Cu(II) Removal From Aqueous Solution Using The Walnut Shell: Adsorption Study, Regeneration Study, Plant Scale-Up Design, Economic Feasibility, Statistical, and GA-ANN Modeling

Continuous adsorptive removal of copper ions by a walnut shell was reported. The walnut shell was characterized by BET analysis, point of zero charge (pH pzc ) estimation, FTIR spectroscopy, and SEM. Behaviors of Cu(II) ion adsorption against different conditions like influent flow rate, depth of the adsorbent bed, and influent Cu(II) concentration were studied. The Langmuir and Freundlich isotherms were applied, and Langmuir was found to be the best. The variation of the operating variables was investigated, pH 5.8, influent Cu(II) concentration (10–20 mg/L), bed height (5–10 cm), the flow rate (10—20 ml/min). The suitability of the different kinetic models was tested. The Thomas kinetic model fits the experimental data well compared to other models; hence it was used for the scale-up design. The 0.4 N HCl solution was found as the optimum regenerant, and regeneration after the 4 th cycle was quite significant. Designing plant scale-up and its economic feasibility proved that walnut shells could be suitable for Cu(II) ions adsorption from effluent water. Multilinear regression (MLR) analysis and GA-NN predicted the percentage removal successfully. Graphic abstract