Inactivation mechanism of E. coli in water by enhanced photocatalysis under visible light irradiation

Light-driven biohybrid for phosphorus recovery via struvite biomineralization in tetracycline-laden livestock wastewater

Struvite biomineralization drives phosphate mineralization, playing a critical role in sustaining biogeochemical phosphorus cycling and industrial phosphorus recovery. Phosphorus-rich wastewater, however, frequently contains inhibitory tetracycline that suppresses microbial activity, diminishes recovery efficiency, and accumulates in recovered struvite. Semiconductor-mediated microbial photoelectrochemical process generate photogenerated electrons to stimulate microbial metabolism. Concurrently, photogenerated reactive oxygen species can degrade tetracycline. Despite extensive evidence of TC's inhibitory effects on biomineralization, the development of integrated photoelectrochemical-microbial process for simultaneous tetracycline degradation and phosphorus recovery remains unexplored. We develop a microbial photoelectrochemical system integrating microorganisms with nano-semiconductor materials. Light-activated carbon nitride generates electrons boosting microbial metabolism and holes degrading tetracycline. Coupling carbon nitride with S. oneidensis under illumination doubles biomineralization rates in tetracycline-laden wastewater versus conventional struvite biomineralization. The system achieves near-complete tetracycline degradation within 48 hours and full nitrate reduction. Those efforts achieve simultaneous phosphorus recovery and tetracycline removal from wastewater, converting pollutants into agriculturally viable struvite without pH adjustment. The system establishes an energy-efficient platform for coupled nutrient recovery and water purification, while creating a closed-loop framework for resource regeneration from contaminated wastewater.

A novel Ag/Bi/Bi2O2CO3 photocatalyst effectively removes antibiotic-resistant bacteria and tetracycline from water under visible light irradiation

Currently, achieving dual applications of Bi2O2CO3-based photocatalysts in photocatalytic degradation and sterilization under visible-light conditions is challenging. In this study, a novel Ag/Bi/Bi2O2CO3 visible-light photocatalyst with bimetallic doping and rich oxygen vacancies was successfully synthesized using a one-pot hydrothermal crystallization method. The existence of oxygen vacancies was verified by X-ray photoelectron spectroscopy (XPS) and Electron spin resonance (ESR) analysis. The experimental results showed that Ag/Bi/Bi2O2CO3 killed ∼100% (log 7) of antibiotic-resistant Escherichia coli (AR-E. coli) within 60 min and degraded 83.81% of tetracycline (TC) within 180 min under visible light irradiation. Moreover, Ag/Bi/Bi2O2CO3 can still remove 61.07% of TC in water after 5 cycles, showing excellent photocatalytic cycle stability and reusability. The possible degradation pathway of TC was determined by liquid chromatography-mass spectrometry. It was found that the main active substances in the photocatalytic disinfection of AR-E. coli were 1O2, h+, and ·OH, while 1O2 was the dominant active species in the photocatalytic degradation of TC. This study presents a promising Bi2O2CO3-based visible light photocatalyst for treating both antibiotics (TC) and antibiotic-resistant bacteria (AR-E. coli) in water.

MIL-Derived Hollow Tubulous-Shaped In2O3/ZnIn2S4 Z-Scheme Heterojunction for Efficient Antibacterial Performance via In Situ Composite

In this study, a hollow tubulous-shaped In2O3 derived from MIL (MIL-68 (In)) exhibited an enhanced specific surface area compared to MIL. To further sensitize In2O3, ZnIn2S4 was grown in situ on the derived In2O3. The 40In2O3/ZnIn2S4 composite (1 mmol ZnIn2S4 loaded on 40 mg In2O3) exhibited degradation rates of methyl orange (MO) under visible light (80 mW·cm-2, 150 min) that were 17.9 and 1.4 times higher than those of the pure In2O3 and ZnIn2S4, respectively. Moreover, the 40In2O3/ZnIn2S4 exhibited an obviously improved antibacterial performance against Pseudomonas aeruginosa, with an antibacterial rate of 99.8% after visible light irradiation of 80 mW cm-2 for 420 min. The 40In2O3/ZnIn2S4 composite showed the highest photocurrent density, indicating an enhanced separation of photogenerated charge carriers. Electron spin resonance results indicated that the 40In2O3/ZnIn2S4 composite generated both ·O2- and ·OH radicals under visible light, whereas ·OH radicals were almost not detected in ZnIn2S4 alone, suggesting the presence of a Z-scheme heterojunction between In2O3 and ZnIn2S4, thereby enhancing the degradation and antibacterial capabilities of the composite. This offers fresh perspectives on designing effective photocatalytic materials for use in antibacterial and antifouling applications.

