Co+2, Ni+2 and Cu+2 incorporated Bi2O3 nano photocatalysts: Synthesis, DFT analysis of band gap modification, adsorption and photodegradation analysis of rhodamine B and Triclopyr.

This study deals with the fabrication of metal ion (M = Co+2, Ni+2, and Cu+2) doped- Bi2O3 photocatalysts by solution combustion method. All the synthesized materials were characterized and analysed with the help of XRD, FESEM, EDX, HRTEM, UVDRS, Zeta potential, PL, and LCMS techniques for the structural, morphological, surface charge, optical and degradation pathways characteristics. Synthesized compounds were used for the decontamination (adsorption and degradation) of two organic pollutants namely Rhodamine B and Triclopyr. Adsorption aspects of the pollutants were studied in terms of different isotherm, kinetic and thermodynamic models. Adsorption phenomenon was best fitted with the Freundlich (R2 = 0.992) and Langmuir isotherm (R2 = 0.999) models along with pseudo second order model of kinetics for RhB and TC, respectively. Moreover, the thermodynamic parameters indicated exothermic and endothermic adsorption (ΔH ° (-7.19 kJ/mol) for RhB) and (ΔH ° (52.335 kJ/mol) for TC), respectively. Evaluated negative values of ΔG ° indicated spontaneous adsorption with most favourable at 298 K and 318 K for both the pollutants (RhB and TC) respectively. Modification with metal ions significantly improved the removal efficiency of pure Bi2O3 photocatalyst and followed the trend Co+2/Bi2O3 > Ni+2/Bi2O3 > Cu+2/Bi2O3 > Bi2O3. DFT calculations demonstrate that amongst the doped materials, only Co+2/Bi2O3 is characterized by an indirect band gap; which exhibited efficacious photocatalytic activity. Besides, the highest degradation efficiency was obtained in the case of Co+2/Bi2O3 (2 mol %); being 99.80% for RhB in 30 min and 98.50% for TC in 60 min, respectively. The doped nanostructures lead to higher absorption of visible light and more separation of light-induced charged carriers. Effect of pH of the reaction medium and role of reactive oxygen species was also examined. Finally, a probable mechanism of charge transfer and degradation of the pollutants was also presented.

Photocatalytic TiO2/CdS/ZnS nanocomposite induces Bacillus subtilis cell death by disrupting its metabolism and membrane integrity.

Titanium dioxide (TiO2) is widely characterized for its application in clinical diagnostics, therapeutics, cosmetics, nutrition, and environment management. Despite enormous potential, its dependence on ultraviolet (UV) light for photocatalytic activity limits its commercialization. Accordingly in the present study, a photo catalytically superior ternary complex of TiO2 with Cadmium sulfide/Zinc sulfide (CdS/ZnS) has been synthesized, as well as, characterized for photo-induced antimicrobial activity. The band gap of crystalline TiO2/CdS/ZnS nanocomposite has been reduced (2.26 eV) and nanocomposite has shown the optimal photo-activation at 590 nm. TiO2 nanocomposite has significant bactericidal activity in visible light (P < 0.01). Exposure of the TiO2 nanocomposite affected the cellular metabolism by altering the 1681 metabolic features (P < 0.001) culminating in poor cellular survivability. Additionally, photo-induced reactive oxygen species generation through nanocomposite disrupts the microbial cellular structure. The present study synthesized photocatalytic nanocomposite as well as unveiled the holistic cellular effect of theTiO2/CdS/ZnS nanocomposite. Additionally, the present study also indicated the potential application of TiO2/CdS/ZnS nanocomposite for sustainable environment management, therapeutics, and various industries. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12088-021-00973-z.

TiO2 and its composites as promising biomaterials: a review.

TiO2 is a well-known material and has remarkable physical, chemical and biocompatible properties which have made it a suitable material in the biological world. The development of new TiO2-based materials is strongly required to achieve desired properties and applications. A large number of TiO2 composites have been synthesized and applied in various fields. The present review reports the utility of TiO2 and its composites in biosensing, in Photodynamic Therapy, as an antimicrobial agent and as a nanodrug carrier. The aim of this review is to discuss the biological application of the TiO2 based materials and some recent advancement in TiO2 to enhance its application in the biological world.

Glacial lake outburst floods threaten China-Nepal connectivity: Synergistic study of remote sensing, GIS and hydrodynamic modeling with regional implications.

Holistic study of glacial lakes and glacial lake outburst floods (GLOFs) in the strategically important China-Nepal transportation corridors is imperative for regional connectivity and disaster risk reduction. This study focuses on four China-Nepal transportation corridors, namely Chentang-Kimathanka, Zhangmu-Kodari, Keyrung-Kathmandu and Taklakot-Hilsa from east to west in the Himalayan region. Within a remote integrated framework, we present the latest high-resolution inventory of glacial lakes, assess their decadal spatio-temporal changes (1992-2022), identify potentially dangerous glacial lakes, and apply hydrodynamic model to assess downstream impacts of possible GLOFs along the study area. The results show 2688 glacial lakes (≥0.001 km2) with a total area of 116.10 ±â€¯8.53 km2 over the study area in 2022. Glacial lakes exhibited spatiotemporal heterogeneity in expansion, with overall expansion of 32 % during 30 years. Keyrung-Kathmandu corridor, among others, was assessed with high GLOF susceptibility. Furthermore, hydrodynamic modeling of four highly dangerous lakes in each transportation area reveals that GLOFs have cross-border effects, impacting ~103 km of China-Nepal highway, 103 bridges, two major dry ports and 3301 buildings in both countries. Based on these findings, we emphasize the joint efforts of both countries for integrated disaster management for smooth connectivity between two countries and saving downstream population through joint cooperation from central to local government levels by initiating artificial lake lowering, developing cross-border early warning systems and cooperation. This study is valuable for presenting a synergistic study of glacial lakes and GLOF for informing decision- and policy-makers of both China and Nepal for a joint approach to disaster mitigation.

Water and methyl isothiocyanate distribution in soil after drip fumigation.

Methyl isothiocyanate (MITC) generators, such as metam sodium (Met-Na), are used for soil fumigation of agricultural land. The ban on the fumigant methyl bromide has resulted in greater use of MITC generators. To understand the efficacy of MITC, it is necessary to assess its generation and disappearance kinetics when Met-Na is applied to soil. This study evaluated the movement of water and distribution and dissipation of MITC in soil after application of Met-Na through surface drip irrigation systems. The effects of varying water application volume (25, 50, and 75 mm) and rate (1.9, 5.0, and 7.5 L h m) were evaluated in a sandy loam soil. Good fumigant distribution within the sandy loam soil was observed under medium water application amount (50 mm) with slow to intermediate drip application rates (1.9-5.0 L h m). Low water application amount (25 mm) or high application rate (7.5 L h m) did not provide adequate MITC distribution throughout the soil bed width and rooting depth. Dissipation patterns of MITC in soil in all water application amounts and rates followed first-order kinetics, with a rate constant of 0.025 ± 0.004 h and a half-life of 27 ± 3 h. Simulated water distribution through the soil profile using HYDRUS 2D/3D fitted measured field data well, and the model accurately simulated MITC fumigant distribution in the soil.