Electronic Theses and Dissertation

Preparasi nanokomposit karbon aktif/ZnO (KA/ZnO) dari seng nitrat heksahidrat sebagai prekursor seng oksida dan karbon aktif dari cangkang biji melinjo telah berhasil dilakukan. Karakterisasi material yang dihasilkan dilakukan menggunakan instrumen X-Ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS), Brunaeur
Emmet Teller (BET) dan UVVis Diffuse Reflectance Spectroscopy (UV-Vis DRS). Seng oksida yang diperoleh memiliki fasa zincite dan karbon aktif memiliki fasa amorf. Perbedaan jumlah karbon
aktif yang ditambahkan pada seng oksida mengakibatkan perbedaan sifat fisik dan kimia nanokomposit KA/ZnO yang dihasilkan dan mempengaruhi aktivitas fotokatalitiknya. Fotokatalis nanokomposit KA/ZnO memiliki aktivitas yang tinggi pada penghilangan zat warna Rhodamine B (RhB) dan Napthol Blue Black (NBB). Nanokomposit 1% KA/ZnO menunjukkan aktivitas fotokatalitik paling tinggi dibandingkan nanokomposit 3% KA/ZnO dan 5% KA/ZnO. Aktivititas tertinggi pada penghilangan zat warna RhB (%D: 99,48%) diperoleh pada kondisi optimum pH 2, massa fotokatalis 100 mg, konsentrasi awal zat warna 4 ppm dan waktu radiasi 45 menit. Aktivitas tertinggi pada penghilangan zat warna NBB (%D: 98,40%) diperoleh pada kondisi optimum pH 2, massa fotokatalis 100 mg, konsentrasi awal zat warna 4 ppm dan waktu radiasi 15 menit. Aktivitas fotokatalitik nanokomposit 1% KA/ZnO lebih tinggi menggunakan radiasi sinar matahari dibandingan sinar UV. Berdasarkan uji scavenger diketahui bahwa radikal hole (hv+) dan ion superoksida (O2) merupakan spesies yang paling berperan dalam aktivitas fotokatalitik KA/ZnO untuk mendegradsi zat warna RhB.

Kata kunci: Seng oksida, karbon aktif, cangkang biji melinjo, nanokomposit KA/ZnO, Rhodamine B, Napthol Blue Black, dan scavenger.

Preparation of activated carbon/ZnO (KA/ZnO) nanocomposites from zinc nitrate hexahydrate as zinc oxide precursor and activated carbon from melinjo seed shells has been successfully carried out. The as-prepared materials were characterized by using the X-Ray Diffraction (XRD) instrument, Scanning Electron MicroscopyEnergy-Dispersive X-Ray Spectroscopy (SEM-EDS), Brunaeur Emmet Teller (BET) and UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis DRS). The synthesized ZnO was in the Zincite phase, while the activated carbon obtained has an amorphous phase. The difference in the amount of activated carbon added to zinc oxide resulted in differences in the physical and chemical properties of the resulting AC/ZnO nanocomposite and affected the photocatalytic activity. The AC/ZnO nanocomposite photocatalyst has high activity in removing Rhodamine B (RhB) and Napthol Blue Black (NBB) dyes. The 1% AC/ZnO nanocomposite showed the highest photocatalytic activity compared to the 3% AC/ZnO and 5% AC/ZnO nanocomposites. The highest activity on the removal of RhB dye (%D: 99.48%) was obtained at the optimum condition of pH = 2, the photocatalyst mass was 100 mg, the initial dye concentration was 4 ppm, and the irradiation time was 45 minutes. The highest activity on the removal of NBB dyes (%D: 98.40%) was obtained at the optimum condition of pH = 2, the photocatalyst mass was 100 mg, the initial dye concentration was 4 ppm, and the irradiation time was 15 minutes. The photocatalytic activity of the 1% AC/ZnO nanocomposite was higher using solar irradiation than UV light. The results of scavenger examination illustrated that holes (h+) and superoxide ion (O2•) contribute mostly to the high photocatalytic activity of AC/ZnO composites on degradation of RhB dye. Keywords: zinc oxide, activated carbon, melinjo seed shells, AC/ZnO composites, Rhodamine B, Napthol Blue Black, and scavenger.