Study On The Control Strategies Of Disinfection By-Product Monobromoacetamide In Drinking Water

Disinfection is an essential part of the drinking water treatment process.In addition to its sterilization,it also will produce a series of disinfection by-products（DBPs）,which is harmful to the human.Therefore,researching on the control strategies of disinfection by-products is of great practical significance.In this test,we use methyl tert-butyl ether（MTBE）as the extractant,and use1,2-dibromopropane as the internal standard,then we establish the method of liquid-liquid extraction-gas chromatograph（LLE-GC）to detect the disinfection by-product monobromoacetamide（MBAcAm）.The removal effect,influencing factors,removal mechanism and kinetics of disinfection by-product MBAcAm were studied and analyzed by powdered activated carbon（PAC）adsorption technology,potassium ferrate（K₂FeO₄）oxidation technology and iron/copper（Fe/Cu）catalytic reduction technology.In the experiment,the recovery rate of MBAcAm was 98.65%¹01.60%,and the relative standard deviation was 1.20%³.82%,and the minimum detection limit was less than 1.79μg/L.So we found the analytical method has high accuracy and precision.The experiment shows that the adsorption process of PAC can be divided into three stages,including rapid adsorption period（0²0 min）,slow adsorption period（20¹80 min）and dynamic equilibrium period（180³00 min）.The adsorption rate of PAC becomes faster at first and then becomes slower.The removal rate of MBAcAm gradually increases with the increase of PAC dosage.Under the conditions of initial concentration of 50 ug/L,pH of 7 and temperature of 25°C,when the dosage of PAC was 0.01⁰.06 g,the increase of the removal of MBAcAm was more significant.When the PAC dosage increased to 0.06 g,the removal rate of MBAcAm did not change significantly.The amount of MBAcAm adsorbed by PAC increased with the increase of initial concentration,while the removal rate of MBAcAm decreased with the increase of initial concentration.The increase of pH and the increase of temperature will enhance the adsorption effect of PAC,which is beneficial to the removal of MBAcAm.The reaction process of PAC adsorption of MBAcAm accords with the quasi-secondary adsorption kinetics equation.The removal rate of MBAcAm by using potassium ferrate increased gradually with the increase of reaction time.Under the conditions of initial concentration of 50ug/L,pH of 7,temperature of 25 ^oC,and dosage of potassium ferrate of 0.004 g,the removal capacity was saturated and the removal rate remained stable after 30 minutes.The removal rate of MBAcAm gradually increased with the increase of potassium ferrate dosage.The pH has a great influence on the degradation effect of potassium ferrate.Excessive acidity and alkalinity are not conducive to the removal of MBAcAm by potassium ferrate,and the removal effect is the best when the pH is 6.The increase of temperature can promote the degradation ability of MBAcAm by potassium ferrate to a certain extent,but the promotion effect is limited,and the removal rate of MBAcAm is not increased much.The degradation of MBAcAm by potassium ferrate is consistent with the first-order reaction kinetics.The removal efficiency of MBAcAm by iron is general.Under the conditions of initial concentration of 50 ug/L,pH of 7 and temperature of 25°C,the removal rate is only 53.29%when the reaction lasts 180 minutes.And the addition of copper powder significantly enhances the removal effect of MBAcAm and MBAcAm removal rate can be increased to 83.08%.The dosage of Fe/Cu mixture has a significant effect on the removal effect of MBAcAm.Under the conditions of initial concentration of 50ug/L,pH of 7,temperature of 25°C and mass ratio of 10,when the dosage of Fe/Cu mixture was 2¹0 g/L,the removal rate of MBAcAm increases obviously with the increase of dosage.And when the Fe/Cu dosage was increased to 10 g/L,the removal rate of MBAcAm changed little.Increasing the temperature helps the Fe/Cu mixture to remove the MBAcAm from the solution.The higher the temperature,the greater the removal rate of MBAcAm.With the increase of the initial concentration of MBAcAm,the removal rate generally showed an upward trend,but after the initial concentration reached 80μg/L,the removal rate did not increase significantly.The degradation of MBAcAm by Fe/Cu catalytic reduction technology accords with the first-order kinetics.