Showing papers on "Sodium hypophosphite published in 2021"

Alternative microwave curing approach for imparting ease and care characteristics and antimicrobial activity to viscose fabric

Abstract: This study aims to use multi-functional viscose fabric that was facilely developed with with respect to ease and care characteristics, reinforcement effect and antibacterial activity by using novel echo friendly antibacterial finish based on citric acid/sodium hypophosphite and the authors’ previously tailor-made poly meth acrylic acid (MAA)-chitosan graft copolymer via alternative microwave curing approach instead of traditional high-temperature cure one.,Viscose fabric was paddled twice in the cross-linking formulations containing different concentrations of citric acid, poly (MAA)-chitosan graft copolymer and sodium hypophosphite to 90 % wet pick up and dried at 100°C for 3 min in an electric oven. Then, the treated fabrics were placed on the disk spinner of the microwave oven and cured at different power (100–800 Watt) for various durations (60–180 s). The fabric was then water-rinsed and dried at ambient condition before use.,Results revealed that the above echo friendly method for finished viscose fabrics was found to achieve relatively high dry wrinkle recovery angle and maintain the loss in tensile strength within the acceptable range, as well as antibacterial activity against Escherichia coli and Staphylococcus aureus as a gram-negative and gram-positive bacteria, respectively; in addition to durability up to ten washing cycles. Furthermore, scanning electron microscope images, nitrogen content and add on % of the finished fabric confirmed the penetration of grafted chitosan inside the fabric structure. The tentative mechanism for these reactions is advocated.,The novelty addressed here is undertaken with the advantages of using citric acid as a nonformaldehyde, safe and cheap poly carboxylic acid as a crosslinking agent and sodium hypophosphite as a potential catalyst, in addition to the authors’ noncitable multifunctional echo friendly tailor-made poly (MAA)-chitosan graft copolymer for imparting reinforcement and antibacterial characteristics to viscose fabric that uses the pad-dry/cure microwave fixation for progressively persuaded heat within the fabric during curing.,This was done to see the impact of microwave as green and efficient tool with respect to reduction in organic solvents, chemicals and exposer time as well as fixation temperature on the finishing reaction in comparison with traditional pad-dry-cure method.,Poly (MAA)-chitosan graft copolymer as amphoteric biopolymer was expected to impart multifunctional properties to viscose fabrics especially with comparable dry wrinkle recovery angle and minimize the loss in tensile strength in addition to antibacterial properties in comparison with untreated one.

Controlled synthesis of P-Co3O4@NiCo-LDH/NF nanoarrays as binder-free electrodes for water splitting.

Abstract: The design and development of robust and environmentally friendly electrocatalytic materials are of great significance to the hydrogen production industry for the electrolysis of water. A series of P-Co3O4@NiCo-LDH/NF materials was firstly successfully synthesized by a hydrothermal method, high temperature calcination and an electrochemical deposition approach when sodium hypophosphite was used as the source of P and Ni(NO3)2·6H2O as the source of nickel and introduced cobalt at the same time. The structure, composition, morphology and electrochemical performance of the P-Co3O4@NiCo-LDH/NF electrocatalytic material were determined by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and electrochemical performance testing. It is worth noting that the P-Co3O4@NiCo-LDH-2/NF material presents excellent hydrogen evolution reaction performance in 1 M KOH alkaline solution. It only needs an overpotential of 181 mV to drive a current density of 100 mA cm−2, which is one of the best catalytic activities reported so far. The experimental results and theoretical calculations demonstrate that the electrocatalytic activity of the P-Co3O4@NiCo-LDH-2/NF material is attributed to the faster electron transfer rate, exposure of more active sites, optimal water adsorption energy and better electrical conductivity.

Enhancement of antifungal capability of cotton textiles coated with TiO2–SiO2/chitosan using citric acid and sodium hypophosphite catalyst

Abstract: The study conducted an entrapment of TiO2–SiO2/chitosan nanocomposite compounds with Ti and Si molar compositions of 1:3 on cotton fibers using citric acid as a crosslinker. It was carried out usin...

