Cr(VI) reduction in aqueous solutions by using synthetic iron sulphide.

This study was carried out to reduce Cr(VI) in aqueous solutions by using synthetic iron sulphide. For that purpose, the effects of acid content, contact time, initial Cr(VI) concentration, temperature of the solution, particle size and dosage of iron sulphide on the Cr(VI) reduction were investigated. Reduction extent of Cr(VI) is, to a great extent, dependent on the amount of acid. The Cr(VI) in the solution containing two times the H2SO4 with respect to stoichiometric amount of Cr(VI) was completely reduced within 45 min by using 2.5 g litre(-1) iron sulphide at 25 degrees C. The reduction efficiency of Cr(VI) was increased with temperature of solution. The variation in particle size of iron sulphide did not affect the reduction yield of Cr(VI). The total reduction capacity of synthetic iron sulphide was found to be 237.6 mg Cr(VI) g(-1). The results related to shrinking particle model showed that the reduction reaction was chemically controlled and activation energy for theprocess was calculated as 38.4 kJ mol(-1).