[ABSTRAK
Fotokatalis bermagnet Fe3O4/SiO2/TiO2 telah dibuat dengan cara heteroaglomerasi.Fotokatalis bermagnet ini diterapkan dalam reaktor sistem slurryuntuk eliminasi zat organik (metilen biru dan paraquat) dalam air. Dan juga,fotokatalis bermagnet ini memberi kemudahan untuk dikumpulkan kembalidengan bantuan medan magnet luar sehingga fotokatalis bekas pakai ini dapatdigunakan kembali secara berulang-ulang.Sintesis fotokatalis bermagnet Fe3O4/SiO2/TiO2 diawali dengan membuatnanopartikel Fe3O4 dengan cara presipitasi menggunakan campuran Fe(III)/Fe(II)(rasio mol 2:1) dalam larutan amonia dan kemudian dilapisi dengan SiO2 dengancara hidrolisis ion silikat. Fe3O4/SiO2 yang terbentuk dicampurkan dengan TiO2dengan cara hetero-aglomerasi, untuk memperoleh fotokatalis bermagnetFe3O4/SiO2/TiO2. Dalam penelitian ini, ada dua jenis TiO2 komersil yangdigunakan, yaitu nanopartikel TiO2 Aldrich dan nanopartikel TiO2 P25 Evonik.Fotokatalis bermagnet yang telah dibuat dikarakterisasi dengan berbagai teknik, diantaranya, difraksi sinar-x (XRD) untuk menentukan fasa kristal, zeta potensialmeter untuk menentukan muatan permukaan partikel, VSM untuk menentukansifat kemagnetan, spektrometer FTIR dan Raman untuk identifikasi gugus fungsidan ikatan logam-oksida, EDS untuk menentukan komposisi unsur permukaan,TEM untuk mengetahui morfologi dan adsorpsi-N2 untuk menetukan luaspermukaan. Hasil karakterisasi XRD menunjukkan bahwa TiO2-Aldrichmengandung fasa anatase 55% dan rutil 45% sedangkan TiO2-P25 Evonikmengandung fasa anatase 86% dan rutil 14%. Fasa magnetit (Fe3O4), TiO2 anatasedan rutil dipertahankan dalam fotokatalis bermagnet yang terbentuk. Dalamtahapan pembentukan bahan, ke dua jenis TiO2 telah berhasil menempel secarapermanen pada Fe3O4/SiO2 melalui interaksi elektrostatik gugus hidroksilpermukaan masing-masing oksida. Spektromentri FTIR mengamati ikatan Si-O-Tiyang terbentuk, hasil interaksi elektrostatik TiO2 dengan Fe3O4/SiO2, selanjutnyadinotasikan sebagai Fe3O4/SiO2/TiO2-Ald dan Fe3O4/SiO2/TiO2-P25. Kedua jenisbahan mempunyai sedikit perbedaan sifat fisika-kimia dan morfologi. Semakinbanyak fraksi TiO2 dalam bahan maka luas permukaannya semakin turun.Fotokatalis bermagnet yang diperoleh mempunyai sifat magnet cukup baik dannilai remanent magnetization dan coercivity yang rendah, artinya bahan ini dapatdengan mudah dikumpulkan kembali dari cairan dengan bantuan medan magnetluar dan tanpa medan magnet dapat terdispersi kembali dengan baik dalam air. Fe3O4/TiO2-Ald dan Fe3O4/TiO2-P25 yang telah dibuat mampu mengeliminasimetilen biru dan paraquat dalam air melalui proses fotokatalitik, namun demikianaktivitasnya dianggap masih rendah. Diduga terjadi pelemahan aktivitas TiO2yang ada dalam fotokatalis bermagnet akibat dari efek fotodisolusi. Adanyabarrier SiO2 di antara Fe3O4 dan TiO2, metilen biru yang terdegradasi meningkatdari 44,2% menjadi 52,3% oleh Fe3O4/SiO2/TiO2-Ald dan paraquat yangterdegradasi meningkat dari 16,3% menjadi 45,8% oleh Fe3O4/SiO2/TiO2-P25.Aktivitas kedua fotokatalis bermagnet yang punya barrier SiO2 ini setara denganaktivitas rasio fraksi aktif TiO2 terhadap TiO2 murninya. Tidak ada kehilanganaktivitas TiO2 dalam fotokatalis bermagnet setelah diberi barrier SiO2. AdanyaSiO2 dalam fotokatalis bermagnet ini juga mampu mengeliminasi senyawametilen biru dan paraquat melalui proses adsorpsi. Maka dari itu, lebih banyaklagi metilen biru dan paraquat tereliminasi melalui kedua proses. Secara total,Fe3O4/SiO2/TiO2-Ald mampu mengeliminasi metilen biru 87,3% dan paraquat71,5%. Sedangkan Fe3O4/SiO2/TiO2-P25 mampu mengeliminasi paraquat 82,6%.Kapasitas adsorpsi Fe3O4/SiO2/TiO2-Ald lebih rendah dari kapasitas adsorpsiFe3O4/SiO2/TiO2-P25, tetapi aktivitas fotokatalitik Fe3O4/SiO2/TiO2-Ald lebihtinggi dari aktivitas fotokatalitik Fe3O4/SiO2/TiO2-P25. Fotokatalis bermagnetyang dikembangkan menunjukkan kestabilan fotokatalitik paling tidak sampaiempat kali pemakaian berulang dan juga masih dapat dikumpulkan kembalidengan mudah dengan bantuan medan magnet luar
