Modeling and regeneration studies for the removal of crystal violet using Balanites aegyptiaca seed shell activated carbon

Activated carbon derived from Balanites aegyptiaca seed shell (ACBS) was employed to remove crystal violet (CV) from aqueous medium. The characterization of this ACBS has been conducted using analytical techniques such as SEM, EDS, and Brunauer-Emmett-Teller (BET) surface area analysis. The adsorption parameters investigated were as follows: contact time (5-120 min), temperature (303-333 K) and initial concentration (100-500 mg/L). The adsorption data were interpreted by using kinetic, isotherms and thermodynamic equations. The kinetic data matched the pseudo-second-order model well, and both external diffusion and internal diffusion influenced the adsorption of the dye onto the adsorbent. The isotherm data was in concurrence with the Freundlich model intimating the multilayer coverage of CV on the heterogeneous surface of the ACBS. The thermodynamic quantities like ΔS°, ΔH° and ΔG° were computed using Gibbs plot. The results implicated the practicability and endothermicity of the dye adsorption process. Regeneration studies show the effectiveness of CH3COOH solution in CV recovery from ACBS than distilled water, H2SO4, HCl, HNO3, and NaOH solutions. The regenerated ACBS was recycled five times and sustained an adsorption efficiency of 92.08%.