TiO2 nanofibres decorated with green-synthesized PAu/Ag@CQDs for the efficient photocatalytic degradation of organic dyes and pharmaceutical drugs

Organic pollutants such as dyes and pharmaceutical drugs have become an environmental menace, particularly in water bodies owing to their unregulated discharge. It is thus required to develop an economically viable and environment-friendly approach for their degradation in water bodies. In this study, for the first time, we report green route-synthesized plasmonic nanostructures (PM-CQDs (where M: Au and Ag)) decorated onto TiO2 nanofibers for the treatment of toxic dye- and pharmaceutical drug-based wastewater. PM-CQDs are efficaciously synthesized using carbon quantum dots (CQDs) as the sole reducing and capping agent, wherein CQDs are derived via a green synthesis approach from Citrus limetta waste. The characteristic electron-donating property of CQDs played a key role in the reduction of Au3+ to Au0 and Ag+ to Ag0 under visible light irradiation to obtain PAu-CQDs and PAg-CQDs, respectively. Thus, the obtained CQDs, PAu-CQDs, and PAg-CQDs are loaded onto TiO2 nanofibers to obtain a PM-CQD/TiO2 nanocomposite (NC), and are further probed via transmission electron microscopy, scanning electron microscopy and UV-visible spectrophotometry. The degradation of organic pollutants and pharmaceutical drugs using methylene blue and erythromycin as model pollutants is mapped with UV-vis and NMR spectroscopy. The results demonstrate the complete MB dye degradation in 20 minutes with 1 mg mL−1 of PAu-CQD/TiO2 NC, which otherwise is 30 minutes for PAg@CQD/TiO2 dose under visible light irradiation. Similarly, the pharmaceutical drug was found to degrade in 150 minutes with PAu-CQD/TiO2 photocatalysts. These findings reveal the enhanced photocatalytic performance of the green-synthesized Au decorated with TiO2 nanofibers and are attributed to the boosted SPR effect and aqueous-phase stability of Au nanostructures. This study opens a new domain of utilizing waste-derived and green-synthesized plasmonic nanostructures for the degradation of toxic/hazardous dyes and pharmaceutical pollutants in water

A Vibrant Accelerating Strategic Solvent System for Sustainability and Functionality for Proteins: Unvarying Structure of Stem Bromelain in Hybrid Ionic Fluids

Very recently, a new class of cosolvents, hybrid ionic fluids (HIFs), have been designed by combining an ionic liquid (IL) and a deep eutectic solvent (DES) with a common anion. The product HIF formed is devoid of the deleterious effects of one component and has augmented advantageous characteristics of the other component, and is emerging as a fascinating sustainable solvent media and a new environmentally friendly solvent for biomolecules. Herein, we present the effects of 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]), DES (synthesized using 1:2 choline chloride and glycerol), and their respective HIF on the structural stability and enzymatic activity of stem bromelain (SB). The spectroscopic results explicitly elucidated that [Emim][Cl] interacts favorably with SB and affects the structural as well as thermal stability of SB, whereas the stability and activity of the enzyme were increased in DES. Interestingly, the results obtained for HIF were the intermediate of the two (IL and DES) as the enzymatic activity of SB in the presence of HIF is maintained at all studied concentrations. Moreover, with the help of TEM and AFM studies, the changes in morphologies of SB in the presence and in the absence of IL, DES, and HIF were ascertained, and it was found that the morphology of SB in the presence of HIF and DES was similar to that of SB in buffer (control), indicating that DES and HIF preserve the native structure of SB. In other words, the morphology of SB has changed in the presence of IL. Apparently, the morphological results are in accordance with the spectroscopic results; thus, HIF significantly enhances the structural stability and enzymatic activity of SB, eventually confirming the suitability of HIF media as a potential and ecofriendly prolonged storage system for SB’s native structure