International Research Journal of Environment Sciences________________________________ ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 60 Adsorptive Removal of Phenols from aqueous solution by Flyash- Kinetics and Equilibrium Study Singh B.K. and Nema Pragya Dept. of chemistry, Govt. M. H College of H.Sc. and Science, Autonomous, JabalpurMP, INDIAAvailable online at: www.isca.in, www.isca.me Received 27th February 2015, revised 20th April 2015, accepted 1st July 2015 Abstract The potentiality of low cost abundantly available material with good adsorption properties for removing phenols is investigated. The adsorbent is characterized using a number of experimental approaches like chemical analysis, XRF, XRD, FTIR and SEM /EDS. Chlorophenols i.e. o-chlorophenol (OCL). m-chlorophenol (MCL) p-chlorophenol(PCL) including phenol (PHL) are selected for the studies. The effect of various factors like adsorbent particle size. pH, phenols concentration and temperature on the adsorption p are investigated. The removals of different phenols are increased with decreasing adsorbent particle size, pH and increasing concentration and temperature. The adsorption of the chlorophenols and phenols studied followed first-order rate kinetics. Langmuir adsorption isotherm constants are calculated and it is seen that the adsorption data for phenols onto flyash fitted the Langmuir model well. Thermodynamic studies are also undertaken and the values of the various parameters such as standard free energy (G°), enthalpy (H°) and entropy () are calculated. Keywords: Flyash, adsorption, phenols, langmuir isotherm model, kinetics, thermodynamic parameters, low cost adsorbent. Introduction Phenols are common raw materials for manufacturing for a large number of chemical products like petrochemicals, plastics, pesticides, pharmaceuticals, dyes etc. Apart from this, these are also used to produce phenolic, epoxy and polyamide resins. Among them, chlorophenols are an important class of aromatic pollutants in industrial wastewaters and belong to a group of common environmental contaminantsChlorophenols are found in the environment due to chlorination of drinking water in municipal water treatment, chlorine bleaching in numerous industries, discharge from a range of incineration processes as well as as common constituents of herbicides and pesticides on agricultural land. So United States Environmental Protection Agency (EPA) has classified phenols as priority pollutants4 due to its toxicity and adverse effect on human beings. Chlorophenols are used mostly in the manufacture of fungicides, herbicides, insecticides, pharmaceuticals, preservatives, glue, paint, fibers, leather as well as in various chemical synthesis. Phenols are the priority contaminants of major environmental concern due to its high toxicity, carcinogenicity and poor biodegradability. Therefore it is very essential to develop efficient and effective processes for the removal of these compounds from wastewaters. Various attempts are made in this respect like physical, chemical and biological processes for the removal of phenols from wastewater. Adsorption, chemical oxidation, precipitation, distillation, solvent extraction, ion exchange, membrane processes, reverse osmosis, etc as a traditional methods have been mostly used for removal of phenols from aqueous solutions7-9. Adsorption as removal of phenols is the most effective and efficient method due to high efficiency, easy handling, high selectivity, lower operating cost, easy regeneration of adsorbent and minimized production of chemical or biological sludge. Adsorption phenomena are affected strongly by the surface morphology as well as chemistry of the adsorbent. So various adsorbents like activated carbon, red mud, rubber seed coat and many more have been used for removal of phenolic compounds10-13. Among them, activated carbon is mostly used for removal of organic compounds from industrial effluents due to its high removal efficiency. But due to its high cost, it is not applicable to industrial effluents containing low concentrations of contaminants14-16. Hence, many more cheap materials have been tested for removal