低阶煤对六价铬的高效吸附及还原脱毒

Efficient Adsorption and Reduction of Hexavalent Chromium by Low Rank Coals

采用低阶煤(Low Rank Coals,LRCs)作为吸附剂去除水溶液中的六价铬(Cr(VI))。通过实验探究了初始溶液浓度、吸附剂用量、pH值及离子强度等影响因素对LRCs吸附Cr(VI)性能影响。结果表明,LRCs对Cr(VI)的最大单位吸附容量为43.066 mg/g。Cr(VI)的去除效率(Removal Efficiency,RE)随着LRCs投加量的增加而增加。相反,RE随pH值的增加而降低,且在pH值>2时从99%急剧下降至18%。此外,Cr(VI)在LRCs上的单位吸附量(the unit adsorption capacity,q_(e))随Cl^(-)浓度的增加而显著降低。吸附过程符合Freundlich等温模型和准二级动力学模型。结合实验结果和表征分析,认为LRCs吸附Cr(VI)的机理为:静电吸引、离子交换及还原作用。

Low Rank Coals(LRCs)were used as adsorbents to remove hexavalent chromium(Cr(VI))from aqueous solution.The effects of the initial solution concentration,the amount of adsorbent,pH and ionic strength on the adsorption of Cr(VI)by LRCs were studied.The results showed that the maximum unit adsorption capacity of LRCs for Cr(VI)was 43.066 mg/g.The removal efficiency(Removal Efficiency,RE)of Cr(VI)increases with the increase of the amount of LRCs added.In contrast,RE decreases with increasing pH and drops sharply from 99%to 18%at pH>2.In addition,the unit adsorption capacity(q_(e))of Cr(VI)on LRCs decreased significantly with increasing Cl^(-)concentration.The adsorption process conforms to freundlich isothermal model and pseudo-second-order kinetic model.Combining experimental results and characterization analysis,it was concluded that the mechanism of adsorption of Cr(VI)by LRCs was:electrostatic attraction,ion exchange,and reduction.