ADSORPTIVE REMOVAL OF PHENOL FROM SYNTHETIC WASTEWATER

Abstract

Phenol is one of the most important organics contributing to environmental pollution. This study elucidates the removal of phenol employing adsorption technique and biological method from synthetic waste water. Since in the prevailing world of commercialization, interest shifts towards economical method, therefore, fly ash (FA), a cheap material, has been used as adsorbent. This study involves the chemical modifications of fly ash by impregnation method using three different metal ions i.e. Al, Fe, and Cu, for phenol removal from synthetic waste water. Characterization of each modified adsorbent was carried out by employing various analytical techniques. Sorption behavior of phenol from synthetic solution containing initial concentration (Co) of 200 mg/I on FA was examined by studying the effect of adsorption parameters: adsorbent dose, pH, contact time, initial concentration and temperature. Impregnation was successful in improving the removal efficiency of FA. Aluminum impregnated fly ash (AFA) was found to show the highest removal which was selected for optimization study and modeling using Central composite rotary design (CCD) by response surface methodology (RSM). Based on CCD design, the quadratic models were developed correlating the adsorption variables to two responses i.e. removal efficiency and adsorption capacity. Analysis of variance (ANOVA) was incorporated to judge the adequacy of model. At Co (200 mg/I), the optimum conditions of 13.63 g/l adsorbent dose, 6.79 h equilibrium time, 5.6 pH and 34.44 °C temperature gave 86.4 % removal efficiency and 12.67 mg/g adsorption capacity respectively. Model prediction was in good agreement with experimental results. Different equilibrium isotherms were examined by using non-linear regression technique and Redlich—Peterson and Toth isotherm was found to best fit the equilibrium data for removal of phenol on AFA. Kinetic and thermodynamic parameters were also evaluated. Pseudo second order was followed for the process on all the adsorbents. Thermodynamic study showed that it is endothermic process. Pseudonionas putida was used for simultaneous adsorption and biodegradation on AFA which showed 94.4 % phenol removal as compared to 85.6 % achieved in adsorption process. Ultimately, the feasibility of using fly ash as cheap adsorbent for its tolerance towards phenol was noted.