Removal of COD, BOD and color of different industrial effluents using activated neem char

Abstract

Characterization of industrial effluent i.e. sugar, dye, paper and pulp; and combined effluent is performed using the standard method, which indicates higher amount of pollutants exist in all the effluents. Adsorptive batch treatment is conducted using activated neem leaf powder (a-NLP), in which adsorbent dose, temperature and contact duration are the factors selected for this study to reduction of COD, BOD and color from individual and combined wastewater. Maximum elimination of COD, BOD and color is attained upto 93.4-82.4, 82.6-75.9 and 93.4-86.1 % respectively from sugar, dye, paper-pulp and combined effluent respectively at dosage of 23 gm/L a-NLP, temperature of 300 K and contact duration of 60 min. Adsorption isotherms such as Freundlich, Langmuir, Dubinin-Raduskevich, Flory-Huggins and Temkin Isotherm are examined in order to explore the adsorption mechanism. The reaction rate is estimated by different kinetic models (Pseudo First-, Pseudo Second-order, Intra-particle and Elovic equation). From correction coefficient value, Freundlich isotherm and Pseudo First-order govern adsorption process. Different thermodynamic parameters such as free energy of adsorption (∆G°), enthalpy change (∆H°) and entropy change (∆S°) are also accessed, which indicates that adsorption is thermodynamically feasible. Solvent desorption is carried out to regenerate this adsorbent for three consecutive cycles.