Adsorption of methyl red dye from aqueous solution onto eggshell waste material: Kinetics, isotherms and thermodynamic studies

Abstract

In the last years, numerous studies were carried out to examine the utilization of low cost adsorbent as an alternative technique for the adsorption of dye. Hence, the main objective of this study is to evaluate the potentiality of eggshell powder (ESP) as an effective adsorbent for the adsorption of methyl red (MR) dye. The prepared adsorbent was characterized by Fourier-transform infrared spectroscopy (FTIR) and Thermo-gravimetric analysis (TGA). The effects of solution pH (2–10), adsorbent dosage (2–10 ​g/300 ​mL), contact time (0–180 ​min), initial dye concentration (20–100 ​mg/L) and temperature (25–55 ​°C) on the decolorization efficiency of MR were studied. The adsorption studies showed that ERP removed almost 82% of MR at the optimized conditions i.e. solution pH of 2, adsorbent dosages of 8 ​g/300 ​mL, initial dye concentration of 20 ​mg/L, contact time of 180 ​min and temperature of 25 ​°C. The pseudo-first order and second order kinetics models were employed to describe the kinetics data. Kinetic data were found to best fit pseudo second order kinetic model than pseudo first order kinetic. The adsorption isotherm study showed that adsorption experimental data were fitted well by Langmuir isotherm model as compared to Freundlich model. The maximum monolayer dye adsorption capacity (qmax) at pH of 2 and temperature of 25 ​°C was found to be 1.66 ​mg/g. Thermodynamic study showed that the adsorption process of MR dye onto ESP was endothermic in nature.

Keywords

• Egg shell powder
• Methyl red dye
• Adsorption
• Wastewater treatment
• Isotherms