Novel Biopolymer-Nanoorganoclay Composites for the Decontamination of Pesticides from Water

Three biopolymer-nanoorganoclay composites were prepared employing carboxy methyl cellulose (CMC) and three nanoorganobentonites [nanobentonite modified with (i) 35–45 w % dimethyl dialkyl (C₁₄-C₁₈) amine (DMDA) and (ii) 15–35 wt % octadecylamine and 0.5–5 w % aminopropyltriethoxysilane (ODAAPS) alone and in equal combination] by solution intercalation method. These were screened for pesticide removal efficiency and the best composite (1: 2.5: 2.5 CMC-DMDA-ODAAPS) was characterised by FTIR spectroscopy. The adsorption study was conducted using a mixture of 9 pesticides namely atrazine, butachlor, carbendazim, carbofuran, imidacloprid, isoproturon, pendimethalin, thiophanate methyl and thiamethoxam, and the sorption data fitted into Freundlich, Langmuir, Temkin and Dubinin-Radushkevich isotherms. Langmuir isotherm was found to be the best fit model and the process of adsorption was found to be physical. The composite removed the tested pesticides with the highest adsorption of thiophanate methyl and the lowest of atrazine. Varying affinity of pesticides for the composite was due to their varying molecular structure and the surface properties of the composite.