Removal of methylene blue from water solution by modified nano-boehmite with Bismuth

Role of transition metals in coinage metal nanoclusters for the remediation of toxic dyes in aqueous systems

A difficult issue in chemistry and materials science is to create metal compounds with well-defined components. Metal nanoclusters, particularly those of coinage groups (Cu, Ag, and Au), have received considerable research interest in recent years owing to the availability of atomic-level precision via joint experimental and theoretical methods, thus revealing the mechanisms in diverse nano-catalysts and functional materials. The textile sector significantly contributes to wastewater containing pollutants such as dyes and chemical substances. Textile and fabric manufacturing account for about 7 × 105 tons of wastewater annually. Approximately one thousand tons of dyes used in textile processing and finishing has been recorded as being discharged into natural streams and water bodies. Owing to the widespread environmental concerns, research has been conducted to develop absorbents that are capable of removing contaminants and heavy metals from water bodies using low-cost technology. Considering this idea, we reviewed coinage metal nanoclusters for azo and cationic dye degradation. Fluorometric and colorimetric techniques are used for dye degradation using coinage metal nanoclusters. Few reports are available on dye degradation using silver nanoclusters; and some of them are discussed in detailed herein to demonstrate the synergistic effect of gold and silver in dye degradation. Mostly, the Rhodamine B dye is degraded using coinage metals. Silver nanoclusters take less time for degradation than gold and copper nanoclusters. Mostly, H2O2 is used for degradation in gold nanoclusters. Still, all coinage metal nanoclusters have been used for the degradation due to suitable HOMO-LUMO gap, and the adsorption of a dye onto the surface of the catalyst results in the exchange of electrons and holes, which leads to the oxidation and reduction of the adsorbed dye molecule. Compared to other coinage metal nanoclusters, Ag/g-C3N4 nanoclusters displayed an excellent degradation rate constant with the dye Rhodamine B (0.0332 min-1). The behavior of doping transition metals in coinage metal nanoclusters is also reviewed herein. In addition, we discuss the mechanistic grounds for degradation, the fate of metal nanoclusters, anti-bacterial activity of nanoclusters, toxicity of dyes, and sensing of dyes.

Carbon sphere doped CdS quantum dots served as a dye degrader and their bactericidal behavior analysed with in silico molecular docking analysis

We have employed a co-precipitation method to synthesize different concentrations of carbon spheres (CSs) doped with cadmium sulfide (CdS) quantum dots (QDs) for catalytic reduction and antibacterial applications. Various morphological and structural characterization techniques were used to comprehensively analyze the CS effect on CdS QDs. The catalytic reduction efficiency of CS-doped CdS QDs was evaluated using rhodamine B dye. The antibacterial efficacy was also assessed against the pathogenic microorganism Escherichia coli (E. coli), and substantial destruction in the inhibitory zone was measured. Finally, the synthesized CS-doped CdS QDs demonstrated favorable results for catalytic reduction and antibacterial applications. Computational studies verified the suppressive impact of these formed QDs on DNA gyrase and β-lactamase of E. coli.

Antimicrobial potential and rhodamine B dye degradation using graphitic carbon nitride and polyvinylpyrrolidone doped bismuth tungstate supported with in silico molecular docking studies

The environmental-friendly hydrothermal method has been carried out to synthesize Bi2WO6 and g-C3N4/PVP doped Bi2WO6 nanorods (NRs) by incorporating different concentrations of graphitic carbon nitride (g-C3N4) as well as a specified quantity of polyvinylpyrrolidone (PVP). Bi2WO6 doped with g-C3N4 provides structural and chemical stability, reduces charge carriers, degrades dyes, and, owing to lower bandgap energy, is effective for antibacterial, catalytic activity, and molecular docking analysis. The purpose of this research is the treatment of polluted water and to investigate the bactericidal behavior of a ternary system. The catalytic degradation was performed to remove the harmful rhodamine B (RhB) dye using NaBH4 in conjunction with prepared NRs. The specimen compound demonstrated antibacterial activity against Escherichia coli (E. coli) at both high and low concentrations. Higher doped specimens of g-C3N4/PVP-doped Bi2WO6 exhibited a significant improvement in efficient bactericidal potential against E. coli (4.55 mm inhibition zone). In silico experiments were carried out on enoyl-[acylcarrier-protein] reductase (FabI) and β-lactamase enzyme for E. coli to assess the potential of Bi2WO6, PVP doped Bi2WO6, and g-C3N4/PVP-doped Bi2WO6 NRs as their inhibitors and to justify their possible mechanism of action.

