Ball Milling-Assisted Fabrication of Zirconium-Biochar-Zeolite Composites for Phosphate Removal in Aquatic Systems
摘要
Phosphate removal from water bodies through adsorption is currently the primary method for managing phosphorus pollution. This study innovatively synthesizes a zirconium-modified biochar-zeolite composite (denoted as Zr-Ze-BC) through a mechanochemical ball-milling approach, leveraging the synergistic adsorption properties of biochar and zeolite. The novelty of this work lies in the innovative use of a one-pot ball-milling process to intimately integrate all three components (Zr, biochar, zeolite), which not only enhances the dispersion of active sites but also improves the structural stability and reusability of the composite, surpassing the performance of composites prepared by conventional methods. Furthermore, the composite demonstrates exceptional potential for environmental application due to its stable performance across a relevant pH range, strong resistance to common interfering anions, and robust recyclability. The results showed that the specific surface area of the optimized Zr-Ze-BC is up to 125.14 m2/g, remaining stable within a pH range of 4 to 7, the maximum adsorption capacity is 14.085 mg/g. This adsorption capacity can rival that of many advanced adsorbents, and even surpass them. For instance, zirconium-modified clay has an adsorption capacity of approximately 10—15 mg/g, and engineered biochar has an adsorption capacity of about 8—20 mg/g. Moreover, it can be synthesized through a simpler and more scalable mechanochemical method. The composite demonstrates a favorable balance between adsorption performance, cost-effectiveness, and reusability, making it a promising candidate for practical phosphate removal applications in municipal and agricultural wastewater treatment. Competitive ion experiments revealed minimal interference from coexisting anions. Remarkably, after five cycles of adsorption experiments, Zr-Ze-BC still maintained a phosphate removal efficiency of about 70%. The adsorption of phosphate by Zr-Ze-BC followed the Langmuir and pseudo-second order adsorption model. Chemisorption, which was dominated by surface coordination and ligand exchange, served as the main mechanism for phosphate adsorption by Zr-Ze-BC. This work not only provides a cost-effective, recyclable adsorbent for phosphorus control but also advances mechanistic understanding of biochar-zeolite interactions in aquatic remediation.