Research Progress on the Removal of Organic Pollutants Removal by Sodium Persulfate and Calcium Peroxide

Abstract

In situ chemical oxidation has the advantages of simplicity, rapidity and thoroughness in removing some biodegradable pollutants (such as trichloroethylene). This paper reviews the research progress of three environmentally friendly oxidants, hydrogen peroxide, calcium peroxide and sodium persulfate, in environmental remediation. This paper mainly traces back the literature from two aspects and summarizes the following: on the one hand, the mechanism of free radicals generated by catalytic activation of hydrogen peroxide, calcium peroxide and sodium persulfate; on the other hand, the main factors affecting the removal of groundwater chlorinated hydrocarbons and other organic pollutants by these three oxidants. Introduction In recent years, along with our country economic and accelerating process of industrialization, "half astern into three", "city back into the garden" policy of further implement, a large number of polluting enterprises were forced to move, the transformation or even shut down production, lead to the city and its surrounding areas appear a large number of industrial pollution of legacy abandoned field[1], causing serious pollution of groundwater and soil, especially with trichloroethylene serious, and the organic pollutant has the "three" effect, a serious threat to human body health[2-4], people urgently need to take quick and effective measures to governance. Method for In-situ Remediation of Chlorinated Hydrocarbon Pollution The treatment of chlorinated hydrocarbon pollution represented by TCE and PCE in groundwater has been studied abroad for decades. The treatment methods include ectopic remediation and in situ remediation. Ectopic remediation requires turning over and excavating the soil, so that the soil structure is damaged and the cost is high, which is suitable for the treatment of areas with small contaminated areas[5].In-situ remediation USES a variety of techniques to degrade or remove contaminants in the source area (aerated zone, groundwater).At present, existing in situ remediation technologies are mainly permeable reactive barrier (PRB) and other technologies that integrate biology, chemistry and physics[7].In situ chemical oxidation (ISCO) is a method of feeding chemical oxidants into the contaminated in-situ regions to remove pollutants. This method relies on the strong oxidation of oxidants to break the chemical bonds of organic compounds such as chlorinated hydrocarbons and make them into harmless substances such as chloride ions, carbon dioxide and water. The chemical oxidants used must have little harm to the environment and be able to effectively destroy pollutants and make the generated oxidation products harmless[8]. Generally speaking, oxidants in ISCO should follow the following principles[9]: first, the reaction must be strong enough to remove pollutants through degradation, evaporation and precipitation, and eliminate or reduce the toxicity of pollutants; Secondly, the oxidants and reaction products should be harmless to human body. Finally, the restoration process should be practical and economical [10].Common chemical oxidants are potassium permanganate (KMnO4), ozone (O3), hydrogen peroxide (H2O2), sodium persulfate (Na2S2O8) and calcium peroxide (CaO2).