Showing papers on "Distilled water published in 1996"

On the properties of washed straw

Abstract: The removal of troublesome elements in biomass to reduce slagging and fouling in furnaces and other thermal conversion systems was tested by washing (leaching) the fuel with water. Rice straw and wheat straw were washed by various techniques and analyzed for composition and ash fusibility. Potassium, sodium, and chlorine were easily removed in both tap and distilled water. Total ash was reduced by about 10% in rice straw and up to 68% in wheat straw, although washing was more effective in increasing ash fusion temperatures for rice straw than for wheat straw due to the higher initial silica concentrations in rice straw. Untreated straw ash which fused below 1000°C was observed to become more refractory at higher temperatures when washed. Scanning electron microscopy of untreated and treated rice straw ashed at 1000°C revealed all untreated ash particles to be fused and glassy, while treated particles remained unfused, were heavily depleted in most elements other than Si, and displayed structures characteristic of original cellular morphology. The fusion temperatures of the straw ash were consistent with predicted temperatures from alkali oxide-silica phase systems based on the observed concentrations of elements in the ash. A simple attempt at simulating a possible full scale washing process was carried out by spraying the surface of a bed of straw with water for an arbitrary time of 1 min. This proved less effective in removing alkali metals and chlorine than soaking the samples in water, flushing water through them in a more controlled manner, or leaving the straw exposed in the field to natural precipitation. Electrical conductivity measurements of leachate revealed that extraction was mostly complete after application of 0.04 l g−1, equivalent to 24 mm of precipitation over uniformly spread rice straw. Full scale furnace experiments have not yet been conducted, and issues involving the practical application of the technique require further investigation, but these results suggest that fouling rates should decline for treated fuels compared to untreated fuels in conventional and advanced biomass power systems.

Filler Leachability of Composites Stored in Distilled Water or Artificial Saliva

Abstract: Though dental composite materials leach filler elements when stored in distilled water, it is not known whether similar leaching occurs in saliva. The hypothesis to be tested was that due to ion exchange occurring at the filler surfaces, more filler elements leach from composites stored in a salt solution simulating saliva than from composites stored in distilled water. Another aim was to determine how matrix selection, filler composition, and filler silanization affect filler leachability of composites after storage in the simulated saliva and water media. We made 128 batches of experimental composites. Half of these used a bis-GMA/TEGDMA matrix and the other a UEDMA/TEGDMA matrix. Either silica or barium glass filler particles were incorporated into these matrices. Filler silanization was followed by a filler drying at 60 degrees C for 24 h. Half of the silanized particles received an additional heat treatment for 1 h at 110 degrees C in vacuum. One specimen per batch was stored in distilled water and the other in artificial saliva at 37 degrees C. After each 30-day interval for one year, the specimens were transferred to either freshly distilled water or newly mixed artificial saliva. The "old" solutions were analyzed by ICP for determination of the Si, Ba, and Al concentrations. Analysis of variance revealed that storage solution, filler composition, and total time in the storage solution had strong effects on the leachability (p < 0.0001 in all cases). The average monthly leakage of Si for quartz-filled composites was 0.22 +/- 0.20 microgram/mL (distilled water) and 2.80 +/- 1.20 microgram/mL (artificial saliva). For barium-glass-filled composites, the corresponding Si leaching values were 0.73 +/- 0.48 microgram/mL and 5.00 +/- 2.20 microgram/mL. The monthly means of the barium leaching values were 2.00 +/- 1.00 microgram/mL (distilled water) and 3.10 +/- 1.80 microgram/mL (artificial saliva). The large difference between leaching in artificial saliva and in distilled water, as well as the interaction between storage medium and filler, cast doubt on the clinical relevance of in vitro studies using distilled water.

Disintegration of Mesoporous Structures of MCM-41 and MCM-48 in Water

Abstract: It has been found that mesoporous structures of MCM-41 and MCM-48 disintegrate readily in distilled water around 370 K, while the structures can be stable in 100%-steam of 1 atmospheric pressure at much higher temperatures around 820 K. Thus, the structure disintegration is thermodynamically more favorable in water than under the steaming condition. X-ray powder diffraction and magic angle spinning 29Si NMR spectroscopy indicate that the disintegration of the mesoporous structures in water occurs due to silicate hydrolysis.

