Penggunaan zat warna sintetis pada industri akan menghasilkan limbah yang membahayakan lingkungan, oleh sebab itu air limbah yang terdapat zat warna perlu penanganan terlebih dahulu sebelum dialirkan ke badan air. Pada penelitian ini telah berhasil disintesis nanopartikel ZnO dan CaFe2O4 dengan metode presipitasi didapatkan energi celah pita masing-masing 3,21 dan 1.90 eV. Selanjutnya nanopartikel ZnO dan CaFe2O4 dikompositkan dengan bentonite sebagai support diperoleh nanokomposit bentonit/ZnO-CaFe2O4 didapatkan nilai energi celah pita 2,09 eV berada pada daerah sinar tampak. Keberhasilan sintesis dari katalis didukung dengan karakterisasi FTIR, XRD, BET, dan SEM. Ukuran partikel rata-rata dari komposit ZnO- CaFe2O4 pada nanokomposit bentonit/ZnO-CaFe2O4 menggunakan TEM adalah 5.799 nm dan keberadaan dari ZnO-CaFe2O4 tersebar merata dipermukaan bentonit. Nanokomposit bentonit/ZnO- CaFe2O4 diaplikasikan sebagai fotokatalisis untuk degradasi malasit hijau didapat persen degradasi terbaik 94,152% dengan berat katalis 0,04 gram, rasio komposit ZnO: CaFe2O4 (1:1), pH 10, selama 60 menit, dan menggunakan sinar tampak. Studi kinetika mengikuti laju orde pertama dengan konstanta laju reaksinya 0,4922 menit-1 dan sesuai dengan isoterm adsorpsi Langmuir yang menunjukkan bahwa proses degradasi adalah fotokatalisis dan terjadi kemisorpsi. Nanokomposit bentonit/ZnO-CaFe2O4 telah menunjukkan persen degradasi yang baik. Oleh karena itu, nanokomposit berbasis bentonit yang ramah lingkungan dan mudah diperoleh perlu dikembangkan untuk material fotokatalisis.

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The usage of synthetic color substances in the industrial factories lead to the production of waste that could endanger the environment. Therefore, the wastewater that contained color substances need to be processed thoroughly before being streamed to the body water. In this research, it was known that the band gap energy of ZnO and CaFe2O4 nanoparticles synthesized using precipitation method are 3,21 eV and 1,90 eV respectively. A composite was made between ZnO, CaFe2O4 and bentonite as a support, resulting in a nanocomposite of bentonite/ZnO-CaFe2O4 with 2,09 eV as the band gap energy value in visible light. The successfully synthesized catalyst was supported by the characterization using FTIR, XRD, BET, and SEM. Based on the results of characterization using TEM, the average size of particle ZnO-CaFe2O4 composite in bentonite/ZnO-CaFe2O4 is 5,799 nm, with ZnO-CaFe2O4 spreading evenly on the bentonite surface. Bentonite/ZnO-CaFe2O4 nanocomposite is being applied as a photocatalytic agent for malasit hijau degradation. The best degradation percentage is known to be 94,152% with several conditions such as; 0,04 grams catalyst weight, the ratio of ZnO:CaFe2O4 composite (1:1), pH 10, under 60 minutes, and using a visible light. Kinetic study follows the first order rate with reaction rate constant of 0,4922 menit-1 and in accordance with Langmuir adsorption isoterm which shows that the degradation process is a photocatalytic activity and a chemisorption occurred. Bentonite/ZnO-CaFe2O4 nanocomposite shows a good degradation percentage. Therefore, a bentonite-based nanocomposite that is environmentally friendly and easy to be produced need to be developed as a photocatalytic material.