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

Abstract

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 H 3 PO 4 in biomass. After activated/carbonized at high temperature and subsequent washing with purified water, H 3 PO 4 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 H 3 PO 4 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 m 2 /g), and mesopores. However, chicken manure led to little loss of P at high temperatures by converting P 2 O 5 /H 3 PO 4 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.

Cu-Based Catalysts Supported on H3PO4-Activated Coffee Biochar for Selective Reduction of Nitroaromatics

“…Moreover, BCR-600 without H 3 PO 4 activated afforded the lowest BET surface areas (23 m 2 ·g) and pore volume (0.021 cm 3 ·g –1 ) (Table S1, entry 5), demonstrating that the post-treatment H 3 PO 4 -activation procedure could sharply improve the BET surface areas and mesopore structures of PBCR- x . Additionally, PBCR-600 has a higher specific surface area and pore volume than those of recently reported biochar prepared from raw biomass (<30 m 2 ·g; <0.5 cm 3 ·g –1 ), , N-doped carbon materials, , and even commercial AC (Table S1, entries 3 and 6). These features could be attributed to the unique properties of coffee residues in that after the boiling process, interior small molecules precipitated out.…”

“…22−24 However, biochar produced by a direct pyrolysis method generally has a low BET surface area, and a posttreatment activation procedure is usually required. 25,26 Due to the pollution-free nature of the resulting biochar, significant preference has been given to the use of H 3 PO 4 as the activating agent. 26,27 Herein, a series of novel and cost-effective Cu-based catalysts supported on H 3 PO 4 -activated coffee biochar was prepared for the first time.…”

“…25,26 Due to the pollution-free nature of the resulting biochar, significant preference has been given to the use of H 3 PO 4 as the activating agent. 26,27 Herein, a series of novel and cost-effective Cu-based catalysts supported on H 3 PO 4 -activated coffee biochar was prepared for the first time. The obtained Cu/PBCR-600 catalyst has a high BET surface area, highly dispersed Cu 0 active sites, and an incredible number of N-doped carbon active sites, which enable Cu/PBCR-600 to achieve superb catalytic performance in nitroaromatics reduction (>99% conversion and >97% aromatic amine selectivity).…”

“…Therefore, it has received wide attention in different emerging fields such as energy storage, environmental remediation, and catalysis. , Coffee residues, which can be produced in coffee shops all over the world, are usually abandoned or landfilled. In contrast to other biochar precursors, coffee residues are rich in starch, vegetable oils, sugars, and proteins and could be used as a promising biomass for the synthesis of heteroatom-doped biochar composites. − However, biochar produced by a direct pyrolysis method generally has a low BET surface area, and a post-treatment activation procedure is usually required. , Due to the pollution-free nature of the resulting biochar, significant preference has been given to the use of H 3 PO 4 as the activating agent. , …”

Nanofiltration membranes composed of carbonized giant cane and Pongamia meal binder for ion sieving in water and molecular sieving in organic solvents

“…resource recovery [32,33], and separation processes [34]. AC materials are often used as adsorptive fillers in membranes [35][36][37][38].…”