《京都议定书》要减排哪些温室气体
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悄然兴起的亚临界萃取中的液化石油气、
丙烷、二甲醚、四氟乙烷、六氟化硫萃取剂令业内人士担忧
http://www.sfst.net.cn 编辑部稿
在防火防爆类的工厂设计规范中明文规定，凡是闪点＜28℃的易燃液体，凡是爆炸下限＜10%的可燃性气体均应列为甲级(最高级)防火防爆等级，而目前在国內悄然兴起的亚临界萃取中，个別企业却选用闪点及爆炸下限均远远低于这两个指标的
LPG(液化石油气)、DME(二甲醚)、丙烷、R600a(高纯度异丁烷)等易燃易爆危险品，用作亚临界萃取的主溶媒，其用于固体物料的间隙式萃取，由于要频繁的装卸物料需不断的打开
、关闭萃取槽顶盖，易燃易爆气体的洩漏在所难免，同时在频繁打开 、关闭萃取槽顶盖的过程中，产生静电火花的概率也较高，在规模化的工业生产中使用这些气体，危险性是显而易见的。
在连续密闭的大规模化的生产
LPG(液化石油气)、DME(二甲醚)、丙烷、R600a(高纯度异丁烷)等
的易燃易爆气体时，相对而言由于是在连续全密闭的条件下进行操作则较为安全。
而R134a(1，1，1，2-四氟乙烷)
的亚临界萃取，由于R134a是温室气体，它能阻挡红外辐射能返回天空，对全球气候变暖直接影响较大，其全球温室效应潜能值GWP高达1300。因此早在1997年12月11日联合国气候变化框架公约缔约国第三次会议通过的《京都议定书》中，R134a是明确规定要控制与削减排放量的六种温室气体之一，其排放(散发)、使用、生产也将受到严格的国际管制。再者工业级R134a的单价高于食品级二氧化碳50倍以上,作为萃取剂使用,生产成本偏高，这也是工业化生产中企业难以接受的。
更有甚者，全氟化碳PFC(如CF4和C2F6)和六氟化硫SF6也是人为产生的气体，它们大气寿命非常长，对红外辐射有强吸收。所以这些化合物虽然排放量较小，但对未来气候的影响很大。CF4在大气中可以至少存留50000年。它有自然源，但目前的人为排放是自然源的1000多倍，并且是观测到浓度增加的主要原因。一个SF6分子的温室效应是一个CO2分子的22200倍。虽然它目前的大气浓度较低(4.2×10-12)，但它的增长速率明显(0.24×10-12/年)。观测到的SF6增长率与根据销售和储存数据而计算所得的排放十分一致。
[200610104744.3]亚临界流体萃取溶剂及萃取方法/其主要特点是以液态六氟化硫为萃取溶剂/2008.04.16公开
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-41℃存在安全隐患等诸多问题]
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2005.10.19公开/本专利以DME作为亚临界流体萃取剂，萃取温度10～60℃萃取压力0.1～1.5MPa[编者按DME：Tc：127.228℃；Pc：5.3558MPa；闪点
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-41℃存在安全隐患等诸多问题]
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Subcritical
Subcritical water chromatography: A green approach to
high-temperature liquid chromatography.
At
temperatures and pressures lower than 374 degrees C and
218 atm, subcritical water has widely tunable properties
such as dielectric constant, surface tension, viscosity,
and dissociation constant achieved by simply adjusting
the temperature with a moderate pressure to keep water
in the liquid state. At elevated temperatures, water
acts like a weak polar organic solvent. Thus,
subcritical water has been used as a green eluent to
replace hazardous solvents commonly used as organic
modifiers in RPLC. Subcritical water chromatography (SBWC)
is capable of separating polar, moderately polar, and
even some nonpolar analytes. Most of these low molecular
weight solutes are stable at elevated temperatures
during a chromatographic run. Some new packing materials
are also quite stable and robust at mild temperatures
ranging from 80 to 150 degrees C. Advantages of SBWC
include the elimination of hazardous organic solvents
used in traditional RPLC, rapid analysis time, improved
selectivity, temperature-dependent separation
efficiency, temperature-programmed elution, and
compatibility with both gas- and liquid-phase detectors.
