Congregating Ag into γ-Bi2O3 coupled with CoFe2O4 for enhanced visible light photocatalytic degradation of ciprofloxacin, Cr(VI) reduction and genotoxicity studies

Flower-like boron-doped zinc single-atom nanozymes for colorimetric sensing and smartphone-assisted detection of Cr(VI)

With the development of electronics, electroplating, printing, and dyeing industries, environmental pollution caused by hexavalent chromium (Cr(VI)) has become increasingly prominent. Skin contact with Cr (VI) can cause allergies or genetic defects, and inhalation can cause cancer, which is a lasting danger to the environment and the human body. Developing effective strategies to monitor Cr(VI) in environmental water or industrial wastewater can evaluate the degree of water pollution and risk warning, thus helping to prevent the spread of Cr(VI) pollution, promote the protection of water resources and the ecological environment, and ensure human safety and sustainable development. On the basis of the regulation of dopamine, boron-doped zinc single-atom nanozymes (Zn/B-NC SAzymes) with three-dimensional nanoflower morphology were controlled in this work. The introduction of B in Zn/B-NC SAzymes and the high metal loading of Zn (6.5 wt%) led to the formation of more active sites, resulting in the material showing excellent enzyme-like activity. H2O2 decomposed to generate superoxide radicals under the catalysis of Zn/B-NC SAzymes, which then oxidized the substrate 3,3',5,5'-tetramethylbenzidine (TMB) to generate blue oxTMB. When Cr(VI) was introduced into the sensor system, the color of blue oxTMB is deepened, and the colorimetric method of Cr(VI) was constructed. The linear range is 0.2-40 μM, LOD is 59 nM, and the visual detection of Cr (VI) is performed with the aid of the smartphone. This work not only provides experimental and theoretical guidance for understanding the active centers of Zn-SAzymes and their catalytic processes, but also provides a promising and alternative detection strategy for the rapid and even visual on-site detection of Cr(VI) in aquatic environments, which is of great significance for the control of Cr(VI) pollution in the environment and industrial wastewater.

Exploring the twin potential of nanostructured TiO2:SeO2 as a promising visible light photocatalyst and selective fluorosensing platform

The present work describes the development of TiO2/SeO2 nanostructure as a potential candidate for visible light photocatalysis as well as selective fluorophore for the sensing of picric acid. The obtained nanostructure consists of uniform globular nanoparticles having approximate size of 170 nm and possess an optical band gap of 2.33 eV with absorption maxima at 473 nm. The photocatalyst was able to achieve 90.34% degradation efficiency for 2, 4-dichlorophenol (2,4-DCP) with rate constant of 0.0046 min-1 in the visible region. Further the nanostructure was able to serve as a selective fluorophore for sensing of Picric acid portraying more than 95% of fluorescence quenching when the concentration of PA is 10-4 M. Theoretical calculations indicate the interaction of organic pollutants with the nanostructure and reveal that both picric acid (- 66.21 kcal/mol) and 2,4-DCP (- 12.31 kcal/mol) possess more negative binding energy values demonstrating a strong interaction of both with the nanostructure, making it suitable for the degradation as well as sensing of organic pollutants. Thus this study explains the potential of prepared catalyst for waste water treatment.

CdIn2Se4@chitosan heterojunction nanocomposite with ultrahigh photocatalytic activity under sunlight driven photodegradation of organic pollutants

This research focused on synthesizing a CdIn2Se4@Ch nanocomposite by doping CdIn2Se4 into chitosan using a photolysis assisted ultrasonic process. The aim was to enhance the photodegradation efficiency of ofloxacin and 2,4-dichlorophenoxyacetic acid under sunlight. The synthesized CdIn2Se4@Ch nanocomposite was investigated via different techniques, including XRD, XPS, FTIR, TEM, DSC, TGA, UV-Vis and PL. The study also investigated the influence of various reaction parameters, including the effects of inorganic and organic ions. The synthesized nanocomposite demonstrated exceptional efficiency, achieving 86 % and 95 % removal rates, with corresponding rate constants of 0.025 and 0.047 min-1. This performance surpasses that of CdIn2Se4 by approximately 1.35 and 2.25 times, respectively. The values of COD were decreased to 78 and 86 % for ofloxacin and 2,4-dichlorophenoxyacetic, while the TOC values decreased to 71 and 84 %, respectively, from their premier values. The improvement in performance is associated with the introduction of CdIn2Se4 into chitosan, resulting in the self-integration of Cd into the catalyst. This creates a localized accumulation point for electrons, enhancing the efficiency of charge separation and further reducing the surface charge of chitosan. Experimental evidence suggests that superoxide and hydroxyl radicals play a significant role in the photodegradation of pollutants. Additionally, the nanocomposite exhibits excellent stability and can be reused up to five times, indicating remarkable stability and reusability of the developed photocatalyst.

Removal of typical pollutant ciprofloxacin using iron-nitrogen co-doped modified corncob in the presence of hydrogen peroxide

Iron-nitrogen co-doped modified corncob (Fe-N-BC) was synthesized using a hydrothermal and calcination method. The material shows excellent oxidation performance and environmental friendliness. When the dosage of Fe-N-BC was 0.6 g L-1, the concentration of H2O2 was 12 mM and pH was 4, ciprofloxacin (CIP) was virtually totally eliminated in 240 min under Fe-N-BC/H2O2 conditions. The TOC removal efficiency was 54.6%, and the effects of various reaction parameters on the catalytic activity of Fe-N-BC were thoroughly assessed. Through electron paramagnetic resonance (EPR) analyses and free radical quenching experiments, it was established that the reactive oxygen species (˙OH, ˙O2-, 1O2) were crucial in the elimination of CIP. Furthermore, the degradation of CIP was accelerated by the synergistic interaction between the transition metal and PFRs. A thorough evaluation was conducted to assess the respective contributions of adsorption and catalytic oxidation in the system. The degradation mechanism of CIP was proposed under Fe-N-BC/H2O2 conditions. Meanwhile, the possible degradation intermediates and pathways were proposed, and the toxicity of the degradation products of CIP was also meticulously investigated in the study. These findings offered the elimination of CIP in water a theoretical foundation and technical support.