Adsorption of chemical oxygen demand from textile industrial wastewater through locally prepared bentonite adsorbent

Abstract

The rapid expansion of industrialization has a significant contribution to the economic development of many nations. But, the untreated discharge from the textile factory is severely impacting freshwater and public health. Therefore, this study was aimed to prepare activated bentonite for removal of chemical oxygen demand (COD) from textile industrial wastewater, and the optimization process was studied using design expert software version 11. The activation of the bentonite was performed using diluted sulfuric acid and followed by a thermal process. Adsorbent characterization was carried out using the proximate analysis (moisture content), bulk density, BET method of specific surface area, scanning electron microscope, Fourier transform infrared spectroscopy, and X-ray diffraction. The COD and pH of textile industrial effluent were 569 ± 23 mg/L and pH 6 ± 0.3, respectively. The specific surface area of modified bentonite was found to be 265 m2/g. Maximum COD removal of 76.5% was recorded at the optimum condition of contact time 120 min., pH 10, and adsorbent dosage 2 g, whereas the maximum predicted COD removal was 76.0%. COD removal was highly influenced by the adsorbent dose described by the regression analysis (R2 = 0.98). Increasing the adsorption factors and interaction effects resulted in increasing the COD removal and vice versa, but the interaction effect between the pH and adsorbent dose was inversely proportional to COD removal. Generally, the adsorption results were encouraging and modified bentonite is a promising candidate to be implemented for organic matter removal from textile industrial wastewater.