Sunset　yellow　(SY)　FCF　is　a　hazardous　azo　dye　pollutant　found　in　food　processing　effluent.　This　study　investigates　the　use　of　diatomaceous　earth　with　chitosan　(DE@C)　as　a　modified　adsorbent　for　the　removal　of　SY　from　wastewater.　Fourier　transform　infrared　spectroscopy　results　indicate　the　importance　of　functional　groups　during　the　adsorption　of　SY.　The　obtained　N-2　adsorption-desorption　isotherm　values　accord　well　with　IUPAC　type　II.　Our　calculations　determined　a　surface　area　of　69.68　m(2)　g(-1)　for　DE@C　and　an　average　pore　diameter　of　4.85　nm.　Using　response　surface　methodology,　optimized　conditions　of　process　variables　for　dye　adsorption　were　achieved.　For　the　adsorption　of　SY　onto　DE@C,　this　study　establishes　mathematical　models　for　the　optimization　of　pH,　contact　time　and　initial　dye　concentration.　Contact　time　plays　a　greater　role　in　the　adsorption　process　than　either　pH　or　initial　dye　concentration.　According　to　the　adjusted　correlation　coefficient　(adj-R-2　＞　0.97),　the　models　used　here　are　suitable　for　illustration　of　the　adsorption　process.　Theoretical　experimental　conditions　included　a　pH　of　2.40,　initial　dye　concentration　of　113　mg　L-1　and　30.37　minutes　of　contact　time.　Experimental　values　for　the　adsorption　rate　(92.54%)　were　close　to　the　values　predicted　by　the　models　(95.29%).