BACKGROUNDIn　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.RESULTSThe　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-.CONCLUSIONThese　results　suggest　that　BC-PH　has　great　potential　for　the　application　of　TcO4-　separation　in　consideration　of　its　high　adsorption　capacity　and　selectivity.　(c)　2024　Society　of　Chemical　Industry　(SCI).