Langmuir Isotherm The development of a monolayer on the adsorbent façade is described quantitatively by this isotherm, and there is no more adsorption. By this means, this isotherm epitomizes the dye molecules dispersal at equilibrium between the two phases. This isotherm is effective for monolayer adsorption on a surface having finite identical sites. The isotherm supposes constant energies of adsorption onto the exterior and no adsorbate transmigration takes place in the plane of the surface. The following equation was pro represented as (Dada et al., 2012). The above equation can be simplified in the linear form as. Where: Ce represents the adsorbate concentration at equilibrium (mgL-1 ) and Qe represents the adsorbate amount adsorbed at equilibrium per unit mass of the adsorbent (mg.g While Qo represents the maximum monolayer coverage capacity (mg.g-1 ) and KL is the Langmuir (Lmg-1 ).The values of KL and Q slope and intercept of the Langmuir plot of 1/C Muhammad Saad et al. Synthesis and characterization of SnO-CoO nanocomposites by bottom up approach and their efficacy for the treatment of dyes assisted simulated waste water ………………………(1) is a constant that shows the adsorbent capacity. ‘n’ is the constant that shows surface homogeneity. Values of ‘n’ ’ were evaluated via linear plotting log Qe versus log Freundlich isotherms at 25o C, 40o C and 50o C The values related to the surface homogeneity ‘n’ were , 1.1061gL-1 and 1.0302gL-1 at 298K, 313K and 323K respectively. The adsorption capacities were determined to be 1.3298mg0.0152 L0.9848 g-1 , and 1.7033mg0.0293 L0.9707 g-1 at 298K, The development of a monolayer on the adsorbent façade is described quantitatively by this isotherm, and there is no more adsorption. By this means, this isotherm epitomizes the dye molecules dispersal at equilibrium between the two phases. s effective for monolayer adsorption on a surface having finite identical sites. The isotherm supposes constant energies of adsorption onto the exterior and no adsorbate transmigration takes place in the plane of the surface. The following equation was proposed by Langmuir is 2012). ………………………(2) The above equation can be simplified in the linear form as. ……………….. (3) esents the adsorbate concentration at represents the adsorbate amount adsorbed at equilibrium per unit mass of the adsorbent (mg.g-1 ) represents the maximum monolayer coverage is the Langmuir isotherm constant and Qo were computed from the slope and intercept of the Langmuir plot of 1/Ce versus 1/Qe. CoO nanocomposites by bottom up approach and their
- 5. Figure7. Langmuir isotherm at 25o C, 40 The values of Qo were calculated to be 156.25mg.g-1 and -250mg.g-1 at 298K, 313K and 323K respectively. The Langmuir constant KL were determined to be -0.01768Lmg-1 , -0.007626 Lmg-1 and 0.005705Lmg respectively, indicating that the data does not follow the Langmuir isotherm. Temkin Isotherm The variables dealing with adsorbent relations with adsorbate are expressed by this isotherm. This isotherm states that the surface coverage decreases the heat of adsorption by neglecting extreme concentrations. The equation indicates that the variation is considered by an even spreading of binding energies. From the help of equation, a graph of the adsorbed quantity Qe versus lnCe was plotted and the values of respective constants were evaluated from the slope and intercept of the plots. The Temkin model is represented as (Dada et al., 2012): ……………………… ……………………... ……………………….. ………………………... AT and bT are Temkin isotherm binding constants (L While R represents the Universal gas constant (8.314Jmol ,T represents Absolute Temperature and B indicates the Constant associated to heat of sorption (Jmol Dubinin Radushkevich Isotherm This isotherm explains the adsorption mechanism on a heterogeneous façade with Gaussian energy distribution. This isotherm fits well quite regularly at moderate concentration range and at high activities of solutes (Dada et al 23546 International Journal of Current Research, C, 40o C and 50o C were calculated to be -57.803 mg.g-1 , at 298K, 313K and 323K were determined to be and 0.005705Lmg-1 respectively, indicating that the data does not follow the aling with adsorbent relations with adsorbate are expressed by this isotherm. This isotherm states that the surface coverage decreases the heat of adsorption by neglecting extreme concentrations. The equation indicates that n even spreading of binding energies. From the help of equation, a graph of the adsorbed quantity Qe versus lnCe was plotted and the values of respective constants were evaluated from the slope and intercept of the plots. The Temkin model is represented as ……………………… (4) ……………………... (5) ……………………….. (6) ………………………...