The Application of the Easily-Obtained Expanded Graphite Synergized with Environment-Friendly Oxalic Acid Under Uv Irradiation in the Hazardous Cr(Vi) Removal

Expanded graphite (EG), an easily-obtained carbon material with the potential of transferring electrons, was originally utilized successfully in the hazardous hexavalent chromium (Cr(VI)) removal by environment-friendly oxalic acid (Ox) under UV irradiation. The effects such as initial concentration of Ox and Cr(VI), EG dosage, co-existing ions, and the reusability of EG on the Cr(VI) removal by the EG+Ox+UV system were investigated. By examining the impact of the starting pH in solution, the trend variation in the solution's pH and Ox concentration during the reaction, the radical scavenging experiments as well as the characterization of EG and EG after reaction, the potential mechanism of Cr(VI) elimination within EG+Ox+UV system was further discovered. The results showed that the EG+Ox+UV system had optimum performance, removing 99.32% of the Cr(VI) (1mM) within 60 min at pH = 3. Three components made up the majority of the potential EG+Ox+UV system's Cr(VI) elimination mechanism: (1) the direct electron transfer (DET) pathway of the EG-Ox-Cr(VI) through the acceleration effect of EG made the majority removal of Cr(VI) under UV; (2) ·CO2− generated from Ox photolysis was used to reduce some Cr(VI); (3) ·CO2− created from Cr(VI)-Ox complexes in the solution through the photoinduced electron transfer (PET) pathway also reduced a little Cr(VI). The advantages of the EG+Ox+UV method for removing Cr(VI) included ease of use and environmental friendliness, indicating a possible application of EG in the treatment of Cr (VI) contamination from water.