Effect Of Silica Gel Research Articles

New pretreatment method for detecting petroleum hydrocarbons in soil: silica-gel dehydration and cyclohexane extraction

Oil is a primary source of energy worldwide. However, the use of oil produces large amounts of pollutants, which are detrimental to the environment. The presence of petroleum hydrocarbons in soil is a critical marker of environmental pollution and safety. Rapid on-site detection technology has been broadly used in emergency tracking, offering critical information support for effective reactions to environmental emergencies. Thus, it is expected to play an increasingly critical role in environmental remediation efforts. The current approach for petroleum hydrocarbon detection in soil mainly involves Soxhlet extraction with a combination of solvents, including acetone and n-hexane. The samples are then analyzed after rotary evaporation, dehydration with anhydrous sodium sulfate, and purification using a magnesium silica-type adsorbent. Unfortunately, this approach requires sample analysis to be performed in the laboratory, which is tedious and time consuming, and consumes large amounts of solvents. Moreover, the rotary evaporator is not portable. Therefore, this method is not appropriate for the rapid on-site detection of petroleum hydrocarbons. In this study, a rapid on-site detection method based on silica-gel dehydration and cyclohexane extraction was developed for the extraction and pretreatment of petroleum hydrocarbons (C10-C40) in soil. First, an appropriate amount of silica gel was added to the soil, and the mixture was completely ground to eliminate moisture. Next, petroleum hydrocarbons were extracted with 40 mL of cyclohexane, and the extract was cleaned by Florisil solid-phase extraction (SPE) column elution. Finally, the samples were analyzed by gas chromatography (GC) to evaluate the above method. The silica gel exhibited optimal adsorption properties compared with anhydrous sodium sulfate, calcium oxide, and molecular sieves, with recovery of 87.5%. The effects of different soil water content (5%, 10%, and 20%) and silica gel (1, 3, 5, and 10 times the moisture content) dosage on the extraction of petroleum hydrocarbons were investigated. The recoveries of petroleum hydrocarbons increased from 74.0% to 103.8% after 15 min of invasive extraction (relative standard deviation, RSD, <10.1%) when silica gel amounting to 10 times the moisture content was used. Five types of silica gels with different properties were purchased from four manufacturers, and the effects of these silica gels on the dehydration and extraction efficiency of petroleum hydrocarbons in soil were assessed. The results showed that amorphous silica gel led to low recoveries (<60%), spherical silica gel achieved extraction efficiencies of approximately 70%-90%, and alkaline silica gel produced recoveries with poor precision. Therefore, neutral spherical silica gel was used for further experiments. The fingerprints of petroleum hydrocarbons with different carbon numbers are an important reference for identifying pollution sources. Thus, ensuring good recoveries throughout the entire carbon range is necessary to ensure the accuracy of the fingerprint analysis results. The proposed method showed good recoveries for petroleum hydrocarbons of all carbon numbers (75%-101%). The findings above indicate that the developed method could be an efficient means to extract petroleum hydrocarbons from soil for both total quantity and fingerprint analyses. Compared with standard methods, the proposed method requires lower solvent dosages and features simpler processing steps. Another advantage of this method is that it does not require the use of highly toxic halogenated solvents; thus, it does not contribute to environmental pollution. It can be applied to the laboratory analysis of soil petroleum hydrocarbons and coupled with other rapid on-site detection techniques for soil petroleum hydrocarbons, such as infrared spectroscopy and portable GC. However, because it does not include a concentration process, the developed method exhibits relatively low sensitivity. In the future, we plan to develop a simple and flexible on-site sample-concentration system to further improve various indicators of this method.

Isolation of Jatropha curcas Oil Based Linoleic Acid By Using Argentation Column Chromatography

Argentation column chromatography is a method used for separating similar molecules such as fatty acids which have a slightly different in stereochemistry. In this study, silver nitrate-impregnated silica gel was used as the adsorbent to isolate and purify Jatropha curcas oil fatty acids mixtures. The effects of silica gel, silver nitrate, adsorbent quantity and fatty acid quantity on the purity and recovery percentage as well as ratio of linoleic acid to oleic acid were investigated. The results showed that at optimal condition of purification, the purity of linoleic acid increased from 38.4% to 78.7%. In the isolation process, linoleic acid adsorbed most strongly on the AgNO3/SiO2 adsorbent followed by oleic acid due to greater number of double bond and high ability to form polar charge-transfer complexes.

