Search

In this study, transport behaviors of graphene oxide (GO) in saturated uncoated (i.e., clean sand) and goethite-coated sand porous media were examined as a function of the phosphate. We found that phosphate enhanced the transport of GO over a wide range of solution chemistry (i.e., pH 5.0–9.0 and the presence of 10 mmol/L Na+ or 0.5 mmol/L Ca2+). The results were mainly ascribed to the increase of electrostatic repulsion between nanoparticles and porous media. Meanwhile, deposition site competition induced by the retained phosphate was another important mechanism leading to promote GO transport. Interestingly, when the phosphate concentration increased from 0.1 to 1.0 mmol/L, the transport-enhancement effect of phosphate in goethite-coated sand was to a much larger extent than that in clean sand. The observations were primarily related to the difference in the total mass of retained phosphate between the iron oxide-coated sand and clean sand columns, which resulted in different degrees of the electrostatic repulsion and competitive effect of phosphate. When the background solution contained 0.5 mmol/L Ca2+, phosphate could be bind to sand/ goethite-coated sand surface by cation bridging; and consequently, promoted competition between phosphate and nanoparticles for deposition sites, which was an important mechanism for the enhanced effect of phosphate. Moreover, the DLVO theory was applicable to describe GO transport behaviors in porous media in the absence or presence of phosphate. Taken together, these findings highlight the important status and role of phosphate on the transport and fate of colloidal graphene oxide in the subsurface environment.

Given the ubiquity and abundance of the iron oxide minerals and their important roles in affecting the environmental fate of graphene oxide (GO) nanoparticles, the attachment of GO onto three iron oxide minerals (i.e., hematite, goethite, and ferrihydrite) under different solution chemistry conditions was investigated in this study. The main mechanism of the attachment of GO was electrostatic interaction. Calculations based on the DLVO theory showed that the attachment was a favorable process. Interestingly, the affinity of GO towards three iron oxide minerals was in the order of ferrihydrite > goethite > hematite. This result indicates that different characteristics of various iron oxides (e.g., specific surface area, crystal structure, and surface charge, and surface hydroxyl densities) can influence their attachment capacities for GO. The attachment of GO depended on the solution pH and ionic strength. Electrostatic attraction and hydrogen bonding were the important retention mechanisms for GO attachment when pH pHPZC, respectively. The attachment capacities of iron oxides decreased with increasing ionic strength at lower pH because of the decrease of the electrostatic attraction. Meanwhile, the presence of divalent cations (i.e., Ca2+ and Cu2+) could significantly promote GO attachment mainly by the surface-bridging mechanism. Meanwhile, the enhancement effect of Cu2+ was greater than Ca2+ due to the greater complexation affinity of Cu2+. Furthermore, attachment isotherms showed that the presence of phosphate could inhibit the attachment of GO onto minerals obviously. Because phosphate could form inner-sphere surface complex on the iron oxide surface, and consequently decreased the electrostatic attraction between nanoparticles and minerals. Our study has important implications for predicting the fate of GO in natural environment where amounts of iron oxide minerals are present.

Efficient and safe nanopesticides play an important role in pest control due to enhancing target efficiency and reducing undesirable side effects, which has become a hot spot in pesticide formulation research. However, the preparation methods of nanopesticides are facing critical challenges including low productivity, uneven particle size and batch differences. Here, we successfully developed a novel, versatile and tunable strategy for preparing buprofezin nanoparticles with tunable size via anodic aluminum oxide (AAO) template-assisted method, which exhibited better reproducibility and homogeneity comparing with the traditional method. The storage stability of nanoparticles at different temperatures was evaluated, and the release properties were also determined to evaluate the performance of nanoparticles. Moreover, the present method is further demonstrated to be easily applicable for insoluble drugs and be extended for the study of the physicochemical properties of drug particles with different sizes.

