Multi-heteroatom self-doped microporous biochar derived from fish scale for boosting uranium immobilization performance

Biochar materials with low cost and desired properties have gradually been widely applied in multitudinous domains, especially in radioactive wastewater remediation. Multi-heteroatom doping is a useful method for the design of doping biochar with uranium immobilization of excellent performance. Herein, multi-heteroatom self -doped microporous carbon was designed and synthesized via extraction and carbonization of collagen by po-tassium compound assisted, which was extracted by low-cost fish scales as the precursor and tested for high-performance uranium immobilization. The multi-heteroatom self-doped biochar exhibited the maximum satu-rated adsorption capacity of 142.06 mg/g for U(VI) at pH = 5, reflecting the significant increase in available adsorption sites from multi-heteroatom doped. The strong complexation process was proposed for the mutual effect between U(VI) and multi-heteroatom doped biochar, where abundant functional groups (oxygen and amino) and sulfur metal sites groups were the primary active sites. The design of multi-heteroatom self-doped biochar provided a universal and effective method for purifying U(VI) from wastewater systems.