Synthesis of Magnetic Iron Oxide Heat-Activated Termite Mound Composite for Adsorption of Basic Blue 41 Dye from Textile Wastewater: Characterization and Box–Behnken Optimization

Abstract

The discharge of textile effluents containing dyes poses severe environmental risks. This study aimed to develop a $\mathrm{m}\mathrm{a}\mathrm{g}\mathrm{n}\mathrm{e}\mathrm{t}\mathrm{i}\mathrm{c} \mathrm{i}\mathrm{r}\mathrm{o}\mathrm{n} \mathrm{o}\mathrm{x}\mathrm{i}\mathrm{d}\mathrm{e}$–HTM (magnetite–heat-activated termite mound) composite via the coprecipitation method for the adsorption of Basic Blue 41 (BB41) dye from textile wastewater under batch conditions. The $\mathrm{m}\mathrm{a}\mathrm{g}\mathrm{n}\mathrm{e}\mathrm{t}\mathrm{i}\mathrm{c} \mathrm{i}\mathrm{r}\mathrm{o}\mathrm{n} \mathrm{o}\mathrm{x}\mathrm{i}\mathrm{d}\mathrm{e}$–HTM composite was characterized using BET (surface area), XRD (crystalline structure), FTIR (functional groups), and SEM (microstructure) analyses, confirming the successful synthesis of $\mathrm{m}\mathrm{a}\mathrm{g}\mathrm{n}\mathrm{e}\mathrm{t}\mathrm{i}\mathrm{c} \mathrm{i}\mathrm{r}\mathrm{o}\mathrm{n} \mathrm{o}\mathrm{x}\mathrm{i}\mathrm{d}\mathrm{e}$–HTM. Comprising 80% HTM by mass, the composite demonstrates economic viability. Using batch experiments and a Box–Behnken design, the adsorption performance of $\mathrm{m}\mathrm{a}\mathrm{g}\mathrm{n}\mathrm{e}\mathrm{t}\mathrm{i}\mathrm{c} \mathrm{i}\mathrm{r}\mathrm{o}\mathrm{n} \mathrm{o}\mathrm{x}\mathrm{i}\mathrm{d}\mathrm{e}$–HTM for BB41 dye removal from aqueous solutions was evaluated. Optimization of the sorption process revealed that a dosage of 2.6 g/L, a contact time of 47.5 min, a temperature of 60 °C, and an initial dye concentration of 100 mg/L resulted in a BB41 dye removal efficiency of 98%. Additionally, $\mathrm{m}\mathrm{a}\mathrm{g}\mathrm{n}\mathrm{e}\mathrm{t}\mathrm{i}\mathrm{c}$–HTM effectively removed BB41 dye from real wastewater samples, achieving a removal efficiency exceeding 80%, highlighting the improved sorption properties of the modified termite mound. The spent $\mathrm{m}\mathrm{a}\mathrm{g}\mathrm{n}\mathrm{e}\mathrm{t}\mathrm{i}\mathrm{c}$–HTM was easily separated from the treated solution using an external magnet and successfully recovered. Its reusability demonstrated a dye removal efficiency of 78% after four cycles, without compromising its magnetic properties. Overall, the magnetically separable $\mathrm{m}\mathrm{a}\mathrm{g}\mathrm{n}\mathrm{e}\mathrm{t}\mathrm{i}\mathrm{c} \mathrm{i}\mathrm{r}\mathrm{o}\mathrm{n} \mathrm{o}\mathrm{x}\mathrm{i}\mathrm{d}\mathrm{e}$–HTM composite shows significant potential for the treatment of textile wastewater.