| 有机改性蒙脱土对萘的吸附机制和影响因子 |
| 摘要点击 1383 全文点击 646 投稿时间：2020-03-26 修订日期：2020-05-05 |
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| 中文关键词 多环芳烃(PAHs) 耗散型石英晶体微天平(QCM-D) 吸附 有机改性蒙脱土 多环芳烃-重金属复合污染 萘 |
| 英文关键词 polycyclic aromatic hydrocarbons (PAHs) dissipative quartz crystal microbalance (QCM-D) adsorption organo-clay particles compound contamination of PAHs & heavy metals naphthalene |
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| 中文摘要 |
| 我国场地土壤中多环芳烃（PAHs）污染或PAHs-重金属复合污染是常见的污染类型，对公众健康与环境构成巨大威胁.本研究利用耗散型石英晶体微天平（QCM-D）技术和批量吸附实验，探究实验室制备的2种有机改性黏土对萘的吸附机制，以及萘与Cu2+共存时黏土颗粒吸附情况.结果表明，25℃时，十六烷基三甲基溴化铵改性蒙脱土（CTAB-SMF）的吸附等温线符合Freundlich模型（R2>0.92，n>1），说明其对萘的吸附位点具有多样性，在较高萘平衡浓度（ce=1 mmol ·L-1）下吸附分配系数Kd为SMF的13.4倍；3-巯基丙基三甲氧基硅烷改性蒙脱土（TMSP-SMF）的吸附等温线符合Langmuir模型（R2>0.96），在较高萘平衡浓度（ce=1 mmol ·L-1）下吸附分配系数Kd为SMF的1.14倍.说明2种有机改性黏土对萘的吸附效果优于SMF颗粒.3种黏土颗粒对萘的吸附焓在-30~-10 kJ ·mol-1之间，均为自发物理吸附.溶液离子强度升高抑制了SMF吸附萘，但对改性黏土吸附萘无显著影响.萘平衡浓度较低（ce=0.1 mmol ·L-1）时，Cu2+的存在使TMSP-SMF对萘的吸附效果增加了3倍；同时萘能促进2种改性黏土对Cu2+的吸附.本研究通过原位在线QCM-D检测了黏土对萘的吸附机制，结果与批量吸附实验结果一致：CTAB-SMF对萘的吸附位点主要为黏土层间的改性剂基团，TMSP-SMF则位于黏土颗粒表面的改性剂基团.本项研究结果显示，QCM-D技术是一种有效的原位在线表征黏土膜吸附有机污染物的方法，2种有机改性的黏土颗粒可作为应用于PAHs或PAHs-重金属复合污染场地的修复材料. |
| 英文摘要 |
| There are many sites contaminated by polycyclic aromatic hydrocarbons (PAHs) or combined PAHs-heavy metal in China, which pose serious health-risks to local people and environments. Dissipative quartz crystal microbalance (QCM-D) was applied to investigate the adsorption of naphthalene to two organic-modified smectite clays (cetyltrimethyl ammonium bromide modified montmorillonite, CTAB-SMF, and 3-mercapto propyl trimethoxy silane modified montmorillonite, TMSP-SMF) and original SMF, together with batch adsorption experiments. The results, based on in-situ online QCM-D experiments, showed that the adsorption sites of CTAB-SMF on naphthalene were mainly CTAB grouped between the interlayers of clay particles, while TMSP-SMF's were TMSP grouped on the surfaces of clay particles. The isotherms of naphthalene adsorption to CTAB-SMF fitted well (R2>0.92) with the Freundlich model, while the adsorption isotherms to TMSP-SMF and SMF fitted well with the Langmuir model (R2>0.96). The parameters of CTAB-SMF (n>1) indicated that the adsorption sites of naphthalene to CTAB-SMF were heterogeneous and the adsorption increases at higher equilibrium concentration. The adsorption capacity qmax of TMSP-SMF is significantly greater than that of SMF (P<0.05). Based on the calculation, the value of ΔHobs for these three clays (CTAB-SMF, TMSP-SMF, and SMF) were within the range of -30 to -10 kJ·mol-1, which indicated that it was a spontaneous exothermic physical process. The solution ionic strength could decrease the adsorption of naphthalene to SMF, but had limited effects on naphthalene adsorption to the two organo-modified clay particles. The existence of Cu2+ in the solution could enhance naphthalene adsorption to the three particles, and naphthalene could improve Cu2+ adsorption to these two modified clays. The results of this study show that QCM-D is a useful technique to indicate the changes of clay film during the process of adsorption, and the two organo-modified clay particles have the potential to be remediation materials to remediate PAHs or PAHs-heavy metal-contaminated sites. |
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