Green valorization of municipal solid waste incineration fly ash into NaP1 zeolite via ultrasonic pretreatment: Low-carbon synthesis and robust oxytetracycline removal

Hydrothermal synthesis of zeolites from municipal solid waste incineration fly ash (MSWI-FA) offers a promising strategy for hazardous waste valorization, yet energy-intensive pretreatments like alkali fusion hinder its scalability. To address this limitation, this study proposes a sustainable ultrasonic pretreatment method to synthesize an MSWI-FA-based NaP1 zeolite (IFA-NaP1). Results demonstrate that ultrasonic cavitation accelerates amorphous phase dissolution, enabling detectable NaP1 zeolite formation within approximately 20 min of subsequent microwave hydrothermal synthesis, corresponding to a 50% reduction relative to alkali-fusion pretreatment. Compared with conventional alkali-fusion, the ultrasonic-derived IFA-NaP1 exhibits an 86% lower risk assessment code (RAC), a 72% reduction in global warming potential, and a 16.5% decrease in synthesis cost. Crucially, IFA-NaP1 effectively adsorbs oxytetracycline (OTC) at environmentally relevant concentrations of 5–30 mg L⁻¹. This endothermic and entropy-driven process is synergistically governed by electrostatic attraction, hydrogen bonding, and metal ion complexation. Validating its practical applicability, the zeolite maintains an OTC removal efficiency of over 85% in simulated wastewater containing complex organic matter and multiple coexisting heavy metals. Overall, this work presents a rapid, cost-effective, and low-carbon pathway for the safe valorization of MSWI-FA, delivering a robust adsorbent for antibiotic remediation in aquatic environments.