Activation of periodate by iron-containing sludge from groundwater treatment plants for degradation of methylene blue in wastewater

Currently, there are well-operated iron removal water plants in the northeast region of China. Among them, the backwash process produces a large amount of iron-containing sludge (IS) year by year, which can cause some harm to the environment if not treated. The main form of existence for IS is amorphous gamma-FeOOH, and this work demonstrates that IS is a natural and highly active catalyst for periodate(PI). Moreover, IS showed strong stability in environmental factor effects and reproducibility experiments. EPR with quenching experiments proved that IS could activate PI to produce center dot OH, O-2(center dot-), O-1(2), and IO3 center dot. In the degradation experiments where methylene blue was chosen as the model pollutant, IO3 center dot, and O-1(2) were the substances that served the prominent role in degradation. This work provides an inexpensive and feasible way to dispose of waste iron-containing sludge from water plants and provides fundamental insights into the degradation mechanism of organic pollutants through the activation of PI by IS.