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ABSTRAKFotokatalis bermagnet Fe3O4/SiO2/TiO2 telah dibuat dengan cara heteroaglomerasi.
Fotokatalis bermagnet ini diterapkan dalam reaktor sistem slurry
untuk eliminasi zat organik (metilen biru dan paraquat) dalam air. Dan juga,
fotokatalis bermagnet ini memberi kemudahan untuk dikumpulkan kembali
dengan bantuan medan magnet luar sehingga fotokatalis bekas pakai ini dapat
digunakan kembali secara berulang-ulang.
Sintesis fotokatalis bermagnet Fe3O4/SiO2/TiO2 diawali dengan membuat
nanopartikel Fe3O4 dengan cara presipitasi menggunakan campuran Fe(III)/Fe(II)
(rasio mol 2:1) dalam larutan amonia dan kemudian dilapisi dengan SiO2 dengan
cara hidrolisis ion silikat. Fe3O4/SiO2 yang terbentuk dicampurkan dengan TiO2
dengan cara hetero-aglomerasi, untuk memperoleh fotokatalis bermagnet
Fe3O4/SiO2/TiO2. Dalam penelitian ini, ada dua jenis TiO2 komersil yang
digunakan, yaitu nanopartikel TiO2 Aldrich dan nanopartikel TiO2 P25 Evonik.
Fotokatalis bermagnet yang telah dibuat dikarakterisasi dengan berbagai teknik, di
antaranya, difraksi sinar-x (XRD) untuk menentukan fasa kristal, zeta potensial
meter untuk menentukan muatan permukaan partikel, VSM untuk menentukan
sifat kemagnetan, spektrometer FTIR dan Raman untuk identifikasi gugus fungsi
dan ikatan logam-oksida, EDS untuk menentukan komposisi unsur permukaan,
TEM untuk mengetahui morfologi dan adsorpsi-N2 untuk menetukan luas
permukaan. Hasil karakterisasi XRD menunjukkan bahwa TiO2-Aldrich
mengandung fasa anatase 55% dan rutil 45% sedangkan TiO2-P25 Evonik
mengandung fasa anatase 86% dan rutil 14%. Fasa magnetit (Fe3O4), TiO2 anatase
dan rutil dipertahankan dalam fotokatalis bermagnet yang terbentuk. Dalam
tahapan pembentukan bahan, ke dua jenis TiO2 telah berhasil menempel secara
permanen pada Fe3O4/SiO2 melalui interaksi elektrostatik gugus hidroksil
permukaan masing-masing oksida. Spektromentri FTIR mengamati ikatan Si-O-Ti
yang terbentuk, hasil interaksi elektrostatik TiO2 dengan Fe3O4/SiO2, selanjutnya
dinotasikan sebagai Fe3O4/SiO2/TiO2-Ald dan Fe3O4/SiO2/TiO2-P25. Kedua jenis
bahan mempunyai sedikit perbedaan sifat fisika-kimia dan morfologi. Semakin
banyak fraksi TiO2 dalam bahan maka luas permukaannya semakin turun.
Fotokatalis bermagnet yang diperoleh mempunyai sifat magnet cukup baik dan
nilai remanent magnetization dan coercivity yang rendah, artinya bahan ini dapat
dengan mudah dikumpulkan kembali dari cairan dengan bantuan medan magnet
luar dan tanpa medan magnet dapat terdispersi kembali dengan baik dalam air. Fe3O4/TiO2-Ald dan Fe3O4/TiO2-P25 yang telah dibuat mampu mengeliminasi
metilen biru dan paraquat dalam air melalui proses fotokatalitik, namun demikian
aktivitasnya dianggap masih rendah. Diduga terjadi pelemahan aktivitas TiO2
yang ada dalam fotokatalis bermagnet akibat dari efek fotodisolusi. Adanya
barrier SiO2 di antara Fe3O4 dan TiO2, metilen biru yang terdegradasi meningkat
dari 44,2% menjadi 52,3% oleh Fe3O4/SiO2/TiO2-Ald dan paraquat yang
terdegradasi meningkat dari 16,3% menjadi 45,8% oleh Fe3O4/SiO2/TiO2-P25.
