Bambang Veriansyah

Synthesis of biodiesel from rapeseed oil using supercritical methanol with metal oxide catalysts.

This study examined the synthesis of biodiesel using supercritical or subcritical methanol with metal oxide catalysts. The transesterification of rapeseed oil was carried out with the metal oxide catalysts (SrO, CaO, ZnO, TiO(2) and ZrO(2)) to determine the most effective heterogeneous catalyst having the highest catalytic activity with minimum weight loss caused by dissolution. SrO and CaO dissolved in the biodiesel during the reaction because they were transformed to strontium methoxide and calcium methoxide, respectively. ZnO was the optimum catalyst for the transesterification of rapeseed oil owing to its high activity and minimum weight loss in supercritical methanol. The optimal reaction conditions included a molar ratio of methanol to oil of 40 in the presence of 1.0wt.% ZnO and a reaction time of 10min. The supercritical process with ZnO as a catalyst appears economically viable.

Supercritical water oxidation for the destruction of toxic organic wastewaters: A review

The destruction of toxic organic wastewaters from munitions demilitarization and complex industrial chemical clearly becomes an overwhelming problem if left to conventional treatment processes. Two options, incineration and supercritical water oxidation (SCWO), exist for the complete destruction of toxic organic wastewaters. Incinerator has associated problems such as very high cost and public resentment; on the other hand, SCWO has proved to be a very promising method for the treatment of many different wastewaters with extremely efficient organic waste destruction 99.99% with none of the emissions associated with incineration. In this review, the concepts of SCWO, result and present perspectives of application, and industrial status of SCWO are critically examined and discussed.

Supercritical water oxidation of wastewater from acrylonitrile manufacturing plant.

The wastewater from an acrylonitrile manufacturing plant, which is difficult to biodegrade, was decomposed in subcritical and supercritical water. Experiments were carried out at temperature ranging from 299 to 552 degrees C and a pressure of 25 MPa. The initial total organic carbon (TOC) of acrylonitrile wastewater was set from 0.27 to 2.10 mol L(-1) with residence times ranging from 3 to 30s. 30 wt.% H(2)O(2) solution was used as an oxidant with the stoichiometric ratios of O(2) based on the initial TOC concentration ranging from 0.5 to 2.5. TOC conversion increased with increasing reaction temperature and residence time, however, beyond the stoichiometric oxygen-TOC ratio of 1:1, TOC conversion was barely affected by excess oxygen. The initial TOC concentration of acrylonitrile wastewater also had a negligible effect on TOC conversion. An assumed pseudo-first-order global rate expression was determined with an activation energy of 53.48(+/-33.57)kJ mol(-1) and a pre-exponential factor of 5.22(+/-1.74)x10(2)s(-1). By considering the dependence of the reaction rate on TOC and O(2) concentration, a global rate expression was regressed from the complete set of 64 data points. The resulting activation energy was 66.33(+/-5.87)kJ mol(-1); the pre-exponential factor was 6.07(+/-6.89)x10(3)mol(-0.26)s(-1); and the reaction orders for initial TOC and O(2) concentration were 1.26(+/-0.15) and 0.00(+/-0.15), respectively.

Physicochemical and mechanical properties of paracetamol cocrystal with 5-nitroisophthalic acid

We report novel pharmaceutical cocrystal of a popular antipyretic drug paracetamol (PCA) with coformer 5-nitroisophhthalic acid (5NIP) to improve its tabletability. The cocrystal (PCA-5NIP at molar ratio of 1:1) was synthesized by solvent evaporation technique using methanol as solvent. The physicochemical properties of cocrystal were characterized by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), fourier transform infrared spectroscopy (FTIR), hot stage polarized microscopy (HSPM) and scanning electron microscopy (SEM). Stability of the cocrystal was assessed by storing them at 40°C/75% RH for one month. Compared to PCA, the cocrystal displayed superior tableting performance. PCA-5NIP cocrystal showed a similar dissolution profile as compared to PCA and exhibited good stability. This study showed the utility of PCA-5NIP cocrystal for improving mechanical properties of PCA.

Supercritical fluid carbon dioxide extraction of Nigella sativa (black cumin) seeds using taguchi method and full factorial design

Abstract Optimum condition for Nigella sativa seeds oil and its bioactive compound, thymoquinone (TQ) using supercritical fluid carbon dioxide extraction (SCFE-CO2), were investigated. The optimization process was

Hydrothermal decomposition of pentachlorophenol in subcritical and supercritical water with sodium hydroxide addition

Hydrothermal decomposition of pentachlorophenol (PCP, C6HCl5O), as the probable human carcinogen, was investigated in a tubular reactor under subcritical and supercritical water with sodium hydroxide (NaOH) addition. The experiments were conducted at a temperature range of 300-420 degrees C and a fixed pressure of 25 MPa, with a residence time that ranged from 10 s to 70 s. Under the reaction conditions, the initial PCP concentrations were varied from 0.25 to 1.39 mmol/L and the NaOH concentrations were varied from 2.5 to 25 times of the concentrations of PCP. The result of this study showed that PCP conversion in supercritical water was highly dependent on the reaction temperature, residence time, and NaOH concentration. PCP conversion in subcritical water is, however, only dependent on reaction temperature. NaOH concentration and residence times were found to have little effect on PCP conversion in subcritical condition. It was found that NaOH concentration affected the dechlorinations of PCP in the supercritical water. The intermediates detected were proposed to be tetrachlorophenol and trichlorophenol, respectively.

