Sulfur-doped activated carbon for the efficient degradation of tetracycline with persulfate: Insight into the effect of pore structure on catalytic performance.

Sulfur-doped activated carbon has proved to be a promising metal-free catalyst for persulfate (PDS) catalytic activation for the oxidation of aqueous refractory organics. Herein, sulfur-doped porous carbon (ACS) catalysts with different pore structures and doped-S contents were prepared via a template method using d(+)-glucose as the carbon source, sulfur as the sulfur source, and nano-MgO with different particle sizes as templates. Characterization results showed that the particle size of MgO significantly affects the pore structure and doped-S content of ACSs catalysts: a sample synthesized with 20 nm MgO as template (ACS-20) presented the highest content of doped-S and a mesoporous structure, which endowed it with superior adsorption and catalytic performance toward tetracycline (TC) removal. The effect of catalyst dosage, TC concentration, PDS concentration and solution pH on TC removal efficiency were evaluated. The reaction mechanism, investigated by combination of EPR, quenching experiments and LC-MS, indicated that the reactive species included HO·, SO4˙-, and 1O2, but that 1O2 played the dominant role in TC oxidation through a non-radical oxidation pathway. In addition, the reusability and regeneration properties of the ACS-20 catalyst were also studied. This work provides a promising strategy and some theoretical basis for the design and preparation of activated carbon catalysts for advanced oxidation reactions from the viewpoint of pore structure design and S-doping.

Biomineralization of uranium by Desulfovibrio desulfuricans A3-21ZLL under various hydrochemical conditions.

Uranium pollution in groundwater environment has become an important issue of global concern. In this study, a strain of Desulfovibrio desulfuricans was isolated from the tailings of acid heap leaching, and was shown to be able to remove uranium from water via biosorption, bio-reduction, passive biomineralization under uranium stress, and active metabolically dependent bioaccumulation. This research explored the effects of nutrients, pH, initial uranium and sulfate concentration on the functional groups, uranium valence, and crystal size and morphology of uranium immobilization products. Results showed that tetravalent and hexavalent phosphorus-containing uranium minerals was both formed. In sulfate-containing water where Desulfovibrio desulfuricans A3-21ZLL can grow, the sequestration of uranium by bio-reduction was significantly enhanced compared to that with no sulfate loading or no growth. Ungrown Desulfovibrio desulfuricans A3-21ZLL or dead ones released inorganic phosphate group in response to the stress of uranium, which associated with soluble uranyl ion to form insoluble uranium-containing precipitates. This study revealed the influence of hydrochemical conditions on the mineralogy characteristics and spatial distribution of microbial uranium immobilization products. This study is conducive to the long-term and stable bioremediation of groundwater in decommissioned uranium mining area.

Surface Engineering Design of Nano FeS@Stenotrophomonas sp. by Ultrasonic Chemical Method for Efficient U(VI) and Th(IV) Extraction.

Nano-FeS has great potential for use in the management of radioactive contaminants. In this paper, we prepared a FeS@Stenotrophomonas sp. composite material by ultrasonic chemistry, and it showed excellent removal of uranium and thorium from the solution. Through optimization of the experimental conditions, it was found that the maximum adsorption capacities for uranium and thorium reached 481.9 and 407.5 mg/g for a composite made with a synthetic ratio of 1:1, pH 5 and 3.5, respectively, for U and Th, and sonication for 20 min. Compared with those of FeS or Stenotrophomonas alone, the removal capacity was greatly improved. The results of a mechanistic study indicated that efficient removal of the uranium and thorium was due to ion exchange, reduction, and microbial surface adsorption. FeS@Stenotrophomonas sp. could be applied to U(VI) and Th(IV) extraction for radioactive water.

Occurrence characteristics of uranium mineral-related substances in various environmental media in China: A critical review.