Aktivitas kedua fotokatalis bermagnet yang punya barrier SiO2 ini setara dengan
aktivitas rasio fraksi aktif TiO2 terhadap TiO2 murninya. Tidak ada kehilangan
aktivitas TiO2 dalam fotokatalis bermagnet setelah diberi barrier SiO2. Adanya
SiO2 dalam fotokatalis bermagnet ini juga mampu mengeliminasi senyawa
metilen biru dan paraquat melalui proses adsorpsi. Maka dari itu, lebih banyak
lagi metilen biru dan paraquat tereliminasi melalui kedua proses. Secara total,
Fe3O4/SiO2/TiO2-Ald mampu mengeliminasi metilen biru 87,3% dan paraquat
71,5%. Sedangkan Fe3O4/SiO2/TiO2-P25 mampu mengeliminasi paraquat 82,6%.
Kapasitas adsorpsi Fe3O4/SiO2/TiO2-Ald lebih rendah dari kapasitas adsorpsi
Fe3O4/SiO2/TiO2-P25, tetapi aktivitas fotokatalitik Fe3O4/SiO2/TiO2-Ald lebih
tinggi dari aktivitas fotokatalitik Fe3O4/SiO2/TiO2-P25. Fotokatalis bermagnet
yang dikembangkan menunjukkan kestabilan fotokatalitik paling tidak sampai
empat kali pemakaian berulang dan juga masih dapat dikumpulkan kembali
dengan mudah dengan bantuan medan magnet luar
ABSTRAKMagnetic photocatalysts of Fe3O4/SiO2/TiO2 have been prepared using heteroagglomeration
method. The magnetic photocatalysts were applied in slurry reactor
system for elimination of organic compounds (methylene blue and paraquat) in
water. In addition, the magnetic photocatalysts are able to be recollected easily
with the assistance of an external magnetic field so that the spent composite can
be used repeatedly.
Synthesis of magnetic photocatalysts of Fe3O4/SiO2/TiO2 were preceded by
preparing Fe3O4 nanoparticles through precipitation method using mixture of
Fe(III)/Fe(II) (2:1 mole ratio) in ammonia solution and further coating with SiO2
through hydrolysis of silicate ion. The formed Fe3O4/SiO2 were mixed with TiO2
in hetero-agglomeration manner, to obtain Fe3O4/SiO2/TiO2 magnetic
photocatalysts. In this study, two type of commercial TiO2 nanoparticles were
used, 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 to
determine the surface charge of particles, VSM to determine the magnetic
properties, FTIR and Raman spectrometer to identify the functional groups and
metal-oxide bond, EDS to determine the surface chemical composition, TEM for
morphological examination and N2-adsorption to determine surface area. The
results of XRD characterization showed that TiO2-Aldrich contains 55% of
anatase and 45% of rutile, while TiO2-P25 Evonik contains 86% of anatase and
14% of rutile. Magnetite (Fe3O4), anatase and rutile phase of TiO2 were retained in
the formed composites. In the stage of composite formation, both TiO2 types have
been successfully attached to Fe3O4/SiO2 via electrostatic interaction of surface
hidroxyl group of oxides. FTIR spectrometry analysis revealed the formed
Si-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. The
both magnetic photocatalysts have a slight different physico-chemical properties
and morphology. The more the fraction of TiO2 in magnetic photocatalysts, the
lower its surface area. The obtained magnetic photocatalysts have high saturation
magnetization and low coercivity and remanent magnetization value. It means that
the magnetic photocatalysts can be still recollected from water with assistance of
external magnetic field. In a non-magnetic field, magnetic photocatalyst can be
well dispersed in water again.
