Intelligent multifunctional ruthenium monoatomic/ZnAl-LDH photocatalysts for simultaneous detection and rapid degradation of antibiotics.

The construction and precise synthesis of materials based on functional and structural orientations have emerged as a pivotal platform in the field of environmental management. In this paper, an efficient and stable catalyst (RuLDH) was constructed to achieve this goal. RuLDH comprises individual Ru atoms that are uniformly dispersed on ZnAl-LDH, achieved by room temperature stirring. Remarkably, RuLDH exhibits exceptional performance under visible light, effectively triggering the photocatalytic degradation of tetracycline hydrochloride (TC) via peroxymonosulfate (PMS) with a remarkable efficiency of 100%, all while avoiding the generation of highly toxic intermediates. In addition, RuLDH0.2 demonstrated its utility in fluorescence detection of TC, showcasing commendable analytical performance characterized by rapid response, low detection limit, and robust resistance to environmental interferences (with a detection limit of 1.0 mg/L). Notably, the RuLDH0.2/PMS/Vis system exhibited remarkable efficacy in treating actual pesticide wastewater, effectively exerting bactericidal and disinfectant effects. This study serves as a source of inspiration for the design of multifunctional single-atom catalysts, thereby pushing the boundaries of "integration of diagnosis and treatment" in environmental management and control.

Benzethonium chloride affects short chain fatty acids produced from anaerobic fermentation of waste activated sludge: Performance, biodegradation and mechanisms.

Benzethonium chloride (BZC) is viewed as a promising disinfectant and widely applied in daily life. While studies related to its effect on waste activated sludge (WAS) anaerobic fermentation (AF) were seldom mentioned before. To understand how BZC affects AF of WAS, production of short chain fatty acids (SCFAs), characteristics of WAS as well as microbial community were evaluated during AF. Results manifested a dose-specific relationship of dosages between BZC and SCFAs and the optimum yield arrived at 2441.01 mg COD/L with the addition of 0.030 g/g TSS BZC. Spectral results and protein secondary structure variation indicated that BZC denatured proteins in the solid phase into smaller proteins or amino acids with unstable structures. It was also found that BZC could stimulate the extracellular polymeric substances secretion and reduce the surface tension of WAS, leading to the enhancement of solubilization. Beside, BZC promoted the hydrolysis stage (increased by 7.09 % to 0.030 g/g TSS BZC), but inhibited acetogenesis and methanogenesis stages (decreased by 6.85 % and 14.75 % to 0.030 g/g TSS BZC). The microbial community was also regulated by BZC to facilitate the enrichment of hydrolytic and acidizing microorganisms (i.e. Firmicutes). All these variations caused by BZC were conducive to the accumulation of SCFAs. The findings contributed to investigating the effect of BZC on AF of WAS and provided a new idea for the future study of AF mechanism.

New insights into atomic layer BiOBr quantum dot/ZnAl-LDH composites in photocatalytic water treatment: Performance and mechanism.

Insufficient absorption sites and low charge separation notably limit the activation of photocatalytic molecular oxygen. In this study, atomic-layer BiOBr (BiOBr-QDs)/ZnAl-LDH composites with a considerable number of edges were developed to address the above-mentioned problems. The result of this study indicated the spatial separation of atomic-layer BiOBr-QDs/ZnAl-LDH's conduction band maximum (CBM) and valence band minimum (VBM). As a result, holes were produced on the substrate surface based on irradiation, and electrons were generated at the sites of the edge, such that ultra-fast charge separation can be carried out. The edges exposed massive adsorption sites in terms of oxygen molecules. Thus, electrons at the sites of the edge led to the reduction of absorbed oxygen molecules, thus exhibiting stronger photocatalytic •O2- production. Furthermore, the result confirmed that the atomic layer BiOBr-QDs/ZnAl-LDH are promising in environmental catalytic degradation for its increased activity of •O2- production. In this study, a novel insight into advanced photocatalyst design based on edge unsaturated ligand engineering at an atomic level is provided.

Metal coordinating-induced self-assembly of cyclic lipopeptides into high-performance antimicrobial supramolecules.

This study designed a green hydrothermally-chelating approach to generate robust antimicrobial complexes via metal-coordinated supramolecular self-assembly of cyclic lipopeptides (CLs). The metal ion (Ca2+ and Zn2+)-coordinated CL (Ca/CL or Zn/CL complex; 1 mg/mL) demonstrated potent antibacterial activity against fungi (A. niger) and bacteria (E. coli and S. aureus) respectively, and in particular, completely suppressed the microbial resistance. Further physicochemical and spectal analysis showed that this coordination approach led to CL with enhanced hydrophobic and intermolecular electrostatic interactions, forming ß-sheet-rich secondary structures allowing the complexes easily contact with and destroy the membrane of microorganisms. Practical application experiments validated that the Ca/CL and Zn/CL complexes strongly avoided table grape and fresh tomato from the contamination of pathogen. The findings of this study laid foundation for the utilization of metal ions to improve the biological activity of natural antimicrobial peptides.

Application of natural minerals in photocatalytic degradation of organic pollutants: A review.

