Chutia Pratap, Kato Shigeru, Kojima Toshinori, Satokawa Shigeo
Department of Materials and Life Science, Seikei University, Tokyo 180-8633, Japan.
J Hazard Mater. 2009 Feb 15;162(1):204-11. doi: 10.1016/j.jhazmat.2008.05.024. Epub 2008 May 13.
Natural mordenite (NM), natural clinoptilolite (NC), HDTMA-modified natural mordenite (SMNM) and HDTMA-modified natural clinoptilolite (SMNC) have been proposed for the removal of As(V) from aqueous solution (HDTMA=hexadecyltrimethylammonium bromide). Influence of time on arsenic sorption efficiency of different sorbents reveals that NM, NC, SMNM and SMNC require about 20, 10, 110 and 20h, respectively to reach at state of equilibrium. Pseudo-first-order model was applied to evaluate the As(V) sorption kinetics on SMNM and SMNC within the reaction time of 0.5h. The pseudo-first-order rate constants, k are 1.06 and 0.52h(-1) for 1 and 0.5g of SMNM, respectively. The observed k values 1.28 and 0.70h(-1) for 1 and 0.5g of SMNC, respectively are slightly high compared to SMNM. Surfactant surface coverage plays an important role and a significant increase in arsenate sorption capacity could be achieved as the HDTMA loading level on zeolite exceeds monolayer coverage. At a surfactant partial bilayer coverage, As(V) sorption capacity of 97.33 and 45.33mmolkg(-1) derived from Langmuir isotherm for SMNM and SMNC, respectively are significantly high compared to 17.33 and 9.33mmolkg(-1) corresponding to NM and NC. The As(V) uptake was also quantitatively evaluated using the Freundlich and Dubinin-Kaganer-Radushkevich (DKR) isotherm models. Both SMNM and SMNC removed arsenic effectively over the initial pH range 6-10. Desorption performance of SMNM and SMNC were 66.41% and 70.04%, respectively on 0.1M NaOH regeneration solution.
天然丝光沸石（NM）、天然斜发沸石（NC）、十六烷基三甲基溴化铵改性天然丝光沸石（SMNM）和十六烷基三甲基溴化铵改性天然斜发沸石（SMNC）已被用于从水溶液中去除五价砷（HDTMA = 十六烷基三甲基溴化铵）。时间对不同吸附剂砷吸附效率的影响表明，NM、NC、SMNM和SMNC分别需要约20、10、110和20小时才能达到平衡状态。应用伪一级模型评估了在0.5小时反应时间内SMNM和SMNC对五价砷的吸附动力学。对于1克和0.5克的SMNM，伪一级速率常数k分别为1.06和0.52h⁻¹。对于1克和0.5克的SMNC，观察到的k值分别为1.28和0.70h⁻¹，与SMNM相比略高。表面活性剂的表面覆盖率起着重要作用，当沸石上的HDTMA负载量超过单层覆盖率时，砷酸盐吸附容量会显著增加。在表面活性剂部分双层覆盖时，根据朗缪尔等温线，SMNM和SMNC的五价砷吸附容量分别为97.33和45.33mmol·kg⁻¹，与NM和NC对应的17.33和9.33mmol·kg⁻¹相比显著更高。还使用弗伦德利希和杜比宁 - 卡加涅尔 - 拉杜什凯维奇（DKR）等温线模型对五价砷的吸附量进行了定量评估。在初始pH范围6 - 10内，SMNM和SMNC都能有效去除砷。在0.1M NaOH再生溶液上，SMNM和SMNC的解吸性能分别为66.41%和70.04%。
