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1 – 10 of 27Rahul Patil, Lina Jadhav, Nikhil Borane, Satyendra Mishra and Vikas Patil
Here, diazo coupling reaction was imparted on chemically inert lignin isolated from natural resources. Activated lignin was coupled with the diazotised aniline, m-nitroaniline, p…
Abstract
Purpose
Here, diazo coupling reaction was imparted on chemically inert lignin isolated from natural resources. Activated lignin was coupled with the diazotised aniline, m-nitroaniline, p-nitroaniline-, and p-anisidine gives organic pigments.
Design/methodology/approach
The continuous increase in particle size of pigments confirms addition of diazotised salt to lignin by coupling reaction. Further, the dispersing ability of these coloured pigments were exploited in polymer matrix. Epoxy-polyamine cross linking system was doped with difference percentage of pigments and coated on mild steel metal surface. The morphology of these composites was understood by SEM, particle size, differential scanning calorimeter and thermo gravimetric analysis.
Findings
The synthesised organic pigments were characterised by FT-IR, 1H NMR and UV-visible spectroscopy. It was observed that hiding power of aniline- and m-nitroaniline–based azo pigments was more than p-nitroaniline- and p-anisidine–based azo pigments. Thermal properties as well as water contact angles of coatings were improved with pigment concentration. The chemical resistivity of coating was observed to be improved with the increasing % of lignin-based azo pigment.
Originality/value
Lignin-based azo pigment has great potential to replace metal oxide pigment and provide strategy for utilisation of lingo-cellulosic biowaste material.
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Yanyan Pu, Zongchao Yu, Fengqin Wang, Yiyuan Fu, Tao Yan and Honglin Cheng
The purpose of this study is to develop luminescence sensors for the detection of nitroaromatic compounds (NACs) and metal ions to protect human health and prevent environmental…
Abstract
Purpose
The purpose of this study is to develop luminescence sensors for the detection of nitroaromatic compounds (NACs) and metal ions to protect human health and prevent environmental pollution.
Design/methodology/approach
The composition and morphology of Eu-metal-organic frameworks (MOF) (1) were well characterized by powder X-ray diffraction, elemental analyses, Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy and scanning electron microscopy. The emission spectrum displays that 1 has significant characteristic emission bands of Eu(III) ions. The authors further investigated the fluorescence sensing performances of 1 to NACs and metal ions.
Findings
The results show that Eu-MOF (1) exhibits significant fluorescence quenching effect toward p-nitroaniline and Fe3+ ions with good stability and recyclability. This means that 1 can be used as a multifunctional sensing material for the detection of p-nitroaniline and Fe3+ ions.
Originality/value
The authors have successfully synthesized a fluorescence Eu-based sensing material under hydrothermal conditions. In addition, the fluorescence property and sensing performances for detecting NACs and metal ions were studied. The results suggest that 1 has highly selective fluorescence quenching toward p-nitroaniline and Fe3+ ions with not only high sensitivity and selectivity but also excellent stability and recyclability. Furthermore, this study has confirmed that the multifunctional MOF material is very useful in environment pollutants’ detection and monitoring.
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B. Ramesh Babu and K. Thangavel
To study the effects of isomers of organic compounds such as phenylenediamine, toluidine and nitroaniline as inhibitors for the corrosion of carbon steel in sulfuric acid.
Abstract
Purpose
To study the effects of isomers of organic compounds such as phenylenediamine, toluidine and nitroaniline as inhibitors for the corrosion of carbon steel in sulfuric acid.
Design/methodology/approach
Standard methods have been adopted in this study such as weight loss, polarization tests, impedance measurements and hydrogen permeation studies to find out the corrosion behavior of carbon steel in sulfuric acid with and without inhibitors.
Findings
All the selected isomers inhibited the corrosion. The best performance was found in ortho‐phenylenediamine when compared with other inhibitors under study.
Originality/value
It clearly shows the effect of isomers of phenylenediamine, toluidine and nitroaniline. The method of study may be applicable to find out the performance of other isomers of organic compounds. As these isomers behave as good inhibitors in sulfuric acid, these may be tried as inhibitors in other acids. Hence, this study is useful to academics and researchers in the field of corrosion science and engineering.