Dimensional stabilisation of Scots pine (Pinus sylvestris L.) sapwood by reaction with maleic anhydride and sodium hypophosphite

Abstract: Wood has the ability to absorb and desorb moisture, which can affect its dimensional size when in use. Limiting this can provide products with greater shape stability and less stresses on external coatings. One method that has been investigated for achieving this has been through chemical modification. In this work, the dimensional stabilisation imparted to Scots pine sapwood by chemical modification with maleic anhydride (MA) combined with sodium hypophosphite (SHP) was investigated. The influence of concentration of MA, treatment temperature and treatment period on weight percent gain (WPG) and bulking coefficient (BC) during treatment with MA and SHP of wood was studied. Furthermore, dimensional stability was determined by the water soak/oven dry method (wet-dry cycle) through five cycles in order to determine the hydrolytic stability of the ester bond and any potential cross-linking reactions. Wood blocks (20 × 20 × 10 mm) modified with MA combined with SHP exhibited lower weight loss following water soaking than unmodified blocks or MA-treated blocks. Wood blocks modified with MA and SHP showed the best anti-swelling efficiency and minimum wet-volume (water-saturated). However, as the concentration of SHP increased, dimensional stability was diminished without any increase in weight percentage gain after water soaking. When combined with FTIR results, it appeared that the modification with MA and SHP seemed to form cross-linking between wood constituents, though high concentration of SHP did not seem to result in additional cross-linking.

An investigation over the effect of the reducing agent on the properties of the ZnO-reinforced Ni–P coatings

Abstract: Electroless ZnO-reinforced Ni–P coatings are developed on mild steel substrates in the Electroless bath, which contains an optimum concentration of ZnO nanoparticles. This work focuses on the characteristics and properties of the Ni–P–ZnO coatings developed at different concentrations of reducing agent (sodium hypophosphite). Results confirm that the reducing agent greatly influences the deposition rate, surface roughness, hardness, and corrosion resistance of the coating. Reducing agent concentration influences the phosphorus present in the coating. An increase in the amorphous nature of the coating with an increase in reducing agent concentration improves the resistance to corrosion of the coating, but at the same time, it decreases the microhardness of the coating. High phosphorus deposition at the maximum amount of reducing agent concentration lowers the microhardness of the coating. The Hard Ni3P crystalline phase formed at 400 °C enhances the resistance to corrosion and microhardness of the coating. Scanning electron microscopy and X-ray diffraction studies are used to characterize the Ni–P–ZnO coating. The microhardness and corrosion resistance of the coating were evaluated using a Vickers microhardness tester and potentiodynamic polarization studies.

Synthesis of ppy–MgO–CNT nanocomposites for multifunctional applications

Abstract: Cotton is one of the most important raw materials for textile and clothing production. The main drawbacks of cotton fibers are their poor mechanical properties and high flammability. Compared with some synthetic polymer fibers, cotton fabrics treated with modern flame-retardant and reinforcement finishes often cannot meet rigid military specifications. Polypyrrole–magnesium oxide (ppy–MgO) and polypyrrole–magnesium oxide–carbon nanotube (ppy–MgO–CNT) composites were prepared with various weight ratios by in situ chemical polymerization method. 1,2,3,4-Butane tetracarboxylic acid (BTCA) was used as a cross-linking agent in the presence of sodium hypophosphite (SHP). The composite sol was coated on cotton fabric using the pad-dry-cure technique. The coated cotton fabrics were characterized by SEM, EDAX, XRD, UV-DRS and FT-IR analysis, and tested for flame retardant and UPF application. The flame-retardant study showed a maximum char length of 0.3 cm and the char yield was about 49% for the ppy–MgO–CNT composite. For that UPF application, a 30 UPF value was shown for the ppy–MgO–CNT composite. In the case of the antibacterial study, the zone of inhibition was observed for all of the test samples against MRSA and PAO1 bacteria. The zone of inhibition showed as 4.0, 3.0 mm for the ppy–MgO–CNT composite. Hence, the ppy–MgO–CNT composite was found to be efficient.

Optimization of electroless Ni-P coating bath and its impact in the Industrial Applications

Abstract: Electroless Ni-P coating is widely used in industrial engineering applications due to its ability to alter and improve the surface properties of the steel substrate. Electroless nickel coating introduce an excellent combination of surface properties. It can add brightness, lustre, and appeal. The final coating layer also possess very good adhesion with coated substrates, this is the reasons for using such layer as an 'undercoat' for other coatings. The ability to produce a very homogenous composition and produce coating with high corrosion resistance are mainly based on the plating bath composition. The present work investigates the influence of bath compositions, which included nickel sulphate, sodium hypophosphite and tri-sodium citrate, on the process of electroless Ni‒P coating. The deposition rate (Dr) as well as the bath stability were monitored to optimize the plating bath conditions with the different composition. The results of this work showed that the deposition rate of coating layer increase with increase of nickel source and reducing agent while; sodium citrate concentration in the plating bath have adverse effect on the deposition rate of coating.

