Characteristics of Novel Extraction and Photoinduced Precipitation Approach by PEG/SA and Fluorescence Monitoring of Cr(VI)

Abstract

A novel route based on biohydrogel sodium alginate (SA) for extraction by an aqueous two-phase system (ATPS), recovery of chromium by a photoinduced precipitation process, and monitoring of the process by fluorescence spectroscopy (F-S) was developed. The processes were explored by means of FTIR, micro-FTIR, XPS, and F-S, and the roles of polyethylene glycol and sodium alginate (PEG/SA) in the process were analyzed. Results showed that SA acted as an extractant to form a complex with Cr(VI). The maximum extraction point appeared at pH 5.50, and its kinetic equation showed that CCr(VI) was the key point that controls the reaction. Cr(VI) was reduced to Cr(III) within 10 min of 300 W solar irradiation in the presence of PEG. Then coprecipitation of water-insoluble polynuclear complexes consisting of SA and trivalent and hexavalent chromium was completed. The biohydrogel from SA underwent a static quenching process, and the extraction process and phase diagram can be monitored by F-S. It belongs to the trans...