Improved visible-light-driven photocatalytic removal of Bisphenol A using V2O5/WO3 decorated over Zeolite: Degradation mechanism and toxicity

Harnessing potassium peroxymonosulfate activation of WO3/diatomite composites for efficient photocatalytic degradation of tetracycline

The increasing prevalence of pharmaceutical contaminants in aquatic ecosystems poses profound challenges for both environmental sustainability and public health. Addressing this pressing issue requires the development of innovative, cost-effective, and efficient remediation approaches. Here we report the synthesis of WO3/diatomite composites and their photocatalytic degradation in conjunction with potassium peroxymonosulfate (PMS) activation. By leveraging the synergistic effects, we observe a remarkable degradation of tetracycline, a significant pharmaceutical contaminant, under visible light. Analytically, we have elucidated the driving factors for the enhanced performance, emphasizing the optimal amount of WO3 (10%) in the composite and PMS concentration (3 mM). Specifically, the WO3/diatomite catalyst presents a degradation rate of 80.75% tetracycline (40 mg L-1) after 180 min of visible light irradiation. Also, we elucidate the primary roles of ˙SO4 - radicals in driving the photocatalytic reaction using free radical trapping studies. Our approach not only offers a direct solution to controlling pharmaceutical contamination but also opens new possibilities for advancing the design of composite-based photocatalysts by taking advantage of nature-derived materials.

Poly Meta-Aminophenol (PmAP) as a Solid-State Electron Mediator in the Z-Scheme, Ag3PO4/CoFe2O4 Heterojunction: Mineralization of Highly Concentrated Bisphenol-A and Reactive Dyes Water Pollutants

This study demonstrated the effectiveness of poly meta-aminophenol (PmAP) as a solid electron mediator in the Z-scheme photocatalytic system for organic pollutants (viz. bisphenol-A and reactive dyes) mineralization and also illustrated how PmAP transported the photogenerated electrons from an O2-emitting photocatalyst (Ag3PO4) to a H2-emitting photocatalyst (CoFe2O4) enabling enhanced photocatalytic activity under visible light irradiation. The PmAP/Ag3PO4-CoFe2O4 (PAC-10), was prepared by a two-step process and characterized by various analytical methods to assess the impact of PmAP on optical, photocatalytic, and electrochemical characteristics of the CoFe2O4 (CFO)/Ag3PO4 composite. The morphological investigation revealed that the PmAP sheet was nicely decorated with evenly distributed Ag3PO4 and CoFe2O4 particles. The M-S plot and impedance analyses were used to assess the electrochemical capabilities of the catalyst. Z-scheme charge transfer pathways were well supported by the radical trapping experiment and HRTEM analysis of Pt photodeposited PAC-10 photocatalysts during the photoreaction. Because of its magnetic nature and ease of synthesis, the PAC-10 offers an easily recyclable Z-scheme photocatalytic system that has the potential for purifying wastewater with high concentrations (up to 100 mg/L) of organic pollutants within 30 min of visible light exposition.

Chelating Coordination Regulated Photochromic Electrospun Nanofibers for Waterproof and Long-Color-Retention Rewritable Wearables

Photochromic materials with rapid color-switching, long color retention times, and rewritability are crucial for meeting the requirements of future rewritable ink-free media. However, these requirements are challenging to satisfy simultaneously due to the inherent constraints among these features. Herein, a novel photochromic nanofiber nonwoven fabric was designed and constructed based on a conjugated organic-inorganic hybrid structure through electrospinning and hot-pressing techniques. The as-prepared fabric can change color in merely 5 s under UV irradiation and can reach saturation within 2 min. In addition, upon the introduction of a potent metal chelator, its color retention time exceeds 14 days under ambient conditions, significantly longer than that of most rewritable materials recently reported (several hours to 5 days). Moreover, the fabric exhibits high writing resolution and can be photoprinted and heat-erased for over 100 cycles while still retaining 96% of its initial reflectivity. Hydrophobic thermoplastic polyurethane provides the fabric with excellent waterproof and antifouling properties, thus preventing the composite from swelling or collecting graffiti due to moisture or dust. This work exploits a competitive approach for designing flexible, rewritable, and superior functional wearables with practical applications.