of organic compounds from water and wastewater. Recently much attention has been focused on the utilization of flyash including peat, wheat shells, wood sawdust, activated sludge, zeolite etc. for the removal of organics from water and wastewater17-19. The potentiality of flyash as a natural adsorbent has been investigated by various authors20-23. In this study, flyash is used as a low cost adsorbent to remove phenol, 2-Chlorophenol, 3-Chlorophenol and 4-Chrorophenol as a target pollutant from aqueous solution. The aim of this research is to study application of flyash for removal of phenol, 2-Chlorophenol, and 3Chlorophenol and 4-chrorophenol from aqueous solutions using batch type kinetic as well as equilibrium experiments under different conditions such as particle size, pH, concentration and temperature. International Research Journal of Environment Sciences ______________________________________________ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 61 Material and Methods Adsorbent and its Characterization: Flyash is obtained from Thermal Power Station, Chachai, Anooppur, Shahdol (M.P.) India. The material is sieved through standard test sieves having geometrical mean particle diameters of 150, 106 and 45 µm respectively. The different fractions of flyash are then dried at 110°C for 2h in an electric oven and stored in desiccators without any pretreatment for subsequent use. The chemical constituents of the flyash are determined using Indian standard methods24 along with other characteristics such as the loss on ignition (LO1) al 800°C, specific gravity, surface area (using a Quantasorb surface area analyzer, Quantachrome, Boynton Beach, FL, USA) and porosity (using a mercury porosimeter). These are all listed in table-1. The chemical compositions of the different fractions of flyash are also determined using Indian standard methods24 and are listed in table-2. Flyash are characterized by a number of experimental approaches like XRF, XRD, SEM/EDS and FTIR in order to investigate all the relevant features25. The chemical composition of different fractions of flyash are confirmed by XRF analysis (PAN Analytical, Model-PW 2404) and given in table-3. X-ray diffraction (XRD) is carried out on Philips PW1710 automatic X-ray diffractometer with Cu-K radiation with a scanning speed of 10° min 1. Different fractions of flyash samples are subjected to Scanning Electron Microscopy on FEG- SEM (Model– JEOL JSM 7600F) coupled with Energy Dispersive X-Ray Spectroscopy (EDS) having XMAX 80 mm 2 as detector in order to investigate the morphology and chemical composition of the samples. The flyash fractions is analyzed with Fourier transform infrared spectroscopy(FTIR) using Perkin Elmer 1800 model instrument in the range 450– 4000 cm–1 as potassium bromide pellet . Adsorbate: Phenol (PHL), 0-chlorophenol (OCP), m-chlorophenol (MC P) and p-chlorophenol (PC P) (A.R. grade) are selected for this study because they represent the most common pollutants and are readily analyzed using UV-VIS spectrophotometer (Shimadzu Model UV-1601) at wavelength of 270,274,280 and also 280 nm. Standard solutions of these phenols (500 mg/dm) are prepared by taking appropriate quantities and dissolving them in a minimum volume of acetone. Portions of these solutions are then diluted with distilled water to give the test samples. Batch experiments: Kinetic Studies: The adsorption kinetics is studied using batch experiments. Thus, 25 cm of a given phenols at a known concentration is placed in a 100-ml conical glass-stoppered flask together with 1.0 g flyash and the flask placed in a thermostatic shaker. Again, various particle sizes (150 µm, 106 µm, 45 µm), pH values (2.0, 4.0, 6.5, 8.0, 10), concentrations (500, 350, 250 mg/dm) and temperatures (30°C, 40°C, 50°C) are employed. However, in this case samples are taken after pre-determined intervals of time and their concentrations determined by means of a spectrophotometer (UV-VIS spectrophotometer (Shimadzu Model UV-1601) at a wavelength of 270,274,280 and also 280 nm corresponding to maximum absorbance. Equilibrium Studies: Batch adsorption experiments for determining equilibrium adsorption