Adsorptive exclusion of crystal violet dye from wastewater using eggshells: kinetic and thermodynamic study

The aim of current research was to remove methyl violet dye (MV) from wastewater by using eggshells. Batch experiments were performed to investigate the effect of different parameters, such as solution pH, adsorbent dose, contact time, dye concentration, and temperature, on adsorption of methyl violet dye. There was maximum, that is, 88% removal of methyl violet dye from wastewater at optimized conditions (i.e., pH 7, 0.6 g adsorbent dose, 10 min contact time, 40 ppm dye concentration, and 10°C temperature). Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were used to examine the adsorption process. Pseudo-second-order model was the best fit model for adsorption process with (R2 = 0.9916). Adsorbent was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy techniques. Adsorption isotherms such as Langmuir and Freundlich were studied and investigated. Langmuir isotherm model was best followed by adsorption process (R2 = 0.9938). Thermodynamic parameters (i.e., ΔH, ΔG, and ΔS) were also investigated and results showed that process was spontaneous and exothermic. Applicability of developed practice with tap water was 82%.