Facile ion-exchange synthesis of mesoporous Bi 2 S 3 /ZnS nanoplate with high adsorption capability and photocatalytic activity

Natural marmatite photocatalyst for treatment of mineral processing wastewater to help zero wastewater discharge

Mineral processing wastewater (MPW) with large discharge and high toxicity affects environmental safety, and the realizing zero discharge of MPW is of great significance for reducing environmental pollution, saving water resources, and promoting the sustainable development of the mining industry. In this study, we reported natural marmatite (NM) as a low-cost and efficient photocatalyst for the treatment of MPW to help zero wastewater discharge. The photocatalytic activity of NM was evaluated by the removal of total organic carbon (TOC) from MPW under visible-light illumination, and the optimal degradation conditions were discussed. Results showed that superoxide free radicals (·O2-) were the dominant active species responsible for organic pollutants degradation, and 74.25% TOC removal was obtained after 120 min reaction under the optimum treatment conditions. Meanwhile, the wastewater treated by NM photocatalysis can be reused in the flotation system without adverse impact on the product index. Based on these findings, a model of zero wastewater discharge for flotation with the help of photocatalytic treatment was established, it indicated that the water of the whole system can be balanced without affecting the ore dressing index, which showed that visible light-driven photocatalyst has a promising application prospect in the treatment and recycling of industrial wastewater.

Photoelectrochemical quenching-recovery biosensor based on NSCQDs/Fe2O3@Bi2S3 for the detection of trypsin

BACKGROUND

The content of trypsin will change when pancreatic diseases occur, therefore developing a high-performance method for trypsin detection is of great significance for guiding patients on medication plans and improving their prognosis. Photoelectrochemical (PEC) analysis techniques have emerged as a solution to apply for bioassays.

RESULTS

Herein, the Fe2O3@Bi2S3 and Nitrogen and sulfur co-doped carbon quantum dots (NSCQDs) were successfully synthesized by a hydrothermal method. Subsequently, NSCQDs/Fe2O3@Bi2S3 with a photocurrent amplification effect covered on fluorine-doped tin oxide (FTO) electrode as the substrate material and apoferritin (APO) as a bio-recognition element to quench the photocurrent of the substrate material which can be excited with light. Due to the decomposition specifically between APO and trypsin, the photocurrent response increased. The linear range for trypsin detection showed satisfied results from 2 to 1000 ng mL-1 under optimal conditions, with a detection limit of 0.42 ng mL-1 and a recovery rate of 97.41 %-103.02 %, enabling efficient quantitative analysis of trypsin.

SIGNIFICANCE

In this experiment, a PEC biosensor with simple operation, low detection limit, excellent selectivity and strong stability was successfully prepared, enabling quantitative analysis of trypsin in human serum samples through the quenching-recovery mechanism. It holds great significance for diagnosis and serves as a practical method for the detection of trypsin in the future.

Rational design of full-spectrum visible-light-responsive bimetallic sulfide Bi2S3/CoS2 composites for high-efficiency photocatalytic degradation of naproxen and bacterial inactivation

Photocatalytic water decontamination has emerged as a highly promising technology for efficient and rapid water treatment, harnessing sustainable solar energy as its driving force. In this study, we prepared visible-light active Bi2S3/CoS2 composites for the degradation of naproxen (NPX) and the inactivation of Escherichia coli (E. coli). The homogeneous dispersion of CoS2 was stably integrated with Bi2S3, resulting in a significant enhancement of the specific surface area, efficient utilization of visible light, and effective separation of photogenerated charge carriers. Consequently, this synergistic photocatalytic system greatly facilitated the successful degradation of NPX and the inactivation of E. coli under visible-light irradiation. Compared to the pure Bi2S3 and CoS2 catalysts, the Bi2S3/CoS2 (1:2) composites displayed significantly enhanced photodegradation activity, achieving 96.46% (k = 0.2847 min-1) degradation of NPX within 90 min and maintaining good recyclability with no significant decline after six successive cycles. Additionally, the photocatalytic inactivation of E. coli results indicated that Bi2S3/CoS2 composites exhibited excellent performance, leading to the inactivation of 7 log10 cfu mL-1 of bacterial cells after 150 min of visible-light exposure. Scanning Electron Microscopy (SEM) and K+ ions leakage tests demonstrated that the destruction of the E. coli cell membrane structure resulted in cell death. The outcomes of this work suggest that Bi2S3/CoS2 composites hold significant potential for treating water contaminated with antibiotic and microbial pollutants.

Peroxymonosulfate enhanced photoelectrocatalytic oxidation of organic contaminants and simultaneously cathodic recycling of silver

Degradation of organic contaminants with simultaneous recycling of Ag⁺ from silver-containing organic wastewater such as photographic effluents is desired. Although photoelectrocatalysis (PEC) technology is a good candidate for this type of wastewater, its reaction kinetics still needs to be improved. Herein, peroxymonosulfate (PMS) was employed to enhance the PEC kinetics for oxidation of phenol (PhOH) at the anode and reduction of Ag⁺ at the cathode. The degradation efficiency of phenol (PhOH, 0.1 mmol/L) was increased from 42.8% to 96.9% by adding 5 mmol/L PMS at a potential of 0.25 V. Meanwhile, the Ag (by wt%) deposited on the cathode was 28.1% (Ag₂O) in PEC process, while that of Ag (by wt%) was 69.7% (Ag⁰) by adding PMS. According to the electrochemistry analysis, PMS, as photoelectrons acceptor, enhances the separation efficiency of charges and the direct h⁺ oxidation of PhOH at the photoanode. Meantime, the increasing cathode potential avoided H₂ evolution and strongly alkaline at the surface of cathode, thus enabling the deposition of Ag⁺ in the form of metallic silver with the help of PMS. In addition, PMS combined with PEC process was effective in treating photographic effluents.

