(380ad) Phthalate Degradation Using a PVDF Biocatalytic Membrane

Phthalic acid esters (PAEs), consisting of a benzene ring attached to two ester groups, are a concern for humans due to harmful effects on the human body. PAEs are endocrine disruptors and cause irreversible damage to the biological reproductive system. Recently PAEs were listed as priority pollutants by the United States Environmental Protection Agency. PAEs are commonly used in plastic industry as plasticizers to make the plastics more flexible; however, the PAES can escape from the bulk, migrate to the surface, and enter the environment. Enzyme immobilization is a novel technology and efficient technique which was recently used for PAEs degradation. Several support materials such as carbon nanotubes, metal nanoparticles, porous silicate, and various polymers were used in enzyme immobilization. In this study, Lipase Candida Rugosa enzyme is covalently attached to a PVDF membrane to give the membrane biodegradation capabilities. Lipase is used to decompose diisononyl phthalate (DINP) in an alcohol/aqueous media. We have used the “grafting from” approach to graft the primary amine functionalities on the PVDF surface using methacrylamide (MAA). The functionalized membranes were modified with glutaraldehyde, a coupling agent commonly used for enzyme attachment. Then, the glutaraldehyde-modified membranes were treated with Lipase to attach to the membrane surface to create an enzyme-immobilized membrane. The SEM, water contact angle, BET, and ATR-FTIR techniques were used to characterize the membranes. Enzyme loading on the membrane was calculated by using a mass balance utilizing the Nanodrop concentration measurement. Electrospray ionization (ESI) test was used to measure the ratio of DINP and bis(2-ethylhexyl) phthalate (standard solution) before and after contact with the enzyme-modified membrane. The initial results show that Lipase was loaded onto the membrane with a maximum loading capacity of about 20.7 g/m² of membrane when a 5 g/L enzyme solution was used. ESI results showed a maximum of 55% degradation when a 10 ppm DINP was used in the water/ethanol media.