Rapid phosphorus adsorption: Polyaluminium chloride (PAC) modified glass pumice (M_PAC-G) with exceptional...

To address the phosphorus challenge in eel aquaculture effluent-characterized by large volumes and low phosphate concentrations-this study synthesized M_PAC-G, a macroporous glass pumice derived from recycled waste glass and modified with polyaluminium chloride (PAC) for the first time. Compared with Fe-modified glass pumice (M_Fe-G), Ca-modified glass pumice (M_Ca-G) and Fe/Al-modified glass pumice (M_Fe/Al-G), M_PAC-G achieved the highest removal efficiency within 2 h and exhibited a 19 fold faster adsorption rate than pristine glass pumice within the first 10 min. Langmuir isotherms confirmed monolayer chemisorption, while pseudo-second-order kinetics yielded an exceptionally high rate constant (1.2 g mg^-1 min^-1) and a short half-life (7.13 min), outperforming reported phosphate adsorbents. Raman, FTIR and XPS revealed covalent bonding between phosphate and metal-active sites as the dominant mechanism; electrostatic interactions were also evidenced by pH-dependent experiments. Moreover, alkaline regeneration enabled M_PAC-G to exceed its original adsorption capacity, and no significant decline in efficiency was observed after five cycles. A newly introduced weighted scoring system further overcame the limitations of single-metric evaluation. Overall, M_PAC-G valorizes construction waste into a sustainable, high-capacity and regenerable adsorbent for phosphorus removal from aquaculture wastewater.