Expeditious isomerization of glucose to fructose in aqueous media over sodium titanate nanotubes

Isomerization reaction of glucose to fructose over sodium titanate nanotubes (Na-TNTs) as a Lewis base catalyst was studied. Analytical instruments recorded the specific structural, textural and basic properties of the as-synthesized Na-TNTs. Furthermore, studying the catalytic isomerization performance of the Na-TNTs confirmed their high catalytic efficiency and suitability in aqueous media. The catalyst prompted rapid glucose isomerization within 2 min by achieving nearly half of the maximum yield, whereas with a prolonged reaction up to 15 min the maximum glucose conversion could be reached with 31.26% fructose yield and 65.26% selectivity under relatively lower operating conditions (100 °C and 10% wt catalyst dose). However, the recyclability performance of the catalyst was not impressive due to the accelerated leaching of cations and surface retention of carbonaceous content, resulting in ∼16% reduced yield after 4 runs. A simple regeneration technique using NaOH led to the initial catalytic activity being totally regained. Overall, a titania-based catalyst (preferably nanotube structured sodium titanate) was shown as a potential catalyst for large-scale demonstration of glucose isomerization to achieve high fructose productivity

Bi2WO6/C-dots/TiO2: A novel z-scheme photocatalyst for the degradation of fluoroquinolone levofloxacin from aqueous medium

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Photocatalytic materials and semiconductors of appropriate structural and morphological architectures as well as energy band gaps are materials needed for mitigating current environmental problems, as these materials have the ability to exploit the full spectrum of solar light in several applications. Thus, constructing a Z-scheme heterojunction is an ideal approach to overcoming the limitations of a single component or traditional heterogeneous catalysts for the competent removal of organic chemicals present in wastewater, to mention just one of the areas of application. A Z-scheme catalyst possesses many attributes, including enhanced light-harvesting capacity, strong redox ability and different oxidation and reduction positions. In the present work, a novel ternary Z-scheme photocatalyst, i.e., Bi2WO6/C-dots/TiO2, has been prepared by a facile chemical wet technique. The prepared solar light-driven Z-scheme composite was characterized by many analytical and spectroscopic practices, including powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), N2 adsorption–desorption isotherm, Fourier-transform infrared spectroscopy (FT-IR), photoluminescence (PL) and UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity of the Bi2WO6/C-dots/TiO2 composite was evaluated by studying the degradation of fluoroquinolone drug, levofloxacin under solar light irradiation. Almost complete (99%) decomposition of the levofloxacin drug was observed in 90 min of sunlight irradiation. The effect of catalyst loading, initial substrate concentration and pH of the reaction was also optimized. The photocatalytic activity of the prepared catalyst was also compared with that of bare Bi2WO6, TiO2 and TiO2/C-dots under optimized conditions. Scavenger radical trap studies and terephthalic acid (TPA) fluorescence technique were done to understand the role of the photo-induced active radical ions that witnessed the decomposition of levofloxacin. Based on these studies, the plausible degradation trail of levofloxacin was proposed and was further supported by LC-MS analysis

Realizing Direct Conversion of Glucose to Furfurals with Tunable Selectivity Utilizing a Carbon Dot Catalyst with Dual Acids Controlled by a Biphasic Medium

Developing cost-effective processing strategies for the preparation of fuel-precursor chemicals, including 5-hydroxymethylfurfural (HMF) and furfural, has been dedicatedly researched over the last few years. These compounds are typically produced using different carbohydrate sources, say furfural using xylose and HMF using glucose. Herein, we report the significant formation of both these furans using a single glucose source over the fine-tuned Fe2+@SO3-CD nanocomposite. The catalyst exhibiting two different acidic sites, such as Lewis and Brønsted, developed by the iron (II) metal and sulfonate groups, respectively, offered a synergistic effect on the glucose decomposition into furfurals. Mechanistically, the iron (II) Lewis metal acid sites play a vital role in the significant formation of furfurals. Furthermore, the THF/H2O biphasic system influenced a selective formation of HMF and furfural, achieving as high as 85% HMF (94% selectivity) in 1:2 THF/H2O and 56% furfural (90% selectivity) in 1:1 THF/H2O. The recyclability study showed that the catalyst is effective for 4 cycles. The green metrics analysis of the solid acid catalysis represented a greener strategy for furans production. Overall, the catalytic setup can be upscaled because of the involvement of cheaper precursors and less labor-intensive catalyst preparation