Increasing Extraction Pressure Research Articles

Simulation of multiphase behavior in supercritical CO2–heavy oil–water sludge extraction systems using Cubic-Plus-Association Equation of State

A new methodology was proposed for predicting the multiphase behavior of a supercritical CO2–heavy oil–water–solvent system during supercritical CO2 extraction. The cubic-plus-association equation of state (CPA EoS) was used to model the hydrogen bond association between asphaltene and water and to develop a nine-step characterization method for asphaltene-containing oil. Results showed that the proposed method could represent phase behavior for three equilibrium phases: the vapor phase and high-density and low-density liquid phases. The absolute average relative deviation between the predicted and experimental phase boundary pressures was 3.6–11.8%, smaller than those (7.0–20.8%) calculated using Soave–Redlich–Kwong EoS with Huron–Vidal mixing rules. Moreover, case studies on appropriate extraction conditions showed that the extraction pressure increased with increasing molecular weight and critical pressure of each pseudocomponent. Increasing extraction pressure for H2O-containing systems was beneficial for improving extraction efficiency.

Combined process of high-pressure homogenization and hydrothermal extraction for the extraction of fucoidan with good antioxidant properties from Nemacystus decipients

Sulfated polysaccharides (fucoidan) were recovered from Nemacystus decipients using a combination of high pressure homogenization (HPH) and hydrothermal extraction process through employing different homogenization pressure (40–100MPa) and cycle times (1–3). HPH treatment could result in a high fucoidan yield with preserving sulfate content and the optimal yield was 16.67±0.36%, obtained from 70MPa for 2 cycles’ extraction. Chemical composition analysis, HPAEC, IR and HPSEC analysis were applied for characterization of extracted polysaccharides. The molecular weight of extracted fucoidan decreased with increasing extraction pressure. All fucoidan exhibited antioxidant activities as determined by DPPH radical scavenging, hydroxyl radical scavenging, and ferrous ion chelating ability as well as reducing power, among which fucoidan extracted at 70MPa (HN2) possessed excellent antioxidant ability. This study shows that HPH can be used as an efficient means to assist extraction of fucoidan from seaweed and N. decipients could potentially be a raw resource for natural antioxidant.

Supercritical CO2 oilseed extraction in multi-vessel plants. 3. Effect of extraction pressure and plant size on production cost

This work completes a series of three studies about the estimation of the cost of extracting vegetable oil from seeds using supercritical CO2. The focus of this work was determining the effect of extraction pressure (30, 50, and 70MPa) in the production cost of a supercritical CO2 extraction of a packed bed of 2-mm oilseeds in plants with two-extraction vessels with aspect ratio of 4.5, using a superficial velocity of 5mm/s. When extraction pressure increased while keeping other variables constant, production cost decreased. For 2×1m3 extraction plants, increasing extraction pressure from 30 to 50MPa decreased production cost 30.9%, but when extraction pressure further increased from 50 to 70MPa production cost only decreased 9.9%. Results suggest that the recommended extraction pressure for oilseed extraction is 50MPa. Also, this work compared plants operating at the three extraction pressures when annual productivity was kept constant (231, 456, or 596 ton of oil per year). The total extraction volume of the plant diminished as the extraction pressure increased. Optimum production cost in these cases was quite similar for plants operating at 30, 50, and 70MPa, but the total volume of the plant decreased 63.6% when increasing extraction pressure from 30 to 50MPa for the plant producing 456 ton of oil per year, and an additional 31% when increasing it from 50 to 70MPa. The lowest production cost estimated was 5.52 USD per kg of oil (optimum extraction time of 2.75h) in a 4×1m3 plant processing 2-mm prepressed oilseeds, and operating at 40°C and 50MPa. The manuscript includes a sensitivity analysis on production cost as a function of a variation of ±50% of uncertain variables cost (respect to nominal values), which were considered as constant in our previous contributions. That cost items were unitary cost of annual labor, CO2, and substrate, being the variation of the last one the more significant effect on production cost.

Micronization of chitosan via rapid expansion of supercritical solution

In this study, rapid expansion of supercritical solution (RESS) was used to micronize the chitosan particles. Design of experiment was implemented with response surface methodology (RSM) using Mini Tab software 17. The operating temperature (30–70°C), pressure (7–22MPa) and effective nozzle diameter (500–1200μm) were considered as the range of operating variables while spraying distance (1cm) and nozzle length (5mm) were held constant. The characterization (size and morphology) of the precipitated particles of chitosan was determined by scanning electron microscopy (SEM). The results show great reduction in the size of the precipitated particles of chitosan compared with the original particles. A decrease in the particle size of chitosan was found with increasing extraction pressure and temperature along with a decreasing of nozzle diameter. Response surface analysis verified that R2 and modified R2 of the model for 500μm effective nozzle diameter were 97.19% and 95.18%, respectively.

