Jae Duck Kim

Extraction of Perillyl Alcohol in Korean Orange Peel by Supercritical CO2

Supercritical fluid extraction (SFE) in a pilot plant was carried out to extract perillyl alcohol (POH) from Korean orange peel. The extract from the powder of Korean orange peel was obtained by supercritical CO2 at operating conditions of 50°C, 200 bar, and 6 CO2 kg/h/kg sample. Most of the POH was extracted within 14 hours in the experiment. The yield of extract containing POH was 2.5% based on the dry powder of the orange peel. The content of POH in the extracts was 2.8 × 10−3 (wt%) by GC analysis based on the dry powder, which indicated that SFE was approximately 30 times more efficient than the solvent-extraction method previously reported. A brief comparison of SFE and solvent extraction was made. The SFE extracts were further purified by open tubular chromatography to confirm POH in the extracts.

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.

Purification of Waste Cooking Oils via Supercritical Carbon Dioxide Extraction

Purification of waste cooking oils (palm oil and soybean oil) using supercritical carbon dioxide (scCO2) extraction has been investigated. The purified oils were characterized by their acid value, conjugated diene value, total polar compound measurements, and high-performance size exclusion chromatography. Using optimal extractions conditions of 353.15 K, 20 MPa, and CO2 flow rate of 40 g/min, 80% of the oil was recovered and the purified oil compositions and properties were very close to those of the fresh oils. At higher pressures or lower temperatures, the separation efficiency of the scCO2 extraction was significantly reduced.

Continuous catalytic hydrodechlorination of polychlorinated biphenyls (PCBs) in transformer oil

Continuous catalytic hydrodechlorination of polychlorinated biphenyls (PCBs) in the presence of transformer oils was carried out in a fixed bed reactor using a 57.6 wt% Ni on silicon oxide-aluminum oxide (SiO2-Al2O3) catalyst. Reaction temperatures ranging 150–300°C, PCBs concentrations ranging 50–200 ppm, and reaction times ranging 1–8 h were tested. At a higher reaction temperature or at a lower PCBs concentration, catalytic activity was higher and complete dechlorination of PCBs resulted even at long reaction time. Catalyst regeneration using hexane and 0.1 M sodium hydroxide (NaOH) was effective to restore the catalytic activity. Fresh, spent and regenerated catalysts were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. XRD analysis revealed growth of Ni crystallite size of the spent and the regenerated catalysts. XPS analysis showed that a considerable amount of chlorine and carbon species were deposited on the surface of the spent catalyst, which may play a role in the catalysts deactivation.