ADSORPTION OF METHANYL YELLOW DYE ON Fe-MODIFIED BENTONITE CLAY

Iron-containing materials were obtained by modifying bentonite clay from the Mukhortalinskoe deposit (Republic of Buryatia, Russia) with polymeric iron hydroxocations and subsequent heating at 500 degrees C. The materials were characterized by chemical analysis, low-temperature nitrogen adsorption, and XRD. The iron content in the samples was 14.5-15.8%. Their specific surface area was 138-143 m(2)/g. The adsorption properties of materials have been studied using the example of the adsorption of an acidic dye Metanyl Yellow from model aqueous solutions. The dependence of the dye adsorption on the physicochemical parameters, such as pH, sorbent loading, and the initial dye concentration has been established. The specific dye adsorption on sorbents increased with a decrease in pH and an increase in the initial concentration of the dye aqueous solutions and with a decrease in the loading of sorbents. The maximum dye adsorption was 88.5 mg/g at pH 3.5 and a sorbent loading of 1 g/l in the range of initial dye concentrations 24-491 mg/l. The dye removal efficiency was 86-95% at an initial concentration of 84 mg/L and a sorbent loading of 3-10 g/l. The sorption capacity of the obtained sorbents in relation to the dye was close to the sorption capacity of some carbon sorbents. It was shown that the adsorption isotherm of the Metanyl Yellow dye on sorbents is well described by the Freundlich adsorption model, which indicates the heterogeneity of the sorbent surface. The results of experiments on desorption and re-adsorption of the Metanyl Yellow dye indicated a high efficiency of the dye extraction and the possibility of re-using sorbents in the adsorption of azo dyes. The sorbents may be of interest for use in wastewater treatment processes from acid dyes.