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Abstrak :
Modifikasi elektroda karbon, glassy carbon (GC) dan boron-doped diamond (BDD), menggunakan nanopartikel emas (AuNP) dilakukan dengan menggunakan teknik self-assembly. Teknik ini dipilih berdasarkan interaksi elektrostatik antara AuNP yang terperangkap ion sitrat dengan gugus amina yang dimodifikasikan pada BDD dan GC. Material yang diperoleh, AuNP-GC dan AuNP-BDD, kemudian digunakan sebagai elektroda pendeteksi As 3+ menggunakan teknik anodic stripping voltammetry (ASV). Anodic stripping voltammograms dari kedua elektroda menunjukkan puncak potensial oksidasi As °pada ~0.21 V (vs. Ag/AgCl) pada kondisi optimum potensial deposisi -500 mV, waktu deposisi 180 s, dan scan rate 100 mV/s. AuNP-BDD memiliki daerah pengukuran yang lebih luas (0-20 mM) dan limit deteksi yang lebih rendah (0.39 μ M atau 4.64 ppb), sedangkan AuNP-GC linier pada daerah konsentrasi 0-10 mM dengan limit deteksi 0.14 μ M (13.12 ppb). Keberulangan yang baik ditunjukkan dengan RSDs (n=20) 2.93% pada AuNP-BDD dan 4.54% pada AUNP-BDD. Meskipun demikian penurunan yang lebih banyak pada pengukuran 6 hari berturut-turut ditemukan pada AuNP-BDD (~20.1%) daripada pada AuNP-GC (~2.8%).

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Modification of carbon, including boron-doped diamond (BDD) and glassy carbon (GC), using gold nanoparticle (AuNP) was developed by self-assembly technique. This technique is based on electrostatic interaction between citrate-capped AuNP to amine terminal groups after surface modification of BDD and GC. The fabricated materials, AuNP-BDD and AuNP-GC, were then utilized as electrodes for As 3+ detection using anodic stripping voltammetry (ASV) technique. Anodic stripping voltammograms of both Au NP-BDD and AuNP-GC electrodes showed similar peak potentials of As ° oxidation at ~0.21 V (vs. Ag/AgCl) in optimum conditions of -500 mV, 180 s, and 100 mV/s for deposition potential, deposition time, and scan rate, respectively. AuNP-BDD shows better performances in the case of wide linear concentration range (0-20 mM) and low limit of detection (0.39μM or 4.64 ppb), whereas those of AuNP-GC were linear in the concentration range of 0-10mM with a detection limit of 0.14μ M (13.12 ppb). Excellent reproducibility was shown with RSDs (n=20) of 2.93% and 4.54% at AuNP-BDD and AuNP-GC, respectively. However, decreasing of current responses in 6-concecutive days was found more at AuNP-BDD (~20.1%) than that at AuNP-GC (~2.8%).

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 :
[Ligan para-di-2-(1-methyl-3-pyridyl-4,5-dihydro-1H-pyrazol-5-yl)benzena sudah berhasil disintesis melalui metode kondensasi Aldol. Hasil yang diperoleh dikarakterisasi menggunakanspektrofotometer UV-Vis, spektrofotometer inframerah dan spektrometer NMR. Aplikasi ligan ini adalah sebagai Sensor ion logam Pb2+dan dilakukan menggunakan spektrometer UV-Vis. Hasil dari studi sensor menunjukkan bahwa ligan mempunyai intensitas absorbansi yang kuat. Hal ini didukung oleh nilai absorptivitas molar (?) yang besar. Studi spektroskopi UV-Vis pada penambahan ion Pb2+ menunjukkan munculnya puncak baru pada daerah panjang gelombang 290 nm. Hal ini menunjukkan adanya pembentukan kompleks antara ion logam (Pb2+) dengan ligan para-di-2-(1-methyl-3-pyridyl-4,5-dihydro-1H-pyrazol-5-yl)benzena. Studi aplikasi sensor menunjukkan bahwa ligan ini dapat dijadikan sensoruntuk ion Pb2+ karena penambahan ion ini menyebabkan penurunan intensitas serapan absorbansi. Hasil studi efektivitas sensor menunjukkan bahwa ligan para-di-2-(1-methyl-3-pyridyl-4,5-dihydro-1H-pyrazol-5-yl)benzena merupakan sensor yang efektif terhadap penambahan ion Pb2+ pada panjang gelombang maksimum (?maks) 291 nm. ...... The Ligand para-di-2-(1-methyl-3-pyridyl-4,5-dihydro-1H-pyrazol-5-yl)benzene has been synthesized well by using Aldol condensation method. The result of synthesizing is characterized byUV-Visible spectrophotometer, Infrared spectrophotometer and NMR spectrometer. The application of this ligand as sensor for Pb2+ metal ions was studied by using UV-Visible spectrophotometer. Sensingstudiesindicatethat theligandhas astrongabsorbans intensity. This is supportedby alarge molarabsorptivity (?) value. UV-Vis spectroscopystudiesonthe addition ofPb2+ ions showedthe emergence ofa newpeakat290nmwavelength region. This indicatesthat thecomplexesformedbetweenmetalions(Pb2+) with para-di-2-(1-methyl-3-pyridyl-4,5-dihydro-1H-pyrazol-5-yl)benzene ligand. Application sensor studies showed that theseligandscanbe used assensorforPb2+ionsdue tothe addition oftheseionscauses a quenched inabsorbans intensity. The results ofthe study ofsensor efectivity showedthattheligandpara-di-2-(1-methyl-3-pyridyl-4,5-dihydro-1H-pyrazol-5-yl)benzeneissensorefectiveaddition ofPb2+ionsat themaximumwavelength(?max) 291 nm., 5he 1igand para-di-%-+!-rnethyl-(-pyridyl-*,3-dihydro-!:-pyra->isible spectrophotorneter, )n2rared spectrophotorneter and NM? spectrorneter. 5he application o2 this ligand as sensor 2or Pb%= rnetal ions was studied by using .>->isible spectrophotorneter. Sensing studies indicate that the ligand has a strong absorbans intensity. 5his is supported by a large rnolar absorpti$ity +@/ $alue. .>->is spectroscopy studies on the addition o2 Pb%= ions showed the ernergence o2 a new peak at %A7 nrn wa$elength region. 5his indicates that the cornpleCes 2orrned between rnetal ions +Pb%=/ with para-di-%-+!-rnethyl-(-pyridyl-*,3-dihydro-!:-pyra