Lindane removal by membrane nanofiltration

Abstract

Lindane is the γ-isomer of 1,2,3,4,5,6-hexachlorocyclohexane (HCH) and it has been widely used in the pesticide industry due to its insecticide properties. In the production of lindane, significant quantities of other HCH isomers are generated as byproducts. All these compounds are typically stored in landfills, often with poor management practices. Polyamide membranes, two commercial membranes from Alfa Laval (NF99HF and NF99) and homemade thin film composite membranes prepared by interfacial polymerization on a porous polyimide support, were evaluated for water nanofiltration (NF) of HCH isomers, including lindane. Homemade membranes, with a lindane rejection of 91.3 % and a permeance of 2.7 L·m−2·h−1·bar−1, offered the highest performance in terms of both permeance and rejection. NF99 and homemade membranes were proven to be equally effective in removing α-HCH and β-HCH, showing similar results. Homemade membranes achieved 99.5 and 99.8 % rejections for α-HCH and β-HCH, respectively. Long-term experiments were carried out with NF99 and homemade membranes to assess their stability during filtrations with lindane solutions for up to 214 h. Homemade TFC membrane maintained its initial rejection (ca. 93.5 %) after 214 h, although its permeance decreased over time, ending in 2.5 L·m−2·h−1·bar−1.