(7) Temkin isotherm binding constants (L.g-1 ), While R represents the Universal gas constant (8.314Jmol-1 K-1 ) ,T represents Absolute Temperature and B indicates the Constant associated to heat of sorption (Jmol-1 ). This isotherm explains the adsorption mechanism on a heterogeneous façade with Gaussian energy distribution. This isotherm fits well quite regularly at moderate concentration et al., 2012). Figure8. Temkin plot of lnCe versus Q = ( ) = − Where, Qe represents the equilibrium adsorbate amount (mg.g1 ), Qs represents theoretical saturation capacity of the isotherm (mg.g-1 ), Kad represents the D (mol2 .k-1 J-2 ) and ε is the Dubinin constant. The value of ε is calculated as: = ln[1 + ](10) The D-R model is distinctive in a way that this is temperature dependant phenomenon (Dada From figure 9, the values of D– evaluated to be 7.0x10-7 mol 2.0x10-7 mol2 k-1 J-2 at 298K, 313K and 323K respectively with the R2 values of 0.9931, 0.9993 and 0.9922 respectively. The values of theoretical isotherm saturation capacity ‘Q were evaluated to be 3.542g.g at 298K, 313K and 323K respectivel Thermodynamic Studies The thermodynamic parameters such as standard Entropy change ∆So (J.mol−1 K−1 ),standard Enthalpy change ∆Ho (kJ.mol-1 ) and standard Gibbs Free Energy Change ∆Go (kJ.mol-1 ) were calculated by using following equations (Zhonghui et al. 2014). ∆ = − = . − . From the Van’t Hoff graph of Log K the standard entropy change ∆S change were determined. International Journal of Current Research, Vol. 7, Issue, 12, pp.23542-23550, December, 201 versus Qe at 25o C, 40o C and 50o C ……………………. (8) ……………………… (9) represents the equilibrium adsorbate amount represents theoretical saturation capacity of the represents the D–R isotherm constant ) and ε is the Dubinin–Radushkevich isotherm R model is distinctive in a way that this is temperature dependant phenomenon (Dada et al. 2012). –R isotherm constant ‘Kad’ were mol2 k-1 J-2 , 3.0x10-7 mol2 k-1 J-2 and at 298K, 313K and 323K respectively with values of 0.9931, 0.9993 and 0.9922 respectively. The values of theoretical isotherm saturation capacity ‘Qs’ were evaluated to be 3.542g.g-1 , 25.68mg.g-1 and 21.73mg.g-1 at 298K, 313K and 323K respectively. The thermodynamic parameters such as standard Entropy ),standard Enthalpy change ) and standard Gibbs Free Energy Change ) were calculated by using following equations …………………. (11) …………………. (12) From the Van’t Hoff graph of Log Kd versus T-1 , the values of ∆So and standard enthalpy ∆Ho 2015
- 6. Figure 9. D-R plot of ε2 versus lnQe at 25o C, 40 Figure 10. Graph of T-1 vs Log K From figure 10, ∆Ho and ∆So values were found out to 3113.3J.mole-1 and 56.712J.mole-1 K-1 respectively. The values of ∆Go were calculated to be -13.823 kJ.mole kJ.mole-1 and -15.270kJ.mole-1 at 298K, 313K and 323K respectively. The negative ∆Go values indicate the spontaneous nature of adsorption. Kinetic Studies The kinetic study will be carried out by pseudo pseudo-second order kinetics, Intra-particle Diffusion model, Elovich model and Boyd’s kinetic model. The rate constants can be calculated by the plots of pseudo first order second order equations that are represented as. log( − ) = log − . ………………… ………………… Where, Qe is the equilibrium amount adsorbed (mg.g represents the adsorbed amount at specified time (mg.g is the time (min) taken for the adsorption to occur. While k1and k2 denote pseudo first order rate constant (min pseudo second order rate constant (g.mg-1 min 23547 Muhammad Saad et al. Synthesis and characterization of SnO efficacy for the treatment of dyes assisted simulated C, 40o C and 50o C vs Log Kd values were found out to be respectively. The values 13.823 kJ.mole-1 , -14.526 at 298K, 313K and 323K values indicate the spontaneous The kinetic study will be carried out by pseudo-first order, particle Diffusion model, Elovich model and Boyd’s kinetic model. The rate constants can be calculated by the plots of pseudo first order and pseudo- second order equations that are represented as. ………………….