Zirconium-modified biochar as the efficient adsorbent for low-concentration phosphate: performance and mechanism
Environmental Science and Pollution Research(2022)
摘要
Achieving advanced treatment of phosphorus (P) to prevent water eutrophication and meet increasingly stringent wastewater discharge standard is an important goal of water management. In this study, a low-cost, high-efficiency phosphate adsorbent zirconium-modified biochar (ZrBC) was successfully synthesized through co-precipitation method, in which the biochar was prepared from the pyrolysis of peanut shell powder. ZrBC exhibited strong adsorption ability to low-concentration phosphate (< 1 mg·L −1 ) in water, and the phosphate removal reached 100% at the investigated dosage range (0.1–1.0 mg·L −1 ). The adsorption process could be described well by pseudo-second-order model and Langmuir isotherm model, indicating that the phosphate adsorption by ZrBC was mainly a chemical adsorption and single-layer adsorption process. The calculated static maximum phosphate adsorption capacity was 58.93 mg·g −1 at 25 °C. The ligand exchange between surface hydroxyl groups and phosphate was the main mechanism for the phosphate adsorption on ZrBC. The presence of coexisting anions except for SO 4 2− had little effect on the phosphate removal. At the column experiment, ZrBC showed superior treatment capacities for simulated secondary effluents and the breakthrough time for 0.5 mg·L −1 effluent phosphate concentration reached 190 h. ZrBC highlights the potential as an effective and environment-friendly adsorbent for the removal of low-concentration phosphate from secondary effluents of municipal wastewater treatment plants (WWTPs).
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关键词
Adsorption, Biochar, Fixed-bed column, Low-concentration phosphate, Zirconium modification
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