二次活化活性炭对饮用水中溴酸盐的去除

Bromate-removing from the drinking water by zinc chloride-treated activated carbon

采用氯化锌对活性炭(AC)进行了二次活化,制得二次活化的活性炭(ZC-AC),对比了ZC-AC和AC对水中溴酸盐(BrO_3^-)的去除活性,并对ZC-AC的高活性进行了BET、SEM、XRD表征分析,同时考察了ZC-AC的稳定性及反应条件对ZC-AC去除BrO_3^-的影响。结果表明,ZC-AC对BrO_3^-的去除活性是AC的6.4倍;ZC-AC重复使用4次后,对BrO_3^-仍保持了89%的去除率;在BrO_3^-初始质量浓度为1000 μg/L时ZC-AC达到最大吸附容量,即每克ZC-AC处理8.23mg BrO_3^-;共存阴离子对ZC-AC去除BrO_3^-都有抑制作用,其抑制作用从大到小为SO_4^(2-)、PO_4^(3-)、NO_3^-、Cl^-、F^-、Br^-,而含氧酸盐对去除BrO_3^-有明显的抑制作用,主要是含氧酸盐与BrO_3^-发生了表面活性位的竞争;溶液的pH值大于10会极大地抑制ZC-AC去除BrO_3^-。

The article is to present the results of our hatch experimetals conducted to investigate thc effect of hromate removal capacity by the virgin grander activated carbon （AC） and the zine chloride treated activated carbon （ZC- AC）. The comparative study between AC and ZC - AC has made us conclude that the treatment with ZnCl2 can significantly improve the adsorption efficacy of AC. For example, the removal rate of BrO3^- by AC and ZC AC was found to be equal to 14.69% and 93.71%, respectively. The ahnve said removal behavior can be explained by the two fullowing facts. First, nmre mieropores were formed after the treatment of ZnCl2 because ZnCl2 is well known to be able to promote the micropnrosity, Seeundly, the presence of zinc oxide can be used to act as the adsorbent for bromate anions. Both ZC - AC and AC are characterized by scanning electronic microscopy （SEM）, Brunauer Emmett Teller （BET） N2 -gas adsorption, surface area and X-ray diffraction （XRD）. The removal of BrO3^- by ZC - AC is likely to remain efficient after a hatch of four repeated experiments with slight decrease from 93.71% to 14.69% . In addition, we have also studied the effect of pH, initial bromate concentration, co-existing anions on the bromate adsorbed by ZC - AC. Thus, the results of our batch experiments show that the capaeity of BrO3^- the adsorption for ZC AC can be increased to its maximum, that is, 8.23 mg/g, when the initial BrO3^- concentration is 1 000 μg/L. The coexisting anions can also inhibit the bromate from adsorbing to ZC - AC in the order of SO4^2- 〉PO4^3- 〉NO3^- 〉Cl^- 〉F^- 〉 Br^- , while the pH value has also had significant effect on the removal of BrO3^- by ZC AC. Last of all, maximal percentage removal capability of bromate was tound taking plaee between pH 6.4 9.8 for lower pH and higher basle pH was not favorable for the higher-rate bromate adsorption.