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Article
Publication date: 10 November 2020

Weiling Tuo, Shun'an Cao and Jie Zhong

The purpose of this study was to investigate the corrosion of low molecular organic acids from water-steam cycles such as acetic acid and formic acid in mental parts of…

Abstract

Purpose

The purpose of this study was to investigate the corrosion of low molecular organic acids from water-steam cycles such as acetic acid and formic acid in mental parts of steam turbine initial condensation zone.

Design/methodology/approach

The corrosion behavior of gray cast iron in initial condensate containing different concentrations of acetic acid and formic acid was studied by weight loss test, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction.

Findings

The results indicated that gray cast iron had a certain degree of corrosion in the simulated initial condensate containing acetic acid and formic acid, but the acid corrosion of gray cast iron was not only caused by low molecular organic acid but also affected by inorganic anions such as Cl. When Cl existed, after removing corrosion products, surface analysis results proved that the surface of gray cast iron was rough and uneven with many cracks, which was corrected more serious.

Originality/value

The corrosion behavior of thermal equipment by low molecular organic acids and inorganic anions in water-steam cycles was studied. The research results can provide theoretical guidelines for corrosion control of steam turbine in power plants.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 6
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 June 1973

M.N. Desai and S.S. Rana

Introduction The corrosive attack of nitric acid on copper is mainly due to the nitrous acid formed by the reaction between copper and nitric acid. The reaction is…

Abstract

Introduction The corrosive attack of nitric acid on copper is mainly due to the nitrous acid formed by the reaction between copper and nitric acid. The reaction is conditioned by: the concentration of the acid; temperature; the presence of nitrous acid; and the solubility of the reaction products in the acid. It has been suggested that as soon as a trace of NO2 has been formed by the reaction, NO3− + 2H+ + e → NO2 + H2O, it is quickly reduced to NO2− by the reaction NO2 + e → NO2−. Then NO2− combines with hydrogen ions to give nitrous acid. Nitrous acid can readily react with nitric acid to regenerate twice the original quantity of NO2 by the reaction, HNO2 + HNO3 → 2NO2 + H2O. In each cycle the quantity of NO2 and HNO2 is doubled.

Details

Anti-Corrosion Methods and Materials, vol. 20 no. 6
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 April 2002

Bodo Müller

A severe problem with water‐borne paints containing aluminium or zinc pigments is hydrogen corrosion of these metals in the aqueous alkaline paint media. The subject of…

Abstract

A severe problem with water‐borne paints containing aluminium or zinc pigments is hydrogen corrosion of these metals in the aqueous alkaline paint media. The subject of the present study is the examination of corrosion inhibition of aluminium and zinc pigments in aqueous alkaline media by different amino and polyamino acids. Aspartic acid inhibits this corrosion reaction of aluminium pigment only at pH 8 (protection factor 96 per cent) whereas polyaspartic acids do not. In contrast, aspartic acid stimulates the corrosion reaction of zinc pigment whereas polyaspartic acids show a moderate corrosion inhibiting effect. So, corrosion inhibition by aspartic and polyaspartic acids is completely different on aluminium and zinc pigment.

Details

Pigment & Resin Technology, vol. 31 no. 2
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 August 1997

S.A. Abdel‐Hafiz, F.F. El‐Sisi, M. Helmy and A. Hebeish

Samples of loomstate cotton fabric were first treated with aqueous potassium permanganate solution at different concentrations in the presence of a non‐ionic wetting…

Abstract

Samples of loomstate cotton fabric were first treated with aqueous potassium permanganate solution at different concentrations in the presence of a non‐ionic wetting agent. The samples were then washed and treated using solutions containing methacrylic acid, wetting agent and acid or basic dye along with citric acid of different concentrations at different temperatures for different times. The critical properties of the fabric such as graft yield (expressed as carboxyl content m.eq/100g cellulose), colour strength before and after soaping and percentage loss in colour strength due to soaping were found to depend on the concentrations of KMnO4, citric acid and methacrylic acid as well as duration of the treatment. Based on the results obtained, treating formulations consisting of KMnO4 (0.1g/l), citric acid (0.1g/l), methacrylic acid (50 per cent), dye (1 per cent) and wetting agent (2g/l) was considered appropriate for concurrent grafting and dyeing of the said fabrics provided that the treatment was carried out at 90°C for 60 minutes.

