Transition Metal Activated Persulfate for Environmental Remediation: A Review

Sulfate radical (SO₄^·-)-based advanced oxidation technologies (AOTs) has received increasing attention for environmental remediation in recent years. Persulfate is a general precursor of sulfate radical, and the activation of persulfate to produce sulfate radicals, which can degrade a wide range of pollutants. Transition metal is one of the most popular activators for persulfate activation, and has been studied extensively for pollutant remediation. Meanwhile, the new mechanisms of persulfate activation by transition metal and free radical generation have been explored. For example, it has been reported that the activation of persulfate by transition metal can produce free radicals, singlet oxygen and high valence of ferrous. In addition, soil properties such as organic matter, minerals and pH would influence the remediation efficiency when persulfate activation by transition metal was used in filed applications. Therefore, the present study reviewed some new progresses on persulfate activation by transition metal for environmental remediation and several mechanisms for activation of persulfate by transition metal were discussed. The potential influence of soil properties such as soil organic matter, mineral and soil pH on the application of persulfate remediation was also elucidated.