Synthesis and Catalytic Properties of CoFe2O4/Fe2O3 Nanosized Composite Material

The present research is devoted to the formation process of a nanoscale composite material with the composition of CoFe2O4/α-Fe2O3. The synthesized material has been studied by the following methods: x-ray phase analysis and scanning electron microscopy. The produced sample is analyzed to be a CoFe2O4 cabic spinel with a unit cell parameters of a = 0.8394 nm and α-Fe2O3. The average crystallite size of the resulting samples, determined by the Debye-Scherrer equation, is 4.8 nm for the cobalt (II) ferrite and 7.9 nm for α-Fe2O3. Reaction rate increase is determined by the incease in hydrogen peroxide amount in the solution. The synthesized composite material is found to exhibit increased catalytic activity in the oxidative degradation reaction of organic dye by hydrogen peroxide. The catalytic activity is established to be particularly high, when the process is occurring in acidic medium. The obtained samples have a highly developed surface and may be of interest as catalysts, adsorbents.

An External Energy Independent WO3/MoCl5 Nano-Sized Catalyst for the Superior Degradation of Crystal Violet and Rhodamine B Dye

In this study, the synthesis of a novel catalyst WO3/MoCl5 was carried out by the thermal method. The method gave an entirely different product compared to previous studies that doped Mo on the surface of semiconductor metal oxides. The degradation reaction of crystal violet (CV) and rhodamine B (RB) dye were done without any energy source. The results showed an incomparably superior result for degradation, with a reaction rate constant of 1.74 s−1 for 30 ppm CV, 1.08 s−1 for 30 ppm RB, and a higher value than 1 s−1 for both cases of 50 ppm dye solution. To the author’s knowledge, this catalyst has the highest reaction rate compared to other studies that targeted CV and RB, with an immense reaction rate increase of more than 100 times. Reusability of the three trials was verified, and the only process required was washing the catalyst after the reaction. One of the drawbacks of the advanced oxidation process (AOP), which has a degradation percent limit, has been solved, since 100% mineralization of the dye was available using this catalyst. FT-IR spectroscopy revealed that W-O-Mo linkage was successfully processed while Mo-Cl linkage has retained. 1H-NMR spectroscopy results confirmed that the degradation product of the dye treated by simple MoCl5 and WO3/MoCl5 was different. Deep inspection of specific regions of NMR fields gave necessary information about the degradation product using WO3/MoCl5.

Characterization of Silver Loaded Activated Carbon Prepared under Supercritical Water Condition

The synthesis of silver nanoparticles loaded on the activated carbon (AC) surface were performed under SCW condition at 673 K and 31.15 MPa in a batch reactor. In supercritical region, fine particles are rapidly synthesized due to reaction rate increase at low dielectric constant of supercritical water. Samples were prepared with different concentrations of silver acetate solution and various reaction times. The synthesized silver loaded on AC particles were characterized by the Fourier transform infrared spectroscopy (FTIR),X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). FTIR spectrum of primary activated carbon, activated carbon treated under supercritical water condition and synthesized AC-Ag was compared. The particles size and crystallite size of silver deposited on AC surface were analyzed by TEM and XRD, respectively.

Electrochemical Promotion of Nanostructured Palladium Catalyst for Complete Methane Oxidation

Electrochemical promotion of catalysis (EPOC) was investigated for methane complete oxidation over palladium nano-structured catalysts deposited on yttria-stabilized zirconia (YSZ) solid electrolyte. The catalytic rate was evaluated at different temperatures (400, 425 and 450 °C), reactant ratios and polarization values. The electrophobic behavior of the catalyst, i.e., reaction rate increase upon anodic polarization was observed for all temperatures and gas compositions with an apparent Faradaic efficiency as high as 3000 (a current application as low as 1 μA) and maximum rate enhancement ratio up to 2.7. Temperature increase resulted in higher enhancement ratios under closed-circuit conditions. Electrochemical promotion experiments showed persistent behavior, where the catalyst remained in the promoted state upon current or potential interruption for a long period of time. An increase in the polarization time resulted in a longer-lasting persistent promotion (p-EPOC) and required more time for the reaction rate to reach its initial open-circuit value. This was attributed to continuous promotion by the stored oxygen in palladium oxide, which was formed during the anodic polarization in agreement with p-EPOC mechanism reported earlier.

EKSPERIMEN PEMBENTUKAN KERAK GIPSUM PADA PIPA BERALIRAN LAMINIR DENGAN PARAMETER LAJU ALIR DAN ADITIF ION CU2+ : KAJIAN KINETIS

Wiji Mangestiyono, , A.P. Bayuseno, Stefanus Muryanto, in this paper explain that the problem of gypsum scaling becomes a trouble for some industry in which use some water for its system. Some disadvanteges come up because of : the time of industrial process will be more longer and production cost increase necesery.To prevent the growth of scale, the experiment must be done. Researcher try to answer this problem so an experimental about kinetic study of gypsum scaling established. Flowrate would be a parameter with assume that it has effect on reaction flow. The result of this experiment are : reaction rate increase when flow rate increase; adition some aditives becomes reaction rate decrease. Keywords : crystal, flow rate, reactio rate, gipsum

Development of Small-Efficient Tool for Ultrasonic Reactor

A small-high efficiency ultrasonic reactor tool is designed by this paper. This tool can promote chemical reaction rate, increase the reaction yield. Having analyzed its modal frequency with ANSYS software and assembled the manufactured tool with transducer and horn, we can use Impedance analyzer to test the actual frequency. Since there are only minor errors between actual resonant frequency and the modal frequency, this method meets the design requirements.

Study of the Influence of Microwaves in the Mechanism of Sulfenamide Accelerated Vulcanization of Natural Rubber Using Squalene as a Model Compound

The natural rubber vulcanization mechanism has been studied using microwaves as a heating source. The influence of such heating system on the mechanism reaction has been elucidated. In order to simplify the study of this process, squalene has been used as a Model Compound Vulcanization (MCV) for natural rubber and N-cyclohexyl-2-benzothiazolesulfenamide (CBS) as an accelerator. The accelerator fading, the crosslinking degree, the reversion process and the effect of the double bond have been studied and the results have been compared with previous results of our group using MCV with conventional heating. As well as the expected reaction rate increase, a noticeable change in the crosslink degree has been observed. Furthermore, some differences have been detected in the amount of the intermediate compounds formed during the reaction and in the sulfur transfer to the squalene chain. Strong differences have been also observed regarding the role of the activator in the vulcanization when microwaves are used.