Hydrogen Production by Gasification of Isooctane Using Supercritical Water

The production of hydrogen by gasification of isooctane, a model compound of gasoline, was investigated in a continuously operated tubular reactor under supercritical water conditions without using any catalyst. Various experimental conditions, feed inlet temperature (80–412°C), residence time (8–16 s), reactor temperature (593–694°C), feed concentration (15–23 wt%), and oxidant concentration (0–2300 mmol/L) at a fixed pressure of 25 MPa, were examined in detail. Hydrogen peroxide was used as the oxidant. The major components of the produced gas were H2, CH4 and CO2 and the minor components of the produced gas were CO and C2H6. As residence time, isooctane concentration, and reactor temperature increased, H2, CH4, and CO2 gas yield increased while CO gas yield did not change much. Possible reaction pathways at each experimental condition are presented.

Recycling of transformer oil contaminated by polychlorinated biphenyls (PCBs) using catalytic hydrodechlorination

Catalytic hydrodechlorination of polychlorinated biphenyls (PCBs) in the presence of transformer oil was carried out in a batch mode to detoxify PCBs and to recycle the treated oil. Various metal supported catalysts, including 0.98 wt% Pt, 0.79 wt% Pd and 12.8 wt% Ni on γ -alumina (γ -Al2O3) support, and 57.6 wt% Ni on silicon oxide-aluminum oxide (SiO2-Al2O3) support were used for the hydrodechlorination. Metal particle size of the Pt catalyst was 2.0 nm and metal particle sizes of the Pd and Ni catalysts were in the range of 6.4–6.9 nm. Various supercritical fluids, supercritical carbon dioxide (scCO2), supercritical propane (scPropane), supercritical dimethyl ether (scDME) and supercritical isobutane (scIsobutane) were used as reaction media. PCBs conversion, dechlorination degree of PCBs, was measured using gas chromatograph (GC) with an electron capture detector (ECD). The hydrodechorination degree increased in the order Ni > Pd > Pt, possibly due to higher metal loading and larger metal size of the Ni catalysts. At temperatures below 175°C, scCO2 was effective as the reaction media for the catalytic hydrodechlorination of PCBs in the presence of the transformer oil. However, PCBs conversion decreased significantly when the hydrodechlorination was carried out in a homogeneous phase with using scPropane, scDME or scIsobutane as a reaction medium. This was attributed to dilution effect of the supercritical fluids. Molecular weights of the transformer oils before and after the catalytic hydrodechlorination were analyzed using high-performance size exclusion chromatography (HPSEC). The molecular weight of the treated oil with 100 % PCBs conversion did not change after the catalytic hydrodechlorination at 200°C. This process has proven to be effective to detoxify PCBs containing transformer oil and to recycle the treated oil.

Total organic carbon disappearance kinetics for supercritical water oxidation of dimethyl methylphospate used as a chemical agent simulant

Supercritical Water Oxidation (SCWO) has been proven to be a powerful technology to treat a wide range of wastes, but there are few references in the literature about the application of SCWO to chemical weapon agents. In this work, SCWO has been tested to treat a chemical agent stimulant, dimethyl methylphosphonate (DMMP), which is similar to the nerve agent VX and GB (Sarin) in its structure. The experiments were performed in an isothermal tubular reactor with H2O2 as an oxidant. The reaction temperatures ranged from 398 to 633 ‡C at a fixed pressure of 24 MPa. The conversion of DMMP was monitored by analyzing total organic carbon (TOC) on the liquid effluent samples. It was found that the oxidative decomposition of DMMP proceeded rapidly and a high TOC decomposition up to 99.99% was obtained within 11 seconds at 555 ‡C. An assumed first-order global power-law rate expression was determined with activation energy of 32.35±2.21 kJ/mol and a pre-exponential factor of 54.63±1.45 s ’ to a 95% confidence level. By taking into account the dependence of the reaction rate on oxidant concentration, a global power-law rate expression was regressed from the complete set of data. The resulting activation energy was 42.00±0.41 kJ/ mol; the pre-exponential factor was 66.56±0.48l1.31 mmol-0.31 s-1; and the reaction orders for DMMP (based on TOC) and oxidant were 0.96±0.02 and 0.35±0.04, respectively.

Destruction of methylphosphonic acid in a supercritical water oxidation bench-scale double wall reactor.

The destruction of methylphosphonic acid (MPA), a final product by hydrolysis/neutralization of organophosphorus agents such as sarin and VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothionate), was investigated in a a bench-scale, continuous concentric vertical double wall reactor under supercritical water oxidation condition. The experiments were conducted at a temperature range of 450-600 degrees C and a fixed pressure of 25 MPa. Hydrogen peroxide was used as an oxidant. The destruction efficiency (DE) was monitored by analyzing total organic carbon (TOC) and MPA concentrations using ion chromatography on the liquid effluent samples. The results showed that the DE of MPA up to 99.999% was achieved at a reaction temperature of 600 degrees C, oxygen concentration of 113% storichiometric requirement, and reactor residence time of 8 sec. On the basis of the data derived from experiments, a global kinetic rate equation for the DE of MPA and DE of TOC were developed by nonlinear regression analysis. The model predictions agreed well with the experimental data.