Preparation of porous composite hydrogel with ultra-high dye adsorption capacity based on biochar: Adsorption behaviors and mechanisms

With the continuous development of industrialization, dyes in industrial wastewater have become a serious environmental issue. To address this environmental issue, a biochar-based composite hydrogel (PAS/aBC-CD) was designed. The use of a simple composite method effectively resolves the challenge of biochar recovery. Furthermore, the modified adsorbent exhibits remarkably high adsorption capacities for all three dyes (MB: 1494 mg/g, MG: 1182 mg/g, and NR: 1031.6 mg/g). It is noteworthy that binary co-adsorption experiments have demonstrated that CrO42− can act as a bridging agent to enhance the adsorption of dyes by the adsorbent. Systematic adsorption–desorption experiments have demonstrated the outstanding recyclability of PAS/aBC-CD, maintaining 98 % of its adsorption capacity after 5 cycles. Additionally, its industrial application potential was demonstrated through column adsorption experiments. In conclusion, this study utilized a simple composite method to produce an adsorbent with high adsorption performance and industrial application potential.