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M.N. DESAI, V.K. SHAH and M.H. GANDHI
Due to the constituent nitrogen atom of the amino group, amines have been extensively used as inhibitors of metallic corrosion. This article reviews the reported uses of aniline…
Abstract
Due to the constituent nitrogen atom of the amino group, amines have been extensively used as inhibitors of metallic corrosion. This article reviews the reported uses of aniline and related aromatic amines as corrosion inhibitors.
Galal H. Elgemeie, Maher H. Helal and Heba M. El‐Sayed
The synthesis and chemistry of nitrogen heterocyclic azo compounds have been extensively studied. Many derivatives of this type were proved to be excellent dyes. Presents a…
Abstract
The synthesis and chemistry of nitrogen heterocyclic azo compounds have been extensively studied. Many derivatives of this type were proved to be excellent dyes. Presents a systematic and comprehensive survey of all recently synthesised nitrogen heterocyclic azo dyes according to dyeing methods.
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M.H. Helal, G.H. Elgemeie, M.A. El‐kashouti, M.M. ElMolla, H.S. Elsayad and K.A. Ahmed
The purpose of this paper is to synthesise some disperse dyes containing a reactive group and study their applications on polyamide and wool printing by heat transfer and screen…
Abstract
Purpose
The purpose of this paper is to synthesise some disperse dyes containing a reactive group and study their applications on polyamide and wool printing by heat transfer and screen printing.
Design/methodology/approach
To prepare these dyes, arylhydrazones of acetylacetone were reacted with cyanothioacetamide in boiling ethanolic sodium ethoxide. The resultant salt was collected by filtration and dried, then the salt was dissolved in ethanol and reacted with chloroacetylchloride with stirring for 3 h, where chloroacetylechloride was added dropwise. The final precipitated product was collected by filtration and crystallised with an appropriate solvent. These prepared dyes were used to print polyamide and wool fabrics by using synthetic thickener in the printing paste for all techniques.
Findings
The structure of the synthesised dyes were established and confirmed for the reaction products on the basis of their elemental analysis and spectral data (MS, IR and 1H‐NMR). The suitability of the prepared dyestuffs for either heat transfer printing or traditional printing on nylon 6 and wool fabrics was investigated. The prints obtained from dyes possess high‐colour strength as well as excellent overall fastness properties.
Research limitations/implications
The synthesised heterocyclic reactive disperse azo dyes were prepared from the reaction of arylhydrazones of acetylacetone and thiocyanoacetamide to form the corresponding pyridinethione salts which underwent further reaction with chloroacetylchloride. The obtained dyes were utilised in preparing a paste for polyamide and wool fabric printing. In addition, both of the variation of the substituents on the synthesised dyes and the fastness properties were also studied.
Practical implications
The synthesis and use of reactive disperse dyes provide practical solution to over come the low fastness on polyamide and wool, when they are printed with disperse dyes only.
Originality/value
The result of the work aimed to define the scope and limitation of the authors' procedures for the synthesis of novel reactive disperse azo dyes to improve the low‐fastness properties of polyamide and wool, the dyes were synthesised in a simple way.
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STEEL Anti‐corrosive carbonate layer. Calcium bicarbonate, which is present in virtually any natural water, suppresses the corrosion of steel if it is allowed to form—together…
Abstract
STEEL Anti‐corrosive carbonate layer. Calcium bicarbonate, which is present in virtually any natural water, suppresses the corrosion of steel if it is allowed to form—together with corrosion products—a coherent adhesive layer of calcium carbonate on the steel surface. The deposition of such a layer depends on the flow and the temperature of the water as well as on the concentration of calcium bicarbonate. Recent Czechoslovak work has been concerned with the use of radioactive calcium‐45 in the study of the influence of these factors on the formation of protective calcium‐carbonate layers in cold and warm water with low calcium bicarbonate content.