Effect of Silica Gel on the Electrical Conductivity of ɤ- Irradiated Pure Water: A Radiation Chemical Study

EFFECTS of silica gel (SG) and its particle size on the radiation-induced electrical conductivity (RIC) and pH of pure water were studied. RIC of pure water in the absence of SG increases as absorbed dose increases. In the presence of SG the values of the RIC are higher than the corresponding values in the absence of SG up to 12.28kGy, which reflects the induced catalytic effect of irradiated SG. Moreover, the particle size of SG seems to affect the RIC of water. Therefore, as the particle size decreases, the RIC increases (below18.99kGy). Also, it was observed that the pH values decrease as the RIC increases and vice versa. The RIC and variation of pH in the studied samples are related to the radiation induced formation of H2O2 and H3O2+. The induced catalytic effect of SG is related to the radiation-induced formation of electron/ +ve hole (e/ h+) pair during ɤ-radiolysis of SG. Therefore, the RIC increases (pH values decrease) as particle size of SG decreases (surface area increases).

Determination of Keeping Quality of Tea using Silica Desiccant

A study was carried out to find out the effect of silica gel on keeping quality of tea. CTC-SRD grade teas each at 250 g were packed in low density poly ethylene pouches with a small pouch containing silica gel (10 g). Another set of samples were packed in low density poly ethylene packing material without silica gel. From sealed pouches, every month one pouch was taken and analysed for their moisture and quality parameters such as theaflavin, thearubigin, high polymerised substance, total liquor colour and biochemical parameters such as total polyphenol, total catechin, water extract and amino acid. Studies conducted after fourteen month indicated that the moisture content increased in teas packed in LDPE alone and it was less in teas packed in LDPE with silica gel. The level of theaflavin content decreased by 24.01% in teas packed LDPE alone and 17.92 % in LDPE with silica gel respectively. Bio chemical parameters decreased in teas packed in LDPE when compared to LDPE with silica gel. The study reveals that silica gel is useful in maintaining the keeping quality of tea.

Effect of Silica Gel in Causticized Calcium Carbonate from Nonwood Pulping on the AKD Sizing Efficiency of Paper

The application of causticized calcium carbonate (CCC) from nonwood pulping as a filler in papermaking is restricted by a marked decrease in alkyl ketene dimer (AKD) sizing efficiency. But the reason for this adverse effect has not been clear. In this paper, effect of carbonization on the AKD sizing efficiency was investigated systematically. The results showed that the hydrated calcium silicate (C-S-H) in the original CCC had been converted into silica gel after carbonization, and this caused the carbonized CCC to have a higher specific surface area and larger pore volume. This could explain the reason why the CCC had a worse AKD sizing efficiency than the conventional CaCO3 fillers. In addition, the effect of pH value of carbonization on the AKD sizing efficiency was also studied. It was discovered that the silica gel generated and the AKD sizing efficiency started to decline dramatically at the pH value of 8.5. Based on the research above, it can be included that pH value of 8.5 is an appropriate pH of carbonization end to maintain the AKD sizing efficiency at a good level.

Adaptation of eco-friendly approach in the production of soluble pozzolanic material