ABSTRAK
Magnetic photocatalysts of Fe3O4/SiO2/TiO2 have been prepared using heteroagglomerationmethod. The magnetic photocatalysts were applied in slurry reactorsystem for elimination of organic compounds (methylene blue and paraquat) inwater. In addition, the magnetic photocatalysts are able to be recollected easilywith the assistance of an external magnetic field so that the spent composite canbe used repeatedly.Synthesis of magnetic photocatalysts of Fe3O4/SiO2/TiO2 were preceded bypreparing Fe3O4 nanoparticles through precipitation method using mixture ofFe(III)/Fe(II) (2:1 mole ratio) in ammonia solution and further coating with SiO2through hydrolysis of silicate ion. The formed Fe3O4/SiO2 were mixed with TiO2in hetero-agglomeration manner, to obtain Fe3O4/SiO2/TiO2 magneticphotocatalysts. In this study, two type of commercial TiO2 nanoparticles wereused, namely; TiO2 Aldrich and TiO2-P25 Evonik.The prepared magnetic photocatalysts were characterized with various techniques,i.e, x-ray diffraction (XRD) to determine the crystal phase, zeta potensial meter todetermine the surface charge of particles, VSM to determine the magneticproperties, FTIR and Raman spectrometer to identify the functional groups andmetal-oxide bond, EDS to determine the surface chemical composition, TEM formorphological examination and N2-adsorption to determine surface area. Theresults of XRD characterization showed that TiO2-Aldrich contains 55% ofanatase and 45% of rutile, while TiO2-P25 Evonik contains 86% of anatase and14% of rutile. Magnetite (Fe3O4), anatase and rutile phase of TiO2 were retained inthe formed composites. In the stage of composite formation, both TiO2 types havebeen successfully attached to Fe3O4/SiO2 via electrostatic interaction of surfacehidroxyl group of oxides. FTIR spectrometry analysis revealed the formedSi-O-Ti bond, resulting of electrostatic interaction both TiO2 and Fe3O4/SiO2.Hence, they were denoted as Fe3O4/SiO2/TiO2-Ald dan Fe3O4/SiO2/TiO2-P25. Theboth magnetic photocatalysts have a slight different physico-chemical propertiesand morphology. The more the fraction of TiO2 in magnetic photocatalysts, thelower its surface area. The obtained magnetic photocatalysts have high saturationmagnetization and low coercivity and remanent magnetization value. It means thatthe magnetic photocatalysts can be still recollected from water with assistance ofexternal magnetic field. In a non-magnetic field, magnetic photocatalyst can bewell dispersed in water again.The formed Fe3O4/TiO2-Ald and Fe3O4/TiO2-P25 was able to eleminatemethylene blue and paraquat in water by photocatalytic process, nevertheless itsactivities was low. Allegedly it occurs weakening of TiO2 activity in magneticphotocatalyst caused by photodissolution effects. The presence of SiO2 barrierbetween Fe3O4 and TiO2, the degraded methylene blue was increased from 44.2%to 52.3% by Fe3O4/SiO2/TiO2-Ald and the degraded paraquat was increased from16.3% to 45.8% by Fe3O4/SiO2/TiO2-P25. The photocatalytic activity of the bothmagnetic photocatalysts which having SiO2 barrier was equivalent to the activityof fraction ratio of TiO2 to its pure TiO2. There was no loss of photocatalyticactivity of TiO2 in magnetic photocatalysts after SiO2 barrier being introduced.The presence of SiO2 on magnetic photocatalysts was also able to eliminatemethylene blue and paraquat compounds through adsorption process. Therefore,more methylene blue and paraquat eliminated via both process. Totally, theFe3O4/SiO2/TiO2-Ald was able to eliminate 87.3% of methylene blue and 71.5%of paraquat. Meanwhile Fe3O4/SiO2/TiO2-P25 was able to eliminate 82.6% ofparaquat. Adsorption capacity of Fe3O4/SiO2/TiO2-Ald was lower than that ofFe3O4/SiO2/TiO2-P25, but photocatalytic activity of Fe3O4/SiO2/TiO2-Ald washigher than that of Fe3O4/SiO2/TiO2-P25. The developed magnetic photocatalystsshow its activity photocatalytic stability and still can be well magneticallyseparated after being repeatedly used for four