Search

The optimum extraction conditions of polysaccharides from roxburgh rose (Rosa roxburghii Tratt.) leaves (RLP) were obtained by response surface methodology (RSM), which were a liquid to solid ratio of 21.16 mL/g, an extraction temperature of 81.32 °C, and an extraction time of 90.49 min. An RLP yield of 11.04% was obtained under these conditions. DEAE-52 cellulose and Sepharose CL-6B columns were used to purify the RLP, and the purified polysaccharide components RLP-1.2 and RLP-2.1 were obtained. Both RLP-1.2 and RLP-2.1 were composed of galacturonic acid (GalA), glucose (Glc), galactose (Gal), and arabinose (Ara). However, the molar ratios of GalA, Glc, Gal, and Ara in RLP-1.2 and RLP-2.1 were different. At a concentration of 10 mg/mL, the α-amylase inhibitory activities of RLP-1.2 and RLP-2.1 reached 80.74% and 89.85% that of acarbose, respectively, and the α-glucosidase inhibitory activity of RLP-1.2 reached 87.91% that of acarbose. In addition, both RLP-1.2 and RLP-2.1 showed good antioxidant activity. These results suggested that RLP-1.2 and RLP-2.1 possess potential as natural hypoglycemic agents or natural antioxidants.

Silicon nitride (Si 3 N 4 ) ceramic is mainly used as the catalyst support for photocatalytic application. In this paper, Si 3 N 4 nanowires (SNWs) were successfully prepared by directly nitriding Si powders and firstly applied as an efficient photocatalyst for the degradation of antibiotic residues. Comparing with commercial Si 3 N 4 powder (SNPs), the prepared SNWs demonstrate enhanced photocatalytic activity for tetracycline hydrochloride (TC-HCl) photodegradation under UV–vis light with good stability. The improved photocatalytic performance should come from its unique morphology and small size. The synthesis and application of Si 3 N 4 nanowires in removing antibiotic residue may contribute to development of newly efficient photocatalyst for environmental issues.

To develop the high-efficient visible-light photocatalyst with good recyclability is curial for its application in environment remediation. Herein, three-dimensional (3D) MoS2 nanosheet/graphene aerogel (MoS2 NS/GA) has been prepared by using 3D GA as the framework from the hydrothermal method. The prepared 3D MoS2 NS/GA is characterized and shows, even a small amount, high efficiency for photodegrading the concentrated TC-HCl. Moreover, the lost activity could be recovered by the compensation with S2− ions.

In advance oxidation processes (AOPs), modulating the activation mechanism from free radical to the non-radical pathway is the most attractive strategy for the treatment of recalcitrant pollutants. Herein, we achieved this goal after modifying the spinel CuFe2O4 catalyst by introducing non-redox metals (M = Mg, Ca, Ba, and Zn) as CuMFe2O4. The modified catalysts were evaluated for the removal of acetaminophen (ACE) using the persulfate (PS) activated system. The results revealed that the non-redox metals not only enhanced the catalytic activity of CuFe2O4 in the order of Mg > Zn > Ca > Ba but also switched the original radical pathway of CuFe2O4/PS system to the non-radical one (i.e., direct electron transfer path) of CuMgFe2O4/PS system. The critical role of non-redox metals to modulate the reaction mechanism was studied in detail using the extensive radical scavengers, EPR analysis, target pollutants selectivity, electrochemical studies, decomposition of oxidants, and identification of degradation products. Additionally, various experiments and characterizations, including XRD, EPR, H2-TPR, XPS, and FTIR, showed that the changes in the activation mechanism and catalytic activity (6–8 folds higher in the case of CuMgFe2O4) were related to the generation of a large amount of surface-bound isolated Cu2+ ions and abundant surface hydroxyl groups. The non-radical pathway of the CuMgFe2O4/PS system showed less susceptibility to the changing solution pH, excessive amount of humic acid (HA) or anions, and complete recyclability, and thus demonstrating good practical utility for wastewater. This study provides deep insight into the intrinsic role of non-redox metals to modulate both the activation mechanism and catalytic properties of the catalyst and to design new catalysts for the persulfate-based advance oxidation process.

