ABSTRAK Penelitian mengenai fotodegradasi zat warna indigo carmine (IC) menggunakan fotokatalis komposit α-Fe2O3/bentonit dan radiasi sinar ultraviolet (UV) telah dilakukan. Hematit (α-Fe2O3) disintesis dari pasir besi yang berasal dari pantai Syiah Kuala, Banda Aceh melalui metode kopresipitasi. Fotokatalis komposit α-Fe2O3/bentonit dipreparasi dengan menggunakan metode ball mill dengan variasi perbandingan berat (b/b) α-Fe2O3 dan bentonit 3:1, 1:3 dan 1:1. Hematit dan fotokatalis komposit α-Fe2O3/bentonit dikarakterisasi menggunakan (X-Ray Diffraction) (XRD) dan (Scanning Electron Microscopy-Energy Dispersive X-Ray) (SEM EDX) untuk mengetahui sifat fisik dan kimianya. Berdasarkan hasil analisis XRD oksida besi yang diperoleh memiliki fasa α-Fe2O3 dan rata-rata ukuran kristal fotokatalis komposit α-Fe2O3/bentonit lebih kecil dibandingkan dengan hematit dan bentonit. Aktivitas fotokatalitik komposit α-Fe2O3/bentonit yang tertinggi diperoleh pada perbandingan α-Fe2O3 dan bentonit 3:1 dengan persen degradasi IC sebesar 89% pada kondisi pH larutan zat warna 1, massa fotokatalis 350 mg, dan konsentrasi zat warna 15 ppm setelah diradiasi dengan sinar UV selama 120 menit. Fotokatalis komposit α-Fe2O3/bentonit menggunakan cahaya matahari menunjukkan aktivitas yang lebih tinggi dibanding menggunakan sinar UV dengan persen degradasi zat warna IC mencapai 93%. Kata Kunci: Fotokatalis, Indigo Carmine, α-Fe2O3 dan bentonit. ABSTRACT Research on photodegradation of indigo carmine (IC) dye using α-Fe2O3/bentonite composite photocatalyst and ultraviolet (UV) irradiation has been conduction. Hematite (α-Fe2O3) was synthesized from iron sand from Syiah Kuala beach, Banda Aceh through coprecipitation methods. α-Fe2O3/bentonite composite photocatalysts were prepared using ball mill method with various weight ratio (w/w) α-Fe2O3 and bentonite 3:1, 3:1 and 1:1. Hematite and α-Fe2O3/bentonite composite photocatalysts are characterized by using X-Ray Diffraction (XRD) and Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM EDX) in order to determine their physical and chemical properties. Based on the results of XRD, iron oxide obtained has a α-Fe2O3 phase and the average crystallite size of the composite are smaller than that of hematite and bentonite. The highest photocatalytic activity of α-Fe2O3/bentonite composite was obtained at a weight ratio α-Fe2O3 and bentonite was 3:1 with the IC degradation of 89% at the initial pH of dye solution was 1, 350 mg photocatalyst mass, and 15 ppm of initial dye concentration after being irradiated with UV light for 120 minutes. The photocatalytic activity of α-Fe2O3/bentonite composite photocatalyst under sunlight irradiation is higher than that of under UV irradiation Keyword: Photocatalytic, Indigo Carmine, α-Fe2O3 and bentonite