Water sorption in cellulose-based hydrogels

Abstract: Sorption of distilled water in a cellulose-based hydrogel is presented. The examined system is based on a mixture of sodium salt of carboxymethylcellulose and hydroxyethylcellulose, crosslinked with divinilsulphone. The effect of chemical composition, manufacturing procedures, as well as desiccation protocols on equilibrium water uptake was investigated. Experimental results were interpreted in terms of crosslinking density, presence of ionic groups on the backbone, as well as macroscopic sample morphology detected by electron scanning microscopy. The reported results evidence the possibility to bias the process parameters in order to obtain hydrogels characterized by the desired water sorption levels. © 1996 John Wiley & Sons, Inc.

Effects of platinum (Pt4+) on Lumbriculus variegatus Muller (Annelida, Oligochaetae): acute toxicity and bioaccumulation

Abstract: The acute toxicity and bioaccumulation (rates, kinetic) of tetravalent platinum in Lumbriculus variegatus under different physicochemical conditions (temperature and total water hardness) were investigated. Increased Pt4+ concentration (from 0.05 to 50 mg/L), exposure (up to 30 days), temperature (from 4 to 20 degrees C) and decreasing water hardness (from 300 to 0 mg/L CaCO3) increased Pt toxicity. The metal accumulated at a constant rate that was concentration, temperature and time dependent. The median lethal concentration (96h LC50) varied greatly from 0.397 mg/L in distilled water to 30 mg/L in the hard water from Champagne. Thus, L. var. can tolerate high levels of Pt. As a result, L. var. can be used in the laboratory to analyze mechanisms of adaptation to the induced stress and in the field as an indicator of Pt pollution.

Uptake and release of fluoride by saliva-coated glass ionomer cement.

Abstract: The ‘recharging’ of aged glass ionomer cement restorations with fluoride by exposing them to a concentrated NaF solution has been suggested to improve their performance as devices with slow fluoride release. We have studied the interference of salivary coatings on glass ionomer cement with the uptake of fluoride in vitro. Freshly prepared glass ionomer discs were leached in distilled water for 14 weeks, then incubated in human saliva for 2 h, 24 h or 1 week before exposure to 0.53 M NaF (1% fluoride) for 5 min. Fluoride uptake by the cement was measured indirectly as the subsequent increase in fluoride release. A 2-hour incubation in saliva reduced the fluoride uptake by half, a 24-hour incubation by 74%. The major part (93–95%) of the fluoride that was taken up was released on the first day. A 1-week salivary coating reduced the uptake by 49%, but also caused some retardation of the fluoride release: 80% of the total release was on the first day. It was concluded that despite the considerable interference by salivary coating, the amount of fluoride that can be taken up by aged glass ionomer cement remains significant. However, the fast release will limit the usefulness of such recharging in vivo.

Influence of water and accelerated aging on the shear fracture properties of glass/epoxy composite

Abstract: The degradation of interlaminar shear strength and shear fracture toughness of glass/epoxy composites due to uptake of distilled water and sea water has been studied. The composites were immersed in water for up to eight months at temperatures up to 70 °C. Unreinforced matrix resin samples were also immersed for periods up to 2 years. Sea water was absorbed less rapidly than distilled water. Weight gains below 1% did not influence the shear strength while higher weight gains reduced shear strength up to 25%. The loss in apparent interlaminar shear strength was uniquely related to specimen weight gain. Mode II fracture toughness, G IIc, also decreased with increasing immersion time after an initial incubation period, but the accelerated tests were found to reduce G IIc less than the room temperature tests at comparable weight gains.

