ZnO, MgO and FeO adsorption efficiencies for direct sky Blue dye: Equilibrium, kinetics and thermodynamics studies

Adsorption is one of the promising techniques for the remediation of wastewater and italso offers advantages such as low cost, availability of the adsorbent and ease in operation.The wastewater treatment using smart materials gained much attention and the presentinvestigation evaluated the adsorption efficiencies of ZnO, MgO and FeO for the removal ofDirect Sky Blue (DSB) dye. The adsorption affecting parameters, i.e., effect of adsorbent dose,pH, concentration of dye, temperature and contact time were studied in association with dyeadsorption. The effect of electrolytes and surfactants was also studied on dye adsorption.The dye adsorption data was analysed using various kinetics parameters, isotherms andthermodynamics models. The maximum adsorption capacities of MgO, FeO and ZnO wererecorded to be 46.7, 42.9 and 40.9 mg/g, respectively at the pH 2, adsorbent dose 0.05 g, contacttime 75 min, 40â-C and 70 mg/L initial concentration of the dye. The dye adsorption onto MgOfollowed a Langmuir isotherm, while ZnO followed Temkin isotherm. Langmuir and Temkinisotherms were satisfactory in the case of FeO. Pseudo second order best explained the dyeadsorption kinetics. The thermodynamics studies revealed non-spontaneous adsorption ofDSB dye onto ZnO, MgO and FeO. In view of promising efficiency, the ZnO, MgO and FeO havepotential to apply for dyes adsorption from textile wastewater.