Naturally dispersed ash components in bio-carbon composites: integrated ammonia nitrogen removal and specific surface area augment

In this work, naturally dispersed ash components in bio-carbon composites were prepared from waste spent mushroom substrate. Two kinds of deashing treatments were used to study the role of soluble and poorly soluble ash in the adsorption of NH₄⁺ and increase specific surface area. The role of ash components on pore structure and the adsorption of ammonia nitrogen were systematically investigated. It is revealed that the relationship of ammonium adsorption capacity of three ACs is MAC > MAC-W > MAC-A at the varied pH conditions. Specifically, the ammonia nitrogen adsorption capacity of MAC increases 108.9% as compared with MAC-A. The bigger pore structure and BET of carbon was obtained after absorption due to naturally dispersed ash components exchanged with NH₄⁺. What is more, Na⁺, K⁺, and Ca²⁺ in the ash have a greater effect on the adsorption of ammonia nitrogen of ACs. The struvite formation will consume the Mg²⁺ and NH₄⁺ ion, leading to the enhanced adsorption properties via chemical deposition. This work provides a new perspective on dispersed ash components in bio-carbon from the low-valued biomass for the ammonia nitrogen removal and specific surface area augment.