times.;Magnetic photocatalysts of Fe3O4/SiO2/TiO2 have been prepared using heteroagglomerationmethod. The magnetic photocatalysts were applied in slurry reactorsystem for elimination of organic compounds (methylene blue and paraquat) inwater. In addition, the magnetic photocatalysts are able to be recollected easilywith the assistance of an external magnetic field so that the spent composite canbe used repeatedly.Synthesis of magnetic photocatalysts of Fe3O4/SiO2/TiO2 were preceded bypreparing Fe3O4 nanoparticles through precipitation method using mixture ofFe(III)/Fe(II) (2:1 mole ratio) in ammonia solution and further coating with SiO2through hydrolysis of silicate ion. The formed Fe3O4/SiO2 were mixed with TiO2in hetero-agglomeration manner, to obtain Fe3O4/SiO2/TiO2 magneticphotocatalysts. In this study, two type of commercial TiO2 nanoparticles wereused, namely; TiO2 Aldrich and TiO2-P25 Evonik.The prepared magnetic photocatalysts were characterized with various techniques,i.e, x-ray diffraction (XRD) to determine the crystal phase, zeta potensial meter todetermine the surface charge of particles, VSM to determine the magneticproperties, FTIR and Raman spectrometer to identify the functional groups andmetal-oxide bond, EDS to determine the surface chemical composition, TEM formorphological examination and N2-adsorption to determine surface area. Theresults of XRD characterization showed that TiO2-Aldrich contains 55% ofanatase and 45% of rutile, while TiO2-P25 Evonik contains 86% of anatase and14% of rutile. Magnetite (Fe3O4), anatase and rutile phase of TiO2 were retained inthe formed composites. In the stage of composite formation, both TiO2 types havebeen successfully attached to Fe3O4/SiO2 via electrostatic interaction of surfacehidroxyl group of oxides. FTIR spectrometry analysis revealed the formedSi-O-Ti bond, resulting of electrostatic interaction both TiO2 and Fe3O4/SiO2.Hence, they were denoted as Fe3O4/SiO2/TiO2-Ald dan Fe3O4/SiO2/TiO2-P25. Theboth magnetic photocatalysts have a slight different physico-chemical propertiesand morphology. The more the fraction of TiO2 in magnetic photocatalysts, thelower its surface area. The obtained magnetic photocatalysts have high saturationmagnetization and low coercivity and remanent magnetization value. It means thatthe magnetic photocatalysts can be still recollected from water with assistance ofexternal magnetic field. In a non-magnetic field, magnetic photocatalyst can bewell dispersed in water again.The formed Fe3O4/TiO2-Ald and Fe3O4/TiO2-P25 was able to eleminatemethylene blue and paraquat in water by photocatalytic process, nevertheless itsactivities was low. Allegedly it occurs weakening of TiO2 activity in magneticphotocatalyst caused by photodissolution effects. The presence of SiO2 barrierbetween Fe3O4 and TiO2, the degraded methylene blue was increased from 44.2%to 52.3% by Fe3O4/SiO2/TiO2-Ald and the degraded paraquat was increased from16.3% to 45.8% by Fe3O4/SiO2/TiO2-P25. The photocatalytic activity of the bothmagnetic photocatalysts which having SiO2 barrier was equivalent to the activityof fraction ratio of TiO2 to its pure TiO2. There was no loss of photocatalyticactivity of TiO2 in magnetic photocatalysts after SiO2 barrier being introduced.The presence of SiO2 on magnetic photocatalysts was also able to eliminatemethylene blue and paraquat compounds through adsorption process. Therefore,more methylene blue and paraquat eliminated via both process. Totally, theFe3O4/SiO2/TiO2-Ald was able to eliminate 87.3% of methylene blue and 71.5%of paraquat. Meanwhile Fe3O4/SiO2/TiO2-P25 was able to eliminate 82.6% ofparaquat. Adsorption capacity of Fe3O4/SiO2/TiO2-Ald was lower than that ofFe3O4/SiO2/TiO2-P25, but photocatalytic activity of Fe3O4/SiO2/TiO2-Ald washigher than that of Fe3O4/SiO2/TiO2-P25. The developed magnetic photocatalystsshow its activity photocatalytic stability and still can be well magneticallyseparated after being repeatedly used for four times., Magnetic