Nitrobenzene is widely used as explosives, pesticides and organic synthesis intermediates, while it imposes serious toxicity to human beings and other living organisms. Chemical reduction is an efficient method for converting nitrobenzene to aniline in the anaerobic conditions, and the product aniline can easily be degraded under the aerobic or denitrifying conditions. Although nitrobenzene could be reduced by sulfide in aqueous solution, the direct reduction of nitrobenzene by sulfide has been documented as a much slow process in anoxic environments. This study evaluated the potential of carbon nanotubes (CNTs) as catalyst for anaerobic abiotic reduction of nitrobenzene. The results showed that the presence of CNTs could catalyze abiotic nitrobenzene reduction by sulfide in aqueous solutions, where the pseudo first-order rate constant was raised by nearly fourfold (from (3.44±0.26)×10-3 to (1.40±0.08)×10-2 h-1) with 300 mg L-1 CNTs. Moreover, CNTs with thermal treatment resulted in higher nitrobenzene reduction rate compared to untreated ones, and the most favorable annealing temperature was at 400°C. While the effect of plasma radiation pretreatment on catalytic activity of CNTs was not significant. It was found that the rate of nitrobenzene removal by sulfides was positive correlated with CNTs dosage in a range of 0.3 to 300 mg L-1. The optimum pH was found at around 8.0 for CNTs-catalyzed reduction of nitrobenzene by sulfide. Higher temperature and initial sulfide concentration facilitated CNTs-catalyzed reduction of nitrobenzene, while the presence of humic acid exhibited a negative effect. This study implies that CNTs-based nanomaterials may effectively catalyze the reductive transformation of nitrobenzene and can contribute to the remediation of this chemical in either natural or engineered system.

Abiotic reduction of nitrobenzene with sulfide catalyzed by carbon nanotubes in aqueous solutions: Effect of surface modification and parameter optimization

255th National Meeting (2018)

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