Flower-like Bi2S3-In2S3 heterojunction for efficient solar light induced photoreduction of Cr(VI)

To develop Bi₂S₃-based heterojunction for efficient solar light induced photoreduction of Cr(VI), flower-like Bi₂S₃-In₂S₃ composites consisted of nanorods were prepared via a microwave-assisted hydrothermal route. In contrast with pure Bi₂S₃, Bi₂S₃-In₂S₃ composites exhibited the enhanced photoreduction activity while the decreased adsorption capacity for Cr(VI) removal. The best removal efficiency of 70 mg L^-1 Cr(VI) solution (99.86%) was achieved by the optimal 3-Bi₂S₃-In₂S₃ with a Bi/In molar ratio of 4:1 within 140 min. It's ascribed to the narrow band gap for strengthened visible-light response, the tight interface between Bi₂S₃ and In₂S₃ for rapid transfer and separation of charge carriers, and the enough S vacancies for highly-efficient active sites of adsorption-photoreduction. However, the long-term photo-corrosion resulted in the slightly inferior reusability of 3-Bi₂S₃-In₂S₃ under solar light irradiation after five cycles.

Bi2S3@NH2-UiO-66-S composites modulated by covalent interfacial reactions boost photodegradation and the oxidative coupling of primary amines

The Bi₂S₃@NH₂-UiO-66-S heterostructures have been synthesized via covalent interfacial reactions, exhibiting excellent performance in the photodegradation of methylene and the oxidative coupling of primary amines compared to reported photocatalysts.

Facile fabrication of visible light photoelectrochemical immunosensor for SCCA detection based on BiOBr/Bi2S3 heterostructures via self-sacrificial synthesis method

A novel visible light photoelectrochemical immunosensor based on BiOBr/Bi₂S₃ heterostructures was fabricated to detect squamous cell carcinoma antigen (SCCA). Bi₂S₃ nanoparticles formed on the BiOBr microflowers by the self-sacrificial synthesis method based on the facile reaction between BiOBr and S^2- ions. The BiOBr/Bi₂S₃ composites exhibited excellent visible light photoelectrochemical activity, when ascorbic acid (AA) was employed as a perfect electron donor. The photocurrent intensity of BiOBr/Bi₂S₃ modified ITO electrode arrived at around 20 µA, which was approximately 30 times than that of pure BiOBr. Dopamine formed easily polydopamine film via self-polymerization on the surface of BiOBr/Bi₂S₃ composites to immobilize SCCA antibody. Under the optimal condition, this photoelectrochemical immunosensor realized the ultrasensitive determination of SCCA. With the logarithm of SCCA concentration in the range of 0.001-75 ng mL^-1, the specific binding between SCCA and antibody led to the linearly decrease of photocurrent signal with a low detection limit of 0.3 pg mL^-1 (S/N = 3). This facilely constructed photoelectrochemical immunosensor maybe have promising practical application in photocatalysis, analytical detection and biosensor, etc.

Review on nanoscale Bi-based photocatalysts

Nanoscale Bi-based photocatalysts are promising candidates for visible-light-driven photocatalytic environmental remediation and energy conversion. However, the performance of bulk bismuthal semiconductors is unsatisfactory. Increasing efforts have been focused on enhancing the performance of this photocatalyst family. Many studies have reported on component adjustment, morphology control, heterojunction construction, and surface modification. Herein, recent topics in these fields, including doping, changing stoichiometry, solid solutions, ultrathin nanosheets, hierarchical and hollow architectures, conventional heterojunctions, direct Z-scheme junctions, and surface modification of conductive materials and semiconductors, are reviewed. The progress in the enhancement mechanism involving light absorption, band structure tailoring, and separation and utilization of excited carriers, is also introduced. The challenges and tendencies in the studies of nanoscale Bi-based photocatalysts are discussed and summarized.

Iron and manganese oxides modified maize straw to remove tylosin from aqueous solutions

Maize straw modified by iron and manganese oxides was synthesized via a simple and environmentally friendly method. Three maize straw materials, the original maize straw, maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides, were detected by SEM, BET, XPS, XRD and FTIR. The results showed that maize straw was successfully modified and maize straw modified by iron and manganese oxides has a larger surface area than MS. According to the experimental data, the sorption trend could conform to the pseudo-second-order kinetic model well, and the sorption ability of tylosin on sorbents followed the order of original maize straw < maize straw modified by manganese oxides < maize straw modified by iron and manganese oxides. The study indicated that manganese oxides and iron-manganese oxides could significantly enhance the sorption capacity of original maize straw. The sorption isotherm data of tylosin on original maize straw fit a linear model well, while Freundlich models were more suitable for maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides. The pH, ionic strength and temperature can affect the sorption process. The sorption mechanisms of tylosin on iron and manganese oxides modified maize straw were attribute to the surface complexes, electrostatic interactions, H bonding and hydrophobic interactions.

Preparation and adsorption capacity of porous MoS2nanosheets

MoS₂nanosheets with higher adsorption capacity for dyes.