Advanced biochar for accelerated and efficient pollutant removal in complex water systems

Abstract

The adsorption efficiency of biochar for water pollutions is closely related to specific surface area (SSA) and pore size, especially in complex water systems. Here, hierarchical pores were constructed to evaluate adsorption efficiency in such system. Three biochar (Hydrothermal loofah sponge, HLS; Hydrothermal loofah sponge-pluronic F127, HLS-F; Hydrothermal loofah sponge-pluronic F127-Dicyandiamid, HLS-FD) were prepared using a combination of template and pyrolysis methods. The SSA of HLS, HLS-F, and HLS-FD were 1769.61, 1829.96, and 2057.43 m²·g⁻¹, with microporosities of 78.14 %, 62.35 %, and 67.51 %. Compared to micropores (HLS), hierarchical pore (HLS-F and HLS-FD) exhibited more interface sites. The pore size adjustment reduced the equilibrium time for methylene blue adsorption from 480 min to 60 min. Since small molecular size, chloramphenicol (CAP) was rapidly adsorbed by all three biochar (60 min, 30 min, and 30 min), while for large molecular (sulfamethoxazole, SMX), HLS-F and HLS-FD showed significantly better adsorption rates than HLS (90 min to 30 min). Isotherm fitting results indicated that CAP and SMX adsorption by HLS-F and HLS-FD involved multilayer adsorption, confirming the presence of hierarchical pore structure. In binary systems, porous biochar maintained high adsorption capacity and pollutant removal efficiency. This study is significant for preparing hierarchical porous biochar (HPBC) and improving its adsorption performance and utilization efficiency, which lays a foundation for the preparation of selectively adsorbed biochar.