Biosorption-Incineration-Leaching-Smelting Sequential Process for Ru Recovery from Ru-Bearing Acetic Acid Waste Solution

Abstract

This study introduces a new method for the recovery of metallic Ru from Ru-bearing acetic acid waste solution through a biosorption-incineration-leaching-smelting sequential process. As a powerful biosorbent for binding anionic Ru complexes, polyethylenimine- (PEI-) modified bacterial biosorbent fiber (PBBF) was prepared by extruding a blended slurry of chitosan and Corynebacterium glutamicum biomass in fiber form, applying a PEI coating, and cross-linking with glutaraldehyde. Biosorption isotherm studies revealed that PBBF showed a much higher Ru uptake than raw biomass and anion-exchange resin (Lewatit MonoPlus M600). In addition, PBBF was stable at water contents less than 10%, and the Ru uptake of PBBF increased with increasing temperature. After sorption, Ru-sorbed PBBF was incinerated, and the metallic form of Ru was recovered. Several oxidizing agents, such as sodium hypochlorite, potassium permanganate, and aqua regia, were sequentially used to leach out the impurities from the ash. Through X-ray photoelectron spectroscopy analysis, it was found that the recovered Ru was present in solid metallic form. According to X-ray fluorescence spectrometry analysis, the metallic Ru achieved from this method had a high weight percentage of 99.75%.