Conversion of chromium from simulated batik waste through the utilization of gamma irradiation technique to produce potassium dichromate

Chromium (Cr(Ⅵ)) is a type of hazardous waste generated by the batik industry. In this study, the gamma irradiation technique was applied to precipitate chromium in simulated batik mordanting waste. Gamma irradiation induced the generation of active species, including hydrated electrons (eaq-) and hydrogen atoms (•H), which effectively reduced Cr(Ⅵ) ions to Cr(Ⅲ) and caused precipitation as chromium hydroxide (Cr(OH)3) upon interaction with hydroxide ions (OH-). Optimal precipitation conditions were observed at 40 kGy irradiation dose, 4M of 2-propanol work as scavenger, and pH 9. The applied reaction conditions led to a decrease in the concentration of Cr(Ⅵ) in simulated waste from 11,673 ppm to 177 ppm. The Cr(OH)3 was calcined to form chromium oxide (Cr2O3) and through a chemical process was synthesized back into K2Cr2O7 with the total Cr recovery of 63.39%. SEM and FTIR analysis indicated that the recovery of Cr(Ⅵ) into Cr(OH)3, Cr2O3, and K2Cr2O7 can be considered successful.