Details

Pigment & Resin Technology, vol. 26 no. 4
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 22 November 2011

Michael J. Mullins, David K. Luttrull and Hans Schumacher

Boric acid has been used for many years as a catalyst inhibitor and crosslinking agent to increase the glass transition temperature of epoxy resins for printed circuit…

Abstract

Purpose

Boric acid has been used for many years as a catalyst inhibitor and crosslinking agent to increase the glass transition temperature of epoxy resins for printed circuit boards (PCB), as well as in the glass fibre reinforcement. Recent regulation related to boric acid and its salts by the ECHA, a regulatory agency in the EU, may limit the use of these materials. The purpose of this paper is to describe the implications of this new regulation and to propose an analytical procedure that is relevant to PCB's.

Design/methodology/approach

Potential analytical procedures, including dissolution in acid and aqueous extraction followed by boric acid titration, are discussed and evaluated.

Findings

The use of acid for the digestion of prepreg, laminates and PCBs has the potential to greatly overstate the concentration of boric acid in PCBs.

Originality/value

An aqueous extraction method (German DIN 38414‐4) gives results that represent a worst‐case leaching process. It is proposed that it becomes the official analytical method for printed circuit boards in order to comply with the ECHA regulation.

Details

Circuit World, vol. 37 no. 4
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 17 May 2013

Pin‐Rou Lee, Rou‐Ming Tan, Bin Yu, Philip Curran and Shao‐Quan Liu

The purpose of this study was to characterise the physiochemical properties of selected exotic seasonal tropical fruits available in Singapore.

Abstract

Purpose

The purpose of this study was to characterise the physiochemical properties of selected exotic seasonal tropical fruits available in Singapore.

Design/methodology/approach

A total of 11 seasonal tropical fruits including cempedak, chiku, custard apple, jackfruit, longkong, mangosteen, red jambu, pearl jambu, rambutan, salak and starfruit were analyzed for their sugars, organic acids and free phenolic acids composition using liquid chromatographic methods. Total phenolic content (free and bound), total soluble solids and pH were determined using Folin‐Ciocalteu method, refractometer and pH meter, respectively.

Findings

Fructose, glucose and sucrose were the main sugars in all the fruits. Cempedak had the highest sucrose concentration, while custard apple had the highest content of fructose and glucose. Malic and citric acids were the major organic acids in most of the fruits, except for pearl jambu and red jambu where succinic acid was the dominant acid. The total phenolic content varied from 122.94 to 712.20 mg gallic acid equivalent (GAE)/kg fresh weight (FW). Ferulic (0.631 mg/kg) and sinapic acids (1.506 mg/kg) were the predominant free phenolic acids in custard apple, while caffeic acid was the main free phenolic acid in jackfruit, salak and starfruit.

Originality/value

The paper demonstrates that the physiochemical characteristics of the 11 tropical fruits varied markedly, which is responsible for the differential flavour and stability. The findings are useful for epidemiological research and predicting the degree of ripeness, stability and post‐harvest processing required for these fruits.

Details

Nutrition & Food Science, vol. 43 no. 3
Type: Research Article
ISSN: 0034-6659

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Article
Publication date: 30 October 2009

Narasimhanaidu Kamalakkannan and Khalid S. Alnumair

The purpose of this paper is to explore the role of rutin, a polyphenolic flavonoid on the fatty acid composition in liver and kidney of streptozotocin (STZ)‐induced diabetic rats.

Abstract

Purpose

The purpose of this paper is to explore the role of rutin, a polyphenolic flavonoid on the fatty acid composition in liver and kidney of streptozotocin (STZ)‐induced diabetic rats.

