In　this　study,　a　3D　CoNiO2/Co　core–shell　structure　biochar　catalyst　derived　from　walnut　shell　was　synthesized　by　hydrothermal　and　ion　etching　methods.　The　prepared　BC@CoNi-600　catalyst　exhibited　exceptional　peroxymonosulfate　(PMS)　activation.　The　system　achieved　100　%　degradation　of　sulfamethoxazole　(SMX).　The　reactive　oxygen　species　in　the　BC@CoNi-600/PMS　system　included　SO4[rad]−,　[rad]OH,　and　O2[rad]−.　Density　functional　theory　calculations　explored　the　synergistic　effects　between　nickel–cobalt　bimetallic　and　carbon　matrix　during　PMS　activation.　The　unique　3D　core–shell　structure　of　BC@CoNi-600　features　an　outer　nickel–cobalt　bimetallic　layer　with　exceptional　PMS　adsorption　capacity,　while　protecting　the　zero-valence　Co　of　the　inner　layer　from　oxidation.　Based　on　the　experimental-data,　machine　learning　modeling　mechanism,　and　information　theory,　a　nonlinear　modeling　method　was　proposed.　This　study　utilizes　a　machine　learning　approach　to　investigate　the　degradation　of　SMX　in　complex　aquatic　environments.　This　study　synthesized　a　novel　biochar-based　catalyst　for　activated　PMS　and　provided　unique　insights　into　its　environmental　applications.　©　2024　Elsevier　Ltd