Hou Jing-Wen, Shi Wei-Lin, Gao Juan
School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China.
Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210018, China.
Huan Jing Ke Xue. 2020 Nov 8;41(11):5133-5142. doi: 10.13227/j.hjkx.202003269.
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 (>0.92) with the Freundlich model, while the adsorption isotherms to TMSP-SMF and SMF fitted well with the Langmuir model (>0.96). The parameters of CTAB-SMF (>1) indicated that the adsorption sites of naphthalene to CTAB-SMF were heterogeneous and the adsorption increases at higher equilibrium concentration. The adsorption capacity of TMSP-SMF is significantly greater than that of SMF (<0.05). Based on the calculation, the value of Δ for these three clays (CTAB-SMF, TMSP-SMF, and SMF) were within the range of -30 to -10 kJ·mol, 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 Cu in the solution could enhance naphthalene adsorption to the three particles, and naphthalene could improve Cu 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.
在中国，有许多受多环芳烃（PAHs）或PAHs与重金属复合污染的场地，这对当地居民和环境构成了严重的健康风险。采用耗散石英晶体微天平（QCM-D）研究萘在两种有机改性蒙脱石粘土（十六烷基三甲基溴化铵改性蒙脱石，CTAB-SMF，和3-巯基丙基三甲氧基硅烷改性蒙脱石，TMSP-SMF）以及原始蒙脱石（SMF）上的吸附情况，并进行了批量吸附实验。基于原位在线QCM-D实验的结果表明，CTAB-SMF对萘的吸附位点主要是位于粘土颗粒层间的CTAB基团，而TMSP-SMF的吸附位点则是聚集在粘土颗粒表面的TMSP基团。萘在CTAB-SMF上的吸附等温线与Freundlich模型拟合良好（>0.92），而在TMSP-SMF和SMF上的吸附等温线与Langmuir模型拟合良好（>0.96）。CTAB-SMF的参数（>1）表明，萘在CTAB-SMF上的吸附位点是不均匀的，且在较高平衡浓度下吸附量增加。TMSP-SMF的吸附容量显著大于SMF（<0.05）。通过计算，这三种粘土（CTAB-SMF、TMSP-SMF和SMF）的Δ值在-30至-10 kJ·mol范围内，这表明这是一个自发的放热物理过程。溶液离子强度会降低萘在SMF上的吸附，但对萘在两种有机改性粘土颗粒上的吸附影响有限。溶液中Cu的存在会增强萘在这三种颗粒上的吸附，且萘会提高Cu在这两种改性粘土上的吸附。本研究结果表明，QCM-D是一种用于指示吸附过程中粘土膜变化的有用技术，且这两种有机改性粘土颗粒有潜力成为修复PAHs或PAHs与重金属复合污染场地的修复材料。