Extent and ecological consequences of hunting in Central African rainforests in the twenty-first century.

Humans have hunted wildlife in Central Africa for millennia. Today, however, many species are being rapidly extirpated and sanctuaries for wildlife are dwindling. Almost all Central Africa's forests are now accessible to hunters. Drastic declines of large mammals have been caused in the past 20 years by the commercial trade for meat or ivory. We review a growing body of empirical data which shows that trophic webs are significantly disrupted in the region, with knock-on effects for other ecological functions, including seed dispersal and forest regeneration. Plausible scenarios for land-use change indicate that increasing extraction pressure on Central African forests is likely to usher in new worker populations and to intensify the hunting impacts and trophic cascade disruption already in progress, unless serious efforts are made for hunting regulation. The profound ecological changes initiated by hunting will not mitigate and may even exacerbate the predicted effects of climate change for the region. We hypothesize that, in the near future, the trophic changes brought about by hunting will have a larger and more rapid impact on Central African rainforest structure and function than the direct impacts of climate change on the vegetation. Immediate hunting regulation is vital for the survival of the Central African rainforest ecosystem.

Recrystallization of adefovir dipivoxil particles using the rapid expansion of supercritical solutions (RESS) process

In this study, recrystallization of adefovir dipivoxil particles was carried out by the rapid expansion of supercritical solutions (RESS) process. Supercritical carbon dioxide, which is a green solvent, was selected as a solvent. The effect of process parameters such as extraction temperature and pressure, pre-expansion temperature, spray distance, and nozzle configuration on the particle size of adefovir dipivoxil was evaluated and it was found that the process parameters did influence the particles size. The solubility of adefovir dipivoxil in CO2 was measured for the purpose of setting proper experimental conditions. Increasing the extraction temperature (308.15–328.15K) caused the particle size of adefovir dipivoxil to increase. Particle size decreased with increasing extraction pressure (20–30MPa). The particle size of adefovir dipivoxil increased with increasing pre-expansion temperature. An increase in the spray distance (8, 16, 32cm) resulted in a decrease in the average size of particles. The effect of the internal nozzle diameter on the size and shape of the precipitated particles was examined using different nozzle internal diameters (152, 500, 762μm). When the internal nozzle diameter size was larger, the particle size did not show significant change. The adefovir dipivoxil particles that underwent RESS process were analyzed by SEM, XRD, DSC and FT-IR spectra.

Investigation of key influence parameters for synthesis of submicron carboxymethylcellulose particles via rapid expansion of supercritical CO2 solution by Taguchi method

The viscosity of suspensions depends strongly on the properties of the applied particles like particle size, particle size distribution, and solid load and especially on the specific surface area. Carboxymethelcellulose is an anionic water soluble polymer. CMC HV is a high viscosity carboxymethylcellulose which is used as a viscosifier and fluid loss reducing agent in different types of water based drilling fluids. The micronization of carboxymethylcellulose using the rapid expansion of supercritical solution (RESS) process was investigated in this study. The effects of the operation parameters for the RESS process were discussed by design of experiment (DOE) for the extraction temperature (35–55°C), extraction pressure (150–200bar), nozzle diameter (500–1200μm), spraying distance (1–5cm) and cosolvent (deionized water, isopropanol). Results from analysis of variance (ANOVA) showed that extraction pressure and cosolvent were the most significant factors, and using deionized water favored the production of smaller particles as cosolvent. The CMC particles were micronized from the original average size of 15μm to the smallest average size of 0.14μm through the RESS process in this study. The optimal operation condition for preparing CMC micro-particles in the range of this work is: the pressure of 200bar, the temperature of 55°C, with 500μm nozzle and 1cm spraying distance in the presence of deionized water as cosolvent. Smaller particles were produced with increasing extraction pressure and temperature. In addition, the smaller the nozzle diameter, the smaller the particles and the narrower the PSD obtained.

Branched polyethylenes fractionated in supercritical propane

A series of polyethylenes (PEs), were synthesized in the presence of a palladium catalyst containing bulky diimine ligands (VERSIPOL™) yielding amorphous PEs. The different PE samples were characterized by Size Exclusion Chromatography (SEC) with on line light scattering, NMR, viscometry or small angle neutron scattering (SANS) techniques to assess the molar mass, molar mass distribution (MMD), radius of gyration (or hydrodynamic radius) and degree of branching. Selected PE samples were fractionated in supercritical propane by isothermal increasing the pressure profile. In most cases, PE fractions with a sharper MMD than the original PEs were obtained. The average absolute molar masses of the resulting fractions increased steadily with increasing extraction pressure. Their dilute solution properties were compared with those of unfractionated PEs. Structural analyses confirmed the homogeneity of the degree of branching within a raw PE sample.

