Ravindra D. Kulkarni

Ultrasound assisted synthesis of polyacrylic acid–nanoclay nanocomposite and its application in sonosorption studies of malachite green dye

Synthesis of nanoclay nanocomposite has been undertaken by using polyacryalic acid (PAA) in aqueous medium and ultrasound environment and its application in dye removal has been investigated. The synthesized product was characterized by using FTIR and XRD techniques. The sonosorption capacity of the product namely PAA-nanoclay composite was determined by choosing malachite green (MG) dye as a model pollutant. The effects of various parameters such as nanocomposite loading, pH, various process conditions etc. have been studied. On comparing the results obtained with that of nanoclay as an adsorbent, it was found for an initial concentration of 500mg/l, the PAA-nanoclay nanocomposite exhibited higher percentage of pollutant removal (68%) and for nanoclay it was 54%. The adsorption data has been correlated using Langmuir and Freundlich models. The fit of the Freundlich isotherm model was found to be good in the entire range of concentration for the experimental sorption data obtained on the nanoclay nanocomposite. A plausible reaction mechanism for use of PAA-nanoclay nanocomposite as an adsorbent is also proposed.

Synthesis and characterisation of polyurethane coatings based on trimer of isophorone diisocyanate (IPDI) and monoglycerides of oils

SummariesMonoglycerides (MGs) of four oils (castor, linseed, soybean and sesame) were prepared. They were reacted with a trimer in definite proportions to prepare polyurethane (PU) coatings. These coatings were applied in the form of thin films on tin plates and analysed for various coating properties such as gloss, scratch resistance, flexibility properties and physicochemical tests. A highly cross-linked product was obtained due to the higher functionality associated with MGs compared with their molecular weight. The trimer also imparted cross-linking due to its trifunctionality, and a hard yet flexible, tough, glossy polyurethane coating was obtained.RésuméDes monoglycérides (MGs) de quatre huiles (ricin, lin, soya et sésame) ont été préparés. On les a fait réagir, dans des proportions définies, avec une trimère afin de produire des revêtements polyuréthaniques (PU). Ces revêtements ont été appliqués, sous la forme de minces films, à des plaques d’étain, et ont été analysés afin de constater des propriétés de revêtement variées, telles que le brillant, la résistance aux éraflures, les propriétés de flexibilité et [leur performance au cours] des essais physicochimiques. On a obtenu un produit qui était très réticulé grâce à la fonctionnalité plus élevée associée aux MGs par rapport à leur poids molaire. La trimère, aussi, a donné de la réticulation, grâce à sa trifontionnalité, et l’on a obtenu un revêtement polyuréthanique qui était robuste et brillant mais aussi flexible.ZusammenfassungDie Monoglyzeride (MGs) von vier Ölen (Rizinus, Leinsamen, Soja und Sesam) wurden hergestellt und mit einem Trimer in bestimmten Proportionen reagiert, um Polyurthanlacke herzustellen. Diese Lacke wurden in dünnen Schichten auf Zinkplatten aufgebracht und nach verschiedenen Eigenschaften wie Glanz, Kratzfestigkeit, Flexibilität und ihren physiochemischen Eigenschaften bewertet. Dank der grösseren Funktionalität im Verhältnis zu ihrem Molekulargewicht erzielten wir mit den MGs ein stark kreuzvernetztes Produkt. Die dreifache Funktionalitat der Trimere trug auch zu der Kreuzvernetzung bei, und der erhaltene Polyurethanlack war sowohl hart als auch flexibel, widerstandsfähig und glänzend.

Development of anticorrosive two pack polyurethane coatings based on modified fatty amide of Azadirachta indica Juss oil cured at room temperature – a sustainable resource

We report the modification of Azadirachta indica Juss oil (renewable source) fatty amide by the piperazine molecule to develop a new polyol. Two pack polyurethane (PU) coatings on mild steel plates were prepared by reacting newly developed polyol with toluene diisocyanate (TDI) at room temperature. Spectral studies of Azadirachta indica Juss oil based fatty amide and piperazine modified fatty amide were carried out using spectroscopic techniques to confirm the modification. The prepared resins were also characterized by end group analysis such as amine and hydroxyl values. Anticorrosive properties of the prepared PU coatings were examined by immersion test in an aqueous salt solution. The thermal stability of coatings was studied by TGA. Other coating properties such as gloss, scratch hardness, adhesion, flexibility, impact resistance and chemical resistance were evaluated using standard methods. It was observed that the presence of nitrogen containing piperazine moiety in the back bone of the PU chain shows better anticorrosive properties compared with the Azadirachta indica Juss oil fatty amide based PU coatings.

Intensification of corrosion resistance of 2 K epoxy coating by encapsulation of liquid inhibitor in nanocontainer core of sodium zinc molybdate and iron oxide

A unique approach for the synthesis of an iron oxide-blended sodium zinc molybdate nanocontainer using an ultrasound-assisted method and its application for 2 K epoxy polyamide nanocomposite coatings has been presented. Sodium zinc molybdate blended with iron oxide was used as the core of the nanocontainer and layer-by-layer assembly of oppositely charged species of polyelectrolyte and inhibitor was made over this core of nanoparticles. The release of imidazole from iron oxide-blended sodium zinc molybdate nanocontainer has been quantitatively evaluated in water at different pH. It has been observed that imidazole plays a major role in the release profile of polyelectrolyte-modified nanocontainer and deciding the corrosion inhibition characteristics. Addition of 4 wt% nanocontainer in coatings results in shifting of corrosion potential (Ecorr) value towards positive direction. The maximum concentration of imidazole released at the end of 1 h was found to be 0.545 mg L−1/g of nanocontainer at pH of 10. The results of corrosion rate analysis, Tafel plots and electrochemical impedance spectroscopy studies of an iron oxide-blended sodium zinc molybdate nanocontainer-based coatings indicated better inhibition performance compared with neat coating.