A fluorescent method for bisphenol A detection based on enzymatic oxidation-mediated emission quenching of silicon nanoparticles

As a common raw material of industrial products, bisphenol A (BPA) is widely used in the production of food contact materials, and there is a high risk of exposure in food. However, BPA is a well-known endocrine disruptor and poses a serious threat to human health. Herein, a fluorescent sensing platform of BPA based on enzymatic oxidation-mediated fluorescence quenching of silicon nanoparticles (SiNPs) is established and used to the detection of BPA in food species. The SiNPs are prepared with a facile one-step synthesis and emit bright green fluorescence. BPA can be oxidized by horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) to form a product which can quench the fluorescence of SiNPs through electron transfer. There is a good linear relationship between the fluorescence intensity and BPA concentration in the range of 1-100 μM. Therefore, a fluorometry of BPA is established with a low limit of detection (LOD) of 0.69 μM. This method has been applied to the determination of BPA in mineral drinking water, orange juice, and milk with satisfactory results. The fluorescent sensor of BPA based on SiNPs has favorable application foreground in the field of food safety analysis.

Emerging micropollutants in aquatic ecosystems and nanotechnology-based removal alternatives: A review

There is a significant concern about the accessibility of uncontaminated and safe drinking water, a fundamental necessity for human beings. This concern is attributed to the toxic micropollutants from several emission sources, including industrial toxins, agricultural runoff, wastewater discharges, sewer overflows, landfills, algal blooms and microbiota. Emerging micropollutants (EMs) encompass a broad spectrum of compounds, including pharmaceutically active chemicals, personal care products, pesticides, industrial chemicals, steroid hormones, toxic nanomaterials, microplastics, heavy metals, and microorganisms. The pervasive and enduring nature of EMs has resulted in a detrimental impact on global urban water systems. Of late, these contaminants are receiving more attention due to their inherent potential to generate environmental toxicity and adverse health effects on humans and aquatic life. Although little progress has been made in discovering removal methodologies for EMs, a basic categorization procedure is required to identify and restrict the EMs to tackle the problem of these emerging contaminants. The present review paper provides a crude classification of EMs and their associated negative impact on aquatic life. Furthermore, it delves into various nanotechnology-based approaches as effective solutions to address the challenge of removing EMs from water, thereby ensuring potable drinking water. To conclude, this review paper addresses the challenges associated with the commercialization of nanomaterial, such as toxicity, high cost, inadequate government policies, and incompatibility with the present water purification system and recommends crucial directions for further research that should be pursued.

Detoxification of p-nitrophenol (PNP) using Enterococcus gallinarum JT-02 isolated from animal farm waste sludge

Enterococcus gallinarum (JT-02) isolated and identified from the animal farm waste sludge was found to be capable of biodegrading p-nitrophenol (PNP), an organic compound used to manufacture drugs, fungicides, insecticides, dyes, and to darken leather. The intention of this study was to optimize the biodegradation by finding the optimal conditions for the specific strain through single-factor experiments. The bacterial strain was grown in Luria Bertani broth and various parameters were optimized to achieve the prime settings for the p-nitrophenol (PNP) biodegradation. The results indicated that the best setups for the biodegradation by the strain JT-02 was 100 mg/L of PNP; pH 7; 30 °C; 150 rpm in a shaker incubator and 3% (v/v) of inoculum dose. Once the optimal conditions were found, the bacteria were capable of degrading p-nitrophenol (98.21%) in 4 days. Intermediates produced during PNP biodegradation were identified using High Performance Liquid Chromatography (HPLC) analysis and the biodegradation pathway was elucidated. Phytotoxicity studies were carried out with Vigna radiata seeds to confirm the applicability and efficiency of PNP biodegradation.

Cobalt-molybdenum-selenide nanoflowers for bifunctional visible light photocatalysis

