Tailoring metal-impregnated biochars for selective removal of natural organic matter and dissolved phosphorus from the aqueous phase

This study aimed to investigate how the production process of metal impregnated biochars (MIBs) affects their selectivity in the simultaneous adsorption of organic matter and dissolved phosphorus from the aqueous phase. MIBs were produced via a two-step pyrolysis procedure including impregnation of metal oxides in the structure of the softwood-derived biochars, resulting in copper-impregnated biochar (Cu-MIB) and iron-impregnated biochar (Fe-MIB). The tailoring process was conducted by optimization of pyrolysis temperature during the biochars production stage. The MIBs were characterized via advanced characterization analyses to acquire structural, elemental, and morphological properties of the adsorbent. The surface area of MIB (99 m2/g and 92 m2/g for Cu-MIB and Fe-MIB respectively) decreased compared to pristine biochar (571 m2/g), indicating a successful impregnation of metal oxide particles within the porous carbon structure. The effect of operational parameters on adsorption as well as selectivity tests were examined in the batch mode. The optimum doses for NOM removal were 2 g/l for Fe-MIB (96%) and 0.5 g/l for Cu-MIB (87%). For phosphorus removal, optimum doses were 1 g/l for Fe-MIB (95%) and 2 g/l for Cu-MIB (93%). The lower pH values favored adsorption for both MIBs. In the binary solution of NOM and phosphorus, the NOM was selectively adsorbed by the Cu-MIB, whereas phosphorus was selectively removed by the Fe-MIB. The results provide a deeper understanding of the tailoring process of biochars for producing new biochars as selective adsorbents for specific target pollutants.

Automated summary

This study focuses on how the production process of metal impregnated biochars affects their selectivity in the adsorption of organic matter and dissolved phosphorus. The results show that by tailoring the production process, biochars with selective adsorption capabilities for specific pollutants can be produced.