Removal of copper ions by modified Unye clay, Turkey

This paper presents the adsorption of Cu(II) from aqueous solution on modified Unye bentonite. Adsorption of Cu(II) by manganase oxide modified bentonite (MMB) sample was investigated as a function of the initial Cu(II) concentration, solution pH, ionic strength, temperature and inorganic ligands (Cl−, SO42−, HPO42−). Changes in the surfaces and structure were characterized using X-ray diffraction (XRD), infrared (IR) spectroscopy, N2 gas adsorption and potentiometric titration data. The adsorption properties of raw bentonite (RB) were further improved by modification with manganese oxide. Langmuir monolayer adsorption capacity of the MMB (105.38 mg/g) was found greater than that of the raw bentonite (42.41 mg/g). The spontaneity of the adsorption process is established by decrease in ΔG which varied from −4.68 to −5.10 kJ mol−1 in temperature range 303-313 K. The high performance exhibited by MMB was attributed to increased surface area and higher negative surface charge after modification.