Study On The Control Strategies Of Dibromoacetonitrile The Disinfection By-product In Drinking Water

Drinking water is often disinfected with liquid chlorine.Natural organic substances and liquid chlorine in water react to produce a variety of harmful disinfection by-products,which pose a great threat to human health,so how to remove disinfection by-products from drinking water has become a hot spot in the field of water treatment..The liquid-liquid extraction?LLE?-gas chromatography?GC?methods for the detection of dibromoacetonitrile?DBAN?was established by using methyl tert-butyl ether?MTBE?as the extractant,then use 1,2-dibromopropane as the internal standard.The removal effect,influencing factors,removal mechanism and kinetics of disinfection by-product DBAN were studied and analyzed by powdered activated NaOH-GAC adsorption technology,potassium ferrate?K₂FeO₄?oxidation technology and UV degradation technology.In the experiment,the recovery rate of DBAN was95.6%¹01.1%,and the relative standard deviation was 2.34³.14%,and the minimum detection limit was 1.01³.74?g/L.So we found the analytical method has high accuracy and precision.When the granular activated carbon?GAC?was modified by NaOH solution?NaOH-GAC?,the specific surface area of NaOH-GAC was increased by 34.6%.When the addition amounts of GAC and NaOH-GAC were all 0.7 g/L,the adsorption removal of DBAN by the GAC and NaOH-GAC was 82.89%?57.07%with the initial DBAN concentration of 40?g/L,which was 1.45 times greater than that by GAC,so the adsorption effect was greatly improved after modification.The adsorption process of DBAN by the NaOH-GAC could be divided into three periods:rapid adsorption period?0².0h?,slow adsorption period?2.0³.5h?and dynamic balance period?3.5⁴.0h?.And the removal rate of DBAN increased with the increase of NaOH-GAC dosage,pH value and temperature.With the increase of initial concentration,the DBAN adsorption by NaOH-GAC was increased in the beginning and then decreased.This adsorption process could be well described by the Freundlich adsorption isotherm equation and also conformed to the pseudo-second order adsorption dynamics equation.The DBAN removal was improved with the increasing intensity of UV light during the degradation process.It is because that the greater the intensity of UV light was,the more the photon were and increasing the removal rate of DBAN.With initial concentration rising,the removal was boosted.With pH value rising,the removal was enhanced.The photolysis reaction rate at the early stage and the hydrolysis reaction rate were both enhanced in the alkaline environment.Temperature has little effect on the removal rate of DBAN.The DBAN degradation process by UV technology conformed to the first-order kinetics.The DBAN removal was improved with the increase of reaction time.The removal amount was basically saturated after 30 min,and the removal rate was basically stable.The DBAN removal gradually increased with the increase of potassium ferrate dosage.The increase of temperature can enhance the removal ability of potassium ferrate to DBAN to a certain extent,but the promotion effect is limited,and the removal rate of DBAN is not increased much.To some extent,with temperature rising,the removal was enhanced,but the removal rate of DBAN increased slightly.The acidity and alkalinity were both not conducive to the removal of DBAN by potassium ferrate,but the removal effect is best at pH 6.The DBAN degradation process by potassium ferrate conformed to the first-order kinetics.