Removal of bisphenol A and trichlorophenol from aqueous solutions by adsorption with organically modified bentonite, activated carbon composites: A comparative study in single and binary systems

Abstract

Three adsorbents have been developed by encapsulation of organo-activated bentonite (OAB), activated carbon (AC) and organo-activated bentonite/activated carbon (AC-OAB) in cross-linked alginate beads (A) with the aim of using them in the removal of bisphenol A (BPA) and 2.4.5-trichlorophenol (TCP). The adsorption capacities of the three adsorbents were investigated in order to choose the best adsorbent for BPA and TCP. The alginate/activated carbon beads (A-AC) exhibit the maximum BPA and TCP adsorption capacities (419.3 and 444.7 mg/g at 25 °C, respectively). In the binary system, a decrease was observed at the adsorbed amount to 291.5 mg/g for BPA and 430.2 mg/g for TCP. The adsorption of BPA and TCP by A-AC composite beads was studied and the effects of solution pH value, temperature and contact time on the adsorption were investigated. Results revealed that BPA and TCP adsorption kinetics onto A-AC are best described by the pseudo-second order model, and the equilibrium adsorption data are well fitted to both Langmuir and Freundlich models. The zero point charge determination (pHPZC), the scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis were carried out. The A-AC composite was used for six cycles without significant adsorptive performance loss. Therefore, the ecofriendly prepared A-AC adsorbent was considered as highly recyclable and efficient adsorbent for BPA and TCP pollutants.