The high demand and extensive exploitation of uranium resources resulted in the ubiquity and high detection levels of uranium mineral-related substances in various environment media in China. The potential adverse effects of uranium mineral-related substances on environment and human health have received extensive attention. Therefore, we reviewed the occurrence and spatial distribution of uranium mineral-related substances in various basins and environmental media in China to obtain an overall understanding. We collected information from over 70 papers reporting the occurrence and distribution of uranium mineral-related substances in multiple environments and 183 articles on the genesis of uranium deposits in China from 2001 to 2021. Then the occurrence of uranium mineral-related substances and corresponding correlation in different basins, environmental media and depth ranges were compared in detail. And this review assessed the uranium mineral-related pollution in China based on various environmental quality standards of China, EPA and WHO, and proposed the priority uranium mineral-related heavy metals and radioactive substances based on cluster analysis. This review showed that there were obvious differences in the occurrence characteristics of various uranium mineral-related substances in different environmental media, especially in the surrounding environment of sandstone type and hard rock type uranium deposits. These results will guide us to tackle the challenge of uranium mineral-related pollution in China. The correlation analysis of uranium mineral-related pollutants in different environmental media and the identification of priority pollutants will also provide instructions for us to control uranium mineral-related pollution. Finally, we put forward a series of urgent and practical suggestions on risk management and control of uranium mining according to the current situation of uranium mining environment in China, which is of guiding significance for the realization of "green uranium mining".

Removal of manganese from aqueous solution by a permeable reactive barrier loaded with hydroxyapatite-coated quartz sand.

Hydroxyapatite-coated quartz sands were synthesized by the sol-gel method and employed as a permeable reactive barrier (PRB) medium for the manganese contaminated aqueous solution treatment. The effects of composite particle size, initial concentration of manganese, and hydraulic load on the manganese removal in aqueous solution were investigated by column test. The Thomas and Yoon-Nelson dynamic models were used to reproduce the Mn(II) adsorption behavior observed in these column experiments. The scanning electron microscope (SEM) coupled with energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), and X-ray photoelectron spectroscopy (XPS) were employed to investigate the Mn(II) removal mechanism. Results showed that the initial concentration of manganese had the greatest influence on Mn(II) removal when the initial concentration of manganese is 3 mg/L, the particle size is 0.15 ~ 0.3 mm, the hydraulic load is 5.5 m3/m2·d, and the adsorption capacity of the composites reached the maximum of 1.10 mg/g. The Thomas model fitted the breakthrough curves better. The maximum adsorption capacity of Mn(II) is 0.7546 mg/g. The adsorption mechanisms are mainly ion exchange and dissolution-precipitation. The results indicate that the hydroxyapatite-coated quartz sands could be an effective PRB media for the manganese-contaminated water treatment.

Efficient charge separation in sulfur doped AgFeO2 photocatalyst for enhanced photocatalytic U(VI) reduction: The role of doping and mechanism insights.

Photocatalytic reduction of U(VI) in aqueous solutions has been considered as an efficient and promising technology to solve radioactive U pollution. In this work, density functional theory (DFT) calculations were firstly employed to optimize and compare the adsorption configurations combined uranium with four given photocatalysts, then their adsorption energies were - 0.97 eV for AgFeO2, - 1.15 eV for Zn doped AgFeO2, - 1.73 eV for Cu doped AgFeO2 and - 2.66 eV for S doped AgFeO2, respectively, indicating the sulfur doping plays a major role in U(VI) photoreduction. Herein, a visible light responsive efficient sulfur doped AgFeO2 photocatalyst (S doped AgFeO2) was synthesized and utilized to photocatalytic reduction of U(VI) in aqueous solutions. According to XRD, XPS and TEM analysis, the sulfur was successfully doped in AgFeO2 via the hydrothermal method. The batch experimental showed that S doping enhanced the U(VI) photoreduction activity of AgFeO2, and the S-AFO-3 photocatalyst exhibited the highest photocatalytic activity (92.57%), which was 1.5 times than that of pure AgFeO2. ESR, PL and DFT results demonstrated that the enhancement of adsorbed U(VI) photoreduction was attributed to the own unique effect of oxygen vacancy defects and efficient charge separation of S doped AgFeO2 photocatalyst. Due to its higher adsorption energies, fast-U(VI) photoreduction rate and superior chemical stability, the sulfur doped AgFeO2 photocatalyst is hoped for water remediation containing U(VI) wastewater.

