Removal of Surfactant Cetyldimethylethyl Ammonium Bromide from Water using Adsorption in Combination with a Membrane Pilot Plant

Abstract

Abstract In this study, a magnetic carbon nanocomposite (MCNC) was prepared using peanut shell biomass as carbon source. The prepared adsorbent was characterised by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric/differential thermal analysis (TGA/DTA) and BET surface analysis. Batch experiments were carried out to determine the adsorption parameters of cetyl dimethylethyl ammonium bromide (CDEAB) on MCNC. Of the isotherm and kinetics models used, the Langmuir model fitted the equilibrium adsorption data best, while the kinetics data were best explained by the second-order kinetic pseudo-equation. The numerical values of enthalpy change (ΔH8 = 38 kJ mol–1) and Gibb free energy (ΔG8 = 70.95 kJ mol–1, 72.19 kJ mol–1 and 73.32 kJ mol–1 corresponding to 20°C, 30°C and 40 °C, respectively) were positive, while the value of entropy change (ΔS8 = –0.11 kJ mol–1 K–1) indicated an endothermic and non-spontaneous process. After determining the optimal adsorption parameters, the adsorbent was used in a hybrid plant with a membrane pilot plant equipped with ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membranes. In MCNC/membrane operation, an improvement in permeate flux was observed for the three selected membranes. The percentage retention of UF and NF membranes was also improved by MCNC pre-treatments in hybrid mode.