The Effect of Using H4P2O7 as Phosphorus Source for Synthesizing Vanadyl Pyrophosphate Catalysts

Vanadyl pyrophosphate (VO)2P2O7 catalysts synthesized via VOPO4·2H2O were investigated by using BET surface area measurement, X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Temperature-Programmed Techniques (TPD and TPRS). H3PO4 and H4P2O7 were used as the phosphorus source. Only pyrophosphate phase was observed for both final catalysts after 75 hours of calcination in a reaction flow of n-butane/air mixture (0.75% n-butane/air). However, catalyst derived from H4P2O7 based preparation (denoted VPDpyro) exhibit better crystallinity and slightly higher BET surface area compared to the H3PO4 based preparation (denoted VPDortho). The nature of the oxidants for both catalysts was investigated by O2-TPD. For VPDpyro, TPD showed an oxygen peak maximum at 986 K and a shoulder at 1003 K, whereas for VPDortho, the oxygen was desorbed as two peaks maxima at 966 and 994 K. The total amount of oxygen desorbed thermally from VPDpyro (3.60×1020 atom×g-1) is higher than that obtained for VPDortho (3.07×1020 atom×g-1). VPDpyro displayed a slightly improved activity and selectivity for n-butane oxidation. A proper amount of V5+ species may have an effect on the enhancement of the catalytic activity

Linear Driving Force Model for Adsorption onto Activated Carbon Monolith

A mathematical model on carbon coated   monolith   using the  linear driving force model is develop. The computer program is writted in MATLAB and simulation using data from [4] for cell density 200 cpsi was used to studies the effect of different variables on breakthrough profiles.  The result showed that the breakthrough curve of the monolith is very sharp. Because of its an open structure and  lower pressure drop,   monolith  is an attractive alternative internals for separation.Keywords:  Adsorption, modeling, simulation, carbon coated monolith, breakthroug

Effects of strobilanthes crispus extract on the apoptotic pathway of human liver carcinoma cell lines

Previous study has been shown the potential anticarcinogenic effect of Strobilanthes crispus, a plant native to countries from Madagascar to Indonesia, on human liver cancer (HepG-2) cell lines. The objective of the present study was to investigate the mechanism of anticarcinogenic effectof S.crispus extract through apoptotic pathway. Exposure of HepG-2 cells to S.crispus extract resulted in induction of apoptosis in a dose-dependent manner as measured by Fluoresence Microscopy and Confocal Laser Scanning Microscopy analysis. These findings provide important new insight into the possible molecular mechanisms of the anticancer activity of S.crispus

Extracted c-Al2O3 from aluminum dross as a catalyst support for glycerol dry reforming reaction

The utilization of extracted c-Al2O3 (EGA) from aluminum dross as catalyst support in glycerol dry reforming reaction (GDR) has been investigated in this current study. In this study, three main stages were evaluated which are; (i) extraction of c-Al2O3; (ii) preparation and characterizations of Ni-based catalyst supported on EGA and (iii) utilization of EGA as catalyst support in the GDR reaction. In the first stage, c-Al2O3 with the specific surface area of 156.5 m2 g�1 was successfully extracted before used as catalyst support. Then, 10%Ni/EGA catalyst with 108.3 m2 g�1 surface area was prepared by wet impregnation method. The glycerol conversion and hydrogen yield achieved in the third stage were 22% and 15% respectively. The results can be attributed to the high specific surface area of EGA, which enhanced the dispersion of Ni particles on the catalyst matrix

Effect of calcination temperatures of CaO/Nb2O5 mixed oxides catalysts on biodiesel production

Calcination temperature greatly influences the total basicity and surface area of catalysts. Investigations were conducted on calcium and niobium (CaO-Nb2O5) mixed oxides catalysts prepared via conventional solid state method (oxides were mixed and ground in agate mortar) and calcined at different temperatures ranging from 300-800oC for 5 h. The catalysts were then characterized by using X-ray diffraction (XRD), CO2 temperature-programmed desorption (TPD-CO2), Brunauer-Emmett-Teller (BET) surface area analyzer and scanning electron microscope (SEM). The formation of Ca(OH)2 and CaCO3 at lower calcination temperatures ( 600oC), due to sintering of the fine crystals, which promotes cluster agglomeration. Thus, the optimum calcination temperature for CaO/Nb2O5 mixed oxides was 600oC, which produced the largest surface area (7 m2/g) and total basicity (1301 μmol/g). The biodiesel was produced via transesterification of palm oil, methanol and the catalysts calcined at various temperatures. CaO/Nb2O5 mixed oxide calcined at 600oC showed the highest biodiesel conversion (98%) with methanol/oil molar ratio of 12, 3 wt.% of catalyst, a reaction temperature of 65oC and reaction time of 2 h

