Removal of butachlor from aqueous solution using cantaloupe seed shell powder: kinetic, equilibrium and thermodynamic studies

In the present study, cantaloupe (Cucumis melo) seed shell powder was utilized to sequester butachlor pesticide from aqueous medium in batch system. The biomass was characterized before and after removal study by SEM, EDX, FTIR and surface area analyzer. The removal study of the butachlor was accomplished concerning the effect of dosage of sorbent, time of contact, solution pH, temperature and initial butachlor concentration. These results indicate that the removal study is considerably pH dependant, and optimum removal (80%) was achieved at pH 3. The butachlor removal data were analyzed by pseudo-first order, pseudo-second order, Elovich, liquid film and intraparticle diffusion. Among these models, pseudo-2nd-order well describes the data owing to not only higher R² value but also due to a close relationship between experimental and calculated sorption capacity of pseudo-second order. The removal data were also analyzed by Dubinin–Radushkevich, Freundlich, Temkin and Langmuir and were found that Freundlich isotherm explains the data better due to high R² value. Langmuir isotherm was used to calculate the maximum sorption capacity of cantaloupe seed shell powder and was found to be 142.857 mg g⁻¹ for butachlor. The values of thermodynamic parameters like enthalpy (− 0.068 kJ mol⁻¹), free energy (− 0.646, − 1.255, − 2.032, − 2.787, − 3.414, − 3.989 kJ mol⁻¹) and entropy (− 20.908 kJ mol⁻¹) suggest that the removal of butachlor using cantaloupe seed shell powder is exothermic and spontaneous in nature.