Gangue-Based SiO₂ Aerogel Used for Pb(II) Adsorption in Wastewater and Mechanism Analysis

Coal gangue, a byproduct of coal mining with massive generation, presents a major challenge for resource utilization. In this study, SiO₂ aerogel was successfully fabricated from coal gangue, via a facile and cost-effective approach. The aerogel boasts an intricate network framework structure internally and functions as a mesoporous material with measurements of 154.5662 m²·g⁻¹ for specific surface area and 7.9557 nm for average pore size. Additionally, exploring the adsorption capabilities of SiO₂ aerogel concerning Pb(II) in wastewater, the research revealed insights. The results demonstrated that the maximum Pb(II) removal efficiency reached 94.09% under pH 6, aerogel dosage of 1.5 g·L⁻¹, and initial Pb(II) concentration of 80 mg·L⁻¹. The adsorption process followed the Langmuir isotherm model and pseudo-second-order kinetic model, suggesting a favorable and predominantly monomolecular layer chemisorption, and the intraparticle diffusion model suggests internal diffusion behavior during adsorption. The SiO₂ aerogel exhibited specific adsorption behavior towards Pb(II). This study offers a promising avenue for repurposing coal gangue while addressing the issue of Pb(II)-contaminated wastewater.