isotherms are also carried out by agitating 1.0 g of the desired grade of flyash with 35 cm of a chosen concentration of a given phenols. Solutions are transferred in 100-ml conical glass-stoppered flasks and maintained in a temperature-controlled shaking thermostat for 120 min. (the time required for attaining equilibrium between the adsorbed phenols and that remaining in solution). Experiments are performed using different particle sizes (150 µm, 100 µm and 45 µm), pH values (2.0, 4.0, 6.5, 8.0, 10.0) and temperatures (30°C, 40°C, 50°C). The pH of the initial solution was adjusted with 0.1N HNO or 0.1N NaOH solution using pH meter. At equilibrium, samples are taken from the flasks, filtered through a filter paper and centrifuged. The concentrations of the residual different phenols are determined as described above. Results and Discussion Characterization of Flyash: XRD analysis: The diffractogram for one of the fraction of flyash (150 µm) is shown in figure-1. The XRD analysis of flyash sample indicates the presence of quartz, alumina, hematite and illite etc. It can be observed from figure-1 that the flyash consists mostly of mullite, quartz, alumina, a small amount of hematite and calcium oxide with intense characteristic peaks of quartz (SiO). The intensity of quartz is very strong with mullite and dense glassy surface layer. It can be seen from the diffractogram of flyash sample that components are mainly present in their oxide form. These results are similar to that reported for a flyash investigated by Dwivedi et al25. SEM/EDS Analysis: SEM stands for scanning electron microscopy which is used for studying the surface morphology of the materials. Energy-dispersive X-ray spectroscopy (EDS) is an analytical technique used for the elemental analysis as well as chemical characterization of samples. The SEM/ EDX analysis results of flyash are represented in figure-2. The image reveals that most of the particles present in the flyash are irregular in shape and covered with relatively smooth grains of quartz. The EDS data suggest that aluminum, oxygen, carbon, iron, titanium and silicon are the primary elements present in fractions of flyash samples. SEM/EDS provide detailed imaging information about the morphology and surface texture of individual particles as well as elemental composition of flyash samples which also confirms the earlier findings26. FTIR Analysis: FTIR spectrum for one of the flyash fraction of size 150 µm is shown in Figure-3. The FTIR data shows the presence of functional groups on the surface of flyash sample. FTIR spectra of flyash sample represent a broad band between 3700cm-1 - 3100cm-1 indicating the presence of -OH group on International Research Journal of Environment Sciences ______________________________________________ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 62 the sample surface. This stretching vibration is due to the silanol groups (Si-OH) present in the flyash sample. The band observed between 1250cm-1- 850cm- of flyah samples show the presence of TO (where T = Si, Al) asymmetric stretching vibrations of internal tetrahedral. The bands between 720cm-1-650cm-1 and 420cm-1-500cm-1 indicate about the presence of symmetric stretching and TO bending mode of internal tetrahedral respectively present in flyash samples. In addition, bands appearing between 800-600 cm-1 are related with tetrahedral vibrations known as secondary building units as well as fragments of aluminosilicate of flyash samples. FTIR studies of this flyash fraction help in the identification of various forms of the minerals present in the sample. The coupled vibrations are found due to the availability of various constituents found in the flyash sample. This result is similar to that reported for a flyash investigated by Dwivedi et.al.25. Effect of particle size of Adsorbent: The adsorptive removal of all the four phenols on different particle size (150 to 45µm) of flyash are studied by variation of contact time (20 to 120 min.) for kinetic modeling and initial phenols concentration (142.85 to 500.00) for equilibrium modeling keeping other parameters constant and the results are shown in Figure 