• Analytical Science and Technology
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• v.25 no.1
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• pp.33-38
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• 2012

Despite the importance of chloride binding, it is very difficult to measure the binding capacity, in particular, for the concrete body in an existing structure: in fact, the measurement procedure for chloride binding is much influenced by the environmental condition such as temperature, fineness of sample and pore water extraction techniques. The present study concerns the quantification of the binding capacity of chloride ions in concrete using the X-ray diffraction (XRD) technique. Once the binding isotherm of chlorides was determined by the Langmuir isotherm, as a function of the W/C, curing age and binder type, the generation of bound chlorides (i.e. Friedel's salt) was simultaneously ensured by the XRD technique. The amount of bound chloride was then determined by analyzing the peak intensity for the bound chlorides in the XRD curve. It was found that an increase in the curing age and a decrease in the W/C resulted in an increase in the binding capacity.

• Analytical Science and Technology
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• v.17 no.6
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• pp.527-531
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• 2004

Treatment with aqueous sodium hydroxide solution plays an important role to impart certain desirable properties - feel and luster on the surface of polyester fiber. In this process alkali wastewater contains disodium terephthalate, ethylene glycol (EG) and residual sodium hydroxide. In this paper we report a new method containing the pretreatments of derivatization with benzoyl chloride and solvent extraction using pentane. The calibration curve of EG determined by GC/MS-SIM shows a good linearity in the range of 0.1 to $25{\mu}g/mL$ having the standard deviation of ${\leq}8.7%$. The recovery and the detection limit of this method are 91.9-93.7% and $0.05{\mu}g/mL$ respectively.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.441-451
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• 2000

Sludge produced from water treatment plants contains plenty of aluminum due to addition of coagulants, polyaluminum chloride(PACI) which has been widely used in most of water treatment plants. however. the whole of PACI is imported from other countries. In this research. the effective methods for recycling PACI from sludge of water treatment plants were developed and evaluated. Aluminum chloride hexahydrate($AlCl_3{\cdot}6H_2O$) was obtained by sparging HCl gas aluminum extracted from sludge using hydrochloric acid (HCI). This aluminum chloride hexahydrate was solidified by decomposition at $180^{\circ}C$. and dissolved in water to produce PACI. The optimum extraction rate was obtained at the condition of 10 minutes of reaction time. $105^{\circ}C$ of reaction temperature. 27.65%(W/W) of HCI concentration. The KS experiment proved that manufactured aluminum chloride hexahydrate was 98.7% degree and the recycled PACI coagulants agreed with the KS standard. The optimum temperature of decomposition was $180^{\circ}C$ and the basicity of the PACI was decided upon the extent of decomposition The compared experiments between purchased coagulant and manufactured coagulant presented that both coagulants had same performance for turbidity, DOC, $UV_{254}$ absorbance. and chlorophyll-a.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1A
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• pp.75-84
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• 2009

The present study assesses the chloride threshold level for corrosion of steel in concrete by examining the properties of four different binders used for blended concrete in terms of chloride binding, buffering of cement matrix to a pH fall and the corrosion behaviour. As binders, ordinary Portland cement (OPC), 30% pulverised fuel ash (PFA), 60% ground granulated blast furnace slag (GGBS) and 10% silica fume (SF) were used in a concrete mix. Testing for chloride binding was carried out using the water extraction method, the buffering of cement matrix was assessed by measuring the resistance to an artificial acidification of nitric acid, and the corrosion rate of steel in mortar with chlorides in cast was measured at 28 days using an anodic polarisation technique. Results show that the chloride binding capacity was much affected by $C_{3}A$ content and physical adsorption, and its order was 60% GGBS>30% PFA>OPC>10% SF. The buffering of cement matrix to a pH fall was varied with binder type and given values of the pH. From the result of corrosion test, it was found that the chloride threshold ranged 1.03, 0.65, 0.45 and 0.98% by weight of cement for OPC, 30% PFA, 60% GGBS and 10% SF respectively, assuming that corrosion starts at the corrosion rate of $0.1-0.2{\mu}A/cm^{2}$. The mole ratio of [$Cl^{-}$]:[$H^{+}$], as a new presentation of the chloride threshold, indicated the value of 0.008-0.009, irrespective of binder, which would be indicative of the inhibitive characteristic of binder.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.685-690
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• 2010

Rubiadin, a major compound of noni ($Morinda$ $citrifolia$) adventitious root, is highly valued in pharmaceutical industry due to hepatoprotective activity. To dissect rubiadin's effective extraction condition, extraction process of noni adventitious roots was performed with different solvent types, ratio of water to methanol (water, 20, 40, 60, 80, and 100% of methanol), extraction time, and extraction method. In contrast, we also developed a reverse- phase HPLC assay method to determine rubiadin from noni adventitious roots. The HPLC assay of rubiadin was performed by C-18 column using a gradient solvent system of methanol and water with UV detector at 280 nm. The extraction efficiency of different types of solvents were increased in order of methanol (0.08%) > ethanol (0.05%) > acetonitrile (0.03%) > acetone (0.02%) and methylene chloride (0.02%). The results of rubiadin extraction using different solvents showed that 1 hour of ultrasonic extraction was effective in order of 60% methanol (0.21%) > 80% methanol (0.13%) > 100% methanol (0.07%), 40% methanol (0.07%) and 2 hours of reflux extraction was effective in order of 60% methanol (0.21%) > 40% methanol (0.17%) > 80% methanol (0.14%). To compare the extraction efficiency of rubiadin according to the extraction methods and time for high rubiadin content, the extracts of rubiadin in noni adventitious roots were isolated with the methods of ultrasonic extraction, shaking extraction and reflux extraction. Rubiadin extracted from the methods of ultrasonic waves and shaking displayed the highest contents at 8 and 24 hours, respectively.

