Zhang Pengfei, Avudzega David M, Bowman Robert S
Department of Earth and Atmospheric Sciences, City College of New York, New York, NY 10031, USA.
J Environ Qual. 2007 May 25;36(4):1069-75. doi: 10.2134/jeq2006.0432. Print 2007 Jul-Aug.
We investigated the potential of using surfactant (hexadecyltrimethylammonium)-modified zeolite (SMZ) as an inexpensive sorbent for removing perchlorate (ClO(4)(-)) from contaminated waters in the presence of competing anions. In batch systems, the presence of 10 mM OH(-) (i.e., pH 12), CO(3)(2-), Cl(-), or SO(4)(2-) had little effect on the sorption of ClO(4)(-) by SMZ, indicating that the sorption of ClO(4)(-) by SMZ was very selective. The presence of 10 mM NO(3)(-), however, reduced the sorption of ClO(4)(-) at low initial concentrations. The maximum sorption capacity for ClO(4)(-) by the SMZ remained relatively constant (40-47 mmol kg(-1)), in the absence or presence of the competing ions. In flow-through systems, ClO(4)(-) broke through the SMZ columns much later than other anions present in an artificial ground water. The affinity of the anions for SMZ followed the sequence of ClO(4)(-) > > NO(3)(-) > SO(4)(2-) > Cl(-). Perchlorate loading under dynamic flow-through conditions was 34 mmol kg(-1), somewhat less than the maximum loading of 40 to 47 mmol kg(-1) determined by the batch method. Less than 1% of previously sorbed ClO(4)(-) was leached out by ultra-pure water, by extraction fluid #1 of the standard toxicity characteristic leaching procedure (TCLP), or by a solution of 0.28 M Na(2)CO(3)/0.5 M NaOH. About 40% of the previously sorbed ClO(4)(-) was leached out from SMZ by a 0.5 M NO(3)(-) solution. The exchange of ClO(4)(-) with NO(3)(-) corroborated results of the batch tests where NO(3)(-) was shown to compete with ClO(4)(-) sorption.
我们研究了使用表面活性剂（十六烷基三甲基铵）改性沸石（SMZ）作为一种廉价吸附剂，在存在竞争阴离子的情况下从受污染水体中去除高氯酸盐（ClO₄⁻）的潜力。在间歇系统中，10 mM OH⁻（即pH 12）、CO₃²⁻、Cl⁻或SO₄²⁻的存在对SMZ吸附ClO₄⁻的影响很小，这表明SMZ对ClO₄⁻的吸附具有很强的选择性。然而，10 mM NO₃⁻的存在会降低低初始浓度下ClO₄⁻的吸附。在不存在或存在竞争离子的情况下，SMZ对ClO₄⁻的最大吸附容量保持相对恒定（40 - 47 mmol kg⁻¹）。在流通系统中，ClO₄⁻突破SMZ柱的时间比人工地下水中存在的其他阴离子要晚得多。阴离子对SMZ的亲和力顺序为ClO₄⁻ >> NO₃⁻ > SO₄²⁻ > Cl⁻。动态流通条件下高氯酸盐的负载量为34 mmol kg⁻¹，略低于通过间歇法测定的40至47 mmol kg⁻¹的最大负载量。超纯水、标准毒性特性浸出程序（TCLP）的萃取液#1或0.28 M Na₂CO₃/0.5 M NaOH溶液浸出的先前吸附的ClO₄⁻不到1%。约40%先前吸附的ClO₄⁻被0.5 M NO₃⁻溶液从SMZ中浸出。ClO₄⁻与NO₃⁻的交换证实了间歇试验的结果，其中NO₃⁻被证明与ClO₄⁻吸附存在竞争。
