Abstract
Nanoscale zerovalent iron (nZVI) has been widely used for the remediation of contaminated in aquatic environments. However, the intrinsic ferromagnetism of ZVI nanoparticles lead to aggregation and result in the loss of reactivity and mobility. In this study, a facile approach for the synthesis and immobilization of ZVI nanoparticles onto titanate nanotubes (TNTs) has been developed using nonaqueous thermal decomposition method. Several parameters including capping agent concentration, loading amount of TNTs, thermal decomposition temperature, aging time, carbonization/pyrolysis temperature, and carbonization/pyrolysis atmosphere were optimized to obtain C/nZVI/TNTs nanocomposites. Results showed that the nZVI were well-disperse on the surface of TNTs, and the average diameter of the nZVI particles was about 13±1 nm, with Fe core and Fe3O4 shell of 10 and 3 nm, respectively. In addition, the coated carbon on surface of the ZVI nanoparticles not only prevented the aggregation of nZVI but also maintained the reactivity. Moreover, the adsorption of TCE was enhanced when the carbon was coated on C/nZVI/TNTs nanocomposites. Therefore, the synthesized C/nZVI/TNTs can rapidly facilitate the dechlorination reaction by pre-concentrated the TCE in the vicinity of ZVI nanoparticles. The pseudo-first order rate constant (kobs) of TCE dechlorination by C/nZVI/TNTs nanocomposites was 1.9×10-3 h-1, which was 3 times higher than that by conventional ZVI. The degradation of TCE by C/nZVI/TNTs nanocomposites can be significantly enhanced when the second metal ions including Co, Cu, and Ni were introduced. The kobs for TCE dechlorination were 4.5×10-3, 3.54×10-2, and 6.29 h-1 at 4 mM Co(II), 0.7 mM Cu(II), and 4 mM Ni(II), respectively, which was higher than C/nZVI/TNTs nanocomposites alone (1.9×10-3 h-1). The results obtained in this study demonstrate that nZVI with carbon coating were successfully immobilized on to TNTs leads to a potential application in water treatment. The developed technique opens a new avenue to fabricate various multifucntional nanocomposite materials with high specific surface area, high adsorption capacity, and efficient removal ability of TCE in aqueous solutions.