Electronic Theses and Dissertation

Sintesis nanopartikel α-Fe₂O₃ melalui metode green synthesis menggunakan ekstrak air daun pala (Myristica fragrans) yang dikombinasi dengan proses hidrotermal dan uji aktivitas fotokatalitiknya pada degradasi zat warna naphthol blue black (NBB) telah berhasil dilakukan. Ekstrak air daun pala mengandung metabolit sekunder seperti fenolik, tanin, saponin. Kandungan fenolik total (total phenolic content, TPC) ekstrak air daun pala adalah sebesar 124,875 mg GAE/g, sedangkan kandungan flavonoid total
(total flavonoid content, TFC) adalah sebesar 8,216 mg QE/g. Sintesis nanopartikel α-Fe2O3 dilakukan menggunakan prekursor Fe(NO₃)₃•9H₂O dengan variasi tanpa dan dengan penambahan NaOH. Karakterisasi nanopartikel α-Fe₂O₃ dilakukan menggunakan X-Ray Diffraction (XRD), Diffuse Reflectance Spectroscopy UV-Vis (DRS UV-Vis), dan Scanning Electron Microscopy (SEM). Hasil karakterisasi menunjukkan bahwa nanopartikel yang dihasilkan memiliki fase hematit (α-Fe₂O₃) berstruktur rhombohedral dengan ukuran kristalit rata-rata 71,60 nm (tanpa NaOH) dan 44,19 nm (dengan penambahan NaOH). Nilai energi celah pita masing-masing nanopartikel α-Fe₂O₃ berturut-turut sebesar, 2,09 eV (tanpa NaOH) dan 2,06 eV (dengan penambahan NaOH). Hasil uji aktivitas fotokatalitik pada degradasi zat warna naphthol blue black menunjukkan nanopartikel α-Fe₂O₃ yang disintesis dengan penambahan NaOH memiliki aktivitas yang lebih tinggi dibanding tanpa penambahan NaOH. Nanopartikel α-Fe₂O₃ tanpa penambahan NaOH dapat menghilangkan NBB hingga 45,92% di bawah sinar UV selama 120 menit dan nanopartikel α-Fe₂O₃ dengan NaOH 98,88% selama 30 menit pada kondisi reaksi pH 1, konsentrasi larutan NBB 15 ppm dan jumlah fotokatalis 250 mg. Pada kondisi reaksi yang sama nanopartikel α-Fe₂O₃ tanpa NaOH menunjukkan efisiensi penghilangan NBB yaitu 90,44% dibawah sinar matahari, sedangkan nanopartikel α-Fe₂O₃ dengan penambahan NaOH menghasilkan persen degradasi NBB sebesar 99,88% selama waktu iradiasi 60 menit. Hasil penelitian menunjukkan bahwa aktivitas fotokatalitik nanopartikel α-Fe₂O₃ lebih tinggi dibawah iradiasi sinar matahari dibandingkan sinar UV. Hasil ini menunjukkan nanopartikel α-Fe₂O₃ yang disintesis menggunakan ekstrak air daun pala berpotensi diaplikasikan pada pengolahan limbah zat warna.

Synthesis of α-Fe₂O₃ nanoparticles through green synthesis using aqueous extract nutmeg (Myristica fragrans) leaves combined with a hydrothermal process, and their photocatalytic activity for the degradation of Naphthol Blue Black (NBB) dye, was successfully carried out. The aqueous extract nutmeg leaves contained secondary metabolites, including phenolics, tannins, and saponins. The total phenolic content (TPC) of the extract was 124.875 mg GAE/g, while the total flavonoid content (TFC) was 8.216 mg QE/g. The α-Fe₂O₃ nanoparticles were synthesized using Fe(NO₃)₃•9H₂O as the precursor with and without the addition of NaOH. The characterization of α-Fe₂O₃ nanoparticles were performed using X-ray Diffraction (XRD), UV–Vis Diffuse Reflectance Spectroscopy (UV–Vis DRS), and Scanning Electron Microscopy (SEM). The characterization results show that the nanoparticles was in hematite (α-Fe₂O₃) phase, a rhombohedral crystal structure with average crystallite sizes of 71.60 nm (without addition of NaOH) and 44.19 nm (with addition of NaOH), respectively. The corresponding band gap energies were 2.09 eV (without NaOH) and 2.06 eV (with NaOH), and the α-Fe₂O₃ without addition of NaOH were in spherical shape with homogeneous distribution, while α-Fe₂O₃ nanoparticles with addition of NaOH were irregular in shape. The results of photocatalitic activity showed that the α-Fe₂O₃ nanoparticles synthesized with NaOH exhibited higher photocatalytic activity than that of synthesized without NaOH. The α-Fe₂O₃ nanoparticles synthesized without addition of NaOH can remove NBB up to 45.92% under UV light irradiation for 120 min, while the α-Fe₂O₃ nanoparticles synthesized with addition of NaOH can remove NBB up to 98.88% for 30 min on the reaction conditions of pH 1, an initial NBB concentration of 15 ppm, and a photocatalyst dosage of 250 mg. Under the same reaction conditions α-Fe₂O₃ nanoparticles synthesized without NaOH exhibited an NBB removal efficiency of 90.44%, while α-Fe₂O₃ with addition of NaOH resulting in NBB removal efficiensy 99.88% after 60 min under natural sunlight irradiation. These findings indicate that the photocatalytic activity of the α-Fe₂O₃ nanoparticles was higher under sunlight irradiation than that of under UV irradiation. Overall, the results demonstrate that α-Fe₂O₃ nanoparticles synthesized using aqueous extract nutmeg leaves are promising photocatalyst for the treatment of dye-contaminated wastewater.