4-5. To reduce the number of figures, only the adsorption of p-chlorophenols having similar shape to other phenols is shown in the Figures. It can be seen from Figures that adsorptive removal of phenols are decreased as follows: 45 m � 1OOm � 150m. This can be explained as amounts of the major constituents of flyash like alumina and silica are increased as the particle size decreased shown in Table-2. The silica and alumina contents of flyash play a significant role in the adsorption of phenols. This is because of the strong chemical bonding between the lone pair of electrons present on the –OH group in the phenol and the central ion of the silicate (Si4+) as well as the presence of a weakly acidic alumina surface19. The surface area also increased as the particle size decreased and so active site increased 27. Hence, in addition to the increase in alumina and silica content with decreasing particle size, the increase in the surface area with availability of more adsorption site also contributed to the observed enhanced adsorptive removal of all four phenols onto the smallest sized fractions of flyash. Among phenols, the removal trend is as follows: PCP � MCP � OCP � PHL It can be explained as activation of the aromatic ring of monochlorophenols by the chlorine favours the existence of donor-acceptor interactions between the phenolic compounds and the adsorbent surface28. It is also obvious that in chloro-phenol that both functional groups may be separately or simultaneously involved in the adsorption process. Higher removal of chloro-substituted phenol is due to the introduction of a chloro group (-Cl) into the benzene ring which increase the acidic character (conjugation effect) responsible for forming an anion on the oxygen atom of the –OH group and which has a strong affinity for alumina and silica surfaces. It is found that adsorption of PCP is higher than that of MCP and OCP. This is because of the position of the -Cl atom in the benzene ring with respect to to phenolic -OH substituent strongly influences the adsorption uptake. Aksu and Yener28 explain this behaviour as a result of steric hindrance between the -Cl and the -OH substituents present in chlorophenols. Similar results are also obtained by Singh et al. in case of phenol 21, 22. Effect of pH: The effect of pH on phenols removal by flyash is studied by variation of solution pH (2.0 to 10.0) both for kinetic and equilibrium modeling and the results are shown in figure 6-7 and the variations of adsorptive removal values for different pH are as follows: pH 2.0 � pH 4.0 � H 6.5� pH 8.0� pH 10. This can be explained by amphoteric nature of adsorbent and different speciation of phenols molecule with variation of solution pH. The hydrogen ion concentration (pH) primarily affects the degree of ionization of the phenolic adsorbate and the surface properties of the adsorbent. Thus, the pH values of the phenols solution play a significant role in the whole adsorption process. The adsorption is strongly pH- dependent, i.e. it increases with decreasing pH. Any oxide surface creates a charge (positive or negative) on its surface and the magnitude of this charge is proportional to the pH of the solution surrounding the oxide particle 19. As mentioned above, the principal constituents of flyash are meal oxides containing mainly Al and Si. Such metal oxides form metal hydroxide complexes at the solution interface leading to the development of a positive or negative charge on the surface. When the pH of the solution decreases, the surface becomes positively charged and the adsorptive removal values towards phenols increases as shown in figure 6-7. Positively charged surface sites on the adsorbent surface favors the adsorption of phenols due to electrostatic attraction. This can be explained on the basis of the formation of a positively charged surface in an acidic medium and a negatively charged oxide surface in a basic medium from the hydroxylated oxide surface of the fly ash. The whole process may be represented by the following set of equations: H+ OH¯ O + M MOH MO +HO At lower pH values, the lone pair of electrons on the oxygen atom of the undissociated – OH group