Efficient synthesis of zeolite-A from bottom ash for sustainable heavy metal removal from real environmental samples

Abstract

This study presents a novel approach to synthesizing zeolite-A (BAZ-A) from bottom ash (BA) using an alkaline fusion method, offering a sustainable solution for environmental remediation. The optimized synthesis, involving a BA-to-NaAlO₂ ratio of 1 : 0.3, yielded BAZ-A with superior crystallinity, a high specific surface area of 211.40 m² g⁻¹, and enhanced adsorption properties. BAZ-A demonstrated exceptional adsorption capacities for Pb(II) (346.65 mg g⁻¹), Cd(II) (291.81 mg g⁻¹), Zn(II) (131.83 mg g⁻¹), and Cu(II) (172.84 mg g⁻¹), with adsorption processes aligning with the Langmuir isotherm. Thermodynamic studies revealed the adsorption to be spontaneous and endothermic, driven by mechanisms including surface complexation, ion exchange, and electrostatic attraction. Practical applications were validated through tests with industrial wastewater and contaminated soil. BAZ-A demonstrated significant efficacy in removing heavy metals, achieving 99.5% removal in wastewater for Pb(II), Cu(II), and Cd(II), and reducing them to 0.5 mg L⁻¹ in soil, except for Zn(II). This underscores its robust performance even in challenging environmental conditions. This research highlights the dual benefit of transforming industrial waste into a high-performance adsorbent while addressing critical issues of heavy metal contamination in water and soil. The novel synthesis strategy and the demonstrated efficiency of BAZ-A position it a promising candidate for scalable, cost-effective, and sustainable environmental remediation.