Bactericidal Action and Industrial Dye Degradation of Graphene Oxide and Polyacrylic Acid-Doped SnO2 Quantum Dots: In Silico Molecular Docking Study

The present work demonstrates the systematic incorporation of different concentrations of graphene oxide (GO) into a fixed amount of polyacrylic acid (PAA)-doped SnO₂ quantum dots (QDs) through a co-precipitation approach. The research aimed to evaluate the catalytic and antibacterial actions of GO/PAA-SnO₂ QDs. Moreover, optical properties, surface morphologies, crystal structures, elemental compositions, and d-spacings of prepared QDs were examined. X-ray diffraction patterns revealed the tetragonal configuration of SnO₂, and the crystallinity of QDs was suppressed upon dopants verified by the SAED patterns. Electronic spectra identified the blue shift by incorporating GO and PAA led to a reduction in band gap energy. Fourier transform infrared spectra showed the existence of rotational and vibrational modes associated with the functional groups during the synthesis process. A drastic increase in the catalytic efficacy of QDs was observed in the neutral medium by including dopants, indicating that GO/PAA-SnO₂ is a promising catalyst. GO/PAA-SnO₂ showed strong bactericidal efficacy against Escherichia coli (E. coli) at higher GO concentrations. Molecular docking studies predicted the given nanocomposites, i.e., SnO₂, PAA-SnO₂, and GO/PAA-SnO₂, as potential inhibitors of beta-lactamase_E. coli and DNA gyrase_E. coli.

Synthesis and characterization of silver-indium and antimony selenide: role in photocatalytic degradation of dyes

These days, water contamination poses a severe threat to the ecosystem and demands immediate care. This study examined the need to reduce water pollution using clean, renewable energy (solar light irradiations) for the degradation of Congo red by Silver-indium and antimony selenide with chemical composition AgInSbSe3. The sample was fabricated through a hydrothermal technique. The synthesized sample was characterized through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Ultraviolet-Visible spectroscopy. The X-ray diffraction confirms crystalline structure of the synthesized sample. The SEM analysis reveals irregular grains and exhibits a very small inter-particle distance. SEM provides the morphology of the synthesized sample, the grain size of the synthesized sample was 0.58 μm. FTIR results revealed specific absorption bands in the range of 400-4000 cm-1; optical properties are studied through UV-Vis-spectroscopy. The synthesized sample has 1.97 eV bandgap which is suitable for degradation of organic pollutants. The photocatalytic activity of the material is checked by degrading the Congo red dye under direct sunlight irradiation and for the 75 min illumination 77.8% degradation efficiency is attained.

Dye degradation, antibacterial activity and molecular docking analysis of cellulose/polyvinylpyrrolidone-doped cadmium sulphide quantum dots

In present study, control sized cadmium sulphide (CdS) quantum dots (QDs) and cellulose nanocrystals grafted polyvinylpyrrolidone (CNC-g-PVP) doped CdS QDs were synthesized via co-precipitation. The suggested pathway is fruitful in throwing out organic pollutants like methylene blue (MB) from industrial water and bactericidal applications. A series of characterization techniques were used to determine the structural, optical and morphological qualities of prepared samples. The X-ray diffraction (XRD) pattern verified hexagonal structure with no significant change occurring in the spectrum upon doping (2, 4, and 6 %). The UV-vis spectrophotometer describes blueshift in absorption pattern, resulting in an increase in band gap energy (E_g) upon doping. Catalytic activity (CA) against MB in basic and neutral medium demonstrated remarkable results compared with the acidic medium. Furthermore, bactericidal potential of doped sample (6 %) exhibited the significantly higher inhibition zones of 5.25 mm and 4.05 mm against Staphylococcus aureus (S. aureus) or Gram-positive (G₊ve) and Escherichia coli (E. coli) or Gram-negative (G-ve), respectively. In silico predictions for these doped QDs were performed against selected enzyme targets (i.e. DNA gyrase and FabI) to unveil the mystery governing these bactericidal activities.

Chemical reduction of methylene blue in the presence of nanocatalysts: a critical review

Methylene blue (MB) (3,7-bis (dimethylamino)-phenothiazin-5-ium chloride) is a harmful pollutant and has been long been known for its detrimental effects on human health. Over the recent years, many strategies including reduction, oxidation, biological and photochemical degradation have been reported for converting this harmful dye into commercially useful products. Among the aforementioned strategies, the nanocatalytic reduction of MB into its reduced counterpart, i.e. leucomethylene blue, is considered more preferable because it has been reported to have numerous applications in various industrial fields in the academic literature. The reduction of MB is the kinetically unfavorable reaction. Henceforth, various nanocatalytic systems utilizing different kinds of stabilization mediums have reportedly been used for speeding up this particular reaction. This article attempts to not only describe the fundamental properties of the reduction reaction of MB but also present the classification of the recently reported nanocatalytic assemblies on the basis of the utilized supporting medium. Various techniques used for the characterization of nanocatalytic systems reported for the reduction of MB have been summarized in this review. The thermodynamics, kinetics and mechanistic studies of this nanocatalytic reaction have also been narrated here. This critical review has been written comprehensively to abridge the recent research progress in the assemblage of nanocatalytic systems used for the reduction of MB and to propose some new ideas for further development in this area.