present in the benzene ring coordinated with the highly positively charged surface. A low pH quite probably resulted in lowering the negative charge on the adsorbent surface, thus enhancing adsorption of the negatively charged adsorbate. At higher pH values, the dissociated phenoxide ion (C) is repelled by the highly negatively charged oxides on the surface .Amongst the phenols studied, this decrease followed the sequence as discussed earlier. Similar observations are observed also by Singh et al. in case of phenol 21, 22. International Research Journal of Environment Sciences ______________________________________________ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 63 Effect of Initial Concentration: The uptake of phenol and its chloro-substituted derivatives are studied on flyash at various concentrations (250 to 500 mgl-1) keeping other parameters constant and only one of the plot of para-chlorophenol for kinetic studies are shown in figure-8 because similar plots are obtained for others phenols. It is clear from the figure-8 that adsorption of phenols increased as its concentration increased and finally becomes constant. The initial concentration provides an important driving force to overcome all mass transfer resistance of solutes between the aqueous and solid phases. The higher removal of phenols at initial period may be due to an increased number of vacant sites on the adsorbent available 25. This result is consistent with the previously reported results29. Thus the adsorptive removal values vary in the order as (500 mg/L) � (350 mg/L) � (250 mg/L) But among the phenols, the variation is the same as given earlier. Similar observations are observed also by Singh et al. in case of phenol22. Effect of Temperature: The effect of temperature for adsorption of phenols on flyash is studied by changing the temperature of the system both for kinetic and equilibrium studies from 30C to 50C and the results are shown in figure 9-10. It is seen from the figures that uptake of phenols increased by increasing temperature indicating endothermic nature of adsorption. This is because of presence of weaker hydrogen bonding (intra and intermolecular) at higher temperature which makes phenols molecule freely available for adsorption29. This may be also due to increase in the number of active surface centres available for adsorption as the temperature increased over the range 30-50C. However, the net increase would depend upon the nature of the solute19. This suggests that the removal of phenol on flyash involves a chemical process. The increase in uptake of the phenol with temperature may also have been due to a change in the pore size19. The variation of the adsorptive removal values at different temperatures with respect to time and concentrations follows the order: 50C�40C�30C. The variation among phenols examined is the same as discussed earlier. Similar observations are reported by Singh et al. in case of phenol21, 22. Kinetic Modeling: The kinetics of adsorption of phenols on flyash is studied on the basis of the most widely used Lagergren equation as shown in equation (1) log (q-q) = log q – k t/2.303 (1) Where q (mg g-1) is the amount of phenol adsorbed at time t, q(mg g-1) is the amount adsorbed at equilibrium and k is equilibrium rate constant of adsorption. The linear plots of log (q-q) vs. t for phenols under different conditions indicate the validity of equation (1) and the process follows first order rate kinetics. Thus, the equilibrium rate constant k values calculated from one of the linear plots (correlation coefficients ranging from0.991to 0.999 indicating about the validity of this equation) corresponding to figure-4,6,8 and 9 according as equation at different conditions are listed in table -4,5,6a,6b and 7. To reduce the number of figures, one of the linear plot of p-chlorophenol at different particle size is shown in Figure-11 because similar plots are obtained for others phenols in different conditions also. Now the kinetic parameters, k for different conditions listed in the table -4, 5,6a and 7 can be summarized as follows, k(45 m) � k(1OOm) � k (150m.) k(pH 2.0} �k( pH 4.0) �k(pH 6.5)� k(pH 