Water assisted synthesis of MWCNTs over natural magnetic rock: An effective magnetic adsorbent with enhanced mercury(II) adsorption property

Herein, multiwalled carbon nanotubes (MWCNTs) were synthesized over natural magnetic rock as an efficient catalyst in the absence or presence of water vapor and the produced magnetic nanocomposites were employed for mercury(II) adsorption. The catalyst and magnetic nanocomposite were characterized using XRD, EDX, VSM, FE-SEM, TEM, FT-IR and Raman techniques. Results of VSM analysis showed that the CNT nanocomposites have superparamagnetic nature which can be applied as magnetic adsorbents. Moreover, Raman study indicated that water vapor increases disorder in CNT structure which simplifies oxidation of raw CNT and as a result enhances mercury adsorption property. Experimental results confirm this hypothesis as maximum adsorptions of 200 and 150 mg g(-1) were obtained using acid activated CNTs synthesized in the presence and absence of water. Equilibrium time was 90 min in three mercury(II) concentration levels i.e., 10, 20 and 30 mg L-1 at ambient temperature and it was revealed that oxidized sorbents followed second order model. It was found that 99.1% of mercury(II) was removed by activated MWCNTs which were synthesized in the presence of water, thus confirmed efficiency of the nanocomposite for mercury(II) uptake. (C) 2015 Elsevier B.V. All rights reserved.