Siddhesh Umesh Mestry, Vardhan B. Satalkar and S.T. Mhaske
This study aims to describe the design and synthesis of two novel azo and imine chromophores-based dyes derived from two different aldehydes with intramolecular colour matching…
Abstract
Purpose
This study aims to describe the design and synthesis of two novel azo and imine chromophores-based dyes derived from two different aldehydes with intramolecular colour matching that are pH sensitive.
Design/methodology/approach
The visible absorption wavelength (λmax) was extended when azo chromophore was included in imine-based systems. The dyed patterns created sophisticated colour-changing paper packaging sensors with pH-sensitive chromophores using alum as a mediator or mordant. Due to the tight adhesive bonding, the dyes on paper’s cellulose fibres could not be removed by ordinary water even at extremely high or low pH, which was confirmed by scanning electron microscopy analysis. The dyed patterns demonstrated an evident, sensitive and fast colour-changing mechanism with varying pH, from pale yellow to red for Dye-I and from pale yellow to brown-violet for Dye-II.
Findings
The λmax for colour changing was recorded from 400 to 490 nm for Dye-I, whereas from 400 to 520 for Dye-II. The freshness judgement of food was checked using actual experiments with cooked crab spoilage, where the cooked crab was incubated at 37 oC for 6 h to see the noticeable colour change from yellow to brown-violet with Dye-II. The colour-changing mechanism was studied with Fourier transform infrared (FTIR) spectra at different pH, and thin layer chromatography, nuclear magnetic resonance and FTIR spectroscopy studied the desired structure formation of the dyes. Potential uses for smart packaging sensors include quickly detecting food freshness during transportation or right before consumption.
Originality/value
1. Two novel azo-imine dyes have been synthesized with a pH-responsive effect. 2. The pH-responsive mechanism was studied. 3. The study was supported by computational chemistry using density functional theory. 4. The obtained dyes were used to make pH-responsive sensors for seafood packaging to judge the freshness.
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Edelmira Rodriguez-Clemente, Victoria Barrera-Pascual, Humberto Cervantes-Cuevas, Jorge Aldana-González, Jorge Uruchurtu-Chavarin, Mario Romero-Romo and Manuel Palomar-Pardavé
This paper aims to evaluate the corrosion inhibition capacities of synthesized compounds 1-(2-pyridinyl)-2-(o, m-, p-hydroxyphenyl) benzimidazoles in API 5L X52 steel/HCl 1M…
Abstract
Purpose
This paper aims to evaluate the corrosion inhibition capacities of synthesized compounds 1-(2-pyridinyl)-2-(o, m-, p-hydroxyphenyl) benzimidazoles in API 5L X52 steel/HCl 1M corrosion system.
Design/methodology/approach
Electrochemical impedance spectroscopy technique was used.
Findings
The studies determined that under stagnant conditions, the durability and efficiency were maintained over 80 per cent for up to 500 h of immersion, while the residence time started to decrease after 150 h at the best inhibitor concentration (150 ppm).
Practical implications
This work may help to attenuate corrosion problems in the petroleum industry.
Originality/value
It is the first time that 1-(2-pyridiniy)-2-(o-, m-, p-hydroxyphenyl) benzimidazoles were evaluated as corrosion inhibitors.
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H.Z. Shams, M.H. Helal and F.A. Mohamed
Three series of azo dye systems are considered, namely, 5‐oxo‐2‐pyrazoline azo dye systems 9 a‐d,1‐oxo‐pyrazolo pyrazole azo dye systems 10 a, b, c, e, 11 a, b, c, e, 12 a, b, c…
Abstract
Three series of azo dye systems are considered, namely, 5‐oxo‐2‐pyrazoline azo dye systems 9 a‐d,1‐oxo‐pyrazolo pyrazole azo dye systems 10 a, b, c, e, 11 a, b, c, e, 12 a, b, c, e, 13 a‐d and 6‐oxo‐pyranopyrzole azo dye systems 14 a‐d. The shifts of ultraviolet‐visible absorption maxima affected by the structural configuration of the pyrazole dye systems are investigated. The structural effects of the polyfunctionally substituted pyrazole dye systems on the intensity of colour and fastness properties of the dyed fabrics are also discussed. The data of these studies are listed. Colour shades of the synthesized dyes on nylon and acetate fabrics are indicated.