8.0)� k(pH 10} k(50C)�k(40C)�k(30C) The above trend can be explained as more the adsorption more the rate constant and vice- versa. However, the sorption rate constant, k, as calculated from linear plot corresponding to Figure-8 according as equation varied in a reverse manner because the fractional adsorption is low at high concentration19. Thus, the values of k varied in the order as k (500 mg/L) k(350 mg/L) k(250 mg/L). The variation among different phenols is as follows: k(PCP) &#x-3.3;女 k(MCP) &#x-3.3;女 k(OCP) &#x-3.3;女 k(PHL) Similar observations are observed by Singh et al.22. Equilibrium Modeling: There are several models available in literature that shows equilibrium relationships between adsorbent and adsorbate. The Freundlich and Langmuir models are the most frequently employed models. In this work, Langmuir model are used to describe the relationship between the amount of phenols adsorbed and its equilibrium concentrations. The linear form of the Langmuir isotherm is given by the relation21: /qe =1/Qb+C/Q (2) Where, q is the amount adsorbed at equilibrium (mg g-1), Q(mg g-1) and b (L mg-1) are the Langmuir constants related to the maximum adsorption and energy of adsorption respectively. The plots of Ce / qe vs. Ce for phenols at different conditions are found to be linear (correlation coefficient ranging from 0.995 to 0.999) indicating the applicability of the Langmuir model. The statistical significance of the correlation coefficient (R) for Ce / e vs. Ce is the criteria by which the fitting of the data to Langmuir isotherm is tested. The parameters Qo and b have been calculated from the slopes and the intercepts of the linear plots corresponding to the figures-5,7and 10 according as equation at different conditions shown in Figure-12 and the results are listed in table -4,5 and 6a .To reduce the number of figures, one of the linear plot of p-chlorophenol at different temperature is shown in figure-11 because similar plots are obtained for others phenols in different conditions. The best fit of equilibrium data in the Langmuir isotherm predicted the monolayer coverage of phenol onto flyash. Now the Langmuir Isotherm parameters Q0 and b for different conditions are listed in the table-4, 5and 6a can be summarized as follows International Research Journal of Environment Sciences ______________________________________________ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 64 , b (45 m) � Qo, b (106 m) � Qo ,b(150 m) ,b(pH 2.0)�Q,b(pH 4.0)�Q,b(pH 6.5)�Q,b(pH8.0)� ,b (pH10.0) , b (30 C) � Q, b (40 C) � Q, b (50 C) The variation among different phenols is as follows: , b (PCP) � Q, b (MCP) � Q, b (OCP) � Q, b (PHL) The above trend can be explained as more the adsorption more the isotherm parameters and vice- versa. Similar observations are observed also by Singh et al.21. Thermodynamic Modeling: The standard free energy change ), standard enthalpy change () and standard entropy change () are calculated using the following equation19 = -RT lnk (3) = RT/ (T-T) ln (K/K) (4) = (H0- G) / T (5) Where K is equilibrium constant for the adsorption process, which can be expressed as the product of the Langmuir constants Qo and b 30K, K1 and K2 are equilibrium constant at temperature T, T1 and 2 respectively and R is the gas constant. The thermodynamic parameters are summarized in table- 6b. Positive values of o suggest the endothermic nature of the sorption and the negative values of o indicate the spontaneous nature of the sorption process. However, the values of o decreased with an increase in temperature, indicating that the spontaneous nature of adsorption. The positive value of o shows the increased randomness of the solid/solution interface during the adsorption of phenols on flyash. The adsorbed water molecules, which are displaced by the adsorbate species, gain more translational energy than the energy lost by the adsorbate ions, thus allowing the prevalence of randomness in the system. The positive value of o also shows affinity of adsorbent for phenols. The enhancement of adsorption at higher temperatures may be attributed to the enlargement of pore size or activation of the adsorbent surface31. Similar