Silica gel made of natural waste materials of sugarcane bagasse has initiated a new trend in pozzolanic area. The employment of eco-friendly approach by using low concentration acids and natural drying via solar heat based equipment in the pre-treatment process were projected to minimize the energy consumption in producing silica ash. Conversion of ultrafine silica ash from sugarcane bagasse into silica gel was conducted by-using a modified hydrothermal method. NaOH and HCI solution were employed in the dissolution and gelification of soluble silica. Analysis on the effect of silica gel in cementitious system was evaluated by including it in mortar specimen as a pozzolan to replace certain portion of Portland cement. Inclusion of additional siliceous gel showed enhancement in the cement hydration process, which resulted in early hardening and consolidatedformation of cement matrix to further contribute in the strength development. Measurement of pozzolanic reactivity of silica gel via Chapelle method verified the active consumption of Ca(OH)2 by the soluble silica, which illustrates the possible formation of secondary calcium silicate hydrate (C-S-H) from the pozzolanic reaction. Densification of pore structure via large voids were observed via porosity test at age of 7 and 28 days. Based on the experimental result in this study, silica gel has presented an encouraging prospect to be used as a cement replacement material. Its rapid reaction during the early age would be beneficial in providing early strength properties to the cement based product.

Effects of silica gel on reduction in gluten during several beer brewing stages

SummaryBeer is an alcoholic beverage made with barley as a basic raw material, and therefore, it is not suitable for people with coeliac disease. During the brewing process, the elimination of the haze‐active precursor is performed at the stabilisation stage. Some breweries use silica gel (SG) as stabilisation precursor. This work presents the studies conducted to identify the stage where the addition of SG is more convenient in order to reduce gluten, and the effect on the yeast nutritional value due its incorporation. The incorporation of SG during fermentation allows the reduction in more gluten than the others brewery stages studied, without changing significantly the yeast nutritional value of beer. Furthermore, the use of SG promotes the reduction in polysaccharides which obstruct filtration.

Rapid reduction of Cr(VI) coupling with efficient removal of total chromium in the coexistence of Zn(0) and silica gel

The effect of silica gel on the efficiency enhancement of Zn(0) for the reduction of Cr(VI) and removal of total chromium was investigated in this study. The batch experiment was carried at 4≤pH≤10 with 50μM initial Cr(VI) concentration, and mass loading of 0–40g/L for silica gel and 0–8g/L for Zn(0). Results showed limited Cr(VI) reduction in the Zn(0)/H2O system, which was attributed to the formation of passivating films on the Zn(0) surface. However, a complete reduction of Cr(VI) by Zn(0) in the presence of silica gel could be achieved at the all tested pHs. The rate of Cr(VI) reduction was markedly enhanced with a pH decrease, an increase of silica gel or Zn(0) loading, and specific surface area of silica gel. Almost complete removal of total chromium was also observed, suggesting that Cr(III) yielded from the reduction of Cr(VI) was adsorbed onto the silica gel and ZnO surface or existed in Zn–Cr mixed oxides or other Zn–Cr co-precipitates. The possible pathways for Cr(VI) reduction and total chromium removal were proposed in this study, revealing the potential mechanism responsible for the rapid reduction of Cr(VI) coupling with the efficient removal of total chromium in the coexistence of Zn(0) and silica gel.

Preparation of Citrus Essential Oils: Effects of Silica Gel Treatment on Volatile Composition of Yuzu (Citrus junos) Cold-pressed Peel Oil

The effects of silica gel, a substance commonly used for fractionation of essential oils during preparation, were investigated on cold-pressed peel oil of yuzu (Citrus junos Sieb. ex Tanaka), a sour Citrus fruit. The silica gel treatment was performed for 24 h at 20°C, 5°C and −2°C. The volatile components were determined using GC and GC-MS. Important compositional changes occurred at 20°C and 5°C and minimally or virtually absent at −21°C. The notably decreased groups were monoterpene hydrocarbons (from 95.7 to 75.2%), sesquiterpene hydrocarbons (from 2.1 to 1.0%) and monoterpene alcohols (from 2.2 to 1.7%). The main decreases were of limonene, phellandrene, y-terpinene, terpinolene, ß-elemene, caryophyllene, trans-ß-farnesene, germacrene D and bicyclogermacrene. Increases of p-cymene, aromadendrene, allo-aromadendrene, cadinene, trans-sabinene hydrate and α-terpineol occurred. Artifact compounds including ß-copaene, d-camphor, viridiflorol and spathulenol were formed. Use of silica gel for preparative treatment of complex Citrus oils could cause alteration of the original composition. The results could be applicable for quality control at the perfume or Citrus juice factory.

