Surface photochemistry: the photolysis of α-methoxy acetophenones on silica gel

1986 ◽  
Vol 64 (7) ◽  
pp. 1243-1246 ◽  
Author(s):  
Paul de Mayo ◽  
N. Ramnath
Keyword(s):  
Silica Gel ◽  
Conformational Control ◽  
Restricted Movement ◽  
Photochemical Reactivity ◽  
Factors Affecting

The photolysis of α-methoxy acetophenones 1a–1e adsorbed on silica gel show a significant deviation from the course of reaction in methanol. The results are discussed in terms of conformational control and restricted movement of the radical through adsorption on silica gel. Factors affecting the efficiency of modification of photochemical reactivity on silica gel surface have been examined.

scholarly journals Desalination of Agricultural Wastewater by Solar Adsorption System: A Numerical Study

2021 ◽  
Vol 10 (4) ◽  
pp. 901-910
Author(s):  
Jehan F AlRubaiea ◽  
Farkad A Latteiff ◽  
Jasim M Mahdi ◽  
Mohammed A Atiya ◽  
Hasan Sh Majdi
Keyword(s):  
Silica Gel ◽  
Numerical Study ◽  
High Energy ◽  
Water Desalination ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Adsorption System ◽  
Factors Affecting ◽  
Usage Cost

There are still areas around the world suffer from severe shortage of freshwater supplies. Desalination technologies are not widely used due to their high energy usage, cost, and environmental damaging effects. In this study, a mathematical model of single-bed adsorption desalination system using silica gel-water as working pair is developed and validated via earlier experiments. A very good match between the model predictions and the experimental results is recorded. The objective is to reveal the factors affecting the productivity of fresh water and cooling effect in the solar adsorption system. The proposed model is setup for solving within the commercially-available software (Engineering Equation Solver). It is implemented to solve the mass and heat balance equations for the adsorbent bed, condenser, and evaporator components. At a typical temperature of 89 °C and flow rate of 30 m3/sec for the hot water entering the bed, the following results are reported: (a) the specific daily water production of 1.89 m3 /ton of silica gel/ day, (b) coefficient of performance of 0.32, and (c) specific cooling power of 40.82 W/kg of silica gel. The concentration of salt (X) in the product (desalinated water) has been set with value of 0.5 gm/kg to be suitable for drinking and irrigation. The salt concentration in the evaporator is estimated to be 4.611 gm/kg during the overall adsorption process. The results from this study should be of wide interest for the field of solar water desalination and air-conditioning.

Factors affecting the sorption of Eu(III) on modified silica gel

2006 ◽  
Vol 268 (2) ◽  
pp. 255-260 ◽  
Author(s):  
E. A. A. El-Shazly ◽  
R. R. Sheha ◽  
H. H. Someda
Keyword(s):  
Silica Gel ◽  
Modified Silica ◽  
Modified Silica Gel ◽  
Factors Affecting

Symmetry-Enforced Conformational Control of Photochemical Reactivity in 2-Vinyl-1,3-terphenyl

2002 ◽  
Vol 124 (46) ◽  
pp. 13664-13665 ◽  
Author(s):  
Frederick D. Lewis ◽  
Xiaobing Zuo ◽  
Vladimir Gevorgyan ◽  
Michael Rubin
Keyword(s):  
Conformational Control ◽  
Photochemical Reactivity

Identification and Photodegradation of Red Pigment from Serratia marcesce zl3

2015 ◽  
Vol 737 ◽  
pp. 349-352
Author(s):  
Lin Zhou ◽  
Shuang Zhu ◽  
Xin Huai Dong
Keyword(s):  
Light Intensity ◽  
Silica Gel ◽  
Column Chromatography ◽  
White Light ◽  
Red Pigment ◽  
Effect Of Ph ◽  
Factors Affecting ◽  
Light Stability ◽  
The Stability

Present study was aimed to identify and isolate the red pigment from Serratia marcesce zl3, and to investigate the factors affecting on the light stability of the purified red pigment. Silica gel and Sephadex LH-20 column chromatography were used for purification, identification was done by TLC, UV, FTIR and HPLC-MS techniques. The effect of pH and light intensity on the light stability of the purified red pigment prodigiosin was analyzed by TLC, UV and HPLC. The stability of identified prodigiosin pigment at pH 1, 3, 5 was superior to that at pH 7, 10, 14 according to the determination of OD535. Significant level of degradation of the prodigiosin was observed for 24 h, using 10 klx continuous white light. The effect of pH to the stability of prodidgiosin was partly reversible, while the degradation of prodigiosin under 4, 10, 20 klx white light was irreversible.

