Rapid and complete dechlorination of PCP in aqueous solution using Ni–Fe nanoparticles under assistance of ultrasound

The Ni–Fe bimetallic particles have been laboratory prepared using sodium borohydride (NaBH4) as the reductant to reduce Ni2+ and Fe2+ in aqueous solution simultaneously, and characterized by TEM, XRD, BET and XPS. The particles were proved to be nanoscale amorphous alloy with an average diameter of about 30 nm and a BET surface area of 20.9 m2 g−1. Experiments for dechlorination of pentachlorophenol (PCP) by the Ni–Fe bimetallic nanoscale particles in aqueous solutions were carried out under the enhancement of ultrasound. Major factors that influence the dechlorination efficiency, such as initial pH value, Ni content in the Ni–Fe particles, and output power of ultrasonic irradiation, were investigated. The results indicated that Ni–Fe nanoscale bimetallic particles were very effective for the dechlorination of PCP. Dechlorination efficiency was 46% in 30 min under the optimal condition without assistance of ultrasound, whereas it increased to 96% when ultrasonic irradiation was present. Initial pH value showed apparent effect on the dechlorination. As the pH varied from acidic condition to neutral condition, the dechlorination efficiency decreased dramatically. In addition, the dechlorination efficiency was improved with increased Ni/Fe ratio and ultrasonic output power. Less chlorinated phenols including tetrachlorophenol, trichlorophenol, dichlorophenol, monochlorophenol were formed during the initial reaction, and phenol was determined by GC–MS as sole product in the end of reaction.