In this paper, the technical aspects as well as the
applications of SBWC are reviewed. Topics addressed in
this review include the unique characteristics of
subcritical water, analytes separated by SBWC, packing
materials tested for SBWC, the application of GC and LC
detection techniques in SBWC, SBWC instrumentation
development, temperature effects on SBWC separation, and
models developed for separation in SBWC.
Rapid column heating method for subcritical water
chromatography.
A novel
resistive heating method is presented for subcritical
water chromatography (SWC) that provides higher column
heating rates than those conventionally obtained from
temperature-programmed gas chromatography (GC)
convection ovens. Since the polarity of water reduces
dramatically with increasing temperature, SWC employs
column heating to achieve gradient elution. As such, the
rate at which the mobile phase is heated directly
impacts the magnitude of such gradients applied in SWC.
Data from the current study demonstrate that the maximum
column heating rate attainable in a typical SWC
apparatus (i.e. using a GC convection oven) is around 10
degrees C/min, even at instrument oven settings of over
three times this value. Conversely, by wrapping the
separation column with ceramic insulation and a
resistively heated wire, the column heating rates are
increased five-fold. As a result, elution times can be
greatly decreased in SWC employing gradients.
Separations of standard alcohol test mixtures
demonstrate that the retention time of the latest
eluting component decreases by 35 to 50% using the
prototype method. Additionally, solute retention times
in this mode deviate by less than 1% RSD over several
trials, which compares very well to those obtained using
a conventional GC convection oven. Results suggest that
the developed method can be a useful alternative heating
technique in SWC.
Hydrolysis kinetics of trisaccharides consisting of
glucose, galactose, and fructose residues in subcritical
water.
The
hydrolysis kinetics of trisaccharides consisting of
glucose, galactose, and fructose residues with different
glycosidic bonds, 1-kestose, d-melezitose, d-raffinose,
and lactosucrose, in subcritical water were conducted
over the temperature range of 150-230 degrees C and at a
constant pressure of 10 MPa. The hydrolysis of
trisaccharides in subcritical water proceeded
consecutively, i.e., one cleavage of the two bonds
antedated the other. The preceding cleavage was not
expressed by the first-order kinetics, but by the
kinetics considering the concentration of the acidic
compounds, which were produced by the degradation of the
constituent monosaccharides. The hydrolysis of the
constituent disaccharides, except sucrose composed of
the alpha-Glc-(1-->2)-beta-Fru bond, obeyed first-order
kinetics. All of the rate constants of the hydrolytic
kinetics were determined, and the values were found to
depend on the type of bond.
Subcritical water extraction of nutraceuticals with
antioxidant activity from oregano. Chemical and
functional characterization.
In the
present work, oregano leaves (Origanum vulgare L.) are
explored as natural source of nutraceuticals with
antioxidant activity. To do this, subcritical water
extraction (SWE), a new environmentally friendly
technique, is employed as extraction procedure and HPLC
coupled to DAD is used for the chemical characterization
of the extracts. Moreover, the radical scavenging
1,1-diphenyl-2-picrylhydrazyl (DPPH) method and the
determination of the total phenolic content (measured
with the Folin test) are applied to evaluate the
antioxidant activity of the extracts. The extraction of
antioxidants from oregano leaves by SWE is studied
considering different temperatures (25, 50, 100, 150 and
200 degrees C) to investigate the selectivity of the
process. The highest antioxidant activity is observed
for the extract obtained at the highest temperature, 200
degrees C (EC(50) equal to 10 microg/ml). Moreover, the
extraction yield was also the highest (54% dry weight)
at these extraction conditions. The total phenolic
content showed no differences among the different
extracts, concluding that the amount of phenolic
compounds extracted was similar but the type and
structure of the phenolics was different, providing in
this way different antioxidant activity. Some compounds
could be tentatively identified, proposing some probable
chemical structures for some of them, such as flavanones,
dihydroflavonols, favonols and flavones.