The formed Fe3O4/TiO2-Ald and Fe3O4/TiO2-P25 was able to eleminate
methylene blue and paraquat in water by photocatalytic process, nevertheless itsactivities was low. Allegedly it occurs weakening of TiO2 activity in magnetic
photocatalyst caused by photodissolution effects. The presence of SiO2 barrier
between 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 from
16.3% to 45.8% by Fe3O4/SiO2/TiO2-P25. The photocatalytic activity of the both
magnetic photocatalysts which having SiO2 barrier was equivalent to the activity
of fraction ratio of TiO2 to its pure TiO2. There was no loss of photocatalytic
activity of TiO2 in magnetic photocatalysts after SiO2 barrier being introduced.
The presence of SiO2 on magnetic photocatalysts was also able to eliminate
methylene blue and paraquat compounds through adsorption process. Therefore,
more methylene blue and paraquat eliminated via both process. Totally, the
Fe3O4/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% of
paraquat. Adsorption capacity of Fe3O4/SiO2/TiO2-Ald was lower than that of
Fe3O4/SiO2/TiO2-P25, but photocatalytic activity of Fe3O4/SiO2/TiO2-Ald was
higher than that of Fe3O4/SiO2/TiO2-P25. The developed magnetic photocatalysts
show its activity photocatalytic stability and still can be well magnetically
separated after being repeatedly used for four times.;Magnetic photocatalysts of Fe3O4/SiO2/TiO2 have been prepared using heteroagglomeration
method. The magnetic photocatalysts were applied in slurry reactor
system for elimination of organic compounds (methylene blue and paraquat) in
water. In addition, the magnetic photocatalysts are able to be recollected easily
with the assistance of an external magnetic field so that the spent composite can
be used repeatedly.
Synthesis of magnetic photocatalysts of Fe3O4/SiO2/TiO2 were preceded by
preparing Fe3O4 nanoparticles through precipitation method using mixture of
Fe(III)/Fe(II) (2:1 mole ratio) in ammonia solution and further coating with SiO2
through hydrolysis of silicate ion. The formed Fe3O4/SiO2 were mixed with TiO2
in hetero-agglomeration manner, to obtain Fe3O4/SiO2/TiO2 magnetic
photocatalysts. In this study, two type of commercial TiO2 nanoparticles were
used, 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 to
determine the surface charge of particles, VSM to determine the magnetic
properties, FTIR and Raman spectrometer to identify the functional groups and
metal-oxide bond, EDS to determine the surface chemical composition, TEM for
morphological examination and N2-adsorption to determine surface area. The
results of XRD characterization showed that TiO2-Aldrich contains 55% of
anatase and 45% of rutile, while TiO2-P25 Evonik contains 86% of anatase and
14% of rutile. Magnetite (Fe3O4), anatase and rutile phase of TiO2 were retained in
the formed composites. In the stage of composite formation, both TiO2 types have
been successfully attached to Fe3O4/SiO2 via electrostatic interaction of surface
hidroxyl group of oxides. FTIR spectrometry analysis revealed the formed
Si-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. The
both magnetic photocatalysts have a slight different physico-chemical properties
and morphology. The more the fraction of TiO2 in magnetic photocatalysts, the
lower its surface area. The obtained magnetic photocatalysts have high saturation
magnetization and low coercivity and remanent magnetization value. It means that
the magnetic photocatalysts can be still recollected from water with assistance of
external magnetic field. In a non-magnetic field, magnetic photocatalyst can be
well dispersed in water again.
The formed Fe3O4/TiO2-Ald and Fe3O4/TiO2-P25 was able to eleminate
methylene blue and paraquat in water by photocatalytic process, nevertheless itsactivities was low. Allegedly it occurs weakening of TiO2 activity in magnetic
photocatalyst caused by photodissolution effects. The presence of SiO2 barrier
between 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 from
16.3% to 45.8% by Fe3O4/SiO2/TiO2-P25. The photocatalytic activity of the both
magnetic photocatalysts which having SiO2 barrier was equivalent to the activity
of fraction ratio of TiO2 to its pure TiO2. There was no loss of photocatalytic
activity of TiO2 in magnetic photocatalysts after SiO2 barrier being introduced.
