Adsorption of Methylene Blue from aqueous Solution on the Surface of Wool Fiber and Cotton Fiber

Adsorption of dye methylene blue from aqueous solution on the surface of sheep wool and cotton fibers was accomplished under the optimize conditions of temperature, concentration, pH, stay time duration and quantity of adsorbent. Spectrometric technique was used for the measurements of concentration of dye before and after adsorption. The percentage removal and distribution constant (KD) values for the removal of of methylene blue were also calculated. The values of % adsorption data for methylene blue – sheep wool system show better adsorption capacity as compared to methylene blue – cotton fiber system. The applicability of Langmuir and Freundlich adsorption isotherm equations for the present system was also tested. The experimental data are fitted to the Langmuir and Freundlich isotherm equations. The values of their corresponding constants were determined from the slope and intercepts of their respective plots. Thermodynamic parameters like ΔG, ΔH and ΔS were calculated on the basis of Langmuir constant K. The methylene blue – sheep wool system show non spontaneous and exothermic behavior, while methylene blue – cotton fiber system show spontaneous and endothermic behavior. The results of these investigations suggested that natural adsorbents can be utilized as adsorbent materials, because of their selectivities for the removal of dyes. @JASEM Global village is facing many issues regarding industrial pollution. Textile, leather, food, agro industries have brought enormous atmospheric changes. The alarming question is the disposal of effluent discharged by these industries. The basis of ISO14000 is mainly for the disposal of residual contents of these industries. But unfortunately the industries are lacking some where in following the procedure recommended for this purpose. The effluent from textile industries is a big question mark, which has created environmental problems around urban areas. The dyes present in the effluent discharged by textile industries are first to be treated for the separation of dyestuff and then send to disposing end. An attempt has been made in this connection. Earlier adsorption of methylene blue and malachite green from aqueous effluent on the surface of wool carbonizing waste is reported [Khan et al 2004]. This method is found useful for this purpose but it is more efficient for the effluent containing methylene blue. In this paper results obtained spectrophotometerically were discussed in the form of Langmuir and Freundlich isotherms. This present work deals with the adsorption of methylene blue from aqueous solution on the surface of natural adsorbent. The concentration of dye was determined spectrophotometrically on the basis of relation between absorbance and concentrations. Percent adsorption before and after treatment gives the amount of dyestuff separated from effluent. The results are treated using the Langmuir and Freundlich isotherms. The values of activation energy, enthalpy change and entropy change were also evaluated. EXPERIMENTAL Preparations of adsorbents: The sheep wool fiber and cotton fiber were used as the natural adsorbent, which are collected from the natural resources. Cotton is very sensitive crop used as a fiber, which is easily available. Sheep wool fiber was obtained from sheep. Both fibers were washed thoroughly with hot water to remove impurities associated with them and then dried in air under shade. MATERIAL Potassium chloride, sodium acetate, citric acid, sodium citrate, acetic acid and hydrochloric acid of analar grade were used and methylene blue of BDH were used. Preparations of buffers: Buffers of pH 1, 2 (HClKCl) , pH 3 (citric acid – trisodium citrate), pH 4.5 (sodium acetateacetic acid) and pH 6 (citric acidtrisodium citrate) were prepared in double distilled water. Stock solution of methylene blue (M.W. 374 ) of strength 1x 10 was prepared in double distilled water. For the determination of λmax of methylene blue, the solution of 1×10 mol. dm strength was prepared. The absorbance was measured on spectrophotometer (ERMA AE200). The value of λmax due to methylene blue was observed as 665 nm. Effect of Amount of Adsorbent: In order to find out optimum amount of adsorbent at which maximum adsorption takes place, 30ml of 6×10 mol. dm of dye solution for sheep wool fiber , 3 ×10 mol. dm of dye solution for cotton fiber system was taken. The dye solution of pH 5 for (sheep wool fiber), 3.5 JASEM ISSN 1119-8362 All rights reserved J. Appl. Sci. Environ. Mgt. 2005 Vol. 9 (2) 29 35 Full-text Available Online at http:// www.bioline.org.br/ja Adsorption of mehtylene blue... A. Rasheed Khan, Hajira Tahir, Fahim Uddin*; Uzma Hameed 30 for (cotton fiber) was added in the column packed with different quantity of adsorbent e.g. 0.3, 0.4, 0.5, 0.6, 0.8, 1.0......1.50 g. The solution of dye was kept