Development of pressurized subcritical water extraction
combined with stir bar sorptive extraction for the
analysis of organochlorine pesticides and chlorobenzenes
in soils.
An
analytical method for the determination of several
organochlorine pesticides (OCPs) like
hexachlorocyclohexanes (HCHs), cyclodiene derivates (dieldrin,
aldrin, endrin, heptachlor, heptachlor epoxide, endrin
aldehyde, endosulfan and ensodulfan sulphate) and DDX
compounds (p,p'-DDE, p,p'-DDD and p,p'-DDT) as well as
chlorobenzenes in soils has been developed. The
procedure is based on pressurized subcritical water
extraction (PSWE) followed by stir bar sorptive
extraction (SBSE) and subsequent thermodesorption-gas
chromatography/mass spectrometry analysis. Significant
PSWE and SBSE parameters were optimized using spiked
soil and water samples. For the PSWE of the
organochlorine compounds, water modified with
acetonitrile as the extraction solvent, at an extraction
temperature of 120 degrees C, and three cycles of 10 min
extraction proved to be optimal. Under optimized
conditions, the figures of merit, such as precision,
accuracy and detection limits were evaluated. The
detection limits obtained for soil samples were in the
range 0.002-4.7 ng/g. Recoveries between 4.1 and 85.2%
were achieved from samples spiked at a concentration
level of 25-155 ng/g. The main advantages of this method
are the avoidance of clean-up and concentration
procedures as well as the significant reduction of the
required volume of organic solvents. The described
method was applied to the determination of the
pollutants in soil samples collected from a polluted
area, the Bitterfeld region (Germany). The results
obtained by PSWE-SBSE were in a good agreement with
those obtained by a reference method, a conventional
pressurized liquid extraction (PLE).
Efficient decomposition of environmentally persistent
perfluorooctanesulfonate and related fluorochemicals
using zerovalent iron in subcritical water.
Decomposition of perfluorooctanesulfonate (PFOS) and
related chemicals in subcritical water was investigated.
Although PFOS demonstrated little reactivity in pure
subcritical water, addition of zerovalent metals to the
reaction system enhanced the PFOS decomposition to form
F-ions, with an increasing order of activity of no metal
approximately equal Al < Cu < Zn << Fe. Use of iron led
to the most efficient PFOS decomposition: When iron
powder was added to an aqueous solution of PFOS (93-372
microM) and the mixture was heated at 350 degrees C for
6 h, PFOS concentration in the reaction solution fell
below 2.2 microM (detection limit of HPLC with
conductometric detection), with formation of F-ions with
yields [i.e., (moles of F- formed)/(moles of fluorine
content in initial PFOS) x 100] of 46.2-51.4% and
without any formation of perfluorocarboxylic acids. A
small amount of CHF3 was detected in the gas phase with
a yield [i.e., (moles of CHF3)/(moles of carbon content
in initial PFOS) x 100] of 0.7%, after the reaction of
PFOS (372 microM) with iron at 350 degree C for 6 h.
Spectroscopic measurements indicated that PFOS in water
markedly adsorbed on the iron surface even at room
temperature, and the adsorbed fluorinated species on the
iron surface decomposed with rising temperature, with
prominent release of F- ions to the solution phase above
250 degrees C. This method was also effective in
decomposing other perfluoroalkylsulfonates bearing
shorter chain (C2-C6) perfluoroalkyl groups and was
successfully applied to the decomposition of PFOS
contained in an antireflective coating agent used in
semiconductor manufacturing.
Resource recovery from excess sludge by subcritical
water combined with magnesium ammonium phosphate
process.
The amount
of excess sludge produced in municipal wastewater
treatment plants in Japan is increasing every year as
the urban population increases. Phosphorus in excess
sludge could be a potential phosphorus resource since at
present, phosphate rock is being exhausted all over the
world. Every year, Japan imports large quantities of
phosphorus from abroad but much is discharged as excess
sludge. Therefore, the solubilization process, one
method of recovering phosphorus from sludge, could be a
promising solution. In this study, a subcritical water
process, a new technology that solubilizes sludge under
subcritical conditions, was applied before the
phosphorus in sludge was recovered with the magnesium
ammonium phosphate (MAP) process. As a result, the
solubilization rate of excess sludge achieved
approximately 80% and about 94-97% of the phosphorus
could be recovered.
