Zaib Qammer, Aina Oluwajinmi Daniel, Ahmad Farrukh
BioEnergy & Environmental Laboratory, Department of Chemical and Environmental Engineering, Masdar Institute of Science and Technology, PO Box 54224, Abu Dhabi, UAE.
Environ Sci Process Impacts. 2014 Aug;16(8):2039-47. doi: 10.1039/c4em00201f.
In this study, multi-walled carbon nanotubes (MWNTs) were employed to remove benzene, toluene, ethylbenzene, and xylenes (BTEX) from low and high salinity water pre-equilibrated with crude oil. The treatment endpoint of crude oil-contaminated water is often controlled by BTEX compounds owing to their higher aqueous solubility and human-health toxicity compared to other hydrocarbons. The MWNT sorbent was extensively characterized and the depletion of the organic sorbate from the produced water was monitored by gas chromatography-mass spectrometry (GC-MS) and total organic carbon (TOC) analyses. The equilibrium sorptive removal of BTEX followed the order: ethylbenzene/o-xylene > m-xylene > toluene > benzene in the presence of other competing organics in produced water. Sorption mechanisms were explored through the application of a variety of kinetics and equilibrium models. Pseudo 2(nd) order kinetics and Freundlich equilibrium models were the best at describing BTEX removal from produced water. Hydrophobic interactions between the MWNTs and BTEX, as well as the physical characteristics of the sorbate molecules, were regarded as primary factors responsible for regulating competitive adsorption. Salinity played a critical role in limiting sorptive removal, with BTEX and total organic carbon (TOC) removal falling by 27% and 25%, respectively, upon the introduction of saline conditions. Results suggest that MWNTs are effective in removing risk-driving BTEX compounds from low-salinity oilfield produced water.
在本研究中，采用多壁碳纳米管（MWNTs）从与原油预平衡的低盐度和高盐度水中去除苯、甲苯、乙苯和二甲苯（BTEX）。由于与其他碳氢化合物相比，BTEX化合物具有更高的水溶性和对人体健康的毒性，因此原油污染水的处理终点通常由BTEX化合物控制。对MWNT吸附剂进行了广泛表征，并通过气相色谱 - 质谱联用（GC - MS）和总有机碳（TOC）分析监测采出水中有机吸附质的消耗情况。在采出水中存在其他竞争性有机物的情况下，BTEX的平衡吸附去除顺序为：乙苯/邻二甲苯＞间二甲苯＞甲苯＞苯。通过应用各种动力学和平衡模型探索了吸附机制。伪二级动力学和Freundlich平衡模型最能描述从采出水中去除BTEX的情况。MWNTs与BTEX之间的疏水相互作用以及吸附质分子的物理特性被视为调节竞争性吸附的主要因素。盐度在限制吸附去除方面起着关键作用，引入盐水条件后，BTEX和总有机碳（TOC）的去除率分别下降了27%和25%。结果表明，MWNTs能有效去除低盐度油田采出水中的风险驱动型BTEX化合物。
