Study onoxidation flocculation property of coal particles in coking wastewater by potassium ferrate oxidation process

The pollutants from coking wastewater are mainly coal particles with high concentration,small size,lighter weight and taking a small amount of negative charge,and toxic and refractory organic compounds with high concentration and complex composition. Various existing wastewater treatment processes are difficult to effectively remove these contaminants to meet the national standard. Based on the characteristics of combined pollution of inorganic and organic compounds,The dual role of strong oxidation and coagulation of ferrate(VI) salts is developed to degrade the high concentrations of suspended coking coal particles and dissolved organic matter from coking wastewater,so as to provide an important theoretical basis for the further development of coking wastewater treatment technology. The surface zeta potential was selected to reflect the sedimentation performance of coal particles. By measuring the zeta potential under different conditions,the effect of potassium ferrate oxidation on the flocculation and sedimentation of coal particles was studied. The influence of pH,Fe(VI) dosage and inorganic salts on the oxidation process were investigated,and the purification effect of ferrate(Ⅵ) process on the oxidation flocculation of actual coking wastewater was evaluated. The results show that the surface of coal particles was negatively charged,and the lower the pH value of the solution,the closer the Zeta potential on the surface of coal particles approached zero and the better the settlement of coal particles. The addition of ferrate(Ⅵ) has some effect on reducing the absolute value of Zeta potential on the surface of coal particles,and the effect is most obvious when the solution is neutral. Inorganic cations can compress the double electric layers on the surface of coal particles,thus reducing the absolute Zeta potential and improving the settlement of coal particles. The removal rates of COD Cr and SS in actual coking wastewater samples increased with the increase of Fe(Ⅵ)) dosage. When Fe(Ⅵ)) dosage is 2 mmol/L,the actual removal rate of SS in coking wastewater has reached 65.44%,indicating that the flocculation effect of high ferrate process on particulate matter in coking wastewater is good.