Rapid determination of inorganic elements in airborne
particulate matter by using acidified subcritical-water
extraction and inductively-coupled
plasma-optical-emission spectrometry.
A rapid and
simple method has been developed for determination of
inorganic elements in airborne particulate matter (PM10)
by using acidified subcritical water and ICP-OES.
Elements such as Al, As, B, Ba, Cd, Cu, Fe, Mn, Pb, Se,
and Zn were rapidly and efficiently extracted from PM10
samples with a solution of 0.1 mol L(-1) HNO(3) under
subcritical conditions. The method requires
approximately 5% of the amount of acid used in the
standard microwave extraction procedure. The material
selected for the subcritical extraction manifold was
poly ether ether ketone (PEEK), to avoid sample
contamination with elements present in previously
reported stainless-steel manifolds. The extraction
temperature, time of static and dynamic extraction, and
flow rate of acidified water were studied keeping the
pressure controlled at about 1,500 psig. The efficiency
of extraction of most of the analytes increased with
temperature, tending to quantitative extraction at
temperatures near 150 degrees C. After the extraction
process the analytes were determined directly in the
extract by ICP-OES. When the method was compared with
the USEPA counterpart, the results indicate that under
optimized conditions (static extraction time: 15 min,
dynamic extraction time: 30 min, flow rate: 2 mL
min(-1)) the analytes were extracted with recoveries
between 73 and 158%. Alternatively, by using an
extraction time of 15 min, the method could be used to
screen for all the elements, with recoveries over 50%.
The developed method was applied to the determination of
inorganic elements in airborne particulate matter in the
atmosphere of Santiago, Chile.
Decomposition kinetics of maltose in subcritical water.
The
decomposition process of maltose in subcritical water
was studied using a tubular reactor in the temperature
range of 180 to 260 degrees C and at 10 MPa. The
formation of glucose and 5-hydroxymethyl-2-furaldehyde
during the maltose decomposition was also observed. The
decomposition rate of maltose was faster at higher
temperatures. The rate was approximated by first-order
kinetics during the early stage of the decomposition,
but was accelerated and deviated from these kinetics at
the later stage. The effluent pH decreased as the
residence time in the reactor increased and the decrease
of pH affected the maltose decomposition rate and
glucose formation. Low pH of a feed solution accelerated
maltose decomposition. A good correlation was obtained
between the pH of the effluent and the rate constant of
the first-order kinetics.
Hydrolysis of ginger bagasse starch in subcritical water
and carbon dioxide.
Ginger
bagasse from supercritical extraction was hydrolyzed
using subcritical water and CO(2) to produce reducing
sugars and other low molecular mass substances. Response
surface methodology was used to find the best hydrolysis
conditions; the degree of hydrolysis and the yield were
the two response variables selected for maximization.
The kinetic studies of the hydrolysis were performed at
150 bar and temperatures of 176, 188, and 200 degrees C.
The higher degree of hydrolysis (97.1% after 15 min of
reaction) and higher reducing sugars yield (18.1% after
11 min of reaction) were established for the higher
process temperature (200 degrees C). Different mixtures
of oligosaccharides with different molecular mass
distributions were obtained, depending on the
temperature and on the reaction time. The ginger bagasse
hydrolysis was treated as a heterogeneous reaction with
a first-order global chemical kinetic, in relation to
the starch concentration, which resulted in an
activation energy of 180.2 kJ/mol and a preexponential
factor of 5.79 x 10(17)/s.
Subcritical (hot/liquid) water dechlorination of PCBs (Aroclor
1254) with metal additives and in waste paint.
No disposal
option exists for "mixed wastes" such as paint scrapings
that are co-contaminated with polychlorinated biphenyls
(PCBs) and radioactive metals. Either removal or
destruction of the PCBs is required prior to disposal.