The presence of SiO2 on magnetic photocatalysts was also able to eliminate
methylene blue and paraquat compounds through adsorption process. Therefore,
more methylene blue and paraquat eliminated via both process. Totally, the
Fe3O4/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% of
paraquat. Adsorption capacity of Fe3O4/SiO2/TiO2-Ald was lower than that of
Fe3O4/SiO2/TiO2-P25, but photocatalytic activity of Fe3O4/SiO2/TiO2-Ald was
higher than that of Fe3O4/SiO2/TiO2-P25. The developed magnetic photocatalysts
show its activity photocatalytic stability and still can be well magnetically
separated after being repeatedly used for four times., Magnetic photocatalysts of Fe3O4/SiO2/TiO2 have been prepared using heteroagglomeration
method. The magnetic photocatalysts were applied in slurry reactor
system for elimination of organic compounds (methylene blue and paraquat) in
water. In addition, the magnetic photocatalysts are able to be recollected easily
with the assistance of an external magnetic field so that the spent composite can
be used repeatedly.
Synthesis of magnetic photocatalysts of Fe3O4/SiO2/TiO2 were preceded by
preparing Fe3O4 nanoparticles through precipitation method using mixture of
Fe(III)/Fe(II) (2:1 mole ratio) in ammonia solution and further coating with SiO2
through hydrolysis of silicate ion. The formed Fe3O4/SiO2 were mixed with TiO2
in hetero-agglomeration manner, to obtain Fe3O4/SiO2/TiO2 magnetic
photocatalysts. In this study, two type of commercial TiO2 nanoparticles were
used, 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 to
determine the surface charge of particles, VSM to determine the magnetic
properties, FTIR and Raman spectrometer to identify the functional groups and
metal-oxide bond, EDS to determine the surface chemical composition, TEM for
morphological examination and N2-adsorption to determine surface area. The
results of XRD characterization showed that TiO2-Aldrich contains 55% of
anatase and 45% of rutile, while TiO2-P25 Evonik contains 86% of anatase and
14% of rutile. Magnetite (Fe3O4), anatase and rutile phase of TiO2 were retained in
the formed composites. In the stage of composite formation, both TiO2 types have
been successfully attached to Fe3O4/SiO2 via electrostatic interaction of surface
hidroxyl group of oxides. FTIR spectrometry analysis revealed the formed
Si-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. The
both magnetic photocatalysts have a slight different physico-chemical properties
and morphology. The more the fraction of TiO2 in magnetic photocatalysts, the
lower its surface area. The obtained magnetic photocatalysts have high saturation
magnetization and low coercivity and remanent magnetization value. It means that
the magnetic photocatalysts can be still recollected from water with assistance of
external magnetic field. In a non-magnetic field, magnetic photocatalyst can be
well dispersed in water again.
The formed Fe3O4/TiO2-Ald and Fe3O4/TiO2-P25 was able to eleminate
methylene blue and paraquat in water by photocatalytic process, nevertheless itsactivities was low. Allegedly it occurs weakening of TiO2 activity in magnetic
photocatalyst caused by photodissolution effects. The presence of SiO2 barrier
between 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 from
16.3% to 45.8% by Fe3O4/SiO2/TiO2-P25. The photocatalytic activity of the both
magnetic photocatalysts which having SiO2 barrier was equivalent to the activity
of fraction ratio of TiO2 to its pure TiO2. There was no loss of photocatalytic
activity of TiO2 in magnetic photocatalysts after SiO2 barrier being introduced.
The presence of SiO2 on magnetic photocatalysts was also able to eliminate
methylene blue and paraquat compounds through adsorption process. Therefore,
more methylene blue and paraquat eliminated via both process. Totally, the
Fe3O4/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% of
paraquat. Adsorption capacity of Fe3O4/SiO2/TiO2-Ald was lower than that of
Fe3O4/SiO2/TiO2-P25, but photocatalytic activity of Fe3O4/SiO2/TiO2-Ald was
higher than that of Fe3O4/SiO2/TiO2-P25. The developed magnetic photocatalysts
show its activity photocatalytic stability and still can be well magnetically
separated after being repeatedly used for four times.]
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