Detoxification of dairy industry effluent from toxic metal ions: Preparation and characterization of a magnetized adsorbent derived from agricultural residues

This study investigated the potential of a mixture of agricultural wastes for the preparation of an adsorbent and evaluated its efficiency in removing Co(II) and Cu(II) ions. Brunauer-Emmett-Teller analysis revealed a surface area of 89.57 m²/g, a total pore volume of 4.92 cm³/g, and an average pore diameter of 43.26 nm. Scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed a layered structure, uniform pore distribution, and successful adsorption of cobalt and copper ions. Vibrating sample magnetometry analysis demonstrated superparamagnetic behavior, with a saturation magnetization of 52.8 emu/g. Fourier-transform infrared spectroscopy identified oxygen-containing functional groups formed during activation, which significantly enhanced the adsorbent’s adsorption capacity. Equilibrium data for pollutant adsorption were well-described by the Freundlich isotherm, with maximum adsorption capacities of 91.7 mg/g for Co(II) and 89.9 mg/g for Cu(II). At 50 °C, the correlation coefficients (R²) were determined to be 0.969 for Co(II) and 0.960 for Cu(II). Under optimal conditions, 75 mg of adsorbent at 50 °C, pH 6.5, and 30 min, the adsorbent achieved 92–93% removal of pollutants from real dairy effluent and 95–96% from synthetic effluent. The process highlights its potential as a sustainable solution for dairy effluent treatment and agricultural waste management, with scalability for industrial applications. This study presents a sustainable magnetic adsorbent synthesized from corn residue, capsicum seeds, and medlar kernels. It efficiently removes Co(II) and Cu(II) from dairy effluents with 92–96% efficiency. Featuring high porosity, surface area, and functional groups, the adsorbent operates effectively at ambient temperatures, saving energy. Its reusability and scalability highlight its potential for cost-effective wastewater treatment in the dairy industry. A novel magnetic adsorbent derived corn residue, capsicum seeds, and medlar kernels, effectively removed Co(II) and Cu(II) from dairy effluents. SEM, EDS, BET, FTIR, and VSM analyses confirmed high porosity, large surface area, and functional groups aiding pollutant removal. Removal efficiencies reached 92–96% for real and synthetic effluents under optimal conditions without energy input. Maximum adsorption capacities were 91.7 mg/g for Co(II) and 89.9 mg/g for Cu(II), following the Freundlich isotherm. The adsorbent remained effective after 12 reuse cycles, offering scalable potential for dairy effluent treatment and sustainable waste management.