有机酸-铁改性活性炭去除饮用水中的砷

Granular activated carbon tailored by organic acid-Fe for arsenic removal

利用有机酸(柠檬酸和EDTA)螯合铁加载来改性活性炭,采用动态活性炭小柱进行吸附穿透实验来检测改性后活性炭对砷的吸附能力.研究表明,加载到活性炭上的铁的量随着有机酸和铁浓度增加而增加,在EDTA和铁的浓度分别为0.1mol/L时,活性炭上的铁含量从未加载时的0.24%升至6.18%.改性后的活性炭对砷吸附能力有显著增加,EDTA-Fe改性后的活性炭对As(V)和As(III)穿透时,运行的床体积达到未改性活性炭的10倍.一般情况下,低pH对As(V)的吸附有利.在水体常见pH值范围内(pH 6～9),As(III)的吸附受到影响较小.活性炭上用有机酸螯合法加载的铁大部分以不定形的形式存在,且晶体化效果不明显.

This research attempted to tailor granular activated carbon（GAC） with organic acid（citric acid and EDTA） and iron.Rapid small-scale column tests（RSSCTs） were set up to appraise the adsorption breakthrough behavior of those modified carbons.Amount of iron thus loaded increased with the increase of organic acid and iron concentration.At concentrations of 0.1 mol/L EDTA and iron respectively,the tailored carbon obtained an iron content of 6.18% as compared to that of 0.24% for virgin GAC.There was remarkable improvement in adsorption capacity for arsenic after carbon tailoring.EDTA-Fe tailored GACs showed bed volumes to breakthrough 10 times that of virgin GAC both for As（V） and As（III）.In general,As（V） adsorption decreased with the increase of pH.In contrast,adsorption of As（III） was found to be less dependent on pH at pH 6 to 9.Also,the irons loaded onto GAC by this organic acid-Fe method were mostly amorphous and were stable.