Study On The Removal Of Diuron By The Coagulation Sedimentation And The Activated Carbon Adsorption

More and more people focus on the environmental pollution caused by pesticides. The pesticides have high toxicity,moreover, they will remain in the vegetables, fruits and other food for a long time and have adverse health effects on human beings. The diuron is one of the most common phenylurea herbicides. There are some studies showing that NDMA, one of the N-DBPs, can be formed during the chlorine disinfection process of diuron with highly carcinogenic. Therefore, in this research, we apply the coagulation and activated carbon adsorption, two physical methods, to remove the diuron. Research results show that:1、We selected different optimum dosage of coagulants(10%PAC、5%PAFC and10%SPFS)、optimum dosage of coagulants aids(0.1%PAM and1%sodium alginate) and pH as influencing factors for six L16(43) orthogonal tests, obtaining the better experimental conditions. Then according to parallel tests, we found six optimum experimental conditions:①The average removal rate is57.75%on the condition:the dosage of10%PAC and0.1%PAM are200mg/L and1.0mg/L respectively, and pH of the wastewater is5.0;②The average removal rate is58.70%on the condition:the dosage of10%PAC and0.1％PAM are200mg/L and40mg/L respectively,and pH of the wastewater is8.0;③The average removal rate is56.58%on the condition:the dosage of5%PAFC and0.1%PAM are300mg/L and3mg/L respectively,and pH of the wastewater is8.0;④The average removal rate is53.22%on the condition:the dosage of5%PAFC and1%sodium alginate are250mg/L and20mg/L respectively,and pH of the wastewater is7.0;⑤The average removal rate is55.67%on the condition:the dosage of10%SPFS and0.1%PAM are150mg/L and1mg/L respectively,and pH of the wastewater is7.0;⑥The average removal rate is49.17%on the condition:the dosage of10%SPFS and1%sodium alginate are100mg/L and20mg/L respectively,and pH of the wastewater is8.0;2、We applied the activated carbon to remove the diuron from the slightly polluted wastewater. Through the experiments of optimum dosage of activated carbon, the adsorption equilibrium, the pH、temperature factors and adsorption equilibrium to analysis the process of adsorption of diuron by activated carbon deeply, concluding that:for the2mg/L of diuron simulated wastewater, the activated carbon optimum dosage is0.1g.Adsorption equilibrium time is7h, and meet the trend of the overall adsorption process. The influence of the wastewater pH is more obvious, and the amount of adsorption reach the maximum when pH=3.5. Activated carbon adsorption process is more suitable to the Freundlich isotherm. The adsorption kinetics experiments and model linear fit result show that, for the adsorption kinetics process of activated carbon adsorption of the diuron from the wastewater, the Lagergren pseudo-first-order kinetic model is more suitable to describe it.