Haradhan Kolya

Bio: Haradhan Kolya is an academic researcher from Chonbuk National University. The author has contributed to research in topics: Noise reduction coefficient & Steam explosion. The author has an hindex of 4, co-authored 16 publications receiving 64 citations.

Bioinspired silver nanoparticles/reduced graphene oxide nanocomposites for catalytic reduction of 4-nitrophenol, organic dyes and act as energy storage electrode material

Abstract: Facile and a novel technique for bioinspired synthesis of silver nanoparticles (AgNPs) using an aqueous extract of mango (Mangifera indica) flower as stabilizing and reducing agent was demonstrated. The formation of AgNPs and AgNPs/rGO nanocomposites were confirmed through extensive experimental characterization and numerical analysis. Both, AgNPs and AgNPs/rGO nanocomposites showed excellent catalytic performance in catalytic hydrogenation of 4-nitrophenol and azo bond in dye molecules. The rGO supported Ag nanocomposites exhibited improved catalytic activity compared to AgNPs due to the enhancement of surface area. Electrochemical analysis of AgNPs/rGO nanocomposites showed specific capacitance (SC) of ∼532 F g−1 at a current density of 1.0 A g−1. About 92% retention in SC after 2000 charge-discharge cycles suggested long-term electrochemical cyclic stability as supercapacitor electrode materials. The biogenic nano-particles and composites implied that the rGO reinforced Ag excellent applicants as hydrogenation refining materials. All these observations demonstrated a novel, eco-cost effective and estimable candidates as hydrogenation refining materials and electrode materials.

Green Synthesis of Ag-Au Bimetallic Nanocomposites Using Waste Tea Leaves Extract for Degradation Congo Red and 4-Nitrophenol

Abstract: A sustainable supply of pure water is a great challenge in most developing and third-world countries. Nanomaterial-based technology offers technological development for wastewater purification. Nanocatalysis hydrogenation of nitroarene and dye molecules is a hot model in many research fields. Herein, we report eco-friendly and facile technology to synthesize Ag-Au bimetallic nanocomposites. The synthesized nanocomposites are characterized by ultraviolet–visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The synthesized nanocomposite can efficiently degrade Congo red and 4-nitrophenol in water and in the presence of sodium borohydride. The results show that it degrades Congo red and 4-nitrophenol entirely within 6 and 7 min, respectively. These results could be useful for the green synthesis of Ag-Au bimetallic nanocomposites and help to remove organic dye molecules and nitroaromatics from wastewater.

Chemical composition of mango (mangifera indica l.) fruit : Nutritional and phytochemical compound

Abstract: Mango fruit has a high nutritional value and health benefits due to important components. The present manuscript is a comprehensive update on the composition of mango fruit, including nutritional and phytochemical compounds, and the changes of these during development and postharvest. Mango components can be grouped into macronutrients (carbohydrates, proteins, amino acids, lipids, fatty, and organic acids), micronutrients (vitamins and minerals), and phytochemicals (phenolic, polyphenol, pigments, and volatile constituents). Mango fruit also contains structural carbohydrates such as pectins and cellulose. The major amino acids include lysine, leucine, cysteine, valine, arginine, phenylalanine, and methionine. The lipid composition increases during ripening, particularly the omega-3 and omega-6 fatty acids. The most important pigments of mango fruit include chlorophylls (a and b) and carotenoids. The most important organic acids include malic and citric acids, and they confer the fruit acidity. The volatile constituents are a heterogeneous group with different chemical functions that contribute to the aromatic profile of the fruit. During development and maturity stages occur important biochemical, physiological, and structural changes affecting mainly the nutritional and phytochemical composition, producing softening, and modifying aroma, flavor, and antioxidant capacity. In addition, postharvest handling practices influence total content of carotenoids, phenolic compounds, vitamin C, antioxidant capacity, and organoleptic properties.

Facile Preparation of MnO2-Deposited Wood for High-Efficiency Solar Steam Generation

Abstract: Wood, a natural renewable material, has drawn great attention in solar steam generation in recent years due to its intrinsic properties such as high hydrophilicity and low thermal conductivity. Unt...

Reduction of 4-nitrophenol using green-fabricated metal nanoparticles

Abstract: Noble metal (silver (Ag), gold (Au), platinum (Pt), and palladium (Pd)) nanoparticles have gained increasing attention due to their importance in several research fields such as environmental and medical research. This review focuses on the basic perceptions of the green synthesis of metal nanoparticles and their supported-catalyst-based reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The mechanisms for the formation of these nanoparticles and the catalytic reduction of 4-NP are discussed. Furthermore, the parameters that need to be considered in the catalytic efficiency calculations and perspectives for future studies are also discussed.