• Resources Recycling
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• v.28 no.1
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• pp.40-46
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• 2019

The solvent extraction of Tb(III) from hydrochloric acid solution was investigated by employing single organophosphorus (D2EHPA, PC88A and Cyanex 272), its mixture with Alamine 336 and ionic liquids with Aliquat 336. The equilibrium pH after the extraction with extractant mixtures and ionic liquids was higher than that by single extractants. Among the mixtures and ionic liquids, only the ionic liquid with Cyanex 272 and Aliquat 336 showed synergism to the extraction of Tb(III). The extraction percentage of Tb(III) by the extractant mixtures was lower than that by single extractant and the extraction order was in the following order : D2EHPA + Alamine 336 > PC88A + Alamine 336 > Cyanex 272 + Alamine 336. The extraction order of Tb(III) by the ionic liquids was Cyanex 272 + Aliqaut 336 > PC88A + Aliquat 336 > D2EHPA + Aliquat 336.

• Resources Recycling
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• v.32 no.1
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• pp.21-32
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• 2023

Because the application of lithium has gradually increased for the production of lithium ion batteries (LIBs), more research studies about recycling using solvent extraction (SX) should focus on Li⁺ recovery from the waste solution obtained after the removal of the valuable metals nickel, cobalt and manganese (NCM). The raffinate obtained after the removal of NCM metal contains lithium ions and other impurities such as Na ions. In this study, we optimized a selective SX system using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as the extractant and tri-n-butyl phosphate (TBP) as a modifier in kerosene for the recovery of lithium from a waste solution containing lithium and a high concentration of sodium (Li⁺ = 0.5 ~ 1 wt%, Na⁺ = 3 ~6.5 wt%). The extraction of lithium was tested in different solvent compositions and the most effective extraction occurred in the solution composed of 20% D2EHPA + 20% TBP + and 60% kerosene. In this SX system with added NaOH for saponification, more than 95% lithium was selectively extracted in four extraction steps using an organic to aqueous ratio of 5:1 and an equilibrium pH of 4 ~ 4.5. Additionally, most of the Na⁺ (92% by weight) remained in the raffinate. The extracted lithium is stripped using 8 wt% HCl to yield pure lithium chloride with negligible Na content. The lithium chloride is subsequently treated with high purity ammonium bicarbonate to afford lithium carbonate powder. Finally the lithium carbonate is washed with an adequate amount of water to remove trace amounts of sodium resulting in highly pure lithium carbonate powder (purity > 99.2%).

• Food Science and Preservation
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• v.8 no.4
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• pp.456-461
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• 2001

To develop the use of natural pigment for food, carotenoids from wasted persimmon peel were extracted with seven organic solvents. Among the solvents, acetone was a high yielding solvent of carotenoids. Extraction trends depending on process variables(temperature, time, solvent ratio to persimmon peel) were explained through response surface which was made by central composite experimental design. Carotenoid contents were increased with the extraction time and solvent ratio but it decreaed in the higher experimental design. Carotenoid contents were increased with the extraction time and solvent ratio but it decreased in the higher extraction temperature. The optimum conditions of extraction process variables were predicted as 29$\^{C}$, 93min. at fixed solvent ratio(1:27).

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.458-461
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• 2003

Solid-phase microextraction (SPME) and gas chromatography/headspace techniques(HS) and flame ionization detection (GC/FID) have been combined for determination of very polar compounds in water, including the widely used gasoline oxygenates and by-products. A relatively simple extraction method using a CAR/PDMS(75${\mu}{\textrm}{m}$) SPME fiber was optimized for the routine analysis of gasoline oxygenates and by-products in groundwater and reagent water. A sodium chloride concentration of 25%(w/w) combined with an extraction time of 20 min provided the greatest sensitivity while maintaining analytical efficiency Replicate analyses in fortified reagent and groundwater spiked with microgram per liter concentrations of gasoline oxygenates and by-products indicate quantitative and reproducible recovery of these and related oxygenate compounds. Method dynamic range was 50$\mu\textrm{g}$ L-1 to 3000$\mu\textrm{g}$ L-1 for gasoline oxygenates and by-products.

• Archives of Pharmacal Research
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• v.23 no.4
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• pp.385-390
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• 2000

To demonstrate the effect of formulation conditions on the controlled release of protein from poly(lactide-co-glycolide) (PLGA) microspheres for use as a parenteral drug carrier, ovalbumin (OVA) microspheres were prepared using the W/O/W multiple emulsion solvent evaporation and extraction method. Methylene chloride or ethyl acetate was applied as an organic phase and poly(vinyl alcohol) as a secondary emulsion stabilizer. Low loading efficiencies of less than 20％ were observed and the in vitro release of OVA showed a burst effect in all batches of different microspheres, followed by a gradual release over the next 6 weeks. Formulation processes affected the size and morphology, drug content, and the controlled release of OVA from PLGA microspheres.