Protonated　de-oiled　soybean　(PDOS)　as　a　low-cost　and　effective　biosorbent　was　used　for　the　biosorption　of　triclosan　(TCS)　from　aqueous　solution.　The　contribution　of　functional　groups　such　as　amine,　carboxyl,　sulfhydryl,　phosphate　and　lipids　on　PDOS　to　TCS　biosorption　was　evaluated　by　means　of　chemical　modification.　The　results　showed　that　sulfhydryl　groups　gave　the　largest　contribution,　followed　by　lipids　and　amine　groups,　while　the　contribution　of　carboxyl　groups　could　not　be　confirmed.　FTIR　spectra　offered　help　to　identify　the　introduced　functional　group　changes.　Based　on　the　results,　it　was　proposed　that　the　TCS　biosorption　onto　PDOS　was　determined　by　hydrophobic　interaction　and　hydrogen　bonding　rather　than　electrostatic　interaction.　The　TCS　biosorption　process　depended　much　on　initial　pH　and　the　optimum　pH　value　was　4.0.　Kinetic　studies　demonstrated　that　a　pseudo-second-order　model　was　more　applicable　for　description　of　the　biosorption　of　TCS　onto　PDOS;　both　intra-particle　diffusion　and　boundary　layer　diffusion　might　affect　the　biosorption　rate.　The　Dubinnin-Radushkevich　(D-R)　isotherm　agreed　well　with　the　biosorption　equilibrium　data　over　the　whole　concentration　range,　and　the　maximum　biosorption　capacity　was　124.55　mg　g(-1),　revealing　that　biosorption　via　PDOS　could　be　used　as　an　effective　method　for　TCS　removal　from　aqueous　solution.