observations are observed also by Singh et al.21. Table -1 Characteristics of flyash Element as oxide Weight % SiO 59.54 Al 27.20 Fe 4.87 CaO 2.91 MgO 0.40 O+NaO 1.00 LOI ( 800 0 C) 12.00 Specific gravity 1.80 Surface Area 7000 – 9000 cm 2 Porosity 0.34 - 0.62 Table–2 Chemical analysis for fractions of flyash Chemical Composition (Percentage by weight) Particle Size µm SiO AI2O Fe CaO MgO LOI 800C 150  m 59.54 27.20 4.87 2.91 0.40 12 106  m 67.00 30.00 6.10 3.80 1.10 08 45  m 77.75 36.00 6.00 4.00 1.50 4.09 Table-3 XRF analysis for fractions of flyash Chemical composition SiO2 Al Fe CaO MgO NaO KO TiO MnO P SrO SO Weight(%) 150  m 59.81724.2906.6641.5990.2540.1202.0824.3140.0440.0010.0560.001 Weight(%) 106  m 60.250 24.373 6.576 1.513 0.248 0.077 1.841 1.841 0.042 0.001 0.054 0.001 Weight(%) 45  m 60.420 25.339 6.192 1.473 0.306 0.071 1.711 3.505 0.040 0.017 0.052 0.012 International Research Journal of Environment Sciences ______________________________________________ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 65 Table–4 Adsorption Kinetic and Isotherm parameter for different fractions of flyash Adsorbate Particle Size of Adsorbent (  m) Rate Constant Langmuir Parameters k (min-1) x 10-2 (mmol g - 1 ) x 10-2b (L mol - 1 ) x 10 3 Phenol 150 3.680.991 3.73 1.90 0.998 106 3.92 0.991 3.97 2.12 0.999 45 5.53 0.993 5.01 2.17 0.998 o-chlorophenol 150 4.14 0.977 7.18 2.71 0.995 106 4.38 0.982 7.56 3.93 0.999 45 4.83 0.989 8.24 4.20 0.999 m-chlorophenol 150 4.83 0.994 8.93 2.93 0.999 106 5.07 0.990 9.67 4.80 0.999 45 5.56 0.993 10.20 7.42 0.999 p-chlorophenol 150 5.07 0.994 10.45 3.49 0.998 106 5.36 0.995 10.90 5.41 0.999 45 5.76 0.986 11.69 7.92 0.998 Adsorption Kinetic condition: pH 6.5 and Temperature 30°c. Isotherm conditions: pH 6.5; Temperature 30°c and concentration 500 mgL-1Table–5 Adsorption Kinetic and Isotherm parameter for different pH values of flyash Adsorbate pH Rate Constant Langmuir Parameters K (min-1) x 10-2 Ro (mmol g - 1 ) x 10-2b(L mol - 1 ) x 10 3 Phenol 2.0 4.38 0.987 4.43 2.16 0.998 4.0 3.92 0.989 4.07 2.09 0.998 6.5 3.68 0.997 3.73 1.90 0.998 8.0 3.22 0.992 3.34 1.80 0.995 10.0 2.99 0.988 2.90 1.42 0.998 o-chlorophenol 2.0 4.84 0.978 4.74 3.92 0.999 4.0 4.61 0.978 4.63 2.87 0.997 6.5 4.15 0.994 4.35 2.71 0.995 8.0 3.92 0.979 4.16 2.15 0.989 10.0 3.46 0.977 3.78 1.98 0.989 m-chlorophenol 2.0 5.76 0.992 5.98 6.35 0.998 4.0 5.29 0.993 5.64 4.55 0.999 6.5 4.84 0.994 5.40 2.93 0.999 8.0 4.38 0.993 5.11 2.23 0.999 10.0 3.92 0.986 4.92 1.78 0.996 p-chlorophenol 2.0 5.99 0.987 6.65 8.81 0.997 4.0 5.29 0.994 6.13 5.46 0.999 6.5 5.06 0.994 6.32 3.45 0.998 8.0 4.84 0.998 6.27 2.56 0.995 10.0 4.15 0.999 5.98 2.17 0.990 Kinetic conditions size 150µm; Temperature 30°C and concentration 500 mgL-1 Isotherm condition: size 150µm and Temperature 30°C. International Research Journal of Environment Sciences ______________________________________________ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 66 Table–6a Adsorption Kinetic and Isotherm parameter for different temperatures Adsorbate Temperature C) Rate Constant Langmuir Parameters K (min-1) x 10-2 (mmol g - 1 ) x 10-2b (L mol - 1 ) x 10 3 Phenol 30 1 3.68 0.991 3.73 1.90 0.998 40 1 3.92 0.999 4.27 2.03 0.999 50 1 4.15 0.999 4.70 2.45 0.999 o-chlorophenol 30 1 4.15 0.977 4.35 2.73 0.995 40 1 4.38 0.972 4.50 3.69 0.999 50 1 4.60 0.946 4.77 4.86 0.999 m-chlorophenol 30 1 4.84 0.994 5.40 2.93 0.999 40 1 5.07 0.994 5.81 4.68 0.999 50 1 5.30 0.992 6.12 6.94 0.997 p-chlorophenol 30 1 5.07 0.994 6.32 3.50 0.998 40 1 5.30 0.999 6.48 7.06 0.999 50 1 5.76 0.999 6.95 11.06 0.998 Kinetic conditions: pH6.5; size 150µm and concentration 500 mgL-1 Isotherm condition: pH 6.5 and size 150µm.Table-6b Thermodynamic Parameters at different temperatures Adsorbate Temperature C) K Langmuir Parameters G ° (k cal mol - 1 ) ° (cal mol - 1 ) ° (k cal mol - 1 ) Phenol 30 70.87 - 2.5563 20.9168 3.7815 40 86.68 -2.7654 26.9957 5.6852 50 115.15 -3.0354 - - o-chlorophenol 30 118.76 -2.8660 30.2314 6.2941 40 166.05 -3.1683 31.4620 6.6793 50 231.82 -3.4829 - - m-chlorophenol 30 158.22 -3.0381 43.5848 10.1681 40 271.91 -3.4739 39.6211 8.9275 50 424.73 -3.8701 - - p-chlorophenol 30 221.20 -3.2391 55.7257 13.6458 40 457.49 -3.7964 45.3153 10.3873 50 768.67 -4.2495 - - Conditions: pH 6.5 and Size 150µm. Table-7 Adsorption Kinetic Parameter at different concentrations Adsorbate Concentration mgL - 1 Rate constant k ( min - 1 ) x 10 - 2 R 2 Phenol 500 3.68 0.991 350 4.15 0.999 250 4.38 0.997 o-chlorophenol 500 4.15 0.977 350 4.38 0.967 250 4.60 0.956 m-chlorophenol 500 4.84 0.994 350 5.06 0.993 250 5.53 0.991 p-chlorophenol 500 5.07 0.994 350 5.53 0.988 250 5.76 0.992 Conditions: pH 6.5, Size 150µm and temperature 30°C. International Research Journal of Environment Sciences ______________________________________________ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 67 Figure-1 X-ray diffractogram of flyash (150 µm ) Figure-2 SEM-EDX photograph of flyash(150 m) Figure-3 FTIR spectrum of flyash (150 µm) International Research Journal of Environment Sciences ______________________________________________ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 68 Figure-4 Adsorption Kinetics of p - chloro phenol on flyash; condition: 500 mgl -1; pH 6.5; Temperature 30°C Figure-5 Adsorption Isotherm for p -chloro phenol on flyash. Condition: Different Size; Temperature 30°C; pH 6.5  \n \nAmount Adsorbed ( mg g-1Time (min) 150 µm 106 µm 45 µm qe (mgg-1Ce (mgl-1) 150 µm 106 µm 45 µm International Research Journal of Environment Sciences ______________________________________________ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 69 Figure-6 Adsorption Kinetics of p - chloro phenol on flyash; condition: 500 mgl -1; size 150 µm; Temperature 30°C Figure-7 Adsorption Isotherm for p -chloro phenol on flyash condition: Different pH; Particle size 150 µm; Temperature 30°C  \n \nAmount Adsorbed ( mg g -1)Time (min)  \r  \r  \r \n \r  \r qe (mgg-1Ce (mgl-1) pH 2.0 pH 4.0 pH 6.0 pH 8.0 pH 10.0 International Research Journal of Environment Sciences ______________________________________________ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 70 Figure-8 Adsorption Kinetics of p - chloro phenol on flyash; condition: pH 6.5; size 150 µm; Temperature 30°C Figure-9 Adsorption Kinetics of p - chloro phenol on flyash; condition: 500 mgl -1; pH 6.5; size 150 µm  \n\nAmount Adsorbed ( mg g -1 500 mgl -1 350 mgl -1 250 mgl -1  \n \nAmount Adsorbed ( mg g -1Time (min) 30 °c 40 °c 50 °c International Research Journal of Environment Sciences ______________________________________________ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 71 Figure-10 Adsorption Isotherm for p -chloro phenol on flyash, Condition: Different Temperature; Particle size 150 µm; pH 6.5 Figure-11 Lagergren plot for the adsorption of p-chlorophenol on flyash; Concentration 500 mgl-1; pH 6.5; Temperature 30°C qe (mgg-1Ce (mgl-1) 30 °c 40 °c 50 °c y = -0.022x + 0.419R² = 0.994y = -0.023x + 0.366R² = 0.995y = -0.025x + 0.38R² = 0.986\nlog ( q-q )Time ( min)       International Research Journal of Environment Sciences ______________________________________________ISSN 2319–1414Vol. 4(8), 60-73, August (2015) Int. Res. J. Environment Sci. International Science Congress Association 72 Figure-12 Langmuir plot for the adsorption of p - chlorophenol on flyash. Particle size 150 µm; pH 6.5Conclusion The present study reports characteristics of adsorbent through a number of experimental approach as well as batch type kinetic and equilibrium adsorption showing the potentiality of flyash for phenolic wastewater treatment .This treatment is simple and economic. Equilibrium data fitted very well to Langmuir model confirming monolayer coverage of phenol onto flyash. It can be concluded that some industrial waste by-products as alternative adsorbents for the adsorption of organics like phenols from aqueous solution can be used due to easily available, low cost and easy handling. Decreasing particle size and pH and increasing temperature increases the adsorption parameters of flyash for phenols. The kinetic and equilibrium data thus generated can be used for designing a treatment plant for phenolic effluents wherein continuous removal or recovery can be achieved on a large scale. 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