photocatalysts of Fe3O4/SiO2/TiO2 have been prepared using heteroagglomerationmethod. The magnetic photocatalysts were applied in slurry reactorsystem for elimination of organic compounds (methylene blue and paraquat) inwater. In addition, the magnetic photocatalysts are able to be recollected easilywith the assistance of an external magnetic field so that the spent composite canbe used repeatedly.Synthesis of magnetic photocatalysts of Fe3O4/SiO2/TiO2 were preceded bypreparing Fe3O4 nanoparticles through precipitation method using mixture ofFe(III)/Fe(II) (2:1 mole ratio) in ammonia solution and further coating with SiO2through hydrolysis of silicate ion. The formed Fe3O4/SiO2 were mixed with TiO2in hetero-agglomeration manner, to obtain Fe3O4/SiO2/TiO2 magneticphotocatalysts. In this study, two type of commercial TiO2 nanoparticles wereused, namely; TiO2 Aldrich and TiO2-P25 Evonik.The prepared magnetic photocatalysts were characterized with various techniques,i.e, x-ray diffraction (XRD) to determine the crystal phase, zeta potensial meter todetermine the surface charge of particles, VSM to determine the magneticproperties, FTIR and Raman spectrometer to identify the functional groups andmetal-oxide bond, EDS to determine the surface chemical composition, TEM formorphological examination and N2-adsorption to determine surface area. Theresults of XRD characterization showed that TiO2-Aldrich contains 55% ofanatase and 45% of rutile, while TiO2-P25 Evonik contains 86% of anatase and14% of rutile. Magnetite (Fe3O4), anatase and rutile phase of TiO2 were retained inthe formed composites. In the stage of composite formation, both TiO2 types havebeen successfully attached to Fe3O4/SiO2 via electrostatic interaction of surfacehidroxyl group of oxides. FTIR spectrometry analysis revealed the formedSi-O-Ti bond, resulting of electrostatic interaction both TiO2 and Fe3O4/SiO2.Hence, they were denoted as Fe3O4/SiO2/TiO2-Ald dan Fe3O4/SiO2/TiO2-P25. Theboth magnetic photocatalysts have a slight different physico-chemical propertiesand morphology. The more the fraction of TiO2 in magnetic photocatalysts, thelower its surface area. The obtained magnetic photocatalysts have high saturationmagnetization and low coercivity and remanent magnetization value. It means thatthe magnetic photocatalysts can be still recollected from water with assistance ofexternal magnetic field. In a non-magnetic field, magnetic photocatalyst can bewell dispersed in water again.The formed Fe3O4/TiO2-Ald and Fe3O4/TiO2-P25 was able to eleminatemethylene blue and paraquat in water by photocatalytic process, nevertheless itsactivities was low. Allegedly it occurs weakening of TiO2 activity in magneticphotocatalyst caused by photodissolution effects. The presence of SiO2 barrierbetween Fe3O4 and TiO2, the degraded methylene blue was increased from 44.2%to 52.3% by Fe3O4/SiO2/TiO2-Ald and the degraded paraquat was increased from16.3% to 45.8% by Fe3O4/SiO2/TiO2-P25. The photocatalytic activity of the bothmagnetic photocatalysts which having SiO2 barrier was equivalent to the activityof fraction ratio of TiO2 to its pure TiO2. There was no loss of photocatalyticactivity of TiO2 in magnetic photocatalysts after SiO2 barrier being introduced.The presence of SiO2 on magnetic photocatalysts was also able to eliminatemethylene blue and paraquat compounds through adsorption process. Therefore,more methylene blue and paraquat eliminated via both process. Totally, theFe3O4/SiO2/TiO2-Ald was able to eliminate 87.3% of methylene blue and 71.5%of paraquat. Meanwhile Fe3O4/SiO2/TiO2-P25 was able to eliminate 82.6% ofparaquat. Adsorption capacity of Fe3O4/SiO2/TiO2-Ald was lower than that ofFe3O4/SiO2/TiO2-P25, but photocatalytic activity of Fe3O4/SiO2/TiO2-Ald washigher than that of Fe3O4/SiO2/TiO2-P25. The developed magnetic photocatalystsshow its activity photocatalytic stability and still can be well magneticallyseparated after being repeatedly used for four times.] |
D1910-Adel Fisli.pdf :: Unduh