Trichlorophenol adsorption on layered double hydroxide: a potential sorbent

Abstract

The objective of this work was to assess the adsorption mechanism of trichlorophenol (TCP) on a layered double hydroxide, the hydrotalcite compound [Mg3Al(OH)8]2CO3xH2O), (HT), and its calcined product Mg3AlO4(OH), (HT500), as exploring their potential use as phenol sorbents. TCP adsorption on HT and HT500 was measured by batch equilibration technique at diverse solid/solution ratios, pH, contact times and TCP concentrations. X-ray diffraction and Fourier Transform-Infrared (FT-IR) spectroscopy were applied to the adsorption products to uscertain TCP-HT interactions. The results showed that TCP adsorption on HT is very low and seems to occur as anion exchange reaction only on the external surface sites at the entrance of the interlayer spaces. TCP adsorption on the calcined compound HT500 is high and irreversible and occurs by the reconstruction of the layered structure. X-ray powder diffraction and FT-IR spectroscopy showed that TCP adsorbed at the interlayer spaces as phenolate form that besides OH- and CO3(=) ions compensate the positive layer charge. The possible use of HT500 as phenol sorbents in waters is suggested.