Effect of activator/precursor mass ratio on sulfur-doped porous carbon for catalytic oxidation of aqueous organics with persulfate.

Sulfur-doped porous carbon has emerged as promising metal-free catalysts toward persulfate (PS) for catalytic oxidation of aqueous organics. Wherein, thermal pyrolysis with activator activation is very common for the preparation of activated carbon. However, the relationship between the mass ratio of activator/precursor and catalytic efficiency has been rarely reported. Herein, a series of sulfur-doped porous carbons (S-AC) were synthesized by one-step chemical activation of (Poly(phenylene sulphide) (PPS)) with K2CO3 as activator at K2CO3/PPS mass ratio ranging from 0 to 3. The effects of K2CO3/PPS mass ratio on its physicochemical properties and its catalytic performance for p-chlorophenol (PCP) degradation with PS were comprehensively investigated. Experiment results show that sulfur doping enhanced its catalytic activity and the sample synthesized with K2CO3/PPS mass ratio of 2 (S-AC-2) exhibited the best adsorption and catalytic performance toward PS for PCP removal. More importantly, S-AC-2 with PS could efficiently degrade various aqueous toxic organics other than PCP, and S-AC-2 showed superior catalytic activity to many recently reported advanced materials. In addition, the effects of several operate parameters, including reaction temperature, PS concentration, pH, humic acid, and inorganic ions on PCP oxidation were evaluated. By combining with the results of quenching experiments and EPR, the PS activation mechanism over S-AC-2 was revealed. Moreover, the reusability and regenerability of S-AC-2 was also studied. It indicates that S-AC-2 showed inferior reusability, but the catalytic activity of which could be fully recovered through thermal treatment at 600 °C for 2 h in N2.

Phosphorus-modified biochar cross-linked Mg-Al layered double-hydroxide stabilizer reduced U and Pb uptake by Indian mustard (Brassica juncea L.) in uranium contaminated soil.

The decommissioning of uranium tailings (UMT) is usually accompanied by uranium (U) contamination in soil, which poses a serious threat to human health and ecological security. Therefore, the remediation of uranium pollution in soil is imminent from ecological and environmental points of view. In recent years, the use of biochar stabilizers to repair uranium tailings (UMT) soil has become a research hotspot. In this study, a novel phosphorus-modified bamboo biochar (PBC) cross-linked Mg-Al layered double-hydroxide composite (PBC@LDH) was prepared. The hyperaccumulator plant Indian mustard (Brassica juncea L.) was selected as the test plant for outdoor pot experiments, and the stabilizers were added to the UMT soil at the dosage ratio of 15 g kg-1, which verified the bioconcentrate and translocate of U and associated heavy metal Pb in the UMT soil by Indian mustard after stabilizer remediated. The results shown that, after 50 days of growth, compared with the untreated sample (CK), the Indian mustard in PBC@LDH treatment possessed a better growth and its biomass weight of whole plant was increased by 52.7%. Meanwhile, the bioconcentration factors (BF) of U and Pb for PBC@LDH treatment were significantly decreased by 73.4% and 34.2%, respectively; and the translocation factors (TF) were also commendable reduced by 15.1% and 2.4%, respectively. Furthermore, the Tessier available forms of U and Pb in rhizosphere soil showed a remarkably decrease compared with CK, which reached by 55.97% and 14.1% after PBC@LDH stabilization, respectively. Complexation, precipitation, and reduction of functional groups released by PBC@LDH with U and Pb described the immobilization mechanisms of biochar stabilizer preventing U and Pb enrichment in Indian mustard. As well as, the formation of U-containing vesicles was prevented by the precipitation of -OH functional groups with free U and Pb ions around the cell tissue fluids and vascular bundle structure of plant roots, thereby reducing the migration risk of toxic heavy metals to above-ground parts. In conclusion, this research demonstrates that the PBC@LDH stabilizer offers a potentially effective amendment for the remediation of U contaminated soil.

