Study on the performance and structure of low graphitized biochar prepared by silica template method for adsorbing odorous gases

Research on the removal of sulfur-containing malodorous gases from air via biochar adsorption demonstrates significant application potential. In this study, silicon-modified graphitized carbon was synthesized through pyrolysis using peanut shells, rice husks, and walnut shells as precursors. Among the resulting materials, rice husk-derived biochar (DK-700–5) and walnut shell-derived biochar (HT-800–10) exhibited pronounced targeted adsorption toward CH₃SH and H₂S, respectively. The sulfur adsorption capacity of DK-700–5 was 8.3 times higher than that of unmodified rice husk biochar, while HT-800–10 achieved a 2.45-fold enhancement in H₂S adsorption compared to its unmodified counterpart. Carboxyl and oxygen vacancies on DK-700–5 were identified as critical for CH₃SH adsorption, facilitating its immobilization and gradual oxidation to sulfate (SO₄²⁻), with intermediate sulfur species such as R–SO–R, S⁰, and C–S detected. In parallel, HT-800–10 adsorbed and oxidized H₂S through its porous structure and surface superoxide radicals, converting it into elemental sulfur (S⁰) and sulfate (SO₄²⁻), thereby achieving efficient adsorption and oxidative transformation.