阴/阳离子有机膨润土制备及其对苯酚吸附性能的实验研究

Preparation of anion-cation organic bentonite and its adsorption of phenol

采用十六烷基三甲基溴化铵(CTMAB)和十二烷基硫酸钠(SDS)对辽宁黑山钙基膨润土进行不同工艺的阴/阳离子有机膨润土制备,并探讨其对被苯酚污染的地下水的吸附机理及其影响因素,为阴/阳离子有机膨润土在污染地下水修复新技术--渗透反应格栅(PRB)中应用的可行性提供必要的技术参数。研究结果表明,制备阴/阳离子有机膨润土的最佳工艺是加入3.0%(质量分数)的Na2CO3钠化,以120CTMAB/15SDS的投加量对其进行阴/阳离子有机改性;阴/阳离子有机膨润土对水中有机物具有协同去除效应;阴/阳离子有机膨润土Na-ACOMMT对苯酚吸附的最佳条件是投加60g/L、80～100目的Na-ACOMMT,在温度20℃、pH为6～8、振荡转速200r/min的条件下振荡30min,此时苯酚的去除率高达78.74%,且吸附等温线符合Langmuir和Fre-undlich方程;Na-ACOMMT可通过多次吸附(累积吸附量为0.0459mg/g)达到降低成本的目的。但是Na-ACOMMT吸附被苯酚污染的地下水时,可能会有微量阴/阳离子表面活性剂的解吸。

Many anion-cation organic bentonite samples were prepared by reaction of raw bentonite （Heishan, Liaoning） with hexadecyl trimethyl ammonium bromide （CTMAB） and/or lauryl sodium sulfate （SDS） for study of the effects of baking temperatures and chemical composition on the organic content and the phenol removal capacity of the product. The most desirable modified bentonite was prepared by reaction with 120CTMAB/15SDS and 3. 0% Na2 CO3. The synergistic effect of ion exchange and adsorption in removing organic substance was demonstrated. Series of batch adsorption runs were conducted to determine the effects of temperature, adsorbent dose, particle size, pH, contact time, and agitation intensity on the modified bentonite’s capacity for phenol. 78. 74% phenol removal was achieved by treatment of 1 mg/L phenol solution by 60 g/L of the modified bentonite under the conditions ： particle size = 80-100 mesh, temperature = 20℃, pH = 6-8, agitation speed = 200 r/min and contact time = 30 min. The observed adsorption isotherm data were well represented by either Langmuir or Freundlich model. Heating the dry spent adsorbent at 105℃ for 1 h recovered a large portion of its original phenol capacity; the regenerated Na-ACOMMT was reusable up to 6 adsorption-regeneration cycles for a cumulative capacity of 0. 045 9 mg/g. About 2.73% of CTMAB and 16.06% of SDS were released from the modified bentonite in the adsorption runs. The chemical release should be reduced for cost effective use of the modified bentonite in groundwater remediation.