Preparation of anthracene fine particles by rapid expansion of a supercritical solution process utilizing supercritical CO2

The rapid expansion of a supercriti cal solution (RESS) process is an attractive technology for the produc- tion of small, uniform and solvent-free particles of low vapor pressure solutes. The RESS containing a nonvolatile solute leads to loss of solvent power by the fast expansion of the supercritical solution through an adequate nozzle, which can cause solute precipitation. A dynamic flow apparatus was used to perform RESS studies for the preparation of fine anthracene particles in pure carbon dioxide over a pressure range of 150-250 bar, an extraction temperature range of 50-70 o C, and a pre-expansion temperature range of 70-300 o C. To obtain fine particles, 100, 200 and 300 µm nozzles were used to disperse the solution inside of the crystallizer. Both average particle size and particle size distribution (PSD) were dependent on the extraction pressure and the pre-expansion temperature, whereas extractor temperature did not exert any significant effect. Smaller particles we re produced with increasing extraction pressure and pre- expansion temperature. In addition, the smaller the nozzle diameter, the smaller the particles and the narrower the PSD obtained.

Extraction of Antioxidants in Sweetpotato Waste Powder with Supercritical Carbon Dioxide.

The application of supercritical carbon dioxide (SC-CO2) extraction to waste powder derived from sweetpotato roots with orange flesh in a food processing factory was examined. The contents of antioxidants, β-carotene, α-tocopherol and chlorogenic acid, remaining in the waste powder after SC-CO2 extraction under different conditions were determined by HPLC. At a constant extraction pressure, the extraction yield of β-carotene from the waste powder was highest at 40°C, decreased at 60°C and decreased further at 80°C; in contrast, the α-tocopherol yield did not vary under different temperature conditions. At a constant extraction temperature, increasing extraction pressure in-creased the extraction yields of both β-carotene and α-tocopherol. Under the conditions tested, the yields of β-carotene (95.1%) and α-tocopherol (76.8%) were highest at 40°C and 35 MPa. Little chlorogenic acid was extracted from waste powder. The β-carotene remaining in the waste powder after SC-CO2 extraction correlated well with its color value of a*.

Supercritical fluid extraction of Vernonia galamensis seeds

Vernonia galamensis is an excellent source of a seed oil rich in vernolic acid. However, the seeds of this plant exhibit a high lipase activity in the dormant state. The activity of this enzyme is apparent as vernonia oil will undergo lipolysis when the seeds are crushed prior to extraction. In this study, supercritical fluid extraction (SFE) utilizing carbon dioxide has been examined as an alternative solvent, at different pressures, temperatures and cosolvent concentrations. The use of supercritical fluid carbon dioxide (SC-CO 2) as the extraction fluid under high temperatures and pressures has the potential to inhibit the lipolysis reaction during the extraction by reducing the activity of the enzyme, and hence the production of undesired fatty acids. Vernonia seeds were ground with dry ice prior to extraction to minimize any nascent lipase activity. Selective SFE was conducted at various pressures, temperatures, modifier concentrations, and total CO 2 volume used to determine whether the vernolic acid content of the resultant extract could be enriched. An increase in pressure and temperature significantly increased the amount of extracted oil as well as the vernolic acid content. In addition, a significant reduction in the free fatty acid content of the oil from 69 to 8 mg/g oil was present with increasing extraction pressure. Exhaustive extraction of the oil could be attained via SFE with neat CO 2 and with ethanol-modified CO 2. However, regrinding the matrix after the initial extraction, followed by re-extraction of the seed matrix was necessary in these cases. The resultant oil and extracted meal were characterized with respect to free fatty acid, phospholipid, and percent protein contents.

Investigations into the Effect of Supercritical Carbon Dioxide Extraction on the Fatty Acid and Volatile Profiles of Cooked Chicken

Chicken fat was cooked to 80 °C and extracted using supercritical carbon dioxide at 40 °C and each of three pressures : 10.3, 20.7, and 31.0 MPa. Fatty acid and volatile profiles were obtained using capillary gas chromatography and GC-MS. Twenty-seven fatty acids were identified (8 saturates, 7 monounsaturates, and 12 polyunsaturates). Extraction pressure affected the relative concentration of 2 fatty acid classes and 13 individual fatty acids, all of which were 18 or more carbons in length. Monounsaturated and polyunsaturated fatty acid concentrations increased among extracts with increasing extraction pressure. Quantitated volatiles numbered 318, of which 99 were classified. The largest classes of volatiles were branched alkanes, enals, and aldehydes. The concentrations of total volatiles, branched alkanes, enals, ketones, lactones, alcohols, and halogenated and aromatic compounds were affected by treatments. All extractions yielded higher volatile concentrations than control. Among extracts, volatile concentration increased with decreasing extraction pressure.