SINTESIS KOMPOSIT Fe3O4/TiO2-Ag/S DAN AKTIVITAS FOTOKATALITIKNYA TERHADAP DEGRADASI METILEN BIRU

STEFEN RUSLI, Dra. Eko Sri Kunarti, M.Si., Ph.D. ; Prof. Dr. Bambang Rusdiarso, DEA.

2021 | Skripsi | S1 KIMIA

Sintesis Fe3O4/TiO2-Ag/S untuk degradasi fotokatalitik metilen biru telah dilakukan. Penelitian ini bertujuan untuk mempelajari pengaruh dopan perak dan sulfur dalam modifikasi fotokatalis TiO2 sehingga lebih responsif pada sinar tampak serta aktivitas fotokatalitik terhadap degradasi metilen biru. Sintesis Fe3O4 dilakukan dengan metode kopresipitasi dari prekursor FeCl3.6H2O dan FeSO4.7H2O. Material Fe3O4/TiO2 dan Fe3O4/TiO2-Ag/S disintesis dengan metode sol-gel. Titanium tetraisopropoksida (TTIP) digunakan sebagai prekursor dari TiO2. Perak nitrat (AgNO3) digunakan sebagai sumber dopan perak dan penggunaan tiourea (CH4N2S) sebagai sumber dopan sulfur. Material hasil sintesis dikarakterisasi dengan spektrofotometer FT-IR, difraktometer sinar-X (XRD), spektrofotometer SR UV-Visibel, Scanning Electron Microscope dengan Energy Dispersive X-Ray (SEM-EDX), Transmission Electron Microscope (TEM) dan Vibrating Sample Magnetometer (VSM). Aktivitas fotokatalis dilakukan dengan cara degradasi fotokatalitik terhadap metilen biru dalam reaktor tertutup disertai variasi perlakuan yaitu pH, waktu penyinaran, massa fotokatalis, volum metilen biru, penambahan enhancing agent (H2O2), jenis sinar, dan pengujian penggunaan kembali. Penentuan hasil degradasi fotokatalitik dilakukan dengan menggunakan spektrofotometri UV-Visibel. Hasil penelitian menunjukkan bahwa sintesis Fe3O4/TiO2-Ag/S berhasil dilakukan. Material Fe3O4/TiO2-Ag/S memiliki sifat kemagnetan dengan nilai saturasi kemagnetan sebesar 5,33 emu/gram. Keberadaan dopan perak dan sulfur menurunkan energi celah pita sehingga responsif terhadap sinar tampak. Aktivitas fotokatalitik optimum terjadi pada Fe3O4/TiO2-Ag/S (2,5%|2,5%) dengan nilai energi celah pita sebesar 2,85 eV. Hasil degradasi fotokatalitik 10 mL metilen biru 5 ppm dengan Fe3O4/TiO2-Ag/S (2,5%|2,5%) mencapai 88,82% di bawah paparan sinar UV dan 99,18% di bawah paparan sinar tampak pada pH 10, waktu paparan selama 120 menit, massa Fe3O4/TiO2-Ag/S sebesar 10 mg, dan penambahan 0,1 mL H2O2. Material Fe3O4/TiO2-Ag/S bersifat stabil dalam empat kali penggunaan.

Synthesis of Fe3O4/TiO2-Ag/S for degradation of methylene blue has been carried out. The purpose of this research was to study the effect of silver and sulphur dopants into TiO2 modification as photocatalyst to be more responsive on visible light and also its photocatalytic activity towards degradation of methylene blue. The synthesis of Fe3O4 was initiated through coprecipitation method from FeCl3.6H2O and FeSO4.7H2O as the precursors. Both Fe3O4/TiO2 dan Fe3O4/TiO2- Ag/S were synthesized by using sol-gel method. Titanium tetraisopropoxide (TTIP) was used as the precursor of TiO2. Silver nitrate (AgNO3) was used as silver dopant source and the usage of thiourea (CH4N2S) as sulphur dopant source. The synthesized materials were characterized by using FT-IR spectrophotometer, X-Ray Difractometer (XRD), SR UV-Visible spectrophotometer, Scanning Electron Microscope with Energy Dispersive X-Ray (SEM-EDX), Transmission Electron Microscope (TEM) and Vibrating Sample Magnetometer (VSM). The activity of photocatalysts were performed by photocatalytic degradation towards methylene blue inside a closed photoreactor with several variations which are pH, irradiation time, photocatalyst mass, methylene blue volume, addition of enhancing agent (H2O2), types of light, and reusability test. The result showed that Fe3O4/TiO2-Ag/S was synthesized successfully. The Fe3O4/TiO2-Ag/S material showed magnetic properties as the magnetic saturation value was 5,33 emu/gram. The presence of silver and sulphur dopants lower the band gap and tended to be responsive towards visible light exposure. The optimum photocatalytic activity was obtained on Fe3O4/TiO2-Ag/S (2,5%|2,5%) with the band gap value was 2,85 eV. The photocatalytic degradation result of 10 mL methylene blue 5 ppm reached 88,82% under UV light exposure and 99,18% under visible light exposure at pH 7, 120 minutes irradiation time, 10 mg of Fe3O4/TiO2-Ag/S, and addition of 0,1 mL H2O2. The Fe3O4/TiO2-Ag/S was stable under four times usage.

Kata Kunci : degradasi, Fe3O4/TiO2-Ag/S, dopan, metilen biru