Design/methodology/approach

Extensive literature review was carried out and no reports on the effect of rutin on the fatty acid composition in diabetic tissues were found.

Findings

Streptozotocin‐induced diabetic rats showed altered lipid concentration in liver and kidney. The fatty acid composition was also altered in these tissues. Treatment with rutin to diabetic rats significantly decreased the concentration of palmitic acid, stearic acid and oleic acid, whereas linolenic and arachidonic acids were significantly increased in liver and kidney of diabetic rats. Rutin administration to normal rats did not show any significant effect on the fatty acid composition in liver and kidney.

Originality/value

This paper gives an idea of the changes in the fatty acid composition of diabetic tissues and during treatment with rutin.

Details

Nutrition & Food Science, vol. 39 no. 6
Type: Research Article
ISSN: 0034-6659

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Article
Publication date: 24 April 2007

Shamina Azeez

The objective of this work is to study the fatty acid profile of coconut oil in the kernel in relation to maturity of the nut and season of fertilization in five selected…

Abstract

Purpose

The objective of this work is to study the fatty acid profile of coconut oil in the kernel in relation to maturity of the nut and season of fertilization in five selected varieties of coconut.

Design/methodology/approach

The coconut oil from the popular cultivars/hybrids were studied in post‐monsoon, pre‐monsoon and monsoon seasons at 7, 8, 10 and 12 months after fertilization.

Findings

Nuts that fertilized in the post monsoon season were found to have higher oil contents. Of the five varieties, COD×WCT had lesser amounts of caprylic, capric and lauric acids and greater amounts of the long chain fatty acids. Though significant differences were observed in fatty acid concentrations in nuts differing in their variety and season of tagging, the trend remained the same.

Originality/value

The study helps to ensure the safety of the usage of coconut oil as dietary oil, from the nature of fatty acids present.

Details

British Food Journal, vol. 109 no. 4
Type: Research Article
ISSN: 0007-070X

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Article
Publication date: 1 June 1997

Inder Singh, A.K. Bhattamishra and D.K. Basu

Stainless steels are very unique in that they offer a wide range and combination of resistance to corrosion, resistance to oxidation at high temperature and good…

Abstract

Stainless steels are very unique in that they offer a wide range and combination of resistance to corrosion, resistance to oxidation at high temperature and good mechanical properties at room temperature. With rapid industrialization all over the world, these very properties have led to extensive use of stainless steels in different industries. Austenitic stainless steels containing molybdenum exhibit corrosion resistance in both sulphuric acid and nitric acid. Stainless steel undergoes severe attack in sulphuric acid having concentrations in the range of 20‐85 per cent, whereas they are immune to nitric acid in any concentration. However, sensitized stainless steels are prone to intergranular attack in acids, even in nitric acid. Further, the attack is aggravated in the presence of aggressive ions. Study of the behaviour of stainless steels in a mixture of acids (nitric and sulphuric acid) is lacking in the literature. This paper, therefore, discusses the performance of AISI‐316 and 316‐L in sulphuric acid and nitric acid and a mixture thereof at room temperature. It is observed that the steels are quite resistant to sulphuric acid and nitric acid, but in the acid mixture they are not so resistant, especially in AISI‐316 SS in respect of corrosion resistance, even in acid mixture containing C1 and Cu++ ions.

Details

Anti-Corrosion Methods and Materials, vol. 44 no. 3
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 February 1992

Richard W. Lacey

Intensive methods of farming and food processing are particularlylikely to result in food inadequate in n‐3 polyunsaturated fatty acids,and also in folic acid. These fatty…

Abstract

Intensive methods of farming and food processing are particularly likely to result in food inadequate in n‐3 polyunsaturated fatty acids, and also in folic acid. These fatty acids are required for numerous metabolic functions including protection against heart attacks. Folic acid is essential for a baby′s developing nervous system.

Details

British Food Journal, vol. 94 no. 2
Type: Research Article
ISSN: 0007-070X

Keywords

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