Utilization of renewable bio-based resources, viz. sorbitol, diol, and diacid, in the preparation of two pack PU anticorrosive coatings

The present research work reveals the use of renewable ingredients to synthesize the polyester polyol part of polyurethanes as a modification different from the traditional pattern via the melt condensation technique. The difunctional acid used in the preparation of polyester polyol was selected according to the chain length and molecular weight. Both renewable and non-renewable difunctional acids were used for comparing the coating properties of each formulation. Chemical and corrosion resistances were also studied with respect to their effects on final coating properties in terms of their structural parameters for sustainable production of 2K PU coatings. Synthesized coatings were further characterized by techniques like gloss, adhesion, flexibility, and pencil hardness. Overall, sebacic acid based formulation was found to be most suitable among all for coating performance, especially anticorrosive property, gloss, and pencil hardness.

UV cure acrylate monomers: synthesis, analysis and storage

Purpose – The purpose of this paper is to provide a critical and in‐depth review of the present status and recent developments in synthetic methodologies, reaction engineering, process design and quality control aspects associated with the manufacture of mono and multifunctional acrylate monomers.Design/methodology/approach – This paper reviews commercially important UV cure mono and multifunctional acrylate monomers. It covers their synthesis, catalyst, and appropriate solvents for azeotropic removal of byproducts. The detail discussion on catalysis, basis of design of reactors and commercial plant and the process engineering associated with the manufacture has been supported through citation of synthesis of various acrylate monomers. The methodologies adopted for determination of physical, chemical and compositional characterisation of acrylate monomers have been presented. In addition, the guidelines regarding the bulk storage and commercial handling of acrylates have been reviewed.Findings – The react...

Ultrasound assisted organic pigment dispersion: advantages of ultrasound method over conventional method

Purpose – The present work aims to deal with ultrasound-assisted organic pigment (phthalocyanine blue and green) dispersion and its comparison with the conventional approach. Design/methodology/approach – Ultrasound is expected to give beneficial results based on the strong shear forces generated by cavitational effects. The dispersion quality for preparation using an ultrasound-based method has been compared with dispersion obtained using high-speed dispersion mill. Effects of different operating parameters such as probe diameter and use of surfactants on the physical properties of dispersion and the colour strength have been investigated. Calculations for the energy requirement for two approaches have also been presented. Findings – The use of sodium dodecyl sulphate and Tween 80 surfactants shows better performance in terms of the colour properties of dispersion prepared in water and organic solvent, respectively. Ultrasound gives better dispersion quality as compared to the conventional approach. Orig...

Investigation of corrosion inhibition performance of ultrasonically prepared sodium zinc molybdate nanopigment in two-pack epoxy-polyamide coating

In the present work, an innovative approach has been used to synthesize sodium zinc molybdate nanopigment using ultrasound-assisted co-precipitation of sodium molybdate and zinc oxide. X-ray diffraction, Fourier transform infrared and elemental analysis of sodium zinc molybdate nanopigment have been performed which confirmed the formation of sodium zinc molybdate particles. Ultrasound-assisted synthesis gave lower particle size of sodium zinc molybdate nanoparticles (467 nm) which can be explained on the basis of improved solute transfer rate, rapid nucleation, and formation of a large number of nuclei in the presence of ultrasound. The corrosion inhibition effect of sodium zinc molybdate nanopigment in 2K (two-pack) epoxy-polyamide clear coat on low carbon steel has also been studied. The results of the corrosion rate analysis, Tafel plots, and electrochemical impedance spectroscopy of the prepared coatings show better corrosion inhibition performance when sodium zinc molybdate particles were incorporated in the 2K epoxy-polyamide clear coat.

Acoustic and Hydrodynamic Cavitations for Nano CaCO 3 Synthesis

Calcium carbonate is a common inorganic compound known as limestone. Calcium carbonate has many applications in industries such as medicine, agriculture, paint plastic and surface coatings etc. The vast majority of calcium carbonate used in industry is extracted by mining process. Pure calcium carbonate (e.g. for food or pharmaceutical use), is synthesized by passing carbon dioxide into a solution of calcium hydroxide slurry. In this process calcium carbonate precipitates out, and this grade of product is referred to as precipitate calcium carbonate (abbreviated as PCC).

An Active Corrosion Inhibition Coating of Two Pack Epoxy Polyamide System using Halloysite Nanocontainer

This work deals with encapsulation of corrosion inhibitor in inorganic nanocontainer and the investigation of the corrosion inhibition rate from the nanocontainer. Halloysite nanotubes were used as inorganic nanocontainer for encapsulating the active corrosion inhibitor. These cylindrical shaped halloysite nanotubes are a natural aluminosilicate, which possesses similar chemical composition as that of pure kaolin clay. The structural morphology and functional organic attachments to the halloysite nanocontainers were determined by using TEM and FTIR analysis. It is found that, halloysite nanocontainers are having external and internal lumen is in nanosize (diameter) and length up to several micrometers. A maximum benzotriazole loading up to 10% (by weight) was achieved in inorganic nanotube of 50 nm external diameters and lumen of 15 nm. The release of corrosion inhibitor was carried out for 18 h at different pH ranging from 3 to 10. The weight percent of the benzotriazole encapsulated halloysite nanocontainer was varied from 2 to 10 and then dispersed in 2K clear coat epoxy-polyamide. The self-healing anticorrosion performance of these nanocomposites coating was tested with help of electrochemical impendence spectroscopy (EIS) and Tafel plot. From Tafel plots it is found that the Icorr value decreases to 1.018E–7A/cm2 from 0.018 A/cm2, when coating was applied with 2 wt % nanocontainer.