Rapid Decoloration of Rhodamine B in Fe(III)/Peroxymonosulfate Process in Presence of Ascorbic Acid

Generally, Fe(II) has an efficiently catalytic activity toward peroxymonosulfate (PMS), but the slow conversion of Fe(III) to Fe(II) and production of iron sludge impede the practical application of Fe(II)/PMS system. In this work, ascorbic acid (AA), a complexing agent and reductant, was introduced to Fe(III)/PMS process to facilitate the Fe(III) reduction. The decoloration of rhodamine B (RhB) was obviously enhanced in Fe(III)/PMS process with the addition of AA. Fe(III)-AA complex was firstly generated in Fe(III)/AA/PMS process via the complexation and then was reduced to Fe(II), which could catalyze PMS to yield oxidative species. Fe(IV), sulfate radical (SO 4 •− ) and hydroxyl radical ( • OH) were the working oxidants for RhB decoloration in this system, and SO 4 •− played a major role. Increasing Fe(III), AA or PMS dosage was beneficial to RhB decoloration, but their excessive concentration would hinder RhB decoloration. The existence of HCO 3 − , SO 4 2− or FA in this system showed an inhibition effect on RhB decoloration, while a facilitation effect was obtained when the high concentration of Cl − was present. This research offers a way to improve PMS activation by Fe(III) and a technology for eliminating the refractory organic pollutants from the contaminated water.