(13) ………………… (14) is the equilibrium amount adsorbed (mg.g-1 ), and Qt represents the adsorbed amount at specified time (mg.g-1 ) and t is the time (min) taken for the adsorption to occur. While denote pseudo first order rate constant (min-1 ) and min-1 ) respectively. Equations (13) and (14) symbolize Pseudo order rate equations. I-Pseudo First Order Kinetics In present studies, the validity of pseudo first order model was confirmed by a plot between Log (Q Figure 11. Graph of pseudo first order kinetics From Figure 11, it can be realized that the adsorption does not strongly follow pseudo first order kinetics. For this kinetic study, a straight line should be obtained but there seemed to be deviation from the straight line showing the deviation. the figure 11, the value of pseudo first order rate constant ‘k was evaluated to be -4.606x10-4 Pseudo Second Order Kinetics A plot between t/Qt and Time (min) was used to confirm the validity of Pseudo second order kinetics. The experimental results were satisfying the second order kinetics as depicted in the Figure 12 as the DATA points were well fit on the straight regression line. Figure 12. Graph between t/Q The parameter Qe value was evaluated to be 2.93mg.g rate constant k2 was calculated to be 3.26g.mg Muhammad Saad et al. Synthesis and characterization of SnO-CoO nanocomposites by bottom up approach and their efficacy for the treatment of dyes assisted simulated waste water s (13) and (14) symbolize Pseudo – first and second Pseudo First Order Kinetics In present studies, the validity of pseudo first order model was confirmed by a plot between Log (Qe-Qt) and Time (min). Graph of pseudo first order kinetics From Figure 11, it can be realized that the adsorption does not strongly follow pseudo first order kinetics. For this kinetic study, a straight line should be obtained but there seemed to be t line showing the deviation. From the figure 11, the value of pseudo first order rate constant ‘k1’ 4 min-1 . Pseudo Second Order Kinetics and Time (min) was used to confirm the validity of Pseudo second order kinetics. The experimental results were satisfying the second order kinetics as depicted in the Figure 12 as the DATA points were well fit on the straight Graph between t/Qt and Time value was evaluated to be 2.93mg.g-1 . The was calculated to be 3.26g.mg-1 min-1 . CoO nanocomposites by bottom up approach and their
- 7. Intraparticle Diffusion Model Weber and Morris based theory of Intraparticle diffusion model is represented as: …………….. Where kp (mg.g-1 min0.5 ) is the intraparticle diffusion rate constant and C represents the width of the boundary layer (mg.g-1 ). A graph between qt and t0.5 was used to evaluate the values of kp (Wojciech et al., 2014). Figure 13. Graph of Intraparticle diffusion model From Figure13 it was estimated that there was no absolutely linear relationship rather it has an R2 coefficient of 0.8147. The intraparticle diffusion rate constant was calculated to be 8.0x10-3 mg.g-1 min0.5 . According to this theory, if the straight line of Qt against t0.5 passes through the origin, then intraparticle diffusion is in command of adsorpt obtained line was not absolutely straight moreover it was not passing through the origin that indicates that the rate controlling step was not only intraparticle diffusion. The value of C was determined to be 2.8729 mg.g-1 thought of the width of boundary layer, indicating that the width of the boundary layer increases linearly with the magnitude of intercept (Wojciech et al., 2014). Boyd Kinetic Model The adsorption mechanism is not fully governed by the diffusion as can be seen in the Figure 13 that the line does not pass through the origin therefore to investigate the adsorption sluggish step, the Boyd model was employed to investigate kinetic data. …………………….. ……………………. Where Qe (mg/g) represents equilibrium capacity of adsorption and Qt (mg.g-1 ) represents adsorption at specified time t. The portion of solute adsorbed at any time t is denoted by F 23548 International Journal of Current Research, Weber and Morris based theory of Intraparticle diffusion …………….. (15) ) is the intraparticle diffusion rate constant and C represents the width of the boundary layer was used to evaluate the Graph of Intraparticle diffusion model From Figure13 it was estimated that there was no absolutely coefficient of 0.8147. The intraparticle