stand for 20 minutes for (sheep wool fiber) and 10 minutes for (cotton fiber). The results are shown in Table 1. Table 1: Optimization for the amount of adsorbent in the adsorption of aqueous solution of methylene blue (MB) on the surface of sheep wool fiber and cotton fiber.) Sheep wool fiber Cotton fiber Amount of adsorbent (g) Ce mol/L %adsorption KD Ce mol/L %adsorption KD 0.2 0.116 50.60 75.98 0.046 17.20 20.60 0.3 0.154 67.20 67.24 0.064 25.40 25.40 0.4 0.149 65.00 48.79 0.127 50.40 37.90 0.5 0.189 82.50 49.50 0.100 53.50 22.40 0.6 0.254 80.30 40.10 0.165 37.40 32.80 0.8 0.207 90.30 33.89 0.181 72.10 27.60 1.0 0.200 94.30 31.40 0.227 85.00 25.80 1.25 0.250 93.60 22.40 1.50 0.259 97.00 19.40 Concentration of adsorbate = 6×10 mol. dm (Sheep wool fiber), 3×10 mol. dm (Cotton fiber) , Volume of adsorbate =30ml , Time= 20 minutes (Sheep wool fiber), 10 minutes (Cotton fiber) pH = 5.0(Sheep wool fiber), 3.5 minutes (Cotton fiber) Table 2: Optimization for the concentration of methylene blue in the adsorption of methylene blue from aqueous solution on the surface of sheep wool fiber and cotton fiber for 3 hours Sheep wool fiber Cotton fiber Conc. of dye(mol/L) Ce mol/L %adsorption KD Ce mol/L %adsorption KD 1×10 0.074 63.00 37.80 0.446 61.80 37.00 2×10 0.075 60.00 36.00 0.094 72.30 43.40 3×10 0.117 62.50 37.60 0.219 84.40 50.70 4×10 0.173 66.80 40.00 0.194 64.40 38.60 5×10 0.204 58.90 35.50 0.280 74.40 44.60 6×10 0.301 71.60 43.00 0.256 57.70 34.60 7×10 0.365 66.1 39.70 0.339 60.50 36.30 9×10 0.443 67.40 40.40 0.446 61.80 37.00 Amount of adsorbent = 0.5g , Volume of adsorbate =30ml , pH = 5.0 (Sheep wool fiber), 3.5 (Cotton fiber) Effect of Concentration of Adsorbate: For this study eight columns with 0.5g of adsorbent were prepared. The pH of methylene blue was maintained as 5.0 (sheep wool) , 3.5 (cotton fiber) and time 3h. The results are summarized in Table 2. Effect of Stay Time:For the determination of the effect of time on the adsorption of dye, 0.5g of adsorbent was packed in each column and 30 ml of 6×10 mol. dm dye for (sheep wool fiber), 3×10 mol. dm dye for (cotton fiber) at pH 5.0 and 3.5 for cotton and sheep wool fiber respectively were added in the column for different intervals of time. When the solution of dye comes in contact with heterogenous surface of adsorbent, as usual unsaturated part of the dye strikes the surface of the adsorbent for adsorption. It was observed that the adsorption of dye increases with increasing in time to 30 minutes and reaches to maximum value and then attains a constant value when adsorption equilibrium is reached. In methylene blue on sheep wool fiber maximum adsorption occurs in 30 minutes as 82.50% whereas in cotton fiber the maximum adsorption occurs in 10 minutes as 72.0%. The results are tabulated in Table 3. Effect of pH: The influence of pH for the adsorption of dye was observed. For this purpose six experiments at different pH for each dye were accomplished. 30 ml of 1×10 mol. dm solution of methylene blue carrying variable pH (1.0 to 6.0) was added in different columns packed with 0.5g adsorbent. Time period for both adsorbent was 3 hours. The results are depicted in Table 4. Effect of Temperature: For the determination of the effect of temperature on the adsorption of dye under optimize adsorption conditions, the adsorption process was proceeded at 293-323 K temperatures at the step of 10 K ± 0.2 C Adsorption of mehtylene blue... A. Rasheed Khan, Hajira Tahir, Fahim Uddin*; Uzma Hameed 31 Table 3: Optimization for the stay time in the adsorption of methylene blue from aqueous solution on the surface of sheep wool fiber and cotton fiber Sheep wool fiber Cotton fiber Time (min) Ce mol/L %adsorption KD Ce mol/L %adsorption KD 5.0 0.113 42.00 50.40 10 0.335 77.70 29.10 0.192 72.00 86.40 20 0.336 84.90 31.80 0.125 47.00 56.40 30 0.356 82.50 30.90 0.131 49.00 58.80 40 0.351 81.40 30.50 0.137 51.00 61.50 50 0.324 75.10 28.10 0.073 27.30 32.70 60 0.361 83.70 31.30 0.052 19.40 23.30 70 0.340 78.80 29.50 80 0.356 82.50 30.20 90 0.067 25.00 30.00 Amount of adsorbent = 0.5g , Volume of adsorbate =30ml , Concentration of adsorbate = 6×10 mol. dm (Sheep wool fiber), 3×10 mol. dm (Cotton fiber) , Time= 20 minutes (Sheep wool fiber), 10 minutes (Cotton fiber) pH = 5.0(Sheep wool fiber) and 3.5 (Cotton fiber) Table 4: Optimization for the pH in the adsorption of methylene blue from aqueous solution on the surface of sheep wool fiber and cotton fiber for 3 hours Sheep wool fiber Cotton fiber Buffer pH Ce mol/L %adsorption KD Ce mol/L %adsorption KD 1.0 0.403 77.20 46.30 0.192 19.20 11.50 2.0 0.603 39.70 23.80 0.230 17.60 10.60 3.0 0.786 21.40 12.80 0.175 14.70 8.850 3.5 0.733 56.70 33.70 0.865 59.60 35.70 4.0 0.821 74.90 44.90 0.770 45.50 27.30 5.0 1.00 81.90 49.10 0.520 34.20 20.50 6.0 0.582 60.70 36.40 Amount of adsorbent = 0.5g , Volume of adsorbate =30ml , Concentration of adsorbate = 1×10mol. dm Time= 3h