An experimental study on biochar-modified foamed concrete: insights into the evaluation of phosphorus removal effect, adsorption kinetics, and sorption mechanisms

The biochar based foamed concrete (RHBC-based FC) has a broad application prospect in the construction field. Moreover, considering its rich functional groups and porous characteristics, it can be used as an ideal material for water pollutant control to realize its environmental value-added value. Based on this, this article explored the combined effect of RHBC-based FC as adsorbents to treat phosphorus in wastewater. The experimental results indicated that RHBC-based FC had significant purification performance. When the replacement amount of rice husk biochar (RHBC) was 5%, the removal performance of total phosphorus (TP) was the best, 30.8% higher than that of the sample without RHBC. Therefore, excellent water purification performance could only be demonstrated with moderate RHBC content. Meanwhile, the influence of the initial concentration and adsorption time of phosphorus in wastewater on adsorption capacity and efficiency was studied using an IC analyzer. According to the outcomrd, RHBC phosphorus adsorption conformed to the Langmuir and Freundlich models, and that the data on adsorption isotherms were well-fitted. In addition, the adsorption kinetics data of RHBC followed a pseudo-first-order model. According to the analysis of FTIR, XRD, and DTG-TG results, there was no significant difference between RHBC-based FC before and after phosphorus removal soaking, which could effectively ensure the durability of FC. The SEM-EDS analysis results indicated that the adsorption effect of RHBC-based FC on P followed physical adsorption. Therefore, RHBC can serve as an effective adsorbent for FC.