Decontamination of pesticide industrial effluent by adsorption-coagulation-flocculation process using biopolymer-nanoorganoclay composite

Release of poorly treated industrial wastewater containing pesticides has adverse effect on aquatic environment. In this study, an attempt was made to evaluate the performance of biopolymer-nanoorganoclay composite based on carboxy methyl cellulose and two nanoorganobentonites viz. DMDA (nanobentonite modified with 35-45 wt% dimethyl dialkyl (C14-C18) amine) and ODAAPS (nanobentonite modified with 15-35 wt% octadecylamine and 0.5-5 wt% aminopropyltriethoxysilane) in the ratio 1:2.5:2.5 for removing nine pesticides, namely atrazine, butachlor, carbendazim, carbofuran, imidacloprid, isoproturon, pendimethalin, thiophanate methyl and thiamethoxam from aqueous solution. The composite dosage was optimized using Jar test in which aluminum sulfate (alum) was used as coagulation/flocculation aid. Decontamination efficiency of the composite was validated in pesticide industrial effluent. Decontamination process was found to be efficient in removing the selected pesticides from water (57-100%) as well as from industrial effluent (63-91%). The prepared composite was very efficient in removing more than 90% of butachlor, isoproturon, pendimethalin and thiophanate methyl from water. Spent or used composite was regenerated by acetone washing followed by thermal regeneration at 200 degrees C. The regenerated composite was able to maintain 57-97% of its initial pesticide removal efficiency even after second regeneration. Preparation and regeneration of the composite is easy and effective making the composite a promising adsorbent for pesticides.