2025

Lemessa Gemechu; Demesa Abayneh Getachew; Chebude Yonas; Sedda Ahmed; Alemyaehu Esayas

Two distinct synthesis procedures have been employed to develop a magnetic–diatomite/carboxymethyl cellulose nanocomposite (MDM-CMC) for the efficient adsorptive removal of Cr (VI) from tannery effluent. These procedures involve co-precipitating the magnetic–diatomite nanocomposite (MDM) and solution blending with carboxymethyl cellulose (CMC). The nanocomposite adsorbents were characterized using XRD, FTIR, SEM, and superconducting quantum interference device (SQUID) magnetometry. The effects of operational factors on Cr (VI) removal efficiencies were investigated using the Box–Behnken design of response surface methodology (BBD-RSM). The factors examined included the starting Cr(VI) loads, pH, adsorbent dose, and contact duration. The MDM-CMC exhibited 89.73% Cr(VI) removal efficiencies and 7.13 mg/g of adsorption capacities from tannery effluent in optimized operational conditions. The adsorption process was best described by the pseudo-second-order kinetic and the Freundlich isotherm, demonstrating the highest correlation coefficient (R2) and the lowest chi-square (?2) values, providing the best fit for the adsorption data. Thermodynamic analysis of the adsorption process indicated that it was endothermic and spontaneous, with the adsorbent exhibiting a degree of randomization in the aqueous solution.