scholarly journals Corrosion Inhibition of Aluminum in Aqueous Alkaline Solutions by Alginate and Pectate Water-Soluble Natural Polymer Anionic Polyelectrolytes

2012 ◽  
Vol 30 (6) ◽  
pp. 419-426 ◽  
Author(s):  
I Zaafarany
Keyword(s):  
Corrosion Inhibition ◽  
Water Soluble ◽  
Alkaline Solutions ◽  
Natural Polymer

scholarly journals A Revisit to the Corrosion Inhibition of Aluminum in Aqueous Alkaline Solutions by Water-Soluble Alginates and Pectates as Anionic Polyelectrolyte Inhibitors

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Refat Hassan ◽  
Ishaq Zaafarany ◽  
Adil Gobouri ◽  
Hideo Takagi
Keyword(s):  
Adsorption Mechanism ◽  
Inhibition Efficiency ◽  
Geometrical Structure ◽  
Physical Adsorption ◽  
Water Soluble ◽  
Alkaline Media ◽  
Alkaline Solutions ◽  
Corrosion Mechanism ◽  
Natural Polymer ◽  
Freundlich Isotherms

The corrosion behavior of aluminum (Al) in alkaline media in presence of some natural polymer inhibitors has been reinvestigated. The inhibition action of the tested inhibitors was found to obey both Langmuir and Freundlich isotherms models. The inhibition efficiency was found to increase with increasing the inhibitors concentration and decrease with increasing the temperature, suggesting physical adsorption mechanism. Factors such as the concentration and geometrical structure of the inhibitor, concentration of the corrosive medium, and temperature affecting the corrosion rates were examined. The kinetic parameters were evaluated, and a suitable corrosion mechanism consistent with the kinetic results obtained is suggested and discussed.

scholarly journals Characterizing Wool Keratin

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
Jeanette M. Cardamone ◽  
Alberto Nuñez ◽  
Rafael A. Garcia ◽  
Mila Aldema-Ramos
Keyword(s):  
Hydrogen Peroxide ◽  
Gel Electrophoresis ◽  
Water Soluble ◽  
Alkaline Solutions ◽  
Biodegradable Material ◽  
Alkaline Hydrogen Peroxide ◽  
Cortical Cells ◽  
Sds Page ◽  
Fibrous Matrices ◽  
Wool Keratin

Keratin from wool is a reactive, biocompatible, and biodegradable material. As the biological structural component of skin (soft keratins) and of nails, claws, hair, horn, feathers, and scales (hard keratins) pure keratin comprises up to 90% by weight of wool. Wool was treated in alkaline solutions to extract from 68% to 82% keratin within 2 to 5 hours of exposure at . The keratin products were water-soluble and were confirmed to contain intermediate filament and microfibrillar component-proteins of fractured, residual cuticle, and cortical cells. Oxidation of wool by peroxycarboximidic acid in alkaline hydrogen peroxide produced keratin products with distinct microcrystalline structures: descaled fibers, fibrous matrices, and lyophilized powders. Morphology and confirmation of peptide functionality were documented by SEM, Amino Acid Analysis, SDS-PAGE gel electrophoresis, MALDI-TOF/TOF, and FTIR analyses. The reactivity of keratin from wool models the reactivity of keratin from low-value sources such as cattle hair.

scholarly journals Development of a Stability Indicating Method for Simultaneous Analysis of Five Water-Soluble Vitamins by Liquid Chromatography

2018 ◽  
Vol 3 (4) ◽  
pp. 207-218 ◽  
Author(s):  
Mouloud Yessaad ◽  
Lise Bernard ◽  
Daniel Bourdeaux ◽  
Philip Chennell ◽  
Valérie Sautou
Keyword(s):  
Liquid Chromatography ◽  
Degradation Products ◽  
Pharmaceutical Preparations ◽  
Water Soluble ◽  
Alkaline Solutions ◽  
Array Detector ◽  
Forced Degradation ◽  
Metaphosphoric Acid ◽  
Stability Indicating ◽  
Stability Indicating Method

