Application of silica-alumina oxides of different compositions for removal of CI Reactive Black 5 dye from wastewaters

摘要

In this paper adsorptive removal of hazardous dye C.I. Reactive Black 5 from aqueous solutions was investigated using the mixed silica-alumina oxides including of 4% SiO2 and 96% Al2O3 as well as 97% SiO2 and 3% Al2O3. The kinetic studies revealed that with the increasing initial dye concentration from 10 to 30 mg/l and contact time from 1 to 240 min, the sorption capacities (q(t)) increased and the equilibrium was observed after 240 min. Sorption of C.I. Reactive Black 5 on 4% SiO2 and 96% Al2O3 and 97% SiO2 and 3% Al2O3 takes place through the pseudo-second-order mechanism rather than the pseudo-first-order one. The experimental data were fitted using the Langmuir and Freundlich isotherm models. The effect of the auxiliaries such as anionic surfactant (sodium dodecyl sulphate) and sodium chloride on C.I. Reactive Black 5 removal was investigated in the 10 mg/l C.I. Reactive Black 5-0.1-1 g/l sodium dodecyl sulphate or 5-20 g/l NaCl systems. The potentiometric titrations indicated that the presence of C.I. Reactive Black 5 changed the surface charge density of silica-alumina mixed oxides, especially in the case of 4% SiO2 and 96% Al2O3 system.