ABSTRAK Modifikasi bentonit alam menjadi bentonit terpilar titania dengan metode sol gel telah dilakukan. Bentonit alam (Ca-bentonit) dimodifikasi terlebih dahulu menjadi organobentonit dengan penambahan surfaktan Tween 80, dilanjutkan dengan penambahan titanium isoproksida sebagai agen pemilar untuk menghasilkan bentonit terpilar titania (TiO2-bentonit). Sifat fisik dan kimia dari Ca-bentonit, organobentonit dan TiO2-bentonit diuji menggunakan XRD, SEM-EDX dan uji aktivitas fotokatalitiknya pada degradasi zat warna naphthol blue black (NBB). Uji aktivitas fotokatalitik dilakukan pada berbagai variasi kondisi pH larutan, jumlah fotokatalis, konsentrasi awal larutan zat warna NBB dan waktu radiasi. Hasil yang diperoleh menunjukkan bahwa persen degradasi zat warna NBB maksimum (92,58%) terjadi pada pH larutan = 2, massa fotokatalis sebanyak 1000 mg, konsentrasi awal zat warna NBB 5 ppm dan waktu radiasi 180 menit. Persen degradasi zat warna NBB menggunakan sinar matahari dengan kondisi yang sama adalah 86,16%. Persen degradasi NBB menggunakan organobentonit lebih besar daripada menggunakan bentonit alam. Fotokatalis TiO2-bentonit dapat digunakan kembali setelah diregenerasi namun aktivitas fotokatalitiknya mengalami penurunan sebesar 12,14%. Kata Kunci : Ca-bentonit, organobentonit, TiO2-bentonit, surfaktan tween 80, degradasi, naphthol blue black ABSTRACT Modification of natural bentonite into titania pillared bentonite by sol gel method has been conducted. Natural bentonite (Ca-bentonite) was modified into organobentonite by adding Tween 80 surfactant followed by adding titanium isopropoxide as pillaring agent convert to titania pillared bentonite (TiO2-bentonite). Physical and chemical characteristics of Ca-bentonite, organobentonite, and TiO2-bentonite were evaluated by using XRD, SEM-EDX and their photocatalytic activities were determined on degradation of naphthol blue black dye (NBB). Photocatalytic activity of titania pillared bentonite was determined under UV irradiation at various of iniatial pH solution, photocatalyst dosage, initial dye concentration and radiation time. The results showed that the highest degradation percentage of naphthol blue black dye was 92.58% which was obtained at pH = 2, photocatalyst dosage 1000 mg, initial dye concentration 5 ppm and radiation time 180 minutes. Degradation percentage of NBB under solar irradiation on the same condition was 86.16%. Degradation percentage of NBB by using organobentonite was higher than that of natural bentonite. TiO2-bentonite can be reused after regeneration but its photocatalytic activity was decreased 12,14%. Keywords: Bentonite, organobentonite, titania pillared bentonite, Tween 80 surfactant, degradation, naphthol blue black