Canopy conductance (Gc) largely regulates carbon/water cycling and land–atmosphere interactions, but quantifying Gc using eddy flux data is limited by the difficulty of partitioning plant transpiration (T) and surface evaporation (E). We introduced an underlying water use efficiency (uWUE) method to partition evapotranspiration (ET) in an oasis maize ecosystem, and cross–compared with the Shuttleworth and Wallace (SW) model, the lysimeter and isotope measurements. We then estimated surface conductance (Gs) by ET and Gc by T partitioned using the uWUE method, followed by a performance evaluation on the Jarvis model parameterized with both Gs and Gc. The results showed that T/ET estimated by the uWUE method was close to the isotope method in the peak growing season of 2012, it showed similar seasonal variations with the lysimeter/eddy covariance method and the SW model throughout this growing season. Daily T partitioned by the uWUE method was in good agreement with the SW model from 2012 to 2015 (r2 = 0.91). Additionally, Gc had more significant seasonal variations than Gs. The Jarvis model parameterized with Gc exhibited superior performance than those with Gs. Our study suggests that the uWUE method can exclude influences of nonstomatal conductances, and will have great potential to provide more reasonable parameterization for simulation of plant stomata.

Surface urban heat island intensity (SUHII) widely acknowledged as the primary indicator has been extensively utilized in previous SUHI spatiotemporal research. However, diverse rural definitions reported in previous studies possibly affect rural temperature and consequently lead uncertainty and incomparability to SUHII dynamics. Despite of previous efforts, there are still some issues in systematic analysis of significance and spatiotemporal variations of SUHII interpretations resulting from these different rural extents. In order to address these issues, this paper quantitvely characterized the significance and spatiotemporal dynamics of RE-induced △SUHII (Rural-extent induced SUHII variations) in 100 major cities across China mainland. Major findings are summarized in the following three aspects. First, considerable SUHII variating with rural buffers extending and majority of △SUHII exceeding 0.5 K especially in the daytime illustrated that different rural definitions can induce significant uncertainty to SUHII studies. Second, RE-induced △SUHII is found to be unevenly distributed across the study area. Moreover, dense distributions of great △SUHII in city agglomerations suggest that city is an inappropriate study object for SUHII urban-cluster research since multi-influences from aggregated urban and rural areas without clear boundaries. Third, RE-induced △SUHII experiences evident seasonal variations especially in the daytime spring and summer, and spoon-shape (peaks in the begins and ends, and bottom in the middle) buffer variations with relatively low correlations among five subdivided buffer rings. Additionally, six potential factors are selected to discuss their possible effects on △SUHII spatiotemporal characters. On the whole, this paper illustrated that diverse rural extents do induce conspicuous uncertainty and incomparability to SUHII interpretations and highlight the necessity to develop uniform rural defining standards in the future SUHII research.

Schiff base metal complexes are effective homogeneous catalysts used in oxidation reactions in organic synthesis. However, application of these catalysts in aqueous solution is limited by their effectiveness and stability. In this study, a novel graphene based Schiff base copper complex (Cu(salen)) was developed to effectively activate persulfate (PS) for the removal of organic pollutants in aqueous solution. Aminated reduced graphene oxide (ArGO) was used as a carrier of the heterogeneous catalyst, DArGO-Cu, which was synthesized by the condensation reaction of 3, 5-dibromosalicylaldehyde with ArGO followed by the complexing reaction with copper acetate monohydrate. The surface structure and morphology as well as elemental composition of DArGO-Cu were characterized by SEM, TEM, XPS, FTIR, Raman and elemental analysis. The catalytic performance of DArGO-Cu to activate PS was evaluated with the degradation of triclosan (TCS) in water at room temperature. The mechanism for DArGO-Cu to activate PS was the generation of SO4 − which was immediately converted to OH to degrade TCS. The role of graphene played in catalysis was not only as a carrier for Cu(salen) but also to build hydrophobic microdomains for the stabilization of the catalytic active sites in the reaction.

Enzyme functionalized porous beads were fabricated through covalently immobilizing Candida antarctica lipase B (CALB) onto high internal phase emulsion (HIPE) templated poly(glycidyl methacrylate) (PGMA) beads. These millimeter-sized beads were prepared by photopolymerizing the continuous phase of HIPE drops and then removing the dispersed phase. By covalently coupling the lysine residues of CALB to the epoxy groups from GMA, a series of enzyme immobilized polyHIPE beads were produced, with an enzyme loading of up to 0.18 g g−1 carrier. The resulting immobilized enzyme was highly stable to temperature and storage and could be recycled multiple times. The immobilized enzyme maintained 85% residual activity after 5 reaction cycles and 60% residual activity after 30 days of storage. The enzymatic esterification between hexanol and hexyl hexanoate had a conversion rate of up to 95%, showing that the enzyme immobilized beads were a good enzyme catalyst.

