Activation of Biochars by Waste Phosphoric Acids: An Integrated Disposal Route of Waste Acids and Solid Waste

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 degrees C, and the obtained AC was of the characteristic of the P dopant, large surfaces (315-811 m(2)/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.

Automated summary

The study utilized coffee grounds and chicken manure to recover phosphorus from waste phosphoric acids. Results showed that coffee grounds were more ideal reagents with a recovery rate of 70%, while chicken manure led to some loss of P at high temperatures.