Hydroxyapatite modified ZIF-67 composite with abundant binding groups for the highly efficient and selective elimination of uranium (VI) from wastewater.

In this work, nanoscale hydroxyapatite (HAP)-modified ZIF-67 composite, HAP/ZIF-67, with abundant functional groups for uranium(VI) binding was synthesized via a facile ultrasound-assisted synthesis method. The prepared HAP/ZIF-67 was characterized by XRD, SEM, TEM, BET, FT-IR and XPS techniques, and was applied to eliminate uranium(VI) from aqueous solutions under various conditions, i.e., pH, coexisting ions, temperature and contact time. The results indicate that the abundant Co-OH, -CN- and -NH- binding groups originating from the ZIF-67 and the Ca-OH and PO43- derived from loaded nanoscale HAP synergistically endowed HAP/ZIF-67 with the excellent U(VI) adsorption capacity of 453.1 mg/g, which is 2.55 and 1.78 times that of pristine HAP and ZIF-67. HAP/ZIF-67 showed high adsorption selectivity toward U(VI), and the U(VI) elimination efficiency for real wastewater by HAP/ZIF-67 reached 97.29%. The adsorption kinetics and isotherms were well simulated by the pseudo-second-order model and Langmuir isotherm model, respectively, suggesting that U(VI) adsorption was an endothermic monolayer chemisorption process. The adsorption mechanism of U (VI) by HAP/ZIF-67 was dominated by surface complexation process. This work is expected to provide an effective strategy for developing HAP-modified MOFs absorbent to be used for the highly efficient elimination of radionuclides from wastewater.

Photocatalytic decontamination of tetracycline and Cr(VI) by a novel α-FeOOH/FeS2 photocatalyst: One-pot hydrothermal synthesis and Z-scheme reaction mechanism insight.

Tetracycline and Cr(VI) as non-biodegradable environmental contaminants have attracted increasing attention because of their chronic toxicity. In this regard, the environmentally friendly Z-scheme photocatalytic decontamination system has been widely used for contaminant treatment. Herein, a novel 3D Z-scheme α-FeOOH/FeS2 composite photocatalyst was successfully synthesized for the first time via a simple one-pot hydrothermal method. X-ray diffraction (XRD) and Fourier-transform infrared (FT-IR) analyses and high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) demonstrated that the O component of the heterogeneous nanostructures formed by the FeOFe linkages in α-FeOOH was replaced by S to generate FeSFe linkages in the resulting FeS2. As expected, the novel 3D Z-scheme α-FeOOH/FeS2 composites exhibited remarkable photocatalytic activity for Cr(VI) reduction and tetracycline degradation compared to pure α-FeOOH. Photoluminesence (PL) measurement and electrochemical impedance spectroscopy (EIS), as well as density functional theory (DFT) calculations, suggested that the enhanced photocatalytic activity of the Z-scheme α-FeOOH/FeS2 composite can be attributed to the improved photo-absorption properties and the effective separation of photo-induced charge carriers caused by the Z-scheme system of the as-prepared 3D α-FeOOH/FeS2 composites. Thus, this work may facilitate the effective design of α-FeOOH-based photocatalysts.

Au nanoparticle-based probe for selenol in living cells and selenium-rich tea and rice.

Selenocysteine (Sec) is a primary kind of reactive selenium species in cells, and its vital roles in physiological processes have been characterized. Therefore, the highly effective method for sensing Sec in metabolic processes and selenium-rich food must be developed. This study presents a new fluorescent probe, namely, GSH-NB@AuNPs, for highly selective detection of selenol based on the fluorescence quenching quality on the surface of gold nanoparticles (AuNPs). The probe consists of glutathione (GSH) and Nile blue (NB) moieties assembled on AuNPs. The probe exhibits excellent sensitivity and selectivity for Sec and is applied in imaging endogenous and exogenous Sec in living cells through confocal fluorescence microscopy. The proposed probe provides a promising and powerful method for detecting selenol in foodstuff (such as selenium-rich rice and tea) with the detection limit of 9.5 nM.

