Coeffect of pyrolysis temperature and potassium phosphate impregnation on characteristics, stability, and adsorption mechanism of phosphorus-enriched biochar

Potassium phosphate (K3PO4)-impregnated bamboo was pyrolyzed at temperatures ranging from 350 to 950 degrees C to explore the coeffect of pyrolysis temperature and K3PO4 impregnation on biochar's characteristics and adsorption behavior. The degree of aromatization and graphitization in phosphorus-enriched biochars (PRBCs) rose as temperature increased, whereas H/C and O/C ratios, pH value, and O-containing group content decreased. The pre-aging impact of K3PO4 impregnation results in increased stability and adsorption performance of PRBCs. Adsorption mechanism of PRBCs to heavy metal varies from pyrolysis temperature. Micropores dominate medium-temperature PRBCs (prepared at 550 similar to 750 degrees C), possessing the highest P-containing group content (116 % that of PRBC-350) and maximal adsorption capacity (greater than 289 mg/g). The medium-temperature PRBCs adsorb Cd (II) via the role of O-containing groups, PO43-, and P2O74-, mainly by reactions of organic complexation, precipitation and inorganic complexation, respectively. 550 degrees C is the optimal pyrolysis temperature for both energy saving and heavy metal adsorption.

Automated summary

The study investigated the coeffect of pyrolysis temperature and K3PO4 impregnation on the characteristics and adsorption behavior of bamboo biochar. The results showed that medium-temperature pyrolysis (550-750 degrees C) produced biochar with higher adsorption capacity for heavy metals, mainly through the adsorption of Cd (II) by O-containing groups, PO43-, and P2O74-.