Research On Bromate Removal By Macroporous Strong Anion Exchange Resin

With the development of water treatment technology and public attention to drinking water quality, ozone is widely applied in drinking water treatment. But in recent years, research has revealed that ozonization will produce many disinfection by-products. Bromate, which is the disinfection by-product of water containing a certain concentration of bromide ions by ozone oxidation, will bring certain harm to human body. The international agency for research on cancer(IARC) has defined bromate as Group 2B(higher carcinogenic potential) potential carcinogen, the newly revised "drinking water health standards"(GB5749-2006) specified that the maximum contaminant level of bromate in drinking water was 10?g/L. Therefore, it is urgent to explore effective method for bromate removal from drinking water. Macroporous anion exchange resin as an efficient adsorbent achieved good results in the removal of nitrogen and phosphorus. In this paper, macroporous anion exchange resin(D201) was chosen as the adsorbent to study the characteristics of static and dynamic adsorption behavior of bromate on the resin.The static study of bromate removal by macroporous anion exchange resin(D201) mainly included the effect of single factor, such as resin dosage, reaction time, initial concentration, p H, temperature and coexisting ions, the analysis of kinetics, thermodynamics and isotherm, as well as the resin regeneration research. The results of static adsorption experiments showed that: the adsorption capacity of resin to bromate increased with resin dosage increasing. Adsorption equilibrium was reached within about five hours. The increasing initial concentration can accelerate the adsorption rate of bromate on resin. The residual concentration of bromate was under the maximum contaminant level of 10?g/L while the p H varying from 4.50 to 9.92. Rising temperature is conducive to the adsorption of bromate on resin. The influence of co-existing anion on bromate removal accorded with the following order: NO3->SO42->Cl-. Kinetics data showed that the pseudo-first-order kinetics(R2>0.95) could better describe the adsorption of bromate in the resin. Freundlich and Redlich Peterson model fitted well with the isotherm data. Thermodynamic studies Gibbs free energy ?G ° <0, showed that bromate adsorbed in resin was spontaneous, thermodynamically feasible, enthalpy value ?H °> 0 indicated that bromate adsorption onto the resin was an endothermic process. Resin maintained a removal rate of 96% after five cycle regeneration.Meanwhile, the effects of flow rate, column height and initial concentration on bromate dynamics adsorption on macroporous anion exchange resin(D201) were studied. Thomas model and Yoon-Nelson model were applied to analysis the dynamic adsorption behavior. Experimental results had shown that: lower flow rates, appropriate higher adsorption column height and lower influent concentration exhibited better treatment performance. Thomas model and Yoon-Nelson model were fitted well with the breakthrough curves of bromate on resin, and the relevant coefficients were above 0.98. The adsorption capacity calc ulated by the Thomas model was some different with the experiment data, breakthrough time for 50% removal rate calculated by Yoon-Nelson model were close to the experimentally measured.