Bismuth oxide (Bi2O3) is a well-studied photocatalyst for degradation of various environmental contaminants. In this research Bi2O3 has been synthesized by precipitation method using two different bases (NH4OH and NaOH). The samples thus obtained were then analyzed using FTIR, XRD, and SEM for surface functionalization, crystal structures and morphological differences, respectively. The Bi2O3 precipitated using NH4OH showed a flower like structure made up of individual plates having α-Bi2O3 crystal structure. The precipitate obtained using NaOH showed a honeycomb like flower structure with a mixture of both α-Bi2O3 and γ-Bi2O3 crystal structure. Degradation of methyl orange (MO) was used as a model system to test the photocatalytic activity of the bismuth oxide. The Bi2O3 synthesized using NH4OH showed superior photocatalytic degradation of methyl orange than the one synthesized using NaOH.
The wide bandgap energy of a TiO2 semiconductor equivalent to ultraviolet light (λ <380 nm) limits photocatalytic applications to confined to the ultraviolet region and not to the visible light region (λ = 400 nm-700 nm). In this research, the nitrogen oxide TiO2 synthesis was prepared by sol-gel method. The TiCl4 precursor was used as a source of titanium dioxide and CO(NH2)2 as a nitrogen source and is varied on the amount of N concentration with variations of 20 g, 30 g, 40 g and 50 g. The reflux was carried out at 100°C for 7 hours followed by drying for 3 hours at 100°C, and calcination at 500°C for 7 hours. The N-doped TiO2 characterization was performed using X-ray Diffraction (XRD), Fourier Transform-Infra Red Spectroscopy (FTIR), and UV-Visible diffuse reflectance spectra (UV-Vis DRS). Based on XRD data it was known that N-doped TiO2 crystals have anatase structure with Miller index of 101. The FTIR spectra showed a shift in the uptake of O-Ti-O vibrations at wave number of 400-1050 cm -1 which estimated as a result of the formation of N-Ti-O bonds. The DRS-UV-visible spectrum showed a decrease in band gap energy from TiO2 of 3.2 eV. It can be concluded that the addition of nitrogen concentration resulted in a decrease in band gap energy, at 20 g variation of 3.12 eV, 30 g of 3.09 eV, 40 g of 3.082 eV, and 50 g of 3.08 eV.A b s t r a k Kata Kunci: Fotokatalis, Ndoped TiO2, Semikonduktor Energi celah pita yang lebar dari semikonduktor TiO2 yang setara dengan cahaya ultraviolet (<380 nm) membatasi aplikasi fotokatalitik hanya terbatas pada daerah ultraviolet dan tidak pada daerah cahaya tampak ( = 400 nm-700 nm). Pada penelitian ini dilakukan sintesis TiO2 teremban nitrogen yang dipreparasi melalui metode sol-gel. Prekursor TiCl4 digunakan sebagai sumber titanium dioksida dan CO(NH2)2 sebagai sumber nitrogen dan divariasi pada jumlah konsentrasi N dengan variasi 20 g, 30 g, 40 g dan 50 g. Refluks dilakukan pada suhu 100 , diperkirakan sebagai akibat terbentuknya ikatan N-Ti-O. Spektrum DRS-UV-tampak menunjukkan penurunan energi celah pita dari TiO2 yakni 3,2 eV. Dapat disimpulkan bahwa penambahan konsentrasi nitrogen mengakibatkan penurunan energi celah pita, pada variasi 20g sebesar 3,12 eV, 30 g sebesar 3,09 eV, 40 g sebesar 3,082 eV, dan 50 g sebesar 3,08 eV.
Telah dilakukan dealuminasi zeolit alam menggunakan asam (HCl dan H2SO4) untuk katalis pada proses sintesis biodiesel. Zeolit dianalisis dengan AAS dan FTIR serta uji aktivitas katalis pada sintesis biodiesel dengan metode GC-MS. Didapatkan bahwa H2SO4 lebih efektif mendealuminasi zeolite dibandingkan dengan HCl. Hasil spektrogram FTIR menunjukkan bahwa proses dealuminasi asam mengakibatkan perubahan bilangan gelombang dan rasio Si/Al yang cukup signifikan, di mana pada rasio Si/Al zeolit meningkat dari 4,57 menjadi 5,41 pada zeolit alam dealuminasi HCl dan menjadi 6,42 pada zeolit alam dealuminasi H2SO4. Zeolit terdealuminasi mampu bekerja sebagai katalis dalam sintesis biodiesel di mana katalis zeolit dealuminasi H2SO4 menghasilkan metil ester dengan senyawa dominan asam 9-oktadekenoat dengan persentase luas area sebesar 63,21% lebih banyak dibandingkan pada katalis zeolit dealuminasi HCl dan zeolite belum didealuminasi.
Penelitian tentang zeolit alam termodifikasi logam Fe sebagai adsorben fosfat (PO43-) pada air limbah telah dilakukan. Zeolit alam diaktivasi menggunakan HCl 2M. Kemudian zeolit teraktivasi dimodifikasi menggunakan FeCl3.6H2O dengan perbandingan massa precursor 10:90, 25:75, 50:50, 75:25, 90:10. Metode modifikasi yang digunakan adalah impregnasi ion logam Fe3+. Pada zeolit-Fe yang diperoleh kemudian dilakukan untuk mengadsorpsi fosfat dengan konsentrasi awal 0,9883 ppm. Hasil yang diperoleh dianalisis dengan FTIR, dan Spektrofotometer UV-Vis. Hasil analisis FTIR terhadap zeolit-Fe menunjukkan adanya puncak pada bilangan gelombang 474,5 cm-1 yang mengindikasikan vibrasi Fe-O. Fosfat (PO43-) yang terserap oleh zeolit-Fe paling banyak diperoleh pada variasi 10:90 yaitu sebesar 30,54% dengan konsentrasi teradsorpsi sebesar 0,3019 mgL-1.
Tembalang is one of the districts in the city of Semarang whose economic growth is rapid. There are 12 sub-districts in Tembalang district, one of which is the Tembalang sub-district, which is within the campus area of Diponegoro University. When compared with other sub-district in the Tembalang district, the Tembalang sub-district community's need for clean water and domestic wastewater disposal is very high because of its dense population. Handling domestic wastewater is one of the environmental problems, which is interesting to study. Domestic wastewater, in addition to causing environmental pollution, can also cause discomfort and even health problems. One way to reduce the impact of domestic wastewater is to treat domestic wastewater before the environment is discharged. This study aims to describe the character of domestic wastewater in Tembalang sub-district, Tembalang district, Semarang city, and the use of activated zeolites and activated zeolites to reduce COD, pH, BOD, and TSS in domestic wastewater. Also, to compare the parameters of wastewater with regulations in force (Minister of Environment and Forestry Regulation No: 68 of 2016). This research is expected to improve the quality of domestic wastewater by adsorption using natural zeolite and activated zeolite adsorbents. The results showed that the adsorption treatment with natural zeolites and activated zeolites significantly improved water quality. The results of adsorption by natural zeolites showed a decrease in COD of 21.8%, a pH of 11.5%, BOD of 9.2%, and a TSS of 10.8%. Whereas adsorption by HCl-activated zeolite resulted in a decrease in COD of 78.9%, pH of 16.2%, BOD of 11.8% & TSS of 74.4%. While H2SO4-activated natural zeolite reduced COD by 85.5%, pH 17.9%, BOD 12.6% and TSS 89.7%.
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