Porous-hydrangea x%BiOBr/BiOI n-n heterojunction with ordered morphology was successfully prepared through a simple solvothermal process using Bi(NO3)3·5H2O, KBr, BiOI, and ethylene glycol as the precursors. The prepared x%BiOBr/BiOI (x = 2, 5, 10, 15 mol ratio) n-n heterojunctions exhibit enhanced photodegradation properties during treatment of tetracycline hydrochloride (TC-HCl) under visible light irradiation. The highest efficiency at optimized x = 5 is 1.3-, 1.7- and 1.3-fold higher than that of the pristine BiOI, BiOBr, and commercial titanium dioxide (P25), respectively. The improved photocatalytic performance was assigned to the optimized charge-separation properties of n-n heterojunction. However, over-loading of BiOBr upon BiOI may restrain the access of light to BiOI, which could limit the light absorption. The active species have been investigated by trapping experiments and it was found that holes (h+) and superoxide radicals (∙O2-) were mainly responsible for the photodegradation of TC-HCl. Additionally, the structure and activity relationship were systemically investigated, and the formation of n-n heterojunction is discussed accordingly. The photodegradation of TC-HCl is proved to be a complete mineralization process and the reaction mechanism is also proposed.

Graphical abstract, Highlights • A summary of key recent advances in photocatalytic removal of antibiotics in water. • Special emphasis on the strategies for improving the photodegradation efficiency. • Major challenges and critical perspectives on photocatalysis of antibiotics., Antibiotics are widely present in the environment due to their extensive and long-term use in modern medicine. The presence and dispersal of these compounds in the environment lead to the dissemination of antibiotic residues, thereby seriously threatening human and ecosystem health. Thus, the effective management of antibiotic residues in water and the practical applications of the management methods are long-term matters of contention among academics. Particularly, photocatalysis has attracted extensive interest as it enables the treatment of antibiotic residues in an eco-friendly manner. Considerable progress has been achieved in the implementation of photocatalytic treatment of antibiotic residues in the past few years. Therefore, this review provides a comprehensive overview of the recent developments on this important topic. This review primarily focuses on the application of photocatalysis as a promising solution for the efficient decomposition of antibiotic residues in water. Particular emphasis was laid on improvement and modification strategies, such as augmented light harvesting, improved charge separation, and strengthened interface interaction, all of which enable the design of powerful photocatalysts to enhance the photocatalytic removal of antibiotics.

Graphitic carbon nitride (g-C3N4) was deposited onto TiO2 nanotube arrays (TNTAs) by a simple impregnation method to afford a Z-scheme g-C3N4/TNTAs photocatalytic system. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectrum, and X-ray photoelectron spectroscopy (XPS). The g-C3N4/TNTAs exhibit improved efficiency for photodegradation of Rh B under visible light irradiation comparing with bare TiO2 nanotube arrays, and CN(10)/TNTAs prepared by 10 times impregnation show the highest activity. The enhanced visible light photocatalytic activity is attributed to the optimized light absorption and effective separation of photogenerated electrons and holes. This article demonstrates a simple way to prepare the Z-scheme heterogeneous photocatalyst with improved performance for potential application in environmental control.

Complete exfoliation bulk MoS2 to 2D nanosheets has been efficiently achieved by the facile NaCl-assisted liquid-phase refluxing and ultrasonication exfoliation method. The obtained nanosheets have good dispersion and stability in aqueous solutions, and exhibit efficiently photocatalytic activity for removing aqueous antibiotic residues under visible light. The present work provides a new approach to achieve completely exfoliated 2D nanosheets for the photocatalytic removal of refractory pollutants.

Highly ordered TiO2 nanotube arrays (TNTAs) have been controllably prepared by anodizing Ti foils and been used as the support for co-depositing noble Au–Pt quantum dots (QDs) with good dispersion. Well dispersed Au–Pt nanoparticles around 5 nm have been simultaneously deposited on the TNTAs through a facilely simultaneous photo-irradiation-reduction method. The prepared samples have been well-characterized by SEM, TEM, XRD, XPS, UV–Vis and EC-AFM methods. The photo-degradation of Rh B under visible light (with a 420 nm cutoff) has been used as a model response to characterize the photocatalytic properties of the prepared samples; and the co-decorated Au–Pt/TNTAs show a remarkable enhancement of visible-light-driven photocatalytic properties with good stability. This shows that the co-decorated Au–Pt quantum dots could effectively utilize the visible light and suppress the recombination of electron-hole pair, although the loaded amount is ultra-low, which induces an optimized photocatalytic activity under visible light.

In skeletal muscle the activation of phosphorylase b is catalyzed by phosphorylase kinase. Both enzymes occur in vivo as part of a multienzyme complex. The two enzymes have been imaged by atomic force microscopy and the results compared to those previously found by scanning tunneling microscopy. Scanning tunneling microscopy and atomic force microscopy have been used to view complexes between the activating enzyme phosphorylase kinase and its substrate phosphorylase b. Changes in the size and shape of phosphorylase kinase were observed when it bound phosphorylase b.