Abstract Background Water-soluble vitamins are often included simultaneously in pharmaceutical formulations as food complements or in parenteral nutrition mixtures. Given their sensitivity to heat, light or pH variations, it is important to study their stability using validated stability indicating methods. We thus aimed to validate a liquid chromatography (LC) stability-indicating method for the simultaneous quantification of 5 water-soluble vitamins. Methods We analyzed four water-soluble B vitamins (nicotinamide, pyridoxine, folic acid, cyanocobalamin) and ascorbic acid using a LC method with diode array detector. They were separated on a C18 stationary phase under gradient elution of solvent A [0.2 % of metaphosphoric acid in water and acetonitrile 98:2] and solvent B (100 % acetonitrile). All vitamins were subjected to forced degradation conditions and we showed that the obtained degradation products didn’t interfere with the vitamins. Results The method allows the separation of the 5 water-soluble vitamins in a 30 minute run without any interference from the breakdown products obtained with acid/alkaline solutions, hydrogen peroxide, temperature and light. It meets all the qualitative and quantitative criteria for validation with an acceptable accuracy and good linearity. Conclusions This stability-indicating method can be used for carrying out stability studies of water-soluble vitamins in pharmaceutical preparations.

scholarly journals Corrosion Inhibition Efficiencies of Polymeric Materials on Alloy Steel in Dilute Hydrochloric Acid and Sodium Hydroxide Solutions at Ambient Temperature

2020 ◽  
Vol 7 (2) ◽  
pp. C27-C32
Author(s):  
I.E. Ekengwu ◽  
O.G. Utu ◽  
K.O. Anyanwu
Keyword(s):  
Corrosion Rate ◽  
Ambient Temperature ◽  
Alloy Steel ◽  
Corrosion Inhibition ◽  
High Density Polyethylene ◽  
Inhibition Efficiency ◽  
Polymeric Materials ◽  
High Density ◽  
Alkaline Solutions ◽  
Ph Values

A corrosion control test was conducted on alloy steel, using polymeric coatings (polyurethane, bitumen (medium airing), and high-density polyethylene) in dilute HCl solutions of pH values 4, 7, and 12, respectively for acid, neutral and alkaline solutions at ambient temperature. In the study, Eighty-four coupons of alloy steel were used. The coupons were mechanized, ground, polished, etched with natal, and weighed using a digital weighing balance (Beva 206B). The mass of each coupon was recorded according to the tag number on them. Twenty-one of the coupons were coated with polyurethane, 21 coated with medium curing bitumen (MC), and 21 coated with high-density polyethylene, while 21 were left uncoated. Seven polyurethane-coated samples, bitumen coating, and uncoated coupons were suspended in dilute HCl solutions of pH values 4, 7, and 12. Every week, one sample is taken from each of the solutions, the coatings and the corrosion products were removed, and the coupons were etched with natal. Then the coupons were reweighed, and their masses were recorded in accordance with their tag number. The weight loss per unit area of the coupons, corrosion rate, and percentage corrosion inhibition efficiencies of the coatings was calculated over seven weeks. The results obtained were tabulated and represented graphically. From the results obtained, it is seen that the corrosion inhibition efficiency of polyurethane coatings is higher compared with bitumen and polyethylene. It is also seen from the graphs that the corrosion rate of the coupons is higher in acid, a little bit lower in alkaline, and much lower in neutral solution. It is also observed that the corrosion rates fall with time as the inhibition efficiency also falls with time.

scholarly journals ENHANCEMENT OF THE SOLUBILITY OF FAMOTIDINE SOLID DISPERSION USING NATURAL POLYMER BY SOLVENT EVAPORATION

2021 ◽  
pp. 193-198
Author(s):  
HUSSEIN K. ALKUFI ◽  
ASMAA M. RASHID
Keyword(s):  
Hyaluronic Acid ◽  
Solid Dispersion ◽  
Solid Dispersions ◽  
Solvent Evaporation ◽  
Water Soluble ◽  
Poorly Soluble Drugs ◽  
Natural Polymer ◽  
Solubility Study ◽  
Poorly Soluble ◽  
Pure Drug

