BACKGROUND:　In　this　study,　a　defective　biochar　with　honeycomb-like　porous　structure　(BC-PH)　was　successfully　prepared　by　the　activation　of　pristine　biochar　derived　from　bamboo　shoot　shell　with　the　chemical　reagent　KOH,　and　was　applied　to　selectively　separate　ReO4−　(a　chemical　analogue　for　radioactive　TcO4−)　from　acidic　solutions.　RESULTS:　The　diffusion,　mass　transfer　and　recovery　for　ReO4−　could　be　significantly　improved　by　the　large　specific　surface　area　(SBET,　2412　m2　g−1)　and　high　total　volume　(Vtot,　1.26　cm3　g−1)　of　BC-PH.　The　influence　of　adsorbent　dosage,　system　pH　and　coexisting　ions　with　different　valence　states　on　the　adsorption　capability　and　selectivity　of　BC-PH　toward　ReO4−　was　systematically　investigated.　BC-PH　exhibited　high　adsorption　capacity　and　selectivity　for　ReO4−　with　a　maximal　sorption　capacity　(qm)　of　73.11　mg　g−1　at　initial　pH　2.　By　applying　an　analysis　of　kinetics　and　isotherm　adsorption　studies,　the　liquid　film　diffusion　was　verified　to　be　the　primary　rate-controlling　step　for　the　sorption　of　ReO4−　and　the　multilayer　adsorption　process　occurred　on　the　heterogeneous　surface　of　BC-PH.　Besides,　the　recovery　of　ReO4−　using　BC-PH　occurred　in　an　exothermic　and　spontaneous　manner　according　to　thermodynamic　analysis.　Furthermore,　an　investigation　of　the　adsorption　mechanism　suggested　that　pore　filling　and　electron　donor–acceptor　interaction　were　mainly　related　to　the　removal　of　ReO4−.　CONCLUSION:　These　results　suggest　that　BC-PH　has　great　potential　for　the　application　of　TcO4−　separation　in　consideration　of　its　high　adsorption　capacity　and　selectivity.　©　2024　Society　of　Chemical　Industry　(SCI).　©　2024　Society　of　Chemical　Industry　(SCI).