Photocatalysis is an effective, inexpensive and environmentally friendly technology for the decomposition of various aqueous organic pollutants and plays an increasingly critical role in the degradation of pollutants. Natural minerals are abundant natural resources on Earth and can be obtained directly from nature. Natural minerals are excellent photocatalyst carriers that are environmentally friendly, low in price, and will not cause secondary pollution to the environment. Natural minerals have the characteristics of a large specific surface area, providing more active centres, and adsorbing pollutants to concentrate catalysis. Natural minerals are also excellent photocatalysts, such as haematite and magnetite, which play a very good role in the degradation of water pollutants. Studies that make full use of natural minerals are of great significance. This review covers the latest research on natural minerals as photocatalytic composite materials to degrade organic pollutants in water, including three parts: the classification of natural minerals, the structural description of natural mineral composites, and the photocatalytic degradation of organic pollutants by natural mineral composites. In addition, the current limitations and opinions of natural mineral composites are discussed to achieve better results in applying natural minerals.

Ultrafast photodegradation of nitenpyram by Ag/Ag3PO4/Zn-Al LDH composites activated by persulfate system: Removal efficiency, degradation pathway and reaction mechanism.

In this study, an investigation is conducted into the degradation of nitenpyram (NTP) using highly efficient APMMO/PDS/Vis system. As photocatalysts, silver phosphate (AP) and calcined Zn-Al layered double hydroxides (MMO) exhibit high efficiency in achieving charge separation. Besides, the injection of electrons into peroxydisulfate (PDS) from the APMMO can contribute to obtaining the species in the active state with higher efficiency. Based on the APMMO/PDS/Vis system, 50 mg/L of nitenpyram (NTP, 50 mL) can be completely removed in 60 min using 0.8 g/L photocatalyst and 0.2 g/L PDS under the optimum condition and visible light (780 nm > λ > 420 nm). Meanwhile, as demonstrated under visible light within 30 min, an ultrahigh degradation efficiency can be achieved by NTP based on APMMO1/PDS/Vis system. Besides, the electron paramagnetic resonance (EPR) technique and radical quenching experiments suggested 1O2, h+, SO4-•, •O2-, and •OH are all contributory to the removal of pollutants. Given the outcomes achieved by LC/MS system and mass spectrometry, the primary degradation intermediates of NTP end up being converted into photodegradation products (such as 2-Chloropyridine, 6-Chloropurine Riboside and dl-Leucine). Additionally, there are three potential photodegradation pathways to NTP degradation have been deployed. Moreover, the NTP light degradation occurring in APMMO1/PDS/Vis system is competent under the three types of real water sample. Accordingly, the high-efficiency APMMO1/PDS/Vis system is fit for use in water pollution control for agricultural productions.

π-π stacking derived from graphene-like biochar/g-C3N4 with tunable band structure for photocatalytic antibiotics degradation via peroxymonosulfate activation.

The severe pollution caused by antibiotics has raised serious concerns in recent decades. In this study, graphene-like Enteromorpha biochar modified g-C3N4 (BC/CN) was synthesized and applied to degrade tetracycline by activating PMS under visible light, obtaining around 90% removal rate within 1 h. The Enteromorpha biochar can provide electron-withdrawing groups to adjust the electronic structure of g-C3N4, and induces more π-π interaction to decline the recombination of photocarriers. The environmental adaptability of the BC/CN/PMS/vis system was confirmed by the TC degradation in different initial pH, coexisting ions, and natural organic materials. In most cases, the system maintained over 78% degradation rate. The kinetics and mechanism of the system indicating that ∙O2-, 1O2 contributed more to the TC photocatalytic degradation than ∙OH, SO4∙-, and h+. During the process, TC underwent serials hydroxylation, demethylation, and ring-opening processes, and produced more than 40 intermediates in three pathways. Moreover, the BC/CN/PMS/vis system was proved to have at least a 50% degradation rate for more tetracyclines and quinolone antibiotics with the same condition.

Magnetically modified in-situ N-doped Enteromorpha prolifera derived biochar for peroxydisulfate activation: Electron transfer induced singlet oxygen non-radical pathway.

Herein, in-situ N-doped Enteromorpha prolifera derived magnetic biochar (MBC) was prepared by loading Fe3O4. It can effectively activate peroxodisulfate (PDS) to degrade tetracycline (TC) and easy recycling. The removal rate of TC reached 87.2%, and its possible degradation pathway was revealed through a liquid chromatography-mass spectrometer. This work first proposes the mechanism of in-situ N-doping and Fe synergistic effect on PDS activation. Unlike the well-reported role of N doping in activating PDS, except for the edge pyridine N plays a significant role in the activation of PDS. After the load of Fe, the synergistic effect of Fe and graphite N induces a non-radical path dominated by singlet oxygen (1O2) due to the excellent electron transfer function. Through chemical quenching experiment, electron spin detection, and electrochemical analysis, the mechanism of PDS activation by MBC was thoroughly investigate. This research will deepen the understanding of the mechanism of transition metals and carbon materials in synergistically driving PDS activation, and guide biochar-mediated PDS activation in environmental remediation.

Facile one-pot magnetic modification of Enteromorpha prolifera derived biochar: Increased pore accessibility and Fe-loading enhances the removal of butachlor.

In this work, Enteromorpha prolifera derived magnetic biochar (MBC) is prepared for the removal of butachlor (BTR) and characterized. The NaOH added during the magnetic loading process has an activating effect and enhancing the accessibility of the pores. Based on the BET result, the importance of pore accessibility rather than the specific surface area has been proposed. The maximum adsorption capacity of BTR for MBC is 158.5 mg/g. Then, the batch experiment shows that the adsorption of MBC to BTR fitted with the quasi-second-order kinetic model. The effect factors on the BTR removal were studied. Through the result of BET, Raman, XPS and FT-IR, the mechanism of MBC adsorption of butachlor was explored. After 3 cycles, the prepared MBC has a negligible reduction in the removal capacity of BTR, which provides a reference scheme for the large-scale application of Enteromorpha prolifera and the water treatment of BTR.