Dechlorination of 3,3′,4,4′-tetrachlorobiphenyl (PCB77) in water, by nickel/iron nanoparticles immobilized on L-lysine/PAA/PVDF membrane

In this study, the dechlorination of chlorinated hydrocarbon 3,3′,4,4′-tetrachlorobiphenyl (PCB77) by bimetallic Ni/Fe nanoparticles immobilized on L-lysine/PAA/PVDF membrane was investigated at ambient conditions through the batch mode operation. The membrane support polyvinylidene fluoride (PVDF) was modified by in situ polymerization of acrylic acid in aqueous phase, then L-lysine was covalently bonded to the polymerized acrylic acid chains with the aid of a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC). The modification procedure involved cationic ion exchange with Fe2+, reduction to Fe0 with NaBH4 and finally deposition of Ni0. The scanning electron microscopic images showed that the Ni/Fe nanoparticles were successfully immobilized inside the membrane using the polyacrylic acid (PAA) as an inter-linkage between PVDF and L-lysine. A systematic characterization of the composite was performed using ATR-FTIR, HRSEM, EDX, HRTEM, XRD, and contact angle measurement studies and a relatively uniform distribution of Ni/Fe was found in L-lysine/PAA/PVDF membrane because of its hydrophilic nature. The obtained Ni/Fe nanoparticles consist of Fe0 core surrounded by the Ni0 shell. The diameter of Ni/Fe nanoparticles was predominantly within the range 20–30 nm. The immobilized Ni/Fe nanoparticles exhibited a good reactivity towards the dechlorination of the chlorinated hydrocarbon since the concentration of the PCB77 was decreased by catalytic dechlorination with Ni/Fe nanoparticles inside the L-lysine/PAA/PVDF membrane. Dechlorination efficiency of 98% was achieved within 9 h.