An optimization study for transesterification of Palm Oil using Response Surface Methodology (RSM)

Biodiesel was produced via transesterification of palm oil with methanol in the presence of CaO-Nb2O5 mixed oxide catalyst. Response surface methodology (RSM) with central composite design (CCD) was performed to determine the optimum operating conditions and to optimize the biodiesel yield. In this study, the reaction variables being optimized were reaction time, catalyst loading and methanol to oil molar ratio. From the analysis of variance (ANOVA), the most influential parameter on biodiesel production was reaction time. The predicted yield was found in good agreement with the experimental value, with R2= 0.9902. The optimum biodiesel yield of 97.67% was achieved at 2.67 h reaction time, with 3.60 wt. % of catalyst and with methanol to oil molar ratio of 13.04. The high biodiesel yield can be correlated to the synergic effect of basicity between the metallic ions of CaO-Nb2O5 shown in the physicochemical analysis

Introducing the novel composite photocatalysts to boost the performance of hydrogen (H2) production

Endeavor has been made in this work to develop a supported Si photocatalyst to efficiently split water into hydrogen under irradiation with visible light. Hydrothermal and solid phase reaction method were used to synthesize of Si/CNTs photocatalysts and characterized by using UV–visible optical absorption spectra (UV–Vis), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Scanning electron microscope (SEM) and etc. By examining their properties, it was found that the two types of surface dangling bonds existed on the surface of CNTs which greatly impacts on reaction efficiency. The generation of hydrogen (H2) onto supported Si catalyst may take place on hydroxyl and hydrogen bond with Si. The bandgap estimated from the reflection spectra was 2.2 eV for Si/CNTs photocatalyst. The highest generation of H2 of Si/CNTs was observed as 648 μmol h−1 which is greater than pristine Si without adding any hole-scavengers. The outcomes demonstrated that CNTs had a significant impact on photocatalytic water splitting activity because of high conductivity on remarkable net-like 2D structure. No apparent decrease in H2 production was detected after three successive runs representing the stability of the catalyst. Surface functions hold to achieve high efficiency in such a photocatalytic framework

Cytotoxic effect of γ-sitosterol from Kejibeling (<em>Strobilanthes crispus</em>) and its mechanism of action towards <em>c-myc</em> gene expression and apoptotic pathway

Background: This study aimed to analyze the cytotoxicity effect of γ-sitosterol isolated from “Kejibeling” (Strobilanthes crispus), a medicinal plant, on several cancer cell lines. The mechanisms of the effects were studied through the expression of cancer-caused gene, c-myc and apoptotic pathways.Methods: This in vitro study was done using human colon cancer cell lines (Caco-2), liver cancer cell lines (HepG2), hormone-dependent breast cancer cell lines (MCF-7) and the normal liver cell lines (Chang Liver). The cytotoxic effect was measured through MTT assay and the potential cytotoxic value was calculated by determining the toxic concentration which may kill up to 50% of the total cell used (IC50). Meanwhile, the cytotoxic mechanism was studied by determining the effect of adding γ-sitosterol to the c-myc gene expression by reverse transciptase-polymerase chain reaction (RT-PCR). The effect of γ-sitosterol through apoptotic pathway was studied by using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay.Results: γ-sitosterol was cytotoxic against Caco-2, HepG2, and MCF-7 with IC50-values of 8.3, 21.8, and 28.8 μg/mL, respectively. There were no IC50-values obtained from this compound against Chang Liver cell line. This compound induced apotosis on Caco-2 and HepG2 cell lines and suppressed the c-myc genes expression in both cells.Conclusion: γ-sitosterol was cytotoxic against colon and liver cancer cell lines and the effect was mediated by down-regulation of c-myc expression and induction of the apoptotic pathways.</p