Application Of Persulfate Activated Advanced Oxidation Technology In Wastewater Treatment

Advanced oxidation of persulfate activation is a water treatment method that has been a focus of attention in the environmental field in recent years.It has attracted more and more attention due to its strong oxidation ability and wide application range.Active substances such as SO₄·^-and·OH produced by activating persulfate,with features of mild reaction condition and ease of use,can rapidly oxidatively degrade refractory organic pollutants in wastewater.At present,there are two main methods for activating persulfate including regulating reaction conditions and using activators.As a new type of catalyst,non-metallic carbon materials can efficiently activate persulfate without load and any metal dopant.They have been widely concerned also because of their high specific surface area,good chemical stability and environmental friendliness.This experiment extends the reported artificial synthesis modification method of carbon nanocomposites to the synthesis system of new carbon materials to prepare reduction reaction for graphene oxide composites with high specific surface area adding carbon nitride dopant.C₃N₄ formed under the condition of common annealing can exist on the surface of rGO with the helpπ-πforce.The main conclusions of the paper are as follow.（1）The experiment of using C₃N₄-rGO to activate Na₂S₂O₈ and KHSO₅ to degrade golden orangeⅡin simulated wastewater shows that C₃N₄-rGO（0.05 g/L）can simultaneously activate Na₂S₂O₈（5 mmol/L）and KHSO₅（3 mmol/L）to effectively degrade golden orangeⅡ（30-50 ppm）.The removal rate of C₃N₄-rGO/Na₂S₂O₈ system for golden orangeⅡincreases with time,and 93.3%of golden orangeⅡcan be removed in 160minutes.The C₃N₄-rGO/KHSO₅ system shows more excellent removal ability that 99.0%of golden orangeⅡcan be removed within 30 minutes.Both reactions are compounded with pseudo-first-order kinetics.（2）The quenching experiment shows that the main active materials of the C₃N₄-rGO/Na₂S₂O₈ and C₃N₄-rGO/KHSO₅ systems are SO4·^-and ¹O₂ respectively.At the same time,C₃N₄-rGO/KHSO₅ showed strong resistance to different temperatures,pH values and background anions in the reaction system.（3）The immobilized C₃N₄-rGO materials were prepared by both sodium alginate and polyurethane foam immobilization technology,and the C₃N₄-rGO activation performance was studied.The sodium alginate immobilization technology successfully solved the problem of recycle and reuse of C₃N₄-rGO,but it caused some active sites of C₃N₄-rGO to be covered and could not be effectively reached by persulfate ions in the solution.Polyurethane foam technology can retain the fast catalytic ability of C₃N₄-rGO to a greater extent.This is because the foam structure of polyurethane foam has a high specific surface area,which can provide more contact area to the activator so as to better contact with the persulfate in the solution.