Occurrence and Distribution of Uranium in a Hydrological Cycle around a Uranium Mill Tailings Pond, Southern China.

Uranium (U) mining activities, which lead to contamination in soils and waters (i.e., leachate from U mill tailings), cause serious environmental problems. However, limited research works have been conducted on U pollution associated with a whole soil-water system. In this study, a total of 110 samples including 96 solid and 14 water samples were collected to investigate the characteristics of U distribution in a natural soil-water system near a U mining tailings pond. Results showed that U concentrations ranged from 0.09 ± 0.02 mg/kg to 2.56 × 104± 23 mg/kg in solid samples, and varied greatly in different locations. For tailings sand samples, the highest U concentration (2.56× 104 ± 23 mg/kg) occurred at the depth of 80 cm underground, whereas, for paddy soil samples, the highest U concentration (5.22 ± 0.04 mg/kg) was found at surface layers. Geo-accumulation index and potential ecological hazard index were calculated to assess the hazard of U in the soils. The calculation results showed that half of the soil sampling sites were moderately polluted. For groundwater samples, U concentrations ranged from 0.55 ± 0.04 mg/L to 3.36 ± 0.02 mg/L with a mean value of 2.36 ± 0.36 mg/L, which was significantly lower than that of percolating waters (ranging from 4.56 ± 0.02 mg/L to 12.05 ± 0.04 mg/L, mean 7.91 ± 0.98 mg/L). The results of this study suggest that the distribution of U concentrations in a soil-water system was closely associated with hydrological cycles and U concentrations decreased with circulation path.

Cascade reaction-based trinal-site probe for sensing and imaging of cysteine and glutathione.

Biothiols, such as glutathione (GSH) and cysteine (Cys), play important roles in many physiological processes, and variations in their levels are related to different diseases. Many fluorescence probes have been developed to understand the function of biothiols, but only few of such probes can detect both Cys and GSH. Herein, a new strategy for specific colorimetric and fluorescent detection of Cys and GSH by different cascade reactions was developed. By utilizing this strategy, we designed and synthesized two fluorescent probes, namely, CR1 and CR2, for detection of Cys and GSH under physiological conditions. CR1 contains a stronger electron-withdrawing substituent group and provides high selectivity and sensitivity for Cys and GSH. This probe is based on the mechanism of Cys-induced native-chemical-ligation-cyclization and GSH-induced transthioesterification-cyclization cascade reactions, with detection limits of 0.029 and 0.371 µM, respectively. CR1 can be successfully applied for imaging Cys and GSH in living cells with low cell toxicity.

Effect of particle size on uranium bioleaching in column reactors from a low-grade uranium ore.

This study evaluated the effectiveness of ore particle size on column bioleaching from low-grade uranium ore using an indigenous Acidithiobacillus ferrooxidans, isolated from local uranium ore. The uranium content was 0.033% by weight and ore particle size was crushed to <50 mm, <30 mm, and <15 mm. The additive content of sulfuric acid 5 g/L, Fe3+ dosage of 5.0 g/L, spray strength of 2.57 L/(h·m2) and temperature of 25 °C were controlled. After 150 days of leaching, acid consumption amounted to 2.73 g H2SO4 per kg ore, the obtained maximum uranium extraction was 64.85% with the ore particle size of <15 mm. The results showed that a smaller particle size ore had a higher uranium extraction and that an economic uranium extraction can be obtained by correctly controlling the ore granularity.

Ternary semiconductor metal oxide blends grafted Ag@AgCl hybrid as dimensionally stable anode active layer for photoelectrochemical oxidation of organic compounds: Design strategies and photoelectric synergistic mechanism.