Comparison of subcritical water dechlorination (350
degrees C, 1 h) of Aroclor 1254 in paint scrapings (180
ppm) and of standard Aroclor 1254 showed significantly
enhanced dechlorination in the presence of paint. While
no significant degradation was observed for standard
Aroclor (no paint), the dechlorination of PCBs in paint
was 99, 99, and 80% for the hepta-, hexa-, and
pentachlorinated congeners, respectively, indicating
that metals in the paint enhanced the dechlorination
reactions. Adding metals to the standard Aroclor (no
paint) reactions enhanced PCB dechlorination in
subcritical water in descending order of activity: Pb
approximately = Cu > Al > Zn > Fe. In the presence of
both zerovalent and divalent lead and zerovalent copper
in subcritical water (350 degrees C, 1 h), 99% of the
Aroclor 1254 mixture (tetra- to heptachlorinated
biphenyls) was dechlorinated. High dechlorination (ca.
95%) was also achieved with zerovalent aluminum. In
contrast to other metals, lead retained its degradation
ability at a lower temperature of 250 degrees C after 18
h. The high degradation efficiency achieved using metal
additives in water at reasonable temperatures and
pressures demonstrates the potential for subcritical
water dechlorination of PCBs in paint scrapings and,
potentially, in other solid and liquid wastes.
Off-line coupling of subcritical water extraction with
subcritical water chromatography via a sorbent trap and
thermal desorption.
In this
study, the off-line coupling of subcritical water
extraction (SBWE) with subcritical water chromatography
(SBWC) was achieved using a sorbent trap and thermal
desorption. The sorbent trap was employed to collect the
extracted analytes during subcritical water extraction.
After the extraction, the trap was connected to the
subcritical water chromatography system, and thermal
desorption of the trapped analytes was performed before
the SBWC run. The thermally desorbed analytes were then
introduced into the subcritical water separation column
and detected by a UV detector. Anilines and phenols were
extracted from sand and analyzed using this off-line
coupling technique. Subcritical water extraction of
flavones from orange peel followed by subcritical water
chromatographic separation was also investigated. The
effects of water volume and extraction temperature on
flavone recovery were determined. Because a sorbent trap
was used to collect the extracted analytes, the
sensitivity of this technique was greatly enhanced as
compared to that of subcritical water extraction with
solvent trapping. Since no organic solvent-water
extractions were necessary prior to analysis, this
technique eliminated any use of organic solvents in both
extraction and chromatography processes.
Subcritical water extraction of antioxidant compounds
from rosemary plants.
Subcritical water extraction at several
temperatures ranging from 25 to 200 degrees C has been
studied to selectively extract antioxidant compounds
from rosemary leaves. An exhaustive characterization of
the fractions obtained using subcritical water at
different temperatures has been carried out by LC-MS,
and the antioxidant activities of the extracts have been
measured by a free radical method (DPPH). Results
indicate high selectivity of the subcritical water
toward the most active compounds of rosemary such as
carnosol, rosmanol, carnosic acid, methyl carnosate, and
some flavonoids such as cirsimaritin and genkwanin. The
antioxidant activity of the fractions obtained by
extraction at different water temperatures was very
high, with values around 11.3 microg/mL, comparable to
those achieved by SFE of rosemary leaves. A study of the
effect of the temperature on the extraction efficiency
of the most typical rosemary antioxidant compounds has
been performed.
Alkaline subcritical-water treatment and alkaline heat
treatment for the increase in biodegradability of
newsprint waste.
This work
describes two alkaline semicontinuous processes for the
conversion of refractory organic materials into
biodegradable substances. Newsprint was used as a
lignocellulosic waste. Methane conversion efficiencies
and cellulose removals were investigated for the two
following processes: alkaline subcritical-water
treatment (ASWT) coupled with methane fermentation and
alkaline heat treatment (newsprint heated with steam in
an autoclave; AHT) coupled with methane fermentation
with a neutral subcritical-water treatment (NSWT)
recycle. Results showed that for ASWT coupled with
methane fermentation higher methane conversion
efficiencies and higher cellulose removals were achieved
as HRT increased. At HRT = 20 days, average CH4
conversion efficiency and average cellulose removal
reached 26% and 44%, respectively. After a final HRT of
40 days, average CH4 conversion efficiency and average
cellulose removal reached 50% and 60%, respectively. On
the other hand, for AHT coupled with methane
fermentation, methane conversion efficiencies did not
show a greater improvement using this pretreatment
process. Average conversion reached 9% with an average
cellulose removal of 20%. In order to improve the yield
of the reactor, approximately one-third of the effluent
was recycled using NSWT (150 degrees C; neutral pH).