Objective: The aims of the study to enhance solubility and dissolution of famotidine using natural polymer. Solubility study of a drug is one of the contributing factors of its oral bioavailability. The formulation of poorly soluble drugs for oral delivery presents a challenge to the formulation technologists. Methods: The present study has shown that it is possible to raise the solubility for poorly soluble drugs like famotidine, by preparing solid dispersion using natural water-soluble polymer (xyloglucan and hyaluronic acid) as solubilizer through solvent evaporation method. Physical mixture and solid dispersion of famotidine with xyloglucan (XG) or hyaluronic acid in a ratio of 1:1, 1:2, 1:3 were prepared. Solubility study, drug content, dissolution profile and compatibility study were performed for famotidine in solid dispersions XS1, XS2, XS3, HS4, HS5, HS6 as well as in physical mixtures at a ratio 1:1 for both polymer (XG and hyaluronic acid). Results: It was observed that solid dispersions of each drugs showed an increase in dissolution rate in comparison with its pure drug in the ratio of 1:1 (Drug: carrier). It can be concluded that with the care and proper use of xyloglucan, the solubility of drugs poorly soluble can be improved. The prepared solid dispersion showed improvement of drug solubility in all prepared formulas. The best result was obtained with formula XS1 (famotidine: xyloglucan at ratio 1:1) that showed 26 fold increase in solubility compared to the solubility of pure drug. Conclusion: The natural solid dispersion, increased wettability and reduced crystallinity of the drug which leads to improving solubility and dissolution.

scholarly journals Water-Soluble and Biodegradable Pectin-Grafted Polyacrylamide and Pectin-Grafted Polyacrylic Acid: Electrochemical Investigation of Corrosion-Inhibition Behaviour on Mild Steel in 3.5% NaCl Media

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
R. Geethanjali ◽  
A. Ali Fathima Sabirneeza ◽  
S. Subhashini
Keyword(s):  
Electron Microscopy ◽  
Mild Steel ◽  
Corrosion Inhibition ◽  
Polyacrylic Acid ◽  
Water Soluble ◽  
Electrochemical Investigation ◽  
Grafted Polymers ◽  
Tafel Polarization ◽  
Inhibition Performance ◽  
Scanning Electron

Pectin-g-polyacrylamide (denoted as Pec-g-PAAm) and pectin-g-polyacrylic acid (denoted as Pec-g-PAA) were synthesized using pectin, acrylamide, and acrylic acid as starting materials. The grafted polymers were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyser (TGA), and scanning electron microscopy (SEM). The corrosion inhibition behaviour of the grafted polymers on mild steel in 3.5% NaCl was evaluated electrochemically through Tafel polarization and impedance studies. The corrosion inhibition performance of both the polymers was found to be around 85%.

scholarly journals Application of Hydrotropic Solubilization in Spectrophotometric Estimation of Lornoxicam from Tablets

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Sindhu Abraham ◽  
Rajamanickam Deveswaran ◽  
Sharon Furtado ◽  
Srinivasan Bharath ◽  
Varadharajan Madhavan
Keyword(s):  
Aqueous Solubility ◽  
Cost Effective ◽  
Water Soluble ◽  
Alkaline Solutions ◽  
Primary Dysmenorrhoea ◽  
Cyclooxygenase 1 ◽  
Water Soluble Drugs ◽  
Label Claim ◽  
Poorly Water Soluble ◽  
Hydrotropic Agent

Lornoxicam is a selective cyclooxygenase-1 and cyclooxygenase-2 inhibitor that exhibits anti-inflammatory, analgesic, and antipyretic activities. It is used in osteoarthritis and rheumatoid arthritis; and in treatment of postoperative pain and primary dysmenorrhoea. Lornoxicam is completely insoluble in water but soluble in alkaline solutions. Hydrotropic solubilization is a technique used to increase the aqueous solubility of poorly water-soluble drugs and the present study was aimed at developing a hydrotropic technique to increase the solubility of lornoxicam, using 2 M sodium benzoate as the hydrotropic agent. Beer’s law was obeyed in the concentration range of 4–24 μg/mL at 381 nm. The solubility of lornoxicam in distilled water considerably increased with the addition of a hydrotropic agent. The analysis of tablets indicated good correlation between the amounts estimated and label claim. The LOD and LOQ of lornoxicam were found to be 0.34 μg/mL and 1.038 μg/mL, respectively, indicating good sensitivity of the proposed method. The percentage recovery was found to be 99.99%–100.21%. Thus the proposed method is new, simple, environmentally friendly, accurate, and cost effective and can be successfully employed in routine analysis of lornoxicam in tablets.

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