Fast and efficient removal of Toluene, Ethylbenzene and O-Xylene from aqueous phase by functionalized carbon micro/nano composites

Abstract

In this work carbon nanotubes (LCNT) and carbon microspheres (LCM) were prepared by floating catalytic chemical vapor deposition method. 2% solution of ferrocene in benzene was used as the source of hydrocarbon. Further oxidation using nitric acid was carried out to obtain LCNT-OX and LCM-OX. Resultant carbon composites were characterized by various techniques. Adsorption properties of toluene(T), ethylbenzene(E) and o-xylene(X) as a function of equilibration time, pH, initial TEX concentrations were evaluated. Equilibrium of TEX for various carbon composites namely (LCNT, LCNT-OX, LCM, LCM-OX) was attained within 20 min in batch mode. The adsorption kinetics of TEX over various prepared carbon composites followed Pseudo Second Order Kinetics with regression coefficients >0.99. Langmuir and Freundlich isotherms were used to model the obtained equilibrium data and various isotherm constants were evaluated. Maximum adsorption capacity of LCNT, LCNT-OX, LCM and LCM-OX towards o-xylene were found to be 47.17, 72.46, 24.27 and 47.16 mg/g, respectively. It was found that using static adsorption test the TEX adsorption capacity for the carbon composites were in the order of LCNT-OX > LCNT, LCM-OX > LCM. Recyclability studies were demonstrated for 5 cycles without any decrease in the sorption capacity. Column studies revealed that 50 bed volumes of (950 ml) of 30 ppm toluene containing distilled water could be treated reducing the concentration from 30 ppm to below detection limit using 3 mg of LCNT. Finally, faster kinetic and its application to remove TEX from ground water demonstrated its applicability as pre-concentration cartridges and real waste water streams.