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Abstrak :
The main problem with the slurry process is the difficulty in recovering the photocatalyst nanoparticle from water following purification. An alternative solution proposed the photocatalyst be immobilized on magnetic carriers, which would allow them to be recollected from the water suspension following treatment using an external magnetic field. Magnetically photocatalyst composites were prepared using simple heteroagglomeration by applying attractive electrostatic forces between the nanoparticles with an opposite surface charge. The Fe3O4/SiO2/TiO2 photocatalysts were synthesized in an aqueous slurry solution containing Fe3O4/SiO2 and TiO2 nanoparticles under pH 5 conditions. Meanwhile, Fe3O4/SiO2 was prepared by a simple procedure via a coprecipitation of iron(II) and iron(III) ion mixtures in ammonium hydroxide and was leached by sodium silicate. The synthesized samples were investigated to determine the phase structure, the magnetic properties, and the morphology of the composites by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and transmission electron microscopy (TEM), respectively. The results indicated that the composites contained anatase and rutile phases and exhibited a superparamagnetic behavior. Fe3O4/SiO2 particles, which were of the aggregation spherical form at 20 nm in size, were successfully attached onto the TiO2 surface. The catalytic activity of Fe3O4/SiO2/TiO2 composites was evaluated for the degradation of methylene blue under ultraviolet (UV) irradiation. The presence of SiO2 as a barrier between Fe3O4 and TiO2 is not only improves the photocatalytic properties but also provides the ability to adsorb the properties on the composite. The Fe3O4/SiO2/TiO2 (50% containing TiO2 in composite) were able to eliminate 87.3% of methylene blue in water through the adsorption and photocatalytic processes. This result is slightly below pure TiO2, which is able to degrade 96% of methylene blue. The resulting Fe3O4/SiO2/TiO2 composite exhibited an excellent ability to remove dye from water and it is easily recollected using a magnetic bar from the water. Therefore, they have high potency as an efficient and simple implementation for the dye effluent decolorization of textile waste in slurry reactor processes.

Abstrak :
The main problem with the slurry process is the difficulty in recovering the photocatalyst nanoparticle from water following purification. An alternative solution proposed the photocatalyst be immobilized on magnetic carriers, which would allow them to be recollected from the water suspension following treatment using an external magnetic field. Magnetically photocatalyst composites were prepared using simple heteroagglomeration by applying attractive electrostatic forces between the nanoparticles with an opposite surface charge. The Fe3O4/SiO2/TiO2 photocatalysts were synthesized in an aqueous slurry solution containing Fe3O4/SiO2 and TiO2 nanoparticles under pH 5 conditions. Meanwhile, Fe3O4/SiO2 was prepared by a simple procedure via a coprecipitation of iron(II) and iron(III) ion mixtures in ammonium hydroxide and was leached by sodium silicate. The synthesized samples were investigated to determine the phase structure, the magnetic properties, and the morphology of the composites by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and transmission electron microscopy (TEM), respectively. The results indicated that the composites contained anatase and rutile phases and exhibited a superparamagnetic behavior. Fe3O4/SiO2 particles, which were of the aggregation spherical form at 20 nm in size, were successfully attached onto the TiO2 surface. The catalytic activity of Fe3O4/SiO2/TiO2 composites was evaluated for the degradation of methylene blue under ultraviolet (UV) irradiation. The presence of SiO2 as a barrier between Fe3O4 and TiO2 is not only improves the photocatalytic properties but also provides the ability to adsorb the properties on the composite. The Fe3O4/SiO2/TiO2 (50% containing TiO2 in composite) were able to eliminate 87.3% of methylene blue in water through the adsorption and photocatalytic processes. This result is slightly below pure TiO2, which is able to degrade 96% of methylene blue. The resulting Fe3O4/SiO2/TiO2 composite exhibited an excellent ability to remove dye from water and it is easily recollected using a magnetic bar from the water. Therefore, they have high potency as an efficient and simple implementation for the dye effluent decolorization of textile waste in slurry reactor processes.

Abstrak :
ABSTRAK Samarium-Metal Organic Frameworks (Sm-MOFs) berhasil disintesis mengunakan metoda solvotermal berbasis ligan 2,6-naftalendikarboksilat (2,6-NDC) sebagai linker dan ion logam samarium (Sm3+) sebagai pusat kluster. Struktur ligan 2,6-NDC yang kaku dan kemampuan logam samarium dalam membentuk bilangan koordinasi tinggi dimanfaatkan untuk memperoleh disain MOFs yang memiliki kerangka koordinasi dengan luas permukaan yang besar. Dalam penelitian ini, dilakukan variasi sintesis Sm-MOFs melalui parameter suhu, perbandingan mol reaktan dan nilai pH. Tidak adanya serapan pada bilangan gelombang 1700cm-1 sebagai vibrasi ulur v(C=O) untuk 2,6-NDC, mengindikasi telah terjadinya deprotonasi ligan pada gugus (O-H) karboksilat, sehingga atom oksigen dari ligan dapat berkoordinasi dengan ion logam samarium. Hal ini menandakan Sm-MOFs telah berhasil terbentuk. Intensitas puncak difraksi yang kuat dan tajam mengindikasi kristalinitas Sm-MOFs yang cukup tinggi. Sm-MOFs yang disintesis pada pH 9 memiliki ukuran partikel yang lebih kecil dibadingkan pH 4, sehingga memiliki luas permukaan yang lebih besar yakni 107m2/g. Energi celah pita dihitung dengan mengunakan teori Kubelka-Munk, secara berurutan diperoleh untuk pH 4,7 dan 9 sebesar 3,1, 3,4 dan 3,42eV. Data siklik voltametri menunjukan nilai potensial reduksi Sm-MOFs pH 4 diperoleh sebesar -2,1volt dan potensial oksidasinya sebesar 0,6volt. Berdasarkan analisis yang telah dilakukan, material ini berpotensi sebagai material semikonduktor dalam fotokatalis degradasi metilen biru, dimana Sm-MOFs pH 4 dalam waktu 240menit mampu mendegradasi metilen biru sebesar 68,6%, sedangkan Sm-MOFs pH 9 mampu mendegradasi sebesar 87,6%.