Detection and stability of Japanese encephalitis virus RNA and virus viability in dead infected mosquitoes under different storage conditions.

A semi-nested polymerase chain reaction (PCR) was evaluated for detection of Japanese encephalitis (JE) virus in infected mosquitoes stored under simulated northern Australian summer conditions. The effect of silica gel, thymol, and a combination of the two on RNA stability and virus viability in dead mosquitoes were also examined. While JE virus RNA was relatively stable in mosquitoes held for up to 14 days after death, viable virus was not detected after day 1. Thymol vapor inhibited fungal contamination. Detection of single mosquitoes infected with JE virus in large pools of mosquitoes was also investigated. Single laboratory-infected mosquitoes were detected in pools of < or = 200 mosquitoes and in pools diluted to 0.2/100 and 0.1/100 mosquitoes, using the semi-nested PCR. However, the ability to detect live virus decreased as pool size increased. The semi-nested PCR proved more expensive than virus isolation for pools of 100 mosquitoes. However, the semi-nested PCR was faster and more economical using larger pools. Results indicate that surveillance of JE virus in mosquitoes using the semi-nested PCR is an alternative to monitoring seroconversions in sentinel pigs.

Hydrogen Peroxide Cleaning of Asphalt from Surfaces The Accelerating Rate Calorimetry (ARC™) Study: The Effect of Silica Gel and Solution pH on Hydrogen Peroxide Decomposition

AbstractThe pharmaceutical, fine chemical, photography, and military industries have aggressively sought means of eliminating organic solvents from their cleaning operations because many organic cleaning solvents have been characterized as hazardous or toxic wastes. As a substitute, we previously found that 3% hydrogen peroxide (H

Photochromic organic-inorganic polymer hybrids from spiropyran-modified poly( N , N -dimethylacrylamide)

Photochromic organic-inorganic polymer hybrids were prepared by the sol-gel reaction of tetramethoxysilane (TMOS) in the presence of spiropyran-modified poly(N,N-dimethylacrylamide) 3. The obtained polymer hybrids were characterized by thermogravimetric analysis (TGA) and FT-IR, and photochromic behavior was followed by electronic absorption spectroscopy. Upon an irradiation of ultraviolet light, an absorption around 557 nm appeared in the visible region and the color of the hybrid turned to be violet. The effect of silica gel on the isomerization behavior seemed to be relatively small.

Effects of Silicium Dioxide on Drug Release from Suppositories

Silica gel is frequently introduced into lipophilic excipients for suppositories as a viscosity agent, to prevent drug sedimentation in the melted mass, and to decrease release rate. The effect of silica gel (Aerosil 200) concentration on the availability of some drugs frequently used in suppositories in different unitary doses was studied. When silica gel concentration in the excipient was increased, a decrease in aminophylline and aminophenazone release rate was observed. Paracetamol in small unitary doses has shown a tendency to increase release rate at higher silica gel concentrations. This behavior was even more evident in suppositories containing promethazine hydrochloride, while for those containing benzydamine hydrochloride the increase in release rate with increasing silica gel concentration was evident for all drug doses. However, the behavior was a consequence of the trend of suppository viscosity during drug release. As a consequence of both the drug and silica gel being discharged, the viscosity progressively decreased with an increased silica gel concentration. The effect on drug availability was conditioned by silica gel concentration, as well as the type and dose of the drug, which could act on the shape of the suppository inner structure that is responsible for viscosity and mobility of drug particles.

Enhanced catalytic efficiency of enzymes in organic media with the addition of the solid support: Effect of silica gel on reaction rates and enzyme agglomeration

Enzymatic esterification of octanoic acid with methanol in cyclohexane was investigated using Candida rugosa lipase in the absence or presence of silica gel. The lipase was added in the form of a suspended dried powder, and the effects of water content and shaking rate on the reaction rates were examined. It was found that the maximal reaction rate could be markedly enhanced by the addition of silica gel to the medium with shifting the optimal water content to a higher value. In order to identify the reasons for the rate improvement in the presence of the support, the effects of water content and silica gel on the distribution of water, partitioning of the substrates, enzyme inactivation, and agglomeration of enzyme particles were examined. Under the conditions studied, enzyme agglomeration was the largest factor reducing activity at high water contents and the enhanced activity with the addition of silica gel was mainly attributed to effective reduction of agglomerate size in the solvent medium. It was also shown that repeated use of the enzyme is very effective in the presence of silica gel. The yields in successive batch runs increased with increasing the ratio of silica gel to the enzyme.

