Innovative boron‐doped biochar enabling extraordinary Congo red depletion from simulated effluent streams

Abstract In this study, boron‐doped biochar (BC) with a well‐developed mesoporous structure was successfully prepared using perishable biomass as the raw material and innovatively adopting the boron‐alkali co‐pyrolysis process. This structure is significantly different from the porous characteristics of conventional biochar, as it can provide more abundant adsorptive active sites and efficient mass transfer channels, thereby essentially enhancing the adsorption performance. The adsorption behavior of BC toward Congo red (CR) was systematically investigated, and the results showed that: under the optimal conditions of pH = 7, temperature 303 K (30°C), initial CR concentration of 80 mg/L, and BC dosage of 0.05 g/L, the maximum adsorption capacity of BC reached as high as 1188.4 mg/g, which is significantly superior to most reported novel adsorbents. The pseudo‐second‐order kinetic model (with the best fitting effect) confirms that chemisorption is the dominant adsorption mechanism, while the Freundlich isotherm model reveals that the adsorption of CR on the heterogeneous surfaces of BC involves a coexistence of multilayer and monolayer adsorption processes. In addition, BC features wide availability and low cost of raw materials, and its preparation process produces no secondary pollution, realizing the resource utilization of perishable biomass and fully conforming to the concepts of green chemistry and sustainable development. It provides a novel solution for the efficient, low‐cost, and green treatment of CR‐containing dye wastewater, while laying a theoretical and experimental foundation for the industrial application of biomass‐based adsorbents.