Nickel ions removal from water by two different morphologies of induced CNTs in mullite pore channels as adsorptive membrane

Abstract

In this study, chemical vapor deposition (CVD) method (with two proposed synthesis processes) was used for inducting two different morphologies of CNTs in mullite pore channels as a novel adsorptive membrane for nickel ions (Ni2+) removal from water. Cyclohexanol and ferrocene were used as carbon source and catalyst, respectively. The first proposed synthesis process involves coevaporation and pyrolysis of a mixed solution composed of cyclohexanol and ferrocene in a neutral atmosphere and the second involves sublimation and decomposition of ferrocene in a reactor individually and subsequently introduction of cyclohexanol as vapor to the reactor by a carrier gas during the reaction. Effects of synthesis parameters such as reaction time, catalyst content and reactor pressure on growth process, and structure and properties of the induced CNTs in pore channels of the mullite substrate were also investigated. Finally the optimized CNTs growth conditions for achieving a uniform distribution of the CNTs in the mullite pore channels were reported. The CNTs–mullite composite membranes prepared under the optimum conditions were oxidized with nitric acid and then successfully used as adsorptive membranes for nickel ions removal from water. Moreover, Langmuir and Freundlich isotherm models were used to describe adsorption behavior of nickel ions by the prepared adsorptive membrane.