scholarly journals Fluorescent Labeling of Silica Gel Powder using Zingiber Montanum Extract fora Bright Latent Fingerprint Detection under UV Light

2021 ◽  
Vol 37 (3) ◽  
pp. 541-546
Author(s):  
Kongsak Pattarith ◽  
Saksit Chanthai ◽  
Rachadaporn Benchawattananon
Keyword(s):  
Silica Gel ◽  
Uv Light ◽  
Chemical Properties ◽  
Surface Characteristics ◽  
Fluorescent Labeling ◽  
Latent Fingerprints ◽  
Factors Affecting ◽  
Naked Eye ◽  
Cheap Method ◽  
Physical And Chemical

This research was to study the preparation of fluorescent dust powder to enhance the detection of ultra-bright latent fingerprints using natural plant extract associated with adsorption on silica gel particles by a simple and cheap method environmentally friendly. To study the physical and chemical properties of the fluorescent powder, various factors affecting the latent fingerprints detection including different surface characteristics, temperature, time, and overlapping passive fingerprints were investigated. From the results, it was found that the fingerprints on the surface of different materials could be performed, and gave good inspection trace,which can be seen with naked eye and appear brightly under UV light at a wavelength of 366 nm. For the persistence study of the latent fingerprints, it was also found that when kept it in a dark place at room temperature for 30 days, the fingerprints were still visible to the naked eye and glow clearly under UV light.In addition, the overlapping fingerprints can be clearly identified. Therefore, the study of the fluorescent silica gel dust powder demonstrates good performance,and it is a potential use to detect latent fingerprints as a witness in forensic processes.

scholarly journals The effects of zeolite and silica gel on synthesis of amylisobutyrate catalyzed by lipase from Candida rugosa

2008 ◽  
Vol 62 (2) ◽  
pp. 64-68
Author(s):  
Sanja Stojakovic ◽  
Dejan Bezbradica ◽  
Dusan Mijin ◽  
Zorica Knezevic ◽  
Slavica Siler-Marinkovic
Keyword(s):  
Silica Gel ◽  
Molecular Sieves ◽  
Candida Rugosa ◽  
Ester Synthesis ◽  
Conversion Yield ◽  
Factors Affecting ◽  
Efficient Control ◽  
Ester Yield ◽  
Hydrolysis Of ◽  
Early Phases

Lipase-catalyzed synthesis of esters has been widely investigated due to numerous advantages in comparison with the conventional chemical process catalyzed with concentrated acids since use of chemical catalysts leads to several problems. The most important disadvantages are corrosion of equipment, hazards of handling of the corrosive acids that are not reused, loss of conversion, yield and selectivity. The activity of water in reaction mixture seems to be one of the crucial factors affecting yield of enzymatic synthesis, since the excess of water promotes hydrolysis of the ester. Therefore, a significant part of related studies was focused on attempts to increase the yield of esters by efficient control of water activity. In our experimental work an attempt was made to regulate the activity of water by addition of water adsorbents in reaction mixture for synthesis of amyl isobutyrate. Two adsorbents were used: silica gel and molecular sieves (zeolites). The use of water adsorbents was optimized with respect to timing of adsorbent addition and pretreatment of adsorbent. The pretreatment of adsorbent with substrate did not increase the yield of ester. It was found that the timing of adsorbent addition is crucial factor. The addition in early phases of reaction leads to the decrease in ester yield compared to reaction without adsorbents. On the other hand, when the adsorbent was added in the late stage of reaction it exhibited beneficial influence on the yield of ester. The increase of yield was higher with silica gel (10%) than with molecular sieves (3.5%). These discrepancies can be ascribed to higher water adsorbing capacity of silica gel in systems with higher water content. Superior behavior of silica gel in ester synthesis in conjunction with simple process of regeneration recommends the use of this adsorbent for increasing the yield of lipase-catalyzed ester synthesis.

Progress In The Practical Application Of Automated Image Analysis To Tem Negatives

1977 ◽  
Vol 35 ◽  
pp. 214-217
Author(s):  
F. A. Heckman ◽  
E. Redman ◽  
J.E. Connolly
Keyword(s):  
Image Analysis ◽  
Image Quality ◽  
Exposure Time ◽  
Image Contrast ◽  
Automated Image Analysis ◽  
Practical Application ◽  
Factors Affecting ◽  
High Image Quality ◽  
Qualitative Evidence ◽  
Comprehensive Study

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.

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