Methane conversion efficiency of this process increased
as more recycles were performed. For the fifth
operation, the total average methane conversion
efficiency was 44% with a total average cellulose
removal of 55%.
A novel process utilizing subcritical water and
nitrilotriacetic acid to extract hazardous elements from
MSW incinerator fly ash.
An
effective process for hazardous element extraction from
municipal solid waste incinerator fly ash was developed.
The key trait of the process was to extract most of the
hazardous elements out of the ash but leave Ca and Si
inside the residue. In the extraction process, the ash
was firstly pre-washed with water, then subjected to
subcritical water (SC water) treatment and
nitrilotriacetic acid (NTA) extraction. SEM images
indicated that SC water is strong enough to destroy the
ash particles, thus greatly improving hazardous elements
extraction efficiency in the subsequent NTA extraction
process. The extraction percentages for Cr, As, Se, Cd
and Pb under SC water+NTA treatment were around 2-6
times higher than those treated by NTA at room
conditions. The preferable SC treatment temperature was
573 K and the treatment time was 3 h. The optimum NTA
concentration, vibration time and liquid/solid ratio
were 0.8 M, 5 h and 10:1 (ml/g), respectively.
Furthermore, it was found that introduction of a
suitable amount of sulfuric acid into the extraction
solution could extract more than 90% of most of the
hazardous elements out of the ash.
Reductive dechlorination of polychlorinated dibenzo-p-dioxins
by zerovalent iron in subcritical water.
A new
method for reductive dechlorination of polychlorinated
dibenzo-p-dioxins (PCDDs) and remediation of
contaminated soils is described that uses zerovalent
iron as the dechlorination agent and subcritical water
as reaction medium and extractive solvent. It is found
that the zerovalent iron can be applied for stepwise
dechlorination of octachlorinated dibenzo-p-dioxin (OCDD)
on various matrixes in subcritical water. By using iron
powder as matrix higher chlorinated congeners were
practically completely reduced to less than
tetra-substituted homologues. A significant part of
residual OCDD, when it was spiked in to soils, and
formed less chlorinated congeners are extracted with
water in the given conditions. The solubility of OCDD
was increased by a 4-6 orders over its solubility at
ambient conditions. The new method of contentious-flow
extraction is described.
Subcritical water extraction and determination of
nifedipine in pharmaceutical formulations.
A rapid and
simple continuous method for the extraction of
nifedipine from tablets was developed by using
pressurized hot water at 150 degrees C. This is the
first time that subcritical water was applied to the
extraction of low-polarity compounds in pharmaceutical
analysis. The method is based on the increment in
solubility of nifedipine in subcritical water.
Extraction temperature and static and dynamic extraction
time were optimized in order to reach quantitative
extraction of the drug from the tablets. After
extraction, the drug was determined by spectrophotometry
by measuring absorbance at 338 nm. Accuracy and
precision of the method were determined by analysis of
10 synthetic samples of pharmaceutical formulations
prepared with common tablet excipients. Recovery was
found to be 99.2% with a relative standard deviation of
1.9%, which indicates that the excipients of the
formulation do not interfere in the determination. The
method was applied to the determination of the drug
content uniformity in tablets.
Subcritical water extraction of essential oils from
coriander seeds (Coriandrum sativum L.)