Decoration of Carbon Dots on Oxygen-Vacancy-Enriched S-Scheme TiO2 Quantum Dots/TiO2 Oxygen Vacancies Photocatalysts: Impressive Quantum-Dot-Sized Photocatalysts for Remediation of Antibiotics, Bacteria, and Dyes

Today, cleaning the environment using photocatalytic technology is one of the main research activities. In this study, carbon dots (C-dots) were anchored on oxygen-vacancy-enriched TiO2 quantum dots (QDs)/TiO2 oxygen vacancies (OVs) using a facile procedure. The resultant ternary TiO2 QDs/TiO2 OVs/C-dots photocatalysts with a quantum dot size of almost 4.55 nm were used for detoxification of aqueous solutions containing four antibiotics and three organic dyes as well as inactivation of two pathogenic bacteria, including Escherichia coli and Staphylococcus aureus, upon visible light. The degradation constant of tetracycline over the optimized TiO2 QDs/TiO2 OVs/C-dots nanocomposite reached 714 × 10-4 min-1, which was 17.3, 12.1, and 2.92 times higher than TiO2 QDs, TiO2 OVs, and TQDs/TOVs (1:1) materials, respectively. Effective separation of electron-hole pairs between TiO2 QDs and TiO2 OVs counterparts through decorated C-dots by an established S-scheme system was the main reason for boosted photocatalytic activity. With regard to the facile growth of wheat and lentil seeds in the treated solutions, it is hoped that the TiO2 QDs/TiO2 OVs/C-dots nanocomposite with significant stability could be used to clean up wastewaters.

Recent advances and new insights on the construction of photocatalytic systems for environmental disinfection

Photocatalysis, as a sustainable and environmentally friendly green technology, has garnered widespread recognition and application across various fields. Especially its potential in environmental disinfection has been highly valued by researchers. This study commences with foundational research on photocatalytic disinfection technology and provides a comprehensive overview of its current developmental status. It elucidates the complexity of the interface reaction mechanism between photocatalysts and microorganisms, providing valuable insights from the perspectives of materials and microorganisms. This study reviews the latest design and modification strategies (Build heterojunction, defect engineering, and heteroatom doping) for photocatalysts in environmental disinfection. Moreover, this study investigates the research focuses and links in constructing photocatalytic disinfection systems, including photochemical reactors, light sources, and material immobilization technologies. It studies the complex challenges and influencing factors generated by different environmental media during the disinfection process. Simultaneously, a comprehensive review extensively covers the research status of photocatalytic disinfection concerning bacteria, fungi, and viruses. It reveals the observable efficiency differences caused by the microstructure of microorganisms during photocatalytic reactions. Based on these influencing factors, the economy and effectiveness of photocatalytic disinfection systems are analyzed and discussed. Finally, this study summarizes the current application status of photocatalytic disinfection products. The challenges faced by the synthesis and application of future photocatalysts are proposed, and the future development in this field is discussed. The potential for research and innovation has been further emphasized, with the core on improving efficiency, reducing costs, and strengthening the practical application of photocatalysis in environmental disinfection.

