Electronic Theses and Dissertation

Green synthesis nanokomposit Fe¬2O3/ZnO menggunakan ekstrak etanol daun pala (Myristica fragrans) yang dikombinasikan dengan proses hidrotermal dan uji aktivitas fotokatalitiknya pada degradasi klorpirifos telah dilakukan. Ekstrak etanol daun pala mengandung metabolit sekunder seperti fenolik, saponin dan steroid yang berperan sebagai agen pereduksi, penstabil dan capping agent. Kandungan total fenolik ekstrak etanol daun pala (total phenolic content, TPC) ditentukan menggunakan metode Folin- Ciocalteu dengan standar baku asam galat, sedangkan total flavonoid (total flavonoid content, TFC) ditentukan menggunakan metode spektrofotometri dengan standar baku kuersetin. Kandungan fenolik total ekstrak etanol daun pala sebesar 126,51 mg GAE/g, sedangkan kandungan falvonoid total adalah sebesar 10,562 mg QE/g. Nanokomposit Fe¬2O3/ZnO disintesis menggunakan precursor Zn(NO₃)₂·6H₂O and Fe(NO₃)₃·9H₂O dengan perbandingan molar 1:1. Nanokomposit Fe¬2O3/ZnO dikarakterisasi menggunakan instrumen X-Ray Diffraction (XRD), Diffuse Reflectance Spectroscopy (UV-Vis DRS), Fourier Transform Infrared (FTIR) dan Scanning Electron Microscopy-Energy-Dispersive X-Ray Spectroscopy (SEM-EDS). Hasil analisis XRD menunjukkan bahwa nanokomposit Fe2O3/ZnO memiliki ukuran kristalit sebesar 45,25 nm, sedangkan nanopartikel Fe2O3 dan ZnO tunggal sebesar 60,84 nm dan 31,26. Karakterisasi DRS UV-Vis menunjukkan bahwa energi celah pita nanokomposit Fe¬2O3/ZnO, nanopartikel Fe2O3 dan ZnO masing-masing sebesar 2,10 eV, 2,15 eV dan 2,99 eV. Penurunan nilai band gap pada nanokomposit Fe¬2O3/ZnO menunjukkan peningkatan kemampuan material dalam menyerap cahaya tampak, sehingga berpotensi meningkatkan kinerja fotokatalitiknya. Hasil FTIR mengonfirmasi terbentuknya ikatan Zn-O dan Fe-O serta adanya interaksi antarfasa pada nanokomposit Fe-2O3/ZnO. Pengujian fotokatalitik dilakukan pada degradasi klorpirifos pada konsentrasi 6 ppm, pH 7 dan massa fotokatalis 300 mg. Nanokompodit Fe¬2O3/ZnO dapat mendegradasi klorpirifos hingga 83,89% setelah penyinaran UV selama 6 jam. Aktivitas ini lebih tinggi dibandingkan menggunakan nanopartikel Fe¬2O3 dan ZnO tunggal dengan persen degradasi sebesar 65,98% dan 73,03%. Aktivitas fotokatalitik nanokomposit Fe¬2O3/ZnO menunjukkan hasil yang lebih tinggi menggunakan sinar matahari dibanding UV dengan persen degradasi sebesar 90,5% selama waktu iradiasi 4 jam. Hasil penelitian menunjukkan bahwa nanokomposit Fe¬2O3/ZnO berpotensi diaplikasikan sebagai fotokatalis yang efektif dan ramah lingkungan dalam pengolahan limbah pestisida.

Kata kunci : Green synthesis, nanokomposit, fotokatalis, ekstrak daun pala, klorpirifos
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Green synthesis of Fe₂O₃/ZnO nanocomposite using ethanolic extract of nutmeg (Myristica fragrans) leaves, combined with a hydrothermal process, and determination of its photocatalytic activity on degradation of chlorpyrifos have been conducted. The ethanolic extract of nutmeg leaves contains secondary metabolites such as phenolics, saponins, and steroids which acted as reducing, stabilizing, and capping agent. The total phenolic content (TPC) of the ethanolic extract of nutmeg leaves was determined using the Folin-Ciocalteu method with gallic acid as the standard, while the total flavonoid content (TFC) was determined using spectrophotometry with quercetin as the standard. The TPC of the ethanolic extract of nutmeg leaves was 126,31 mg GAE/g, while the TFC was 10.562 mg QE/g. The Fe₂O₃/ZnO nanocomposite was synthesized using Fe(NO₃)₃·9H₂O and Zn(NO₃)₂·6H₂O as precursor with molar ratio 1:1. The Fe₂O₃/ZnO nanocomposite was characterized using X-ray diffraction (XRD), diffuse reflectance spectroscopy (UV-Vis DRS), Fourier transform infrared (FTIR), and scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDS). The XRD analysis results showed that the Fe₂O₃/ZnO nanocomposite had a crystallite size of 45.25 nm, while Fe₂O₃ and ZnO single nanoparticle had crytallite sizes of 60,84 nm and 31.26 nm, respectively. UV-Vis DRS characterization showed that the bandgap energy of the Fe₂O₃/ZnO nanocomposite, Fe₂O₃ and ZnO nanoparticles were 2.10 eV, 2.15 eV, and 2.99 eV, respectively. The decrease in the bandgap value of the Fe₂O₃/ZnO nanocomposite indicates an increase in the material’s ability to absorb visible light, thereby potentially enhancing its photocatalytic performance. FTIR results confirmed the formation of Zn-O and Fe-O bonds as well as the presence of interphase interactions in the Fe₂O₃/ZnO nanocomposite. Photocatalytic testing was conducted on the degradation of chlorpyrifos at a concentration of 6 ppm, pH 7, and a photocatalyst mass of 300 mg. The Fe₂O₃/ZnO nanocomposite was able to degrade chlorpyrifos up to 83.89% after UV irradiation for 6 h. This activity is higher than that of by using Fe₂O₃ and ZnO single, which exhibited degradation percentages of 65.98% and 73.03% respectively. The photocatalytic activity of the Fe₂O₃/ZnO nanocomposite was higher under sunlight iradiation compared to UV light, with a degradation percentage of 90.5% during a 4 h irradiation time. The research results indicate that the Fe₂O₃/ZnO nanocomposite has the potential to be applied as an effective and environmentally friendly photocatalyst in pesticide wastewater treatment. Keywords: Green synthesis, photocatalyst, nanocomposyte, Myristica fragrans (nutmeg) leaf ethanol extract, and chlorpyrifos