Subcritical water extraction (SCWE),
hydrodistillation and Soxhlet extraction were compared
for the extraction of essential oil from coriander seeds
(Coriandrum sativum L.). The extraction
efficiencies of different temperatures (100, 125, 150
and 175 °C), mean particle sizes (0.25, 0.50 and 1 mm),
and water flow rates (1, 2 and 4 ml/min) were
investigated. Separation and identification of the
components were carried out by GC–FID and GC–MS. The
results showed that the optimum temperature, mean
particle size, and flow rate were 125 °C, 0.5 mm, and
2 ml/min. The SCWE was compared with both conventional
methods in terms of the efficiency and the essential oil
composition. Hydrodistillation and Soxhlet extraction
showed higher extraction efficiencies, but the SCWE
resulted to the essential oils more concentrated in
valuable oxygenated components.
Ethanol-modified subcritical water extraction combined
with solid-phase microextraction for determining
atrazine in beef kidney.
The
determination of the levels of pesticides in food
products has prompted the development of sensitive and
rapid methods of analysis that are solvent-free or
utilize solvents that are benign to the environment and
laboratory worker. In this study we have developed a
novel extraction method that utilizes ethanol-modified
subcritical water in combination with solid-phase
microextraction (SPME) for the removal of atrazine from
beef kidney. In situ sample cleanup was achieved using
the technique of matrix solid-phase dispersion. A
cross-linked polymer, XAD-7 HP, was utilized as a
dispersing material for kidney samples. Subcritical
water extractions were performed with a pressurized
solvent extraction unit at 100 degrees C and 50 atm.
Experimental parameters investigated were the volume of
solvent and amount of modifier required for the complete
extraction of atrazine and optimization of the
extraction time. It was determined that 30% ethanol in
water (v/v) is adequate for the complete extraction of
atrazine. A Carbowax-divinylbenzene SPME fiber was used
to sample the aqueous extracts. Analysis of the fiber
contents was by ion-trap GC/MS utilizing the single ion
mode. The total time of analysis for a single kidney
sample is 90 min. The average percent recoveries from
samples spiked to the concentrations of 2 and 0.2 microg/g
were 104 and 111, respectively. The average relative
standard deviations were 10 and 9, respectively. The
method limit of detection for beef kidney spiked with
atrazine was found to be 20 ng/g of sample.
Extraction of tricyclazole from soil and sediment with
subcritical water.
The use of
subcritical water to extract tricyclazole from soils and
sediments was examined. Extraction efficiency and
kinetics were determined as a function of temperature,
sample age, sample matrix, sample size, and flow rate.
Extraction temperature was the most influential
experimental factor affecting extraction efficiency and
kinetics, with increasing temperature (up to 150 degrees
C) yielding faster and higher efficiency extractions.
Higher extraction temperatures were also important for
quantitative recovery of tricyclazole from aged samples.
Extraction at 50 degrees C yielded 97% recoveries from
samples aged 1 day but only 30% recoveries for samples
aged 202 days, whereas extraction at 150 degrees C
yielded recoveries of 85-100% that were independent of
incubation time and sample matrix, with the exception of
one sediment that contained a large amount of organic
matter. Sample extracts from subcritical water
extraction were generally a pale yellow color,
contrasted with a dark brown color from organic solvent
extractions of the same matrixes. Less sample cleanup
was therefore required prior to analysis, with the total
time for the extraction and analysis of a single sample
being approximately 2 h. Subcritical water extraction is
an effective technique for the rapid and quantitative
extraction of tricyclazole from soils and sediments.
Continuous subcritical water extraction of medicinal
plant essential oil: comparison with conventional
techniques
A
subcritical extractor equipped with a three-way inlet
valve and an on/off outlet valve has been used for
performing subcritical water extractions (SWE) in a
continuous manner for the isolation of the essential oil
of fennel, a medicinal plant. The target compounds were
removed from the aqueous extract by a single extraction
with 5 ml hexane, determined by gas-chromatography-flame
ionization (GC-FID) and identified by mass spectrometry
(MS). The proposed extraction method has been compared
with both hydrodistillation and dichloromethane manual
extraction. Better results have been obtained with the
proposed method in terms of rapidity, efficiency,
cleanliness and possibility of manipulating the
composition of the extract.
