Characterization of bentonite modified with humic acid for the removal of Cu (II) and 2,4-dichlorophenol from aqueous solution

Abstract

This study examines the modification of bentonite with humic acid (HAB) as a novel sorbent for simultaneous removal of Cu(II) and 2,4-dichlorophenol (2,4-DCP) from aqueous solution. Batch experiments were conducted employing either single sorption or simultaneous sorption of Cu(II) and 2,4-DCP. Results indicated that the sorption of either Cu(II) or 2,4-DCP onto HAB was little influenced by the presence of the other contaminant. The amount of sorption was 22.40mgg−1 and 14.23mgg−1 for Cu(II) and 2,4-DCP, respectively at 30°C. Scanning electron microscopy (SEM) indicated that HA was immobilized on the surface of bentonite. Energy dispersive spectroscopic (EDS) analysis indicated that Cu(II) was sorbed onto HAB. X-ray diffraction (XRD) analysis demonstrated that the crystalline structure of bentonite did not change after being modified with HA. Fourier-transform infrared (FTIR) spectra confirmed that new bonds and band intensity emerged after the sorption of Cu(II) and 2,4-DCP onto the HAB. These suggest that simultaneous sorption of 2,4-DCP and Cu(II) onto HAB could occur through: firstly, a mechanism that partitions between 2,4-DCP and HA; and secondly, the ion-exchange mechanism between Cu(II) and bentonite.