Promoting effect of EDTA on catalytic activity of highly stable Al–Ni bimetal alloy for dechlorination of 2-chlorophenol

Abstract

Abstract The low-cost Al–Ni alloy particles could achieve high dechlorination activity for 2-chlorophenol (2-CP) with the addition of tetrasodium EDTA (EDTA-4Na) in this study. The species of chelating agent, pH values, and the dosages of chelating agent were investigated for their effects on dechlorination efficiency of 2-CP in solution. EDTA-4Na presented the highest promoting effect for Al–Ni alloy in dechlorination process compared with other chelating agents, which is closely correlated with the conditional stability constant ( K f ′ ) of chelates formed. The optimized result showed that 0.389 mM of 2-CP was completely dechlorinated into phenol using 10 g L −1 of Al–Ni alloy and 10 mM of EDTA-4Na at initial pH 11.0 within 45-min reaction. Recycling tests of the alloy particles showed that Al–Ni alloy coupling with EDTA in aqueous solution exhibited high dechlorination activity and stability before being exhausted. The maintenance of Al–Ni alloy activity for dechlorination was mainly attributed to the promoting effect of EDTA-4Na on Al corrosion, the inherent structure of alloy with Ni crystal homogeneously dispersing into Al substrate, and the change of its surface morphology with more active sites formed by EDTA corrosion.