Low-level determination of EDTA and DTPA in natural waters by gas chromatography

Abstract: A new analytical method and the method validation for the determination of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) in lake and sea water is presented. An aqueous sample, after evaporation to dryness, was treated with an esterification reagent. The resulting ethyl ester derivates were determined by capillary gas chromatography using a nitrogen phosphorus specific detector (GC-NPD). The response was linear up to 5 mg L−1. The recoveries from lake and sea waters were 59–105 % for EDTA and 86–112 % for DTPA. The run-to-run repeatabilities (R.S.D.) were 2–8 % for EDTA and 4–11 % for DTPA depending on concentration and the reproducibilities (R.S.D.) were 6–13 % and 3–11 %, respectively. The limits of detection for EDTA and DTPA were 3 and 12 μg L−1 in distilled water, respectively. The method is simple to use and reliable as shown by the analysis of samples of lake water that is influenced by pulp and paper industry.

Effect of hard river water on the surface properties of surfactants

Abstract: The surface properties [effectiveness of surface tension reduction (γ CMC ), critical micelle concentration (CMC), efficiency of surface tension reduction (pC 20 ), maximum surface excess concentration (Γ max ), minimum area/molecule at the interface (A min ), and the (CMC/C 20 ) ratio] of well-purified anionic, nonionic, and cationic surfactants, some of which are widely used in daily chemical and industrial products, were investigated at 25 °C in hard river water. The studied surfactants show somewhat greater surface activity in hard river water than in distilled water, but in particular, for anionic surfactants a marked effect of hard river water on surface active properties was observed. The effect of hard river water on surface active properties is, in decreasing order, anionics > cationics > nonionics. For alkyl poly(oxyethylene) glycols, the effect on surface properties is interpreted in terms of complex formation between the ether oxygen atoms of the poly(oxyethylene) group and divalent hardness ions. The linear relationship between the pC 20 or CMC values and the number of carbon atoms in the alkyl chain observed in distilled water was confirmed in hard river water. For alkyl poly(oxyethylene) sulfates, the slope of the plot indicates an effect of the alkyl chain on adsorption at the air/water interface or on micellization similar to that observed for nonionic surfactants in distilled water.

The production of activated carbon from a bituminous coal

Abstract: Devolatilization of an Illinois-basin coal was carried out under a nitrogen atmosphere in the temperature range 600 to 900°C. A vertical heated-wall fixed-bed furnace reactor was used. Char produced was activated in the presence and absence of steam using the same furnace setup. The surface area of the activated carbon produced was found to be equal to 54.4 m 2 g -1 when steam was absent and 226.2 m 2 g -1 when steam was present using the same process and conditions of activation. Breakthrough curves for the adsorption of toluene in water activated carbons prepared from that coal were obtained. They were compared with a commercially available activated carbon. On one hand, poor adsorptive properties were obtained for coal-carbons produced by the process of activation under oxygen-nitrogen gas atmospheres. On the other hand, it was found that good adsorption characteristics were obtained by using a steam-oxygen-nitrogen gas mixture. Following the preparation of activated carbon, it was necessary to treat the carbon produced in boiling distilled water. Boiling carbon in water for a short period of time (about 30 min), effectively improves the adsorption performance.

Influence of peracetic acid on Escherichia coli H10407 strain in laboratory microcosms

Abstract: The bactericidal properties of peracetic acid (PAA) were tested using Escherichia coli H10407, in sterilized artificial seawater, sewage effluent water, and distilled water microcosms. No LT entero...

Phototransformation of Chlorimuron-ethyl in Aqueous Solution

Abstract: Chlorimuron-ethyl is relatively stable in water buffered to pH 7.0 and 9.0, but hydrolyzes readily (half-life, 14 d) in water buffered to pH 4.0. In addition, chlorimuron-ethyl photodegrades rapidly and extensively in aqueous solution. The predominant photoproducts are 4-methoxy-6-chloro-2-aminopyrimidine, ethyl 2-aminosulfonylbenzoate, N-(4-methoxy-6-chloropyrimidin-2-yl)methyl urea, and o-benzoic sulfimide (saccharin). A minor deesterified product (chlorimuron) was evident. The decrease in chlorimuron-ethyl concentration in aqueous solutions followed first-order kinetics. The rate of degradation in different types of water followed the order irrigation water > tap water > distilled water. Chlorimuron-ethyl photodegraded in pH 4, 7, and 9 buffer solutions under both UV and sunlight. A faster degradation rate in pH 4.0 buffer solution was observed. Keywords: Chlorimuron-ethyl; aqueous solution; photolysis

