ABSTRAK Modifikasi hematit (α-Fe2O3) dengan karbon aktif untuk mendapatkan komposit Karbon Aktif/α-Fe2O3 melalui metode hidrotermal dan uji aktivitas fotokatalitiknya pada degradasi zat warna tartrazin telah dilakukan. Hematit yang digunakan berasal dari pasir besi yang diperoleh dari pantai Syiah Kuala, Deah Raya, Aceh Besar yang diekstraksi menggunakan asam klorida (HCl) dan dikopresipitasi menggunakan ammonium hidroksida (NH4OH). Karbon aktif yang digunakan berasal dari pati umbi janeng yang dikarbonisasi melalui metode hidrotermal dan diaktivasi menggunakan asam klorida (HCl). Karakterisasi produk dilakukan menggunakan instrumen X-Ray Diffraction (XRD), Scanning Electron Microscopy-EnergyDispersive X-Ray Spectroscopy (SEM-EDS) dan Brunaeur Emmet Teller (BET). Hematit yang disintesis menunjukkan bahwa hematit telah terbentuk dengan fasa α- Fe2O3, karbon aktif memiliki fasa amorf dan komposit KA/α-Fe2O3 memiliki ukuran rata-rata partikel sebesar 26,54 nm. Hasil uji aktivitas menunjukkan bahwa komposit KA/α-Fe2O3 dapat mendegradasi zat warna tartrazin hingga 69,49% di bawah sinar UV dan 95,39% di bawah sinar matahari. Aktivitas fotokatalitik tersebut diperoleh pada kondisi optimum pH 1, massa fotokatalis 350 mg dan konsentrasi awal zat warna tartrazin 12,5 ppm dengan waktu radiasi selama 210 menit di bawah sinar UV sedangkan radiasi sinar matahari membutuhkan waktu selama 180 menit. Kata kunci : Hematit, karbon aktif, pati umbi janeng, komposit Karbon Aktif/α- Fe2O3, tartrazin dan fotokatalis. ABSTRACT Modification of hematite (α-Fe2O3) with activated carbon to produce Activated Carbon/α-Fe2O3 composite by hydrothermal method and its photocatalytic activity on the degradation of tartrazine dye was conducted carried out. Hematite was obtained from iron sand taken from Syiah Kuala beach, Deah Raya, Aceh Besar which was extracted by using hydrochloric acid (HCl) and coprecipitated using ammonium hydroxide (NH4OH). Activated carbon was derived from janeng tuber starch which was carbonized by hydrothermal method and activated using hydrochloric acid (HCl). The material were characterized by using X-Ray Difraction (XRD), Scanning Electron Microscopy-Energy-Dispersive X-Ray Spectroscopy (SEM-EDS) and Brunaeur Emmet Teller (BET). Iron (III) oxide extracted from iron sand is α-Fe2O3 phase and activated carbon has an amorphous phase. AC/α-Fe2O3 composite has an average crystallite size of 26,54 nm. The result of photocatalytic activity showed that C/α-Fe2O3 composite can remove tartrazine up to 69,49% under UV light and 95,39% under sunlight. This highest photocatalytic activity was obtained on optimum conditions at pH 1, a photocatalyst mass of 350 mg and initial tartrazine of 12,5 ppm under UV light irradiation for 210 min and under sunlight irradiation for 180 min. Keywords: Hematite, activated carbon, janeng tuber starch, Activated Carbon/α- Fe2O3 composite, tartrazine and photocatalyst.