This　study　investigated　how　the　particle　size　of　the　modified　adsorbent　diatomite　earth　&　chitosan　(DE&C)　affects　the　removal　of　sunset　yellow　(SY)　from　water　using　a　fixed　bed　column.　Fourier　Transform　Infrared　Spectroscopy　(FTIR)　analysis　indicated　that　the　amino　group　(-NH2)　played　an　important　role　during　the　adsorption　of　SY.　The　calculated　surface　area　of　the　DE&C　absorbent　was　found　to　be　69.68　m(2)　g(-1)　and　SEM　images　showed　that　DE&C　is　a　superior　porous　adsorbent.　Four　dimensions　of　DE&C　were　measured　in　a　fixed　bed　column.　The　breakthrough　time　of　SY　increased　as　the　size　of　DE&C　decreased　and　the　effluent　concentration　showed　a　trend　of　first　increasing　and　then　decreasing.　It　was　also　found　that　the　nature　of　the　variation　in　the　effluent　concentration　with　time　was　parabolic　and　that　the　adsorption　data　fitted　the　parabolic　equation　at　C-t/C-0　=　0-0.1.　Due　to　the　different　combination　ability　with　hydrogen　bonding,　the　phenomenon　of　parabolic　variation　is　quite　disparate　from　other　adsorbents.　But,　compared　with　the　breakthrough　time,　the　saturation　time　was　close　to　other　particle　sizes,　except　for　2.86-3.35　mm　in　size.　pH　is　an　important　parameter　for　the　adsorption　of　SY　and　the　main　mechanism　is　adsorption　with　each　other　between　positive　and　negative　charges.　The　Thomas　model　shows　lower　correlation　with　the　smaller　sizes　and　R-2　with　an　average　of　0.9413.　The　Thomas　model　indicated　that　the　maximum　value　of　q(0)　was　97.06　mg　g(-1)　and　with　an　increase　in　the　initial　SY　concentration,　the　bed　height　and　the　values　of　q(0)　decreased　as　k(t)　increased.　The　Yoon-Nelson　model　describing　the　theoretical　required　time　was　close　to　the　experimental　values　and　k(YN)　increased　as　C-0　increased.