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ABSTRACT Samarium-Metal Organic Frameworks (Sm-MOFs) have been successfully synthesized based on 2,6-naphthalenedicarboxylic acid ligand (2,6-NDC) and ion samarium (Sm3+) as metal linkers using solvothermal methods. Rigidity 2.6-NDC structure and the ability of the samarium metal forming high coordination numbers are utilized to obtain the MOF disain has a coordination framework with a large surface area. In this study, parameters variations in the synthesis of Sm-MOFs were carried out through temperature, mol of reactants and pH. The absence of absorption at wave number 1700cm-1 as vibration stretching v(C = O) from 2.6-NDC, indicates that there has been deprotonation of the ligand on the carboxylic group, the oxygen atom from ligand can coordinate with the samarium metal ion. This indicates that Sm-MOFs has been successfully formed. Peak intensity of strong and sharp from x-ray diffraction indicates the high crystallinity of Sm-MOFs. Sm-MOFs synthesized at pH 9 have a smaller particle size compared to pH 4, it has a larger surface area of 107m2/g. Band gap energy was calculated using the Kubelka-Munk theory, sequentially obtained for pH 4, 7 and 9 of 3,1 ; 3,4 and 3,42eV. Cyclic voltammetry data shows that the value of Sm-MOFs reduction potential pH 4 is obtained -2,1volt and oxidation potential is 0,6volt. Based on the analysis data, this material has the potential as a semiconductor for photocatalysts methylene blue degradation, where Sm-MOFs pH 4 in 240minutes can degradation methylene blue by 68,6%, while Sm-MOFs pH 9 can degrade 87,6%.

Abstrak :
Lantanum-Metal Organic Frameworks (La-MOFs) berhasil disintesis mengunakan metode solvotermal berbasis ligan perylene-3,4,9,10-tetracarboxylic sebagai linker organik dan ion logam lantanum (La3+) sebagai pusat kluster. Pada penelitian ini, dilakukan variasi sintesis La-MOFs melalui parameter perbandingan rasio molar dan waktu reaksi. Tidak adanya serapan pada bilangan gelombang 1700 cm-1 sebagai vibrasi ulur v(C=O) untuk La-MOFs, mengindikasikan atom oksigen dari ligan dapat berkoordinasi dengan ion logam lantanum. Hal ini menandakan La-MOFs telah berhasil terbentuk. Intensitas puncak X-ray difraksi yang kuat dan tajam mengindikasikan kristalinitas La-MOFs yang cukup tinggi. La-MOFs dengan perbandingan rasio molar 0,33:0,25 dan 0,29:0,29 secara berturut-turut memiliki luas permukaan sebesar 72,445 m2/g dan 102,565 m2/g. La-MOFs dengan perbandingan rasio molar 0,33:0,25 dan 0,29:0,29 secara berturut-turut memiliki nilai band gap sebesar 2,686 eV dan 2,732 eV. La-MOFs 0,33:0,25 yang memiliki band gap terkecil digunakan pada aplikasi fotokatalisis untuk produksi gas hidrogen. Hasil voltametri siklik dari La-MOFs 0,33:0,25 diperoleh nilai potensial reduksi (LUMO) sebesar -2,0735 V vs NHE dimana lebih negatif dari potensial reduksi H+/H2 maka dapat disimpulkan bahwa La-MOFs memiliki potensi persyaratan termodinamika untuk reduksi H+/H2. Produksi gas hidrogen tertinggi diperoleh pada massa La-MOFs 0,03 gram yang mencapai 8463,742 µmol.

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Lanthanum-Metal Organic Frameworks (La-MOFs) have been successfully synthesized based on perylene-3,4,9,10-tetracarboxylic dyes as organic linker and ion lanthanum (La3+) as cluster center using solvothermal methods. In this study, parameters variations in the synthesis of La-MOFs were carried out through the ratio of molar ratios and reaction time. The absence of absorption at wave number 1700 cm-1 as vibration stretching v(C═O) from La-MOFs, indicates that the oxygen atom from ligand can coordinate with the lanthanum metal ion. This indicates that La-MOFs has been successfully formed. Peak intensity of strong and sharp from X-ray diffraction indicates the high crystallinity of La-MOFs. La-MOFs with a ratio of molar ratios of 0.33:0.25 and 0.29:0.29 respectively have a surface area of ​​72.445 m2/g and 102.565 m2/g. La-MOFs with molar ratios of 0.33: 0.25 and 0.29:0.29 have a band gap value of 2.686 eV and 2.732 eV, respectively. La-MOFs 0.33:0.25 which has the smallest band gap used in photocatalytic applications for hydrogen gas production. The results of cyclic voltammetry from La-MOFs 0.33:0.25 obtained a reduction potential value (LUMO) of -2.0735 V vs. NHE which was more negative than the H+/H2 reduction potential, it can be concluded that La-MOFs have potential thermodynamic requirements for reduction of H+/H2. The highest production of hydrogen gas was obtained at the La-MOFs mass of 0.03 g which reached 8463.742 µmol.