Study On The Adsorption Characteristics Of Mg-Al-Fe Hydrotalcite To Chlorite And Chlorate

There is a direct relationship between the safety of drinking water and human life and health.Chlorine dioxide（ClO₂） is a relatively advanced disinfectant developed and applied by humans.It has the characteristics of high efficiency,fast,broad spectrum,long-lasting and safe.The fourth-generation disinfectant recognized on the market,however,will also produce chlorite（ClO₂^-）and chlorate（ClO₃^-） that are harmful to human health.The current"Sanitary Standards for Drinking Water"in China also stipulates two The content of these substances in drinking water should not exceed 0.7mg/L.It is very urgent to carry out research to remove chlorate and chlorite.Therefore,this article intends to carry out experimental research on the removal of chlorite and chlorate by Mg-Al-Fe hydrotalcite to better enhance the safety of drinking water.Mg-Al-Fe hydrotalcites with different metal atomic ratios and roasting products at different temperatures were prepared by co-precipitation method,and experimental studies were carried out to remove chlorite and chlorate in water.Based on the measurement of specific surface area,infrared spectroscopy and other methods,the Mg-Al-Fe hydrotalcite with good thermal stability and good surface properties was obtained through screening.It was found that the hydrotalcite-like effects of different metal atomic ratios,before and after roasting,and at different roasting temperatures were different for the removal of chlorite and chlorate.When the calcination temperature is 500℃and the metal atomic ratio of Mg-Al-Fe hydrotalcite is 8:3:1,hydrotalcite can achieve the best adsorption treatment effect.On this basis,with 3LDHs-500（Mg:Al:Fe=8:3:1,roasting temperature 500℃）as the adsorbent,comprehensive analysis time,3LDHs-500 dosage,chlorite and chlorate The initial concentration,p H value,coexisting anions in aqueous solution,etc.studied the effect of 3LDHs-500 on the adsorption amount of ClO₂^-and ClO₃^- and found that with the increase of the dosage of 3LDHs-500,the removal efficiency of ClO₂^- and ClO₃^-increased,but when When the dosage is above 1.0 g/L,there is little change;and3LDHs-500 has a wide range of p H for adsorption and removal of chlorite and chlorate,and the p H can reach a good removal effect in the range of 4-11;Under the condition that the water temperature is 25℃,the p H is 7.0,the dosage is 1.0 g/L,and the initial concentration of ClO₂^-and ClO₃ -is 5 mg/L,the removal of ClO₂^-and ClO₃^- by 3LDHs-500 can basically reach China’s"According to the requirements of the Sanitary Standards for Drinking Water,the overall removal effect is very good.In addition,the kinetic analysis study shows that the adsorption and removal of ClO₂^-and ClO₃^- by 3LDHs-500 conforms to the second-order kinetic model,and the rate control step is a chemical reaction;the thermodynamic study shows that the adsorption process complies with the Langmuir adsorption isotherm,and the thermodynamic parameters indicate that The removal of ClO₂^- and ClO₃ -is a spontaneously generated exothermic process.