National Chemical Laboratory

About: National Chemical Laboratory is a facility organization based out in Pune, Maharashtra, India. It is known for research contribution in the topics: Catalysis & Enantioselective synthesis. The organization has 8891 authors who have published 14837 publications receiving 387600 citations.

Effect of surface chemistry of Fe-Ni nanoparticles on mechanistic pathways of azo dye degradation.

Abstract: The degradation of Orange G, a monoazo dye, in aqueous solutions was investigated using as-synthesized and stored Fe-Ni bimetallic nanoparticles. Batch experiments with a nanocatalyst loading of 3 g/L showed complete dye degradation (150 mg/L) after 10 min of reaction time. HPLC-MS analysis of the degradation products showed that as-synthesized nanoparticles reductively cleaved the azo linkage to produce aniline as the major degradation product. However, 1-year-stored nanoparticles showed an oxidative degradation of Orange G through a hydroxyl-radical induced coupling of parent and/or product molecules. XPS analysis in corroboration with HPLC-MS data showed that the surface chemistry between Fe and Ni in as-synthesized and stored nanoparticles play a crucial role in directing the mode of degradation. Reductive dye degradation using as-synthesized nanoparticles proceeded through hydride transfer from nickel, whereas formation of a Fe2+ -Ni(0) galvanic cell in stored nanoparticles generated hydroxyl radicals from water in a nonFenton type reaction. The latter were responsible for the generation of radical centers on the dye molecule, which led to a coupling-mediated oxidative degradation of Orange G. The generation of hydroxyl radicals is further substantiated with radical quenching experiments using ascorbic acid indicating that stored nanoparticles degrade Orange G through a predominantly oxidative mechanism. HPLC-MS and XPS analysis of dye degradation using as-synthesized nanoparticles exposed to air and water confirmed that the reductive or oxidative degradation capability of Fe-Ni nanoparticles is decided by the time and type of catalyst aging process.

Local electronic structure and magnetic properties of LaMn0.5Co0.5O3 studied by x-ray absorption and magnetic circular dichroism spectroscopy dichroism spectroscopy

Abstract: We have studied the local electronic structure of $\mathrm{La}{\mathrm{Mn}}_{0.5}{\mathrm{Co}}_{0.5}{\mathrm{O}}_{3}$ using soft-x-ray absorption spectroscopy at the $\mathrm{Co}\text{\ensuremath{-}}{L}_{3,2}$ and $\mathrm{Mn}\text{\ensuremath{-}}{L}_{3,2}$ edges. We found a high-spin ${\mathrm{Co}}^{2+}\text{\ensuremath{-}}{\mathrm{Mn}}^{4+}$ valence state for samples with the optimal Curie temperature. We discovered that samples with lower Curie temperatures contain low-spin nonmagnetic ${\mathrm{Co}}^{3+}$ ions. Using soft-x-ray magnetic circular dichroism, we established that the ${\mathrm{Co}}^{2+}$ and ${\mathrm{Mn}}^{4+}$ ions are ferromagnetically aligned. We also revealed that the ${\mathrm{Co}}^{2+}$ ions have a large orbital moment: ${m}_{\mathrm{orb}}∕{m}_{\text{spin}}\ensuremath{\approx}0.47$. Together with model calculations, this suggests the presence of a large magnetocrystalline anisotropy in the material and predicts a nontrivial temperature dependence for the magnetic susceptibility.

Biomass to biodegradable polymer (PLA)

Abstract: Lignocellulosic biomass is renewable and cheap, and it has the potential to displace fossil fuels for the production of fuels and chemicals. Biomass derived lactic acid is an important compound that can be used as a chemical platform for the production of a variety of important chemicals on a large scale. The quality of the monomers of lactic acid and lactide, as well as the chemical changes induced during polymerization and processing, are crucial parameters for controlling the properties of the resulting polylactic acid (PLA) products. In this review, we outline the process of exploiting biomass for the production of polylactic acid, a biodegradable polymer which is well-known as a sustainable bioplastic material.