The development of ultra-efficient, sustainable, and easily accessible anode with relative non-precious semiconducting metal oxides is highly significant for application in the practical treatment of organically polluted water. Herein, we report SnO2, TiO2, and Ag2O ternary semiconductor metal oxide blend grafted Ag@AgCl hybrids, prepared with the one-step sol-gel method and applied as a dimensionally stable anode (DSA)-active layer on a SnO2-Sb/Ti electrode. Factors affecting crystal formation, including the presence or absence of O2 during calcination, the calcination temperature, and Ag@AgCl additive dosage were discussed. The micromorphology, phase composition, and photoelectrochemical activity of the newly designed anode were comprehensively characterized. The optimized preparation, which yielded a solid-solution structure with flat and smooth surface and well-crystallized lattice configuration, occurred in the absence of O2 during calcination at 550 ℃ with an Ag@AgCl additive dosage of 0.2 g in the sol-gel precursor. The newly designed DSA displayed improved electrocatalysis (EC) and photoelectrical catalysis (PEC) capacity. The phenol and its TOC removal efficiency reached 90.65% and 58.17% for 10 mA/cm2 current density with a metal halide lamp in 3 h. The lifespan was four times that of SnO2-Sb/Ti electrode. This proposed DSA construction strategy may support improved EC and PEC reactivities toward the decomposition of organic pollutants.

Highly Efficient Interception and Precipitation of Uranium(VI) from Aqueous Solution by Iron-Electrocoagulation Combined with Cooperative Chelation by Organic Ligands.

A new strategy combining iron-electrocoagulation and organic ligands (OGLs) cooperative chelation was proposed to screen and precipitate low concentrations (0-18.52 µmol/L) of uranium contaminant in aqueous solution. We hypothesized that OGLs with amino, hydroxyl, and carboxyl groups hydrophobically/hydrophilically would realize precuring of uranyl ion at pH < 3.0, and the following iron-electrocoagulation would achieve faster and more efficient uranium precipitation. Experimentally, the strategy demonstrated highly efficient uranium(VI) precipitation efficiency, especially with hydrophilic macromolecular OGLs. The uranium removal efficiency at optimized experimental condition reached 99.65%. The decrease of zeta potential and the lattice enwrapping between U-OGLs chelates and flocculation precursor were ascribed to the enhanced uranium precipitation activity. Uranium was precipitated as oxides of U(VI) or higher valences that were easily captured in aggregated micelles under low operation current potential. The actual uranium tailing wastewater was treated, and a satisfied uranium removal efficiency of 99.02% was discovered. After elution of the precipitated flocs, a concentrated uranium solution (up to 106.52 µmol/L) with very few other metallic impurities was obtained. Therefore, the proposed strategy could remove uranium and concentrate it concurrently. This work could provide new insights into the purification and recovery of uranium from aqueous solutions in a cost-effective and environmentally friendly process.

Enhanced photocatalytic reduction activity of uranium(vi) from aqueous solution using the Fe2O3-graphene oxide nanocomposite.

Photocatalytic technologies are a potential solution for remediation of radioactive wastewater, including the reduction of radioactive hexavalent uranium, which is commonly found in wastewater from the nuclear industry. In this study, Fe2O3-graphene oxide composites were synthesized by an easy and scalable impregnation method as a catalyst for the reduction of U(vi). X-ray photoelectron spectroscopy analysis and high-resolution transmission electron microscopy images of this composite clearly showed that the Fe2O3 nanoparticles exist in the layered structure of graphene oxide. The photocatalytic activity of the Fe2O3-graphene oxide composite was evaluated by the reduction of U(vi) to U(iv) in aqueous solution under visible light. The results showed that the photocatalytic process of the Fe2O3-graphene oxide composite was always faster than that of the Fe2O3 nanoparticles. Moreover, the experimental kinetic data for the catalytic process followed a pseudo-first-order model. The stability of the Fe2O3-graphene oxide composites was studied over successive experiments, with the photocatalytic reduction efficiency of U(vi) decreasing to 76.0% after four cycles. Based on these experimental results, the enhanced photocatalytic activity and stability of Fe2O3-graphene oxide composites can be attributed to the improved adsorption properties of U(vi) at GO and the electron transfer from iron oxide to GO.

Enhanced decolorization of methyl orange in aqueous solution using iron-carbon micro-electrolysis activation of sodium persulfate.

