Facile preparation of rhamnolipid-layered double hydroxide nanocomposite for simultaneous adsorption of p-cresol and copper ions from water

Abstract

Rhamnolipid-layered double hydroxide (RL-LDH) nanocomposite for simultaneous adsorption of p-cresol and Cu2+ from aqueous solution was synthesized through delamination/reassembling process. The characteristics of the obtained RL-LDH nanocomposite was analyzed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, inductively coupled plasma atomic emission spectrometry, CHN elemental analysis, specific surface area, zeta potential, and transmission electron microscopy, confirming that RL− anions were successfully introduced into the interlayers of LDH. The adsorption of p-cresol and Cu2+ in single and binary systems by RL-LDH was studied in detail. The effect of factors including RL-LDH dosage, initial solution pH, contact time, initial p-cresol/Cu2+ concentration, and temperature on the adsorption were investigated. The results showed that (1) the adsorption capacities of RL-LDH for both p-cresol and Cu2+ were much larger than that of LDH; (2) the pseudo-second-order kinetic model fitted well with the adsorption of p-cresol (or Cu2+) on RL-LDH; (3) the p-cresol (or Cu2+) adsorption isotherm could be well described by Freundlich model. The RL-LDH nanocomposite after adsorption was characterized by XRD, FTIR, and X-ray photoelectron spectroscopy, and the adsorption mechanism was discussed. Efficient p-cresol (and Cu2+) adsorption was mainly due to the hydrophobic interaction of p-cresol (and the complexation of Cu2+) with RL− anions in the interlayer of RL-LDH.