The renewability and zero carbon emissions of hydrogen make it a promising clean energy resource to meet future energy demands. Owing to its benefits, photocatalytic water-splitting has been extensively investigated for hydrogen production. However, the low efficiency poses a serious challenge to its implementation. Herein, we attempted to synthesize bimetallic transition metal selenides, namely Co/Mo/Se (CMS) photocatalysts, with varying atomic compositions (CMSa, CMSb, and CMSc) and investigated their photocatalytic water splitting efficiencies. The observed hydrogen evolution rates were as follows: 134.88 μmol g^-1 min^-1 for CoSe₂, 145.11 μmol g^-1 min^-1 for MoSe₂, 167.31 μmol g^-1 min^-1 for CMSa, 195.11 μmol g^-1 min^-1 for CMSb, and 203.68 μmol g^-1 min^-1 for CMSc. Hence, we deemed CMSc to be the most potent photocatalytic alternative among the compounds. CMSc was also tested for its efficiency towards degradation of triclosan (TCN), and results substantiated that CMSc succeeded degrading 98% TCN while CMSa and b were able to degrade 80 and 90% TCN respectively-the attained efficiency being exponentially higher than CoSe₂ and MoSe₂ taken for comparative analysis in addition to complete degradation of the pollutants leaving no harmful intermediaries during the process. Thus, CMSc shall be identified as a highly potential photocatalyst with respect to both environmental and energy applications.

Biotransformation of bisphenol A in vivo and in vitro by laccase-producing Trametes hirsuta La-7: Kinetics, products, and mechanisms

Bisphenol A (BPA) is a ubiquitous endocrine disruptor that poses adverse human health risks. Herein, biotransformation kinetics, products, and mechanisms of BPA undergoing a laccase-producing Trametes hirsuta La-7 metabolism were for the first time reported. Strain La-7 could completely biotransform ≤0.5 mmol·L^-1 BPA within 6 d in vivo. Notably, its extracellular crude laccase solution (ECLS) and intracellular homogenized mycelium (HM) only required 6 h to convert 85.71% and 84.24% of 0.5 mmol·L^-1 BPA in vitro, respectively. The removal of BPA was noticeably hampered by adding a cytochrome P-450 inhibitor (piperonyl butoxide) in HM, disclosing that cytochrome P-450 monooxygenase participated in BPA oxidation and metabolism. BPA intermediates were elaborately identified by high-resolution mass spectrometry (HRMS) combined with ¹³C stable isotope ratios (BPA: ¹³C₁₂-BPA = 0.25: 0.25, molar concentration). Based on the accurate molecular mass, isotope labeling difference, and relative intensity ratio of product peaks, 6 versatile metabolic mechanisms of BPA, including polymerization, hydroxylation, dehydration, bond cleavage, dehydrogenation, and carboxylation in vivo and in vitro, were confirmed. Germination index values revealed that inoculating strain La-7 in a BPA-contaminated medium presented no phytotoxicity to the germinated radish (Raphanus sativus L.) seeds. In vivo, Mg²⁺, Fe²⁺, Fe³⁺, and Mn²⁺ were conducive to BPA removal, but Cd²⁺ and Hg²⁺ significantly obstructed BPA elimination. Additionally, strain La-7 also exhibited high-efficiency metabolic ability toward estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2), with more than 96.13%, 96.65%, and 100% of E1, E2, and EE2 having been converted, respectively. Our findings provide an environmentally powerful laccase-producing fungus to decontaminate endocrine disruptor-contaminated water matrices by radical polymerization and oxidative decomposition.

Comparison of three different structures of zeolites prepared by template-free hydrothermal method and its CO2 adsorption properties

In this study, zeolite sodalite SOD (50NaO₂:Al₂O₃:5SiO₂), zeolite LTA (2NaO₂:Al₂O₃:1.926SiO₂) and zeolite FAU (16NaO₂:Al₂O₃:4SiO₂) of different structures were synthesized successfully through simple conventional hydrothermal crystallization technique without using any template agent. Morphological analysis of three different types of zeolites revealed that the samples exhibit three different shapes such as the "Raspberry-like", "Dice" cube like and "Octahedral" shaped morphology respectively. The thermal stability was found to be about 4.8%, 14.6% and 20.5% for the synthesized zeolites SOD, LTA and FAU respectively. From the N₂ adsorption-desorption studies, it was observed that adsorption types IV and I correspond to the synthesized samples. CO₂ adsorption by the synthesized zeolite SOD, LTA and FAU were examined in the pressure range from 0 to 101.325 kPa at a constant temperature of 297.15 K. The highest adsorption capacity of 3.7 mmol/g was obtained for zeolite FAU. The synthesized zeolite was studied using a nonlinear regression curve fit to determine the adsorption isotherm model using Langmuir and Freundlich isotherm model. It has been found that the synthesized zeolites have a large electric field gradient due to which they can strongly adsorb quadrupole of CO₂ molecules.