Sulfate radicals-based advanced oxidation technology in various environmental remediation: A state-of-the–art review

Sulfate radicals are well-known for their strong oxidation potential (2.60 V), their high reaction rate (106–109 M/s) and longer life span (t_1/2 = 30–40 μs). Owing to the revealed impact it is accomplished by oxidizing, many pesticides, dye, and heavy organic substances such as waste activated sludge (WAS) in a very short time duration. In this review, current research exploration, novel encounters, long pathway of sulfate radicals travelling in environmental management and commercial implementation prominence to persulfate oxidation process are abridged and revealed. A broad evaluation analysis intended in this review established its mesmerizing ascendancies over the conventional persulfate oxidation process with respect to rapid, more efficient, broad pH range and outstanding reaction. Regardless of the abundant improvement attained earlier, there are still several challenges for persulfate activation through transition metals such as heavy metal deposit, metal leaching, removal of sulfate, reusability, etc. To tackle the overhead complications, a novel scenario catalyst with a non-radical pathway, i.e. carbon-grounded catalyst (activated carbon, graphene oxide, biochar, etc.) is under extensive trials. The challenge and practical problems faced in the course of sulfate radical usage are deliberated and the upcoming need for a study to promote full-scale implementations of those approaches are proposed.