In　this　paper,　a　novel　silica　gel　affinity　sorbent　with　poly(1-vinylimidazole)　(PVI)　ligand　was　prepared　for　the　selective　removal　of　endotoxin　(LPS)　from　a　water　or　a　BSA　solution.　The　vinyl　silane-modified　porous　silica　gel　particle　SiO2-g-KH570　was　used　as　macromonomer,　and　PVI　was　grafted　on　by　heterogeneous　graft　copolymerization.　First,　the　effect　of　reaction　conditions　on　the　grafted　degree　(GD)　of　PVI　was　investigated　in　detail　by　thermogravimetry.　Then,　the　influences　of　initial　LPS　concentration,　pH　and　ionic　strength　of　the　tested　aqueous　solutions　on　LPS　removal　ability　of　PVI-g-SiO2　affinity　sorbent　were　studied　and　compared　with　those　of　His-g-SiO2　affinity　sorbent.　The　results　showed　that　maximum　LPS　removal　capacity　was　obtained　with　a　GD　about　2.5　wt%　and　the　PVI-g-SiO2　affinity　sorbent　had　better　selective　removal　of　LPS　compared　to　His-g-SiO2　affinity　sorbent　in　both　water　and　BSA　solution.　The　affinity　mechanism　between　PVI　and　LPS　is　also　discussed　in　this　paper.　All　of　our　results　indicate　that　PVI　is　a　good　ligand　for　LPS　removal.　(C)　2011　Elsevier　Ltd.　All　rights　reserved.