Adsorptive removal of safranin from aqueous solution onto avocado seed

Abstract

The most naturally distinguishable pollutants in the environments are dyes or colored compounds. Maximum of the industries use dyes and pigments to color their products. Thus, the removal of dyes from effluents could be considered as an important issue for risk assessment.In this work, locally available biomass obtained from avocado seed was investigated as adsorbent for the removal of Safranin dye. The study employed a batch method to investigate the adsorptiveremoval of Safranin dye from aqueous solution. Parameters that influence adsorption such as pH, adsorbent dose, initialconcentration of Safranin dye, contact time and temperature have been studied. The Langmuir and Freundlich adsorption isotherm models were applied to describe the equilibrium isotherms and the isotherm constants were also determined. TheFreundlich adsorption isotherm model agrees with the experimental data well.The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data and the rate constants were evaluated. The results of kinetic models showed that the pseudo-second order kinetic model best fitted with the experimental data and was found to have R 2 = 0.9999. Thermodynamic parameters, enthalpy change (ΔH), entropy change (ΔS) and Gibbs free energy change (ΔG) were also calculated for the removal of Safranin dye. The results of thermodynamic parameters showed that the adsorption process is feasible, spontaneous in nature and endothermic. Maximum adsorption efficiencies was 98.48% for Safranin dye at pH 10.