Reactivity of sodium persulfate (PS) in the decolorization of methyl orange (MO) in aqueous solution using an iron-carbon micro-electrolysis (ICE) method was investigated. The effects of sodium persulfate doses, pH, Fe-to-C mass ratios, initial MO concentration as well as the reaction temperature were comprehensively studied in batch experiments. The ICE-PS coupled process was more suitable for wide ranges of pH, initial MO concentration and reaction temperature, accompanied by the reduction of Fe compared ICE. The MO removal efficiency improved substantially by ICE-PS technique, 76.03% for ICE and 91.27% for ICE-PS at experimental conditions of pH 3.0, Fe-to-C mass ratio 3:1, PS addition 10 mM and initial MO concentration 0.61 mM. Furthermore, the biodegradability index (BI) dramatically increased from 0.26 to 0.65. The binary hydroxyl and sulfate radicals that non-selectively degrade MO to the derivatives with small molecules are ascribed to ICE-PS method as detected by the UV-vis spectra. The PS activation resource was Fe2+ through the hydroxyl radical quenching reaction by the additive tert-butanol (TBA). This study provides an in-depth theoretical understanding of the development and wide commercial application of the ICE technology to refractory industrial dye wastewater treatment.

Ag3PO4/rectorite nanocomposites: Ultrasound-assisted preparation, characterization and enhancement of stability and visible-light photocatalytic activity.

To overcome the drawback of low stable brought by the transformation of Ag+ into Ag, a highly efficient and stable photocatalyst Ag3PO4/rectorite composite was successfully synthesized by ultrasound-assisted precipitation method. The as-prepared samples were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N2 adsorption-desorption, room-temperature photoluminescence spectra, Fourier transform infrared spectrum measurements and UV-vis diffuse reflectance spectra. The absorption edges of the Ag3PO4/rectorite display a noticeable shift to the visible light region as compared to that of the Ag3PO4. Compared with bare Ag3PO4, the Ag3PO4/rectorite composite by ultrasound-assisted precipitation process exhibits significantly enhanced photocatalytic activity and stable for methyl orange (MO) degradation under visible light irradiation. The improved activity of the Ag3PO4/rectorite photocatalyst could be attributed to the expanded visible light absorption, the enhanced interfacial charge transfer and the inhibited recombination of electron-hole pairs. Therefore, the facile ultrasound-assisted preparation process provides some insight into the application of Ag3PO4/rectorite nanocomposites in photocatalytic degradation of organic pollutants.

Whey protein concentrate doped electrospun poly(epsilon-caprolactone) fibers for antibiotic release improvement.

Design and fabrication of scaffolds using appropriate biomaterials are a key step for the creation of functionally engineered tissues and their clinical applications. Poly(epsilon-caprolactone) (PCL), a biodegradable and biocompatible material with negligible cytotoxicity, is widely used to fabricate nanofiber scaffolds by electrospinning for the applications of pharmaceutical products and wound dressings. However, the use of PCL as such in tissue engineering is limited due to its poor bioregulatory activity, high hydrophobicity, lack of functional groups and neutral charge. With the attempt to found nanofiber scaffolds with antibacterial activity for skin tissue engineering, in this study, whey protein concentrate (WPC) was used to modify the PCL nanofibers by doping it in the PCL electrospun solution. By adding proteins into PCL nanofibers, the degradability of the fibers may be increased, and this further allows an antibiotic incorporated in the fibers to be efficiently released. The morphology, wettability and degradation of the as-prepared PCL/WPC nanofibers were carefully characterized. The results showed that the PCL/WPC nanofibers possessed good morphology and wettability, as well as high degradation ability to compare with the pristine PCL fibers. Afterwords, tetracycline hydrochloride as a model antibiotic drug was doped in the PCL/WPC nanofibers. In vitro drug release assays demonstrated that PCL/WPC nanofibers had higher antibiotic release capability than the PCL nanofibers. Also, antibacterial activity evaluation against various bacteria showed that the drug-doped PCL/WPC fibers possessed more efficient antibacterial activity than the PCL nanofibers.