Copper-doped bismuth oxychloride nanosheets assembled into sphere-like morphology for improved photocatalytic inactivation of drug-resistant bacteria

The devastating microbiological contamination as well as emerging drug-resistant bacteria has posed severe threats to the ecosystem and public health, which propels the continuous exploitation of safe yet efficient disinfection products and technology. Here, copper doping engineered bismuth oxychloride (Cu-BiOCl) nanocomposite with a hierarchical spherical structure was successfully prepared. It was found that due to the exposure of abundant active sites for the adsorption of both bacteria cells and molecular oxygen in the structure, the obtained Cu-BiOCl with nanosheets assembled into sphere-like morphology exhibited remarkable photocatalytic antibacterial effects. In particular, compared to the pure BiOCl, composite Cu-BiOCl possessed improved antibacterial effects against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Methicillin-resistant Staphylococcus aureus (MRSA). The combination of physicochemical characterizations and theoretical calculations has revealed that copper doping significantly promoted the light absorbance, inhibited the recombination of electron-hole pairs, and enhanced molecular oxygen adsorption, which resulted in more generation of active species including reactive oxygen species (ROS) and h+ to achieve superior photocatalytic bacterial inactivation. Finally, transcriptome analysis on MRSA pinpointed photocatalytic inactivation induced by Cu-BiOCl may retard largely the development of drug-resistance. Therefore, the built spherical Cu-BiOCl nanocomposite has provided an ecofriendly, economical and robust strategy for the efficient removal of drug-resistant bacteria with promising potentials for environmental and healthcare utilizations.

Construction of antibacterial bone implants and their application in bone regeneration

Bacterial infection represents a prevalent challenge during the bone repair process, often resulting in implant failure. However, the extensive use of antibiotics has limited local antibacterial effects at the infection site and is prone to side effects. In order to address the issue of bacterial infection during the transplantation of bone implants, four types of bone scaffold implants with long-term antimicrobial functionality have been constructed, including direct contact antimicrobial scaffold, dissolution-penetration antimicrobial scaffold, photocatalytic antimicrobial scaffold, and multimodal synergistic antimicrobial scaffold. The direct contact antimicrobial scaffold involves the physical penetration or disruption of bacterial cell membranes by the scaffold surface or hindrance of bacterial adhesion through surface charge, microstructure, and other factors. The dissolution-penetration antimicrobial scaffold releases antimicrobial substances from the scaffold's interior through degradation and other means to achieve local antimicrobial effects. The photocatalytic antimicrobial scaffold utilizes the absorption of light to generate reactive oxygen species (ROS) with enhanced chemical reactivity for antimicrobial activity. ROS can cause damage to bacterial cell membranes, deoxyribonucleic acid (DNA), proteins, and other components. The multimodal synergistic antimicrobial scaffold involves the combined use of multiple antimicrobial methods to achieve synergistic effects and effectively overcome the limitations of individual antimicrobial approaches. Additionally, the biocompatibility issues of the antimicrobial bone scaffold are also discussed, including in vitro cell adhesion, proliferation, and osteogenic differentiation, as well as in vivo bone repair and vascularization. Finally, the challenges and prospects of antimicrobial bone implants are summarized. The development of antimicrobial bone implants can provide effective solutions to bacterial infection issues in bone defect repair in the foreseeable future.

Modeling and optimization of synergistic ozone-ultraviolet-chlorine process for reclaimed water disinfection: From laboratory tests to software simulation

The ozone-ultraviolet (UV)-chlorine process is a highly effective method of disinfection in water reuse system, but currently still lacks precise quantification and accurate control. It is difficult to determine the dosage of each disinfectant because of the complex interactions that occur between disinfection units and the complicated mathematical calculation required. In this study, we proposed a dosage optimization model for ozone-UV-chlorine synergistic disinfection process. The model was able to identify the cost-effective doses of the disinfectants under the constraints of microbial inactivation, decolorization, and residual chlorine retention requirements. Specifically, the simulation of microbial inactivation rates during synergistic disinfection process was accomplished through quantification of the synergistic effects between disinfection units and the introduction of enhancement coefficients. In order to solve this optimization model rapidly and automatically, a MATLAB-based software program with graphical user interface was developed. This software consisted of calibration unit, prediction unit, assessment unit, and optimization unit, and was able to simulate synergistic ozone-UV-chlorine process and identify the optimal dose of ozone, UV, and chlorine. Validation experiments revealed good agreements between the experimental data and the results calculated by the developed software. The developed software is believed to help the water reclamation plants improve disinfection efficiency and reduce the operational costs of synergistic disinfection processes.