Characteristics of lithium iron phosphate (LiFePO4)
particles synthesized in subcritical and supercritical
water
The effect
of temperature, pH, time, and reactant concentrations on
the size and morphology of lithium iron phosphate
(LiFePO4) particles synthesized in a batch
hydrothermal reactor was investigated in this work. It
was found that LiFePO4 could only be
synthesized at neutral or slightly basic pH in both
subcritical and supercritical water. Synthesis in
subcritical water resulted in micron-sized particles of
high crystallinity, whereas synthesis in supercritical
water produced submicron particles. A more uniform
particle size distribution was obtained at low reactant
concentrations, irrespective of the synthesis
temperature. Qualitative explanations for these
observations are provided in terms of nucleation,
growth, and agglomeration phenomena at subcritical and
supercritical conditions.
Results of Search in US Patent
Collection db for:
"Subcritical": patents.
| |
PAT. NO. |
|
Title |
| 1 |
7,387,761 |
 |
Method for
manufacturing a glass infiltrated metal oxide
infrastructure
|
| 2 |
7,386,985 |
|
Detection of
refrigerant charge adequacy based on multiple
temperature measurements
|
| 3 |
7,385,057 |
|
Method and
device for producing melamine in a single-phase
tubular reactor
|
| 4 |
7,384,484 |
|
Substrate
processing method, substrate processing
apparatus and substrate processing system
|
| 5 |
7,381,439 |
|
Method and
composition for washing poultry during
processing
|
| 6 |
7,381,320 |
|
Heavy oil
and bitumen upgrading
|
| 7 |
7,381,278 |
|
Using
supercritical fluids to clean lenses and monitor
defects |
| 8 |
7,374,900 |
|
Fluorescent
substrates for detecting organophosphatase
enzyme activity
|
| 9 |
7,365,236 |
|
Generation
of a creosote-like mixture, or recovery of
metals, or both from preserved wood by reaction
in supercritical water
|
| 10 |
7,365,234 |
|
Tuning
product selectivity in catalytic
hydroformylation reactions with carbon dioxide
expanded liquids
|
| 11 |
7,364,839 |
|
Method for
forming a pattern and substrate-processing
apparatus |
| 12 |
7,361,231 |
|
System and
method for mid-pressure dense phase gas and
ultrasonic cleaning
|
| 13 |
7,360,420 |
|
Method and
bearing for balancing rotors without journals
|
| 14 |
7,353,113 |
|
System,
method and computer program product for aquatic
environment assessment
|
| 15 |
7,349,517 |
|
System for
measuring burn-out of fuel elements of a
high-temperature reactor
|
| 16 |
7,347,193 |
|
Method and
device for determining the mass flow rate
passing through the air-bleed valve of an
internal combustion engine tank
|
| 17 |
7,344,746 |
|
Process for
the hydrogenation of hop resin acids
|
| 18 |
7,337,742 |
|
Twin fin
fairing |
| 19 |
7,337,356 |
|
Systematic
and random error detection and recovery within
processing stages of an integrated circuit
|
| 20 |
7,335,296 |
|
System and
device for processing supercritical and
subcritical fluid
|
| 21 |
7,335,287 |
|
Solid
electrolyte sensor for monitoring the
concentration of an element in a fluid
particularly molten metal
|
| 22 |
7,334,430 |
|
Refrigerating cycle
|
| 23 |
7,331,313 |
|
Continuous
steam generator with circulating atmospheric
fluidised-bed combustion
|
| 24 |
7,326,756 |
|
High
temperature bulk polymerization of branched
crystalline polypropylene
|
| 25 |
7,326,337 |
|
System for
oxidation of organic bodies present in an
aqueous effluent
|
| 26 |
7,326,001 |
|
Wave forming
apparatus and method
|
| 27 |
7,323,096 |
|
Method for
treating the surface of object and apparatus
thereof |
| 28 |
7,322,101 |
|
Turbine
engine disk spacers
|
| 29 |
7,320,229 |
|
Ejector
refrigeration cycle
|
| 30 |
7,320,091 |
|
Error
recovery within processing stages of an
integrated circuit
|
| 31 |
7,319,125 |
|
|