Surface-Mediated Reactions. 6. Effects of Silica Gel and Alumina on Acid-Catalyzed Reactions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSurface-Mediated Reactions. 6. Effects of Silica Gel and Alumina on Acid-Catalyzed ReactionsPaul J. Kropp, Gary W. Breton, Stephen L. Craig, Scott D. Crawford, William F. Durland Jr., John E. Jones III, and J. Scott RaleighCite this: J. Org. Chem. 1995, 60, 13, 4146–4152Publication Date (Print):June 1, 1995Publication History Published online1 May 2002Published inissue 1 June 1995https://doi.org/10.1021/jo00118a035RIGHTS & PERMISSIONSArticle Views1892Altmetric-Citations70LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (934 KB) Get e-Alerts Get e-Alerts

Effect of gelation on setting time in ethyl silicate-bonded investment

Ethyl silicate-bonded cristobalite-quartz investment used silica gel as the binder. The effect of silica gel as the SiO 2 in hydrolysed silica sol solution was examined using differential thermal analysis (DTA) and theromgravimetry (TG) with respect to thermal change of the investment when the concentration of silica gel changed within hydrolysed solution. The setting time that elapsed from the beginning of mixing until the material hardened was determined using a Vicat needle

Ethyl silicate-bonded investments: Effect of silica gel as a binder on DSC results

Ethyl silicate-bonded investments: Effect of silica gel as a binder on DSC results

Effect of Silica Gel ‘G’ on the Ion Exchange Behaviour of Antimonic Acid Thin Layers in The Chromatographic Study of Anions in Some Aqueous Organic Acid Systems: Determination of Ferricyanide and Dichromate Ions

Abstract The ion exchange potential of antimonic acid and silica gel ‘G’ has been explored in thin layer chromatographic studies for the separation of anions. Several important and difficult binary separations of anions have been achieved as a result of these studies. Io− 3-Bro− 3, I−-Io− 3, Io− 4-Io− 3, Io− 4-Po−- 4, Br−-Bro− 3, Aso−- 4-Cro−- 4, S2o−- 3-Po−- 4, CNS−-S2o−- 3, Io− 4-Cro−- 4, Bro− 3-Cro−- 4, Io− 3-Cr2o−- 7 and s2o3-Cro−- 4 etc. are separations of analytical interest. Besides, a rapid microgram determination of [Fe(CN)6]3− (1–10 μg) and Cr2o2- 7 (2–10 μg) ions have been made.

The effects of silica gel (carrier) on the activity (hydrogen yield) of photocatalytic decomposition of water over [pol-Ti(OBu)4 + CH3OH]-complex

A significant effect of pore size has been found on the yield of photolysis of water to hydrogen, ozone (oxidising product) and methane (decomposing product of catalyst or solvent) using [pol-Ti(OBu)4 + CH3OH]-complex/SiO2. The pore structure of silica gel has been found to provide good conditions for forming this type of catalyst.

Carbonization behaviour of pitch in the presence of inert material

The influence of silica gel (< 45 μm) as an inert additive on the carbonization reactions of A240 pitch was investigated by optical microscopy, measurements of transferable hydrogen, high-temperature e.s.r. and high-temperature 1H n.m.r. Additions of silica gel have the effect of reducing the size of the optical texture of mesophase which appears in the early stages of carbonization. The higher the concentration of silica gel, the smaller is the amount of transferable hydrogen. The spin concentration of pitch increases with increasing silica gel content. Measured values of ΔH 1 2 , using high-temperature 1H n.m.r., suggest that the molecular motions in the pitch become restricted on addition of silica gel. The effect of silica gel on the physical properties and chemical reactivity of carbonizing pitch is discussed.