diffusion rate constant was calculated to be . According to this theory, if the straight passes through the origin, then on is in command of adsorption. The obtained line was not absolutely straight moreover it was not passing through the origin that indicates that the rate controlling step was not only intraparticle diffusion. The value 1 which present an of the width of boundary layer, indicating that the width of the boundary layer increases linearly with the 2014). The adsorption mechanism is not fully governed by the in the Figure 13 that the line does not pass through the origin therefore to investigate the adsorption sluggish step, the Boyd model was employed to investigate …………………….. (16) ……………………. (17) (mg/g) represents equilibrium capacity of adsorption ) represents adsorption at specified time t. The portion of solute adsorbed at any time t is denoted by F and Bt represents mathematical variable of F. Solving the above two equations (16) and (17) we get A graph between Bt and time ‘t’ was plotted but the linear line was not passing through the origin that show external mass transport primarily govern tartrazine adsorption over the nanocomposites where diffusion of particle was the slowest step (Ramachandra et al., 2014). Figure 14. Graph of Boyd’s Kinetic Model. Elovich Model This is an important model to illustrate the The model is mathematically represented as. The initial sorption rate (mg.g level of facade coverage and energy of activation is represented by ‘b’ (g.mg-1 ).The amount adsorbed at time‘t’ (min) is denoted by ‘Qt’ (mg.g evaluated by plotting Qt against time‘t’. Figure 15. The graph of Elovich Model International Journal of Current Research, Vol. 7, Issue, 12, pp.23542-23550, December, mathematical variable of F. Solving the above two equations (16) and (17) we get …………………. (18) and time ‘t’ was plotted but the linear line was not passing through the origin that show external mass rt primarily govern tartrazine adsorption over the nanocomposites where diffusion of particle was the slowest 2014). Graph of Boyd’s Kinetic Model. This is an important model to illustrate the chemisorptions. The model is mathematically represented as. ……………………. (19) The initial sorption rate (mg.g-1 .min-1 ) is denoted by ‘a’. The level of facade coverage and energy of activation is ).The amount adsorbed at time‘t’ ’ (mg.g-1 ). The constants were against time‘t’. The graph of Elovich Model , 2015
- 8. From the Figure 15, the constant ‘a’ was evaluated to be 3.28x1063 mg.g-1 min-1 and ‘b’ was determined as 52.63g.mg-1 respectively. pH at point of zero charge pHpzc was evaluated by plotting the final pH after 24 hours and 48 hours against the initial pH. The curves intersect at 6.2 which indicates that at this pH value, the surface charge was neutral and below this pH value, the adsorbent possess positive charge and higher than this pH value, the nanocomposites surface possess overall negative charge as shown in Figure 16. Figure 16.Plot of initial pH versus Final pH at24 hours and 48 hours Conclusion Nanocomposites of SnO-CoO were synthesized by a reported method. The characterization of the prepared nanocomposites was carried out by Fourier Transformed Infrared Spectroscopy and Scanning Electron Microscopy. The adsorption of tartrazine dye was studied by using SnO-CoO nanocomposites working as adsorbent under various conditions. The optimum conditions for the adsorption of tartrazine dye on SnO-CoO nanocomposites were determined. The optimum initial concentration was found to be 20ppm, the optimum adsorbent amount was evaluated to be 0.3g and the optimum stay time was determined to be 60 minutes. The experimental data indicate the adsorption obeys pseudo second order kinetics. The data also fitted well in Freundlich isotherm with n values of 1.0154, 1.1061 and 1.0302 at 298K, 313K and 323K respectively. The negative ∆Go value indicates the spontaneity of adsorption. Other rate determining factors were also taking their part along with diffusion as it was revealed by intraparticles diffusion model with kp value of be 8.0x10- 3 mg.g-1 min0.5 . pHzpc value was determined to be 6.2. The maximum removal of tartrazine dye by our experimental results was found to be 87.78%, so we can conclude that this specific method can be employed on industrial scale for waste minimization. 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