Organomodified bentonite clay: Characterization and sorptive properties towards phenol and its derivatives

Abstract

Bentonite clay from Mečji Do locality in Serbia was organomodified. The organomodification was performed with hexadecyltrimethylammonium (HDTMA) bromide, and the sample was denoted as HDTMA-MD. The characterization of the clay-based material consisting of X-Ray diffraction, elemental analysis and point of zero charge determination, was performed. The sorption of phenol and its three nitro derivatives: 2-nitrophenol (2NP), 3- nitrophenol (3NP) and 4-nitrophenol (4NP) on HDTMA-MD was investigated. The experiments were performed in aqueous solution, during three hours, at constant temperature (25 °C) and with initial sorbate concentrations of 2×10-4 mol dm-3. The sorption capacity of HDTMA-MD toward phenol derivatives increased in the following order qe (phenol) < qe (3NP) < qe (2NP) < qe (4NP). The sorption capacity of different phenol derivatives could be affected by their solubility in water, hydrogen bonds that they could form with sorbent, acidity and chemical structure of the sorbate, including the presence of the nitro group and its position in phenol ring. The influence of sorption time and initial concentration on the sorption efficiency of HDTMA-MD was studied for 4NP since it showed the best sorption on the investigated material. The isotherm data were best fitted with Langmuir model, while the sorption dynamics obeyed the pseudo-second-order kinetic model for all initial concentrations.