PENGARUH JUMLAH PREKURSOR TITANIUM TETRAISOPROPOKSIDA TERHADAP AKTIVITAS FOTOKATALIS NANOKOMPOSIT Fe3O4/SiO2/TiO2-PANI PADA FOTOREDUKSI ION [AuCl4]-

BAMBANG EKO SETYONO, Dr. Eko Sri Kunarti, M.Si.; Dr. Indriana Kartini, M.Si.

2017 | Skripsi | S1 KIMIA

Sintesis fotokatalis nanokomposit Fe3O4/SiO2/TiO2 tersensitisasi polianilin dengan variasi jumlah prekursor titanium tetraisopropoksida telah dilakukan untuk mempelajari pengaruh terhadap aktivitas fotokatalitiknya pada fotoreduksi ion [AuCl4]-. Penelitian ini diawali dengan sintesis magnetit (Fe3O4) melalui kopresipitasi dan sonikasi, diikuti dengan pelapisan silika (SiO2) pada magnetit melalui proses sol-gel dan sonikasi, kemudian pelapisan titania (TiO2) dengan variasi jumlah titanium tetraisopropoksida (TTIP) sebanyak 0, 1, 2, 4 dan 6 mmol melalui proses sol-gel dan sonikasi, dilanjutkan sensitisasi polianilin (PANI) melalui polimerisasi oksidatif anilin dengan oksidator amonium peroksidisulfat (APS). Produk sintesis dikarakterisasi dengan X-ray diffractometer (XRD), fourier transform infrared (FTIR) spectrophotometer, scanning electron microscope-energy dispersive X-ray (SEM-EDX), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) dan specular reflectance (SR) UV-Vis spectrophotometer. Uji aktivitas fotokatalis nanokomposit Fe3O4/SiO2/TiO2-PANI berbagai variasi jumlah TTIP dilakukan dengan mencampur fotokatalis dan larutan [AuCl4]- dalam sistem batch pada pH optimum dengan paparan sinar UV dan sinar tampak. Hasil penelitian menunjukkan bahwa berdasarkan analisis FTIR, XRD, SEM-EDX, TEM dan VSM, fotokatalis nanokomposit Fe3O4/SiO2/TiO2-PANI berbagai variasi jumlah TTIP berhasil disintesis. Aktivitas dan energi celah pita Fe3O4/SiO2/TiO2-PANI meningkat seiring dengan bertambahnya jumlah prekursor TTIP yang digunakan. Kemampuan fotoreduksi [AuCl4]- oleh fotokatalis nanokomposit Fe3O4/SiO2/TiO2-PANI paling efisien berlangsung pada kondisi pH 4. Fotokatalis nanokomposit Fe3O4/SiO2/TiO2-PANI(6 mmol) menunjukkan aktivitas fotoreduksi tertinggi sebesar 98,2 dan 92,5 % pada radiasi sinar UV dan tampak. Nanokomposit Fe3O4/SiO2/TiO2-PANI dapat dipisahkan secara efektif oleh medan magnet eksternal. Penurunan aktivitas fotokatalis nanokomposit Fe3O4/SiO2/TiO2-PANI setelah 4 kali pemakaian sebesar 18,7 % pada pH 4.

Synthesis of polyaniline sensitized Fe3O4/SiO2/TiO2 nanocomposite photocatalyst had been performed by altering the amount of titanium tetraisopropoxide to study the effect of their photocatalytic activity on [AuCl4]- ion photoreduction. Firstly, magnetite (Fe3O4) was synthesized through coprecipitation and sonication. Silica (SiO2) coating on magnetite was done through sol-gel and sonication processes. Then, titania (TiO2) coating was done by altering the amount of titanium tetraisopropoxide (TTIP) of 0, 1, 2, 4 and 6 mmol through sol-gel and sonication process. Lastly, polyaniline (PANI) sensitization was done through oxidative polymerization of aniline with ammonium peroxydisulfate oxidator (APS). The synthesis products were characterized by X-ray diffractometer (XRD), fourier transform infrared (FTIR) spectrophotometer, scanning electron microscope-energy dispersive X-ray (SEM-EDX), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and specular reflectance (SR) UV-Vis spectrophotometer. Photocatalytic activity of Fe3O4/SiO2/TiO2-PANI nanocomposite photocatalysts with various TTIP amount were done by interacting the photocatalyst and the [AuCl4]- solution in a batch system at optimum pH with exposure to UV and visible light. The results showed that according to FTIR, XRD, SEM-EDX, TEM and VSM analysis, photocatalysts of Fe3O4/SiO2/TiO2-PANI nanocomposite of various TTIP amount were successfully synthesized. Activity and band gap energy of Fe3O4/SiO2/TiO2-PANI were increased as increasing the number of TTIP precursors used. The capability of [AuCl4]- photoreduction by Fe3O4/SiO2/TiO2-PANI nanocomposite photocatalysts were carried out efficiently at pH 4. Fe3O4/SiO2/TiO2-PANI(6 mmol) nanocomposite photocatalyst showed highest photoreduction activity of 98.2 and 92.5 % under UV and visible radiation respectively. The Fe3O4/SiO2/TiO2-PANI nanocomposites could be effectively separated by the external magnetic field. After used for 4 times, the photocatalytic activity of Fe3O4/SiO2/TiO2-PANI nanocomposite decreased by 18.7 % at pH 4.

Kata Kunci : TiO2, Fe3O4, fotoreduksi [AuCl4]-, PANI, variasi TTIP