Activation of Biochars by Waste Phosphoric Acids: An Integrated Disposal Route of Waste Acids and Solid Waste
2021
Niu, Hongyun | Jin, Huiwen | Sun, Qing | Shi, Yali | Zhang, Xiaole | Cai, Yaqi
Waste phosphoric acid can pose severe adverse effects to environments and ecological systems if directly discharged. As an important and irreplaceable element, the recovery of phosphorus (P) is essential for the sustainability of modern world. To recover P from waste acids, we impregnated coffee ground or chicken manure into waste phosphoric acid polishing solution to store H₃PO₄ in biomass. After activated/carbonized at high temperature and subsequent washing with purified water, H₃PO₄ was recollected and activated carbon (AC) was achieved. The results indicated that the coffee ground was ideal reagents to recover P, and the recovery of H₃PO₄ was as high as 70% when the carbonization temperature was 500–600 °C, and the obtained AC was of the characteristic of the P dopant, large surfaces (315–811 m²/g), and mesopores. However, chicken manure led to little loss of P at high temperatures by converting P₂O₅/H₃PO₄ into metaphosphate salts. This novel strategy realizes efficient utilization of solid waste, P recovery, heavy metal separation, and organic chemical elimination from waste acids, without producing new solid or liquid waste.
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