Removal of High-Concentration Acid Red 73 in Aqueous Solution by Using the Prepared Fe/Cu Bimetallic Particles

Abstract

In order to further confirm the effect of theoretical Cu mass loading on the catalytic activity of Fe/Cu bimetallic particles, batch experiments using the Fe/Cu bimetallic particles were set up to treat the high concentration Acid Red 73 (AR73) in aqueous solution. The surface morphology and elementary composition of Fe/Cu bimetallic particle with an optimal theoretical Cu mass loading (0.24 g Cu/g Fe) was observed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), respectively. The operating parameters containing concentration of Fe/Cu bimetallic particles, stirring speed, initial AR73 concentration, and pH were investigated thoroughly. The results show that 2,500 mg/L AR73 could be completely removed after only 5 min of treatment by Fe/Cu bimetallic particles under the optimal conditions. The degradation rate of AR73 by using Fe/Cu bimetallic particles could be described by the pseudo-first-order reaction and the degradation capacity of Fe/Cu bimetallic particles was much stronger than that of zero-valent iron (ZVI). The chemical-oxygen demand (COD), total organic carbon (TOC), ultraviolet-visible (UV-vis) spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy were used to analyze the mineralization of AR73. The results suggest that the azo bonds ─N=N─ of AR73 could be decomposed completely by Fe/Cu bimetallic particles, but only a little part of the phenyl and naphthyl could be degraded. Although the Fe/Cu bimetallic system cannot mineralize the AR73 completely, it can transfer AR73 into less toxic products which facilitate to improve the biodegradability of the dyeing wastewater. Thus the Fe/Cu bimetallic system was a promising pretreatment process for the toxic and refractory dyeing wastewater.