Facile synthesis of surfactant-modified layered double hydroxide magnetic hybrid composite and its application for bisphenol A adsorption: Statistical optimization of operational variables

Abstract

A novel hexadecyltributylphosphonium bromide modified magnetic composite based on calcined Ni-Mn layered double hydroxide (HDTBP@Fe3O4@NiMn-CLDH) was synthesized and evaluated for the removal of bisphenol A (BPA) from aquatic media. The structural features of the synthesized hybrid material were determined by Fourier transform infrared (FTIR) spectroscopy, vibrating-sample magnetometer (VSM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray analysis (EDX). Response surface methodology (RSM) was used to investigate the influences of operational variables and optimize the adsorption process. The BPA adsorption process was developed by considering a central composite design (CCD) under RSM with four independent variables (initial BPA concentration (Co), agitation time, initial pH, and adsorbent dosage). From the statistical results, the optimal adsorption conditions for Co, agitation time, initial pH, and adsorbent dosage were determined as 22.53 mg/L, 80.05 min, 7.07, and 1.14 g/L, respectively, and under these conditions, the maximum yield was obtained as 86.85%. The kinetic study results showed the kinetic data was perfectly represented by the pseudo-second-order model. Furthermore, the isotherm data fitted very well to the Langmuir and Dubinin-Radushkevich (D-R) models. Additionally, the results based on the adsorption thermodynamics indicated that the process was spontaneous and endothermic. The findings of the present work indicate that RSM is suitable for optimization of the BPA adsorption process onto HDTBP@Fe3O4@NiMn-CLDH and the synthesized composite has great application potential for the remediation of water polluted with organic contaminants like BPA.