Release of Fenamiphos, Atrazine, and Alachlor into Flowing Water from Granules and Spray Deposits of Conventional and Controlled-Release Formulations

Abstract: The release into water of active ingredients from spray deposits or granules of fenamiphos, atrazine, and alachlor was measured for commercial and experimental controlled-release formulations. Granules or spray mixtures of the pesticides were mixed with coarse sand and dried if necessary, and the mixture was placed in 5 mm × 35 mm stainless steel cylinders through which distilled water was then pumped for 24 h. Pesticide concentrations in the eluate were determined by HPLC analysis. The conventional formulations (emulsifiable concentrates, granulars, and dispersible granules) gave total release in 5−24 h and in some cases appeared to release particles into contacting water. Controlled-release starch-encapsulated formulations gave between 5% and 94% release in 24 h. Clay/alginate and clay/alginate/linseed oil formulations gave 0.3−100% release in 24 h, depending mainly on the aqueous solubility and lipophilicity of the pesticide. This simple technique provides comparative insights into the amounts and rate...

Effect of water salinity and temperature on the hydrophobicity of ethylene propylene diene monomer insulator

Abstract: Ethylene propylene diene monomer (EPDM) is extensively used in outdoor composite polymer insulators. The effects of water salinity and temperature on the hydrophobicity of EPDM rubber were studied The hydrophobicity was determined by measuring the contact angle using a droplet of distilled water. The specimens were immersed in saline water solutions for up to 576 h. The salinity levels used were 5, 10/sup 3/, 10/sup 4/ and 10/sup 5/ /spl mu/S/cm. The aging temperatures were 0, 25, 50, 75 and 98/spl deg/C. The weight was also measured to determine the amount of water absorption in the polymer as might occur during a heavy rain. The change in the contact angle is related to the amount of water absorption, the salinity level of solution and the temperature. The absorption of saline water into the bulk is larger at higher temperatures and decreases with increasing salinity. At 25/spl deg/C and higher the absorption of saline water at all salinity levels was saturated during the aging period Generally, after long immersion the contact angle decreased. At 0/spl deg/C the decrease of contact angle was larger at higher salinity. At high temperatures (/spl ges/75/spl deg/C), the sample surface gradually changed its color from the original dark gray to white.

Development of a gas chromatographic method for the simultaneous determination of trace amounts of ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid in natural waters

Abstract: A GC method for the simultaneous determination of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) in natural waters is described. The method was studied with spiked samples of distilled water, sea-water (2 matrices) and humic-containing lake water. An acidified 5–10 ml sample was evaporated and esterified with C2H5OH, containing H2SO4 and CH3COOH catalysts and CH3(CH2)15CN as an internal standard. The esterified sample was extracted with C6H5CH3, neutralized with KHCO3, dried with anhydrous Na2SO4 and analysed by GC with nitrogen–phosphorus selective detection. The best recoveries were obtained by the esterification in 100 °C for 3 h. The tetraethyl ester of EDTA and pentaethyl ester of DTPA were further identified by mass spectrometry. In the sea- and lake water matrices, the recoveries of EDTA and DTPA were 80–110%. High concentrations (above 50 mg l–1) of iron (Fe3+) interfered considerably in the determination of DTPA. For EDTA the interference was insignificant with iron concentrations below 500 mg l–1.

Effect of microwave heating on the migration of dioctyladipate and acetyltributylcitrate plasticizers from food-grade PVC and PVDC/PVC films into olive oil and water

