Removal of nitrobenzene by immobilized nanoscale zero-valent iron: Effect of clay support and efficiency optimization

In this study, natural clays were used as the support for nanoscale zero-valent iron (nZVI) to fulfill affordable and efficient decontamination materials. In comparison with the kaolinite (K) and montmorillonite (M) supported nZVI materials (K-nZVI and M-nZVI), Hangjin clay supported nZVI (HJ-nZVI) exhibited the best performance for nitrobenzene (NB) removal because of its favorable characteristics, such as higher specific surface area (SSA, 82.0 m(2) g(-1)), larger pore volume (0.1198 cm(3) g(-1)) and bigger average pore diameter (6.2 nm). The NB removal efficiency achieved by HJ-nZVI (93.2 +/- 2.8%) was much higher than these achieved by HJ clay alone (38.2 +/- 2.3%), nZVI alone (52.3 +/- 2.5%) and by the combined use of nZVI and HJ clay (70.2 +/- 1.3%). The superior performance of HJ-nZVI was associated with three aspects: the even distribution of nZVIs onto HJ clay, higher payload efficiency of nZVIs and the stronger adsorption capability of HJ clay support. Higher SSA, larger pore volume, favorable cation exchange capacity and structural negative charges all facilitated the payload of iron onto HJ clay. The adsorption process accelerated the reduction via increasing the local concentration of aqueous NB. The high efficiency of HJ-nZVI for decontamination warranted its promising prospect in remediation applications. (C) 2016 Elsevier B.V. All rights reserved.