Innovative use of recycled aluminum adsorbent for methylene blue adsorption and post-application for soil...

Methylene blue (MTB) dye from the textile manufacturing industry is harmful to the ecological environment and human health in aquatic ecosystems due to its toxicity, environmental resistance, and bioaccumulation. This study investigates the potential of aluminum oxide nanoparticles (AONPs) sourced from industrial swarf waste as a sorbent for removing MTB dye in wastewater. Under optimized conditions of 6 (pH), 200 (rpm), and 30 (minutes), 97.34 % removal was observed, and 48.65 mg. g^-1 uptake capacity of the adsorbent was achieved. The adsorption process obeyed the Langmuir model with monolayer adsorption on a surface. It conformed with a pseudo-second-order kinetic model (R² = 0.9878), indicating that the chemisorption is the rate-controlling step. Thermodynamic analyses showed that the adsorption process is exothermic and spontaneous, thus confirming the feasibility and eco-friendliness of the potential low-cost adsorbent for MTB dye removal from wastewater. The AONPs after methylene blue dye removal, were integrated into clayey soil at an appropriate concentration of 1 % to assess their influence on geotechnical parameters. Experimental findings indicated substantial enhancements, with maximum dry density rising from 1660 kg/m³ to 1700 kg/m³ and unconfined compressive strength increasing from 143.9 kPa to 198.6 kPa, with a decrease in plasticity index and liquid limit. These improvements are attributed to the nanoparticles' capacity to occupy soil voids, reduce porosity, and increase interparticle bonding. Applying AONPs offers a cost-effective and eco-friendly method for treating dyes in wastewater, while concurrently enhancing soil characteristics and promoting sustainable wastewater treatment and soil stability.