Abstract: Migration of dioctyladipate (DOA) and acetyltributylcitrate (ATBC) plasticizers from plasticized polyvinylchloride (PVC) and polyvinylidene chloride (PVDC)/PVC (Saran) films into both olive oil and distilled water during microwave heating has been studied. The plasticizer migrating into olive oil and water was determined using an indirect GC method after saponification of the ester-type plasticizer (DOA or ATBC) and subsequent collection of the alcohol component of the ester, namely: 2-ethyl-1-hexanol and 1-butanol, respectively. Migration was dependent on heating time, microwave power setting, the nature of the food simulant and the initial concentration of the plasticizer in the film. Migration of DOA into olive oil reached equilibrium after heating for 10 min at full power (604.6 mg DOA/l). Migration into distilled water was 74.1 mg/l after 8 min of microwave cooking at full power. The amount of ATBC migrating into olive oil reached equilibrium after heating for 10 min at full power (73.9 mg ATBC/l). Migration into distilled water was 4.1 mg/l after heating at full power for 8 min. Control samples containing olive oil gave DOA migration values which were significantly higher than the upper limit for global migration (60 mg/l) set by the European Community. It is proposed that PVC should not be used in direct contact with food in the microwave oven, while Saran may be used with caution in microwave heating and reheating applications, avoiding its direct contact with high fat foodstuffs.

In vitro comparative fluoride release, and weight and volume change in light-curing and self-curing glass ionomer materials

Abstract: The purpose of this study was to evaluate and compare in vitro -fluoride release from and weight and volume changes of Photac-Fil TM, a light-curing polymaleinate restorative glass ionomer, with Ketac-FiU M, a self-curing glass ionomer, and Ketac-Silver TM, a metal reinforced glass ionomer. Five discs of each material, measuring 2 mm height and 5 mm diameter, were suspended in separate vials of distilled water and laboratory artificial saliva. Fluoride release into the solutions was measured using a calibrated fluoride-sensitive ion meter initially at 24 hr and then weekly from 1 to 9 weeks. These results were evaluated statistically using repeated measures analysis of variance. Volumes and weights were recorded at the start and end of the experiment and analyzed using the paired t-test. Photac-Fil released similar amounts of fluoride to Ketac-Silver, but significantly less than Ketac-Fil in distilled water (P ~_ 0.05). In artificial saliva, PhotacFil released similar amounts to Ketac-Fil, but significantly more than Ketac-Silver (P <_0.05). Photac-Fil volume increased in distilled water and artificial saliva (P <_ 0.05) as did Ketac-Fil and Ketac-Silver in artificial saliva (P _~ 0.05). The only material that demonstrated significant net weight increase was Ketac-Silver in artificial saliva (P _< 0.05). In summary, differences in.fluoride release between these three glass ionomer materials varied as a function of the media in which they were stored, lArhereas KetacFil exhibited significantly greater fluoride release than the other materials in distilled water, in artificial saliva KetacFil and Photac-Fil exhibited comparable-fluoride release. Dimensional change, as evaluated by volume and weight differences, was also affected by storage media. (Pediatr Dent 18:210-14, 1996)

Rinse aid compositions comprising non-nitrogen-containing organs diphosphonic acid, salt or complex thereof

Abstract: There is provided a rinse aid composition containing an organo diphosphonic acid or its salts or complexes. The pH of said composition as a 1% solution in distilled water at 20° C. is preferably less than 7.

New silk fibroin peptide, its production and cosmetic and detergent composition containing the same

Abstract: PURPOSE:To obtain a new silk fibroin peptide excellent in film formability, water holding ability, solubility and long-term preservability, useful for cosmetics having of high humectancy and safety or detergent having high foaming power and detergency, by treating silk fibroin at high temperatures and pressures to effect its hydrolysis. CONSTITUTION:This new fibroin peptide of the formula (R and R' are each side chain of the various amino acids constituting the silk fibroin; (n) is an integer of 0-20) is easily and industrially obtained at low cost by the following process: silk fibroin powder and distilled water are put into a pressure vessel and treated in the presence of a <=0.1N acid or <=0.1N alkali in a nitrogen atmosphere in a high-pressure water at 150-250 deg.C for 16hr to effect its hydrolysis followed by cooling and then filtering off minute amounts of insolubles to collect a filtrate which is then concentrated. This fibroin peptide is excellent in film formability, water-holding ability, solubility and long-term preservability, therefore being useful for cosmetics of high humectancy, film formability and safety, and detergent compositions of good foaming power, detergency, foam properties and safety.