College of Chemistry and Chemical Engineering, Shaoxing University, Zhejiang 312000, PR China.
Chemosphere. 2013 Jul;92(4):368-74. doi: 10.1016/j.chemosphere.2013.01.030. Epub 2013 Feb 8.
The reactivity of nanoscale zerovalent iron (NZVI) on removing chlorophenols (2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol) was remarkably enhanced by using a hydrophobic support of organobentonite (CTMA-Bent), namely the bentonite modified with organic cetyltrimethylammonium (CTMA) cations. The complete dechlorination of chlorophenols and total conversion into phenol using this novel NZVI/CTMA-Bent combination was observed in batch experiments. The kinetic studies suggested that the reduction of chlorophenols by NZVI was accelerated due to the enhanced adsorption onto CTMA-Bent, which facilitated the mass transfer of chlorophenols from aqueous to iron surface. The enhanced reduction rate by NZVI/CTMA-Bent was positively related to the hydrophobicity of chlorophenols, and an increasing linear relationship was obtained between the relative enhancement on reaction rate constants (k2/k1) and logKow values of chlorophenols. XPS results suggested there were fewer precipitates of ferric (hydro)xides formed on the surface of NZVI/CTMA-Bent, which may also lead to the improved reactivity and repetitive usability of NZVI/CTMA-Bent on removing chlorophenols.
利用疏水载体有机膨润土（CTMA-Bent），即有机十六烷基三甲基铵（CTMA）阳离子改性的膨润土，可显著提高纳米零价铁（NZVI）去除氯酚（2-氯酚、2,4-二氯酚、2,4,6-三氯酚和五氯酚）的反应活性。在批实验中，使用这种新型 NZVI/CTMA-Bent 组合可观察到氯酚的完全脱氯和完全转化为苯酚。动力学研究表明，由于 NZVI 对 CTMA-Bent 的吸附增强，氯酚的还原反应得到加速，这促进了氯酚从水相向铁表面的传质。NZVI/CTMA-Bent 的增强还原速率与氯酚的疏水性呈正相关，并且在反应速率常数（k2/k1）的相对增强与氯酚的 logKow 值之间获得了递增的线性关系。XPS 结果表明，在 NZVI/CTMA-Bent 表面形成的铁（氢）氧化物沉淀较少，这也可能导致 NZVI/CTMA-Bent 去除氯酚的反应活性和可重复使用性得到提高。