Preparation of Cu@Ag Core-Shell Nanoparticles by NaBH4 Combined with NaH2PO2 as Reductants

Abstract: In this work, sodium borohydride (NaBH4) and sodium hypophosphite (NaH2PO2) were simultaneously used as reductants to prepare Cu@Ag core-shell nanoparticles with a particle size of 300–500 nm. Resu...

Parametric Optimization of Surface Roughness of Electroless Ni-P Coating

Abstract: The present experimental work has been performed to optimize the process parameters of electroless Ni-P coating with the use of statistical modelling via Box–Behnken design of experiment The concentration of nickel sulphate, concentration of sodium hypophosphite and the bath temperature have been chosen as process parameters which have to be optimized considering surface roughness as a response Analysis of variance (ANOVA) method has been employed to determine the significant factors and significant interactions of the factors The statistical model of Box–Behnken design (BBD) method has been successfully utilized to optimize the process parameters for surface roughness of the electroless Ni-P coating Using the response surface model, the optimized conditions to minimize surface roughness have been determined The surface roughness at optimized condition has been observed as 032 µm The Ni-P-coated sample prepared at optimum condition has been characterized by energy dispersive X-ray spectroscopy (EDX) for compositional analysis and scanning electron microscopy (SEM) for explaining the surface morphology

Characterisation of Moisture in Scots Pine (Pinus sylvestris L.) Sapwood Modified with Maleic Anhydride and Sodium Hypophosphite

Abstract: In this study, the wood–water interactions in Scots pine sapwood modified with maleic anhydride (MA) and sodium hypophosphite (SHP) was studied in the water-saturated state. The water in wood was studied with low field nuclear magnetic resonance (LFNMR) and the hydrophilicity of cell walls was studied by infrared spectroscopy after deuteration using liquid D2O. The results of LFNMR showed that the spin–spin relaxation (T2) time of cell wall water decreased by modification, while T2 of capillary water increased. Furthermore, the moisture content and the amount of water in cell walls of modified wood were lower than for unmodified samples at the water-saturated state. Although the amount of accessible hydroxyl groups in modified wood did not show any significant difference compared with unmodified wood, the increase in T2 of capillary water indicates a decreased affinity of the wood cell wall to water. However, for the cell wall water, the physical confinement within the cell walls seemed to overrule the weaker wood–water interactions.

Simple hydrothermal synthesis of g-C3N4/Ni9S8 composites for efficient photocatalytic H2 evolution

Abstract: The prompt recombination between photogenerated electrons and holes is the common problem for improving the hydrogen evolution performance of a photocatalyst, which could be solved greatly by composite co-catalysis. Herein, a simple hydrothermal reaction was utilized to prepare g-C3N4/Ni9S8 composite photocatalysts. Through electroless nickel plating, Ni9S8 nanostructure was homogeneously grown onto the g-C3N4 surface by using sodium hypophosphite as reducing agent. With the optimum loading amount of Ni9S8, the acquired composite, compared with the raw g-C3N4, presented a significant increase in hydrogen evolution rate under visible light irradiation, which was measured as 355.7 μmol g−1 h−1 at 7 °C, being 21.2 times that of raw g-C3N4. The mechanism for the hydrogen evolution reaction over the present g-C3N4/Ni9S8 composite photocatalysts was discussed in detail.

Ru-gC3N4 Catalyzed Hydrodebenzylation of Benzyl Protected Alcohol and Acid Groups Using Sodium Hypophosphite as a Hydrogen Source

Abstract: A straightforward process for hydrodebenzylation of benzyl protected acid and alcohol derivatives to the corresponding acids and alcohols using sodium hypophosphite in the presence of Ru-GCN catalyst is reported. The developed Ru-GCN catalyst is cost effective compared to other noble metal-based catalysts and has been explored to exhibit excellent activity for catalytic hydrodebenzylation reactions under moderate reaction conditions. The non-corrosive sodium hypophosphite has been found as a better hydrogen donor compared to alkali metal formats in presence of Ru-GCN catalyst. The stated catalyst was characterized using several spectrometric and material characterization methods such as PXRD, IR, SEM, TEM, XPS, and TGA. The Ru-GCN catalyst corroborated good reusability and stability for multiple cycles. The catalyst preparation is facile and the developed process is simple and safe as it avoids use of high hydrogen pressure. The developed protocol can also be replicated on industrial scale on account of excellent recyclability and retained activity after multiple cycles and makes the process sustainable. Gram scale reaction was performed to verify the industrial potential of reported catalyst.