Despite the rapid development of Pickering interfacial catalysis (PIC) at oil–water interfaces with chemocatalysts, highly efficient Pickering interfacial biocatalyst systems, having a high oil/water ratio, super-stability and recyclability, are still urgently desired. In this study, a Pickering gel emulsion stabilized by enzyme-decorated copolymeric nanoparticles is developed for biphasic biocatalysis. The nanoparticles are synthesized by surfactant-free emulsion polymerization and covalently decorated with a model lipase Candida antarctica lipase B (CALB). An oil-in-water Pickering gel emulsion with an oil/water ratio of 3 could then be prepared by homogenizing heptane into the CALB decorated nanoparticle aqueous dispersion. The catalysing efficiency is evaluated by just allowing the Pickering gel system to stand at room temperature and studying the enzymatic esterification of hexanoic acid with hexanol in the oil phase. It is found that CALB immobilized on the nanoparticles in the Pickering gel emulsion shows a highly enhanced enzyme activity compared with free CALB, with a conversion rate of up to 96.5%. In addition, the Pickering gel emulsion maintains 92.5% residual activity after 10 reaction cycles, in each cycle the oil and aqueous phases are separated simply by centrifugation. This approach herein opens the door to the development of a Pickering interfacial biocatalyst system with a high water/oil volume ratio, super-stability, and easy recyclability for sustainable applications in biphasic enzyme catalysis.

Atorvastatin (ATV), a second generation cholesterol-lowering drug, is detected frequently in natural water because of its extensive use and incomplete removal from wastewater. In this study, the photochemical behavior of ATV under simulated solar irradiation was systematically investigated in order to assess the potential of photolysis as its transformation pathway in aquatic environment. The quantum yield of ATV direct photolysis was determined to be 0.0041. Among various water components investigated, including pH, Suwannee River Fulvic Acid (SRFA), Fe3+, HCO3-, SO42- and NO3-, the major factors contributing to the indirect photolysis of ATV were SRFA and NO3-, and the co-existence of SRFA and NO3- showed no interaction in synthetic water containing the above water components. The results were further verified in natural water samples. Singlet oxygen (1O2) played dominant role in the indirect photolysis of ATV, and the contributions of 1O2 and ·OH to the photolysis of ATV in the solution with optimum combination of water components were calculated to be 67.14% and 0.66%, respectively. Nine phototransformation intermediates were identified by liquid chromatography - time-of-flight - mass spectrometry (LC-TOF-MS), and the degradation pathways were speculated as hydroxyl addition, pyrrole-ring open and debenzamide reactions. In addition, the evolution of products in the degradation process showed that the ring-opened product P416 and hydroxylation product P575 still remained at a certain level after two days of photodegradation, which may accumulate and cause additional ecological risks. This study provides significant information for understanding the risk and fate of ATV in aquatic environment.

Models of the coupling of electromagnetic and gravitational fields have been studied extensively for many years. In this paper, we consider the coupling between the Maxwell field and the Weyl tensor of the gravitational field to study how the wavevector of the electromagnetic wave is affected by a plane gravitational wave. We find that the wavevector depends upon the frequency and direction of polarization of the electromagnetic waves, the parameter that couples the Maxwell field and the Weyl tensor, and the angle between the direction of propagation of the electromagnetic wave and the coordinate axis. The results show that this coupling model can be tested by the detection of high-frequency gravitational waves.

Glucose-regulated protein 94 (Grp94), a member of the Heat shock protein 90 (Hsp90) family, is implicated in many human diseases, including cancer, neurodegeneration, inflammatory, and infectious diseases. Here, we describe our effort to design and develop a new series of Grp94 inhibitors based on Phe199 induced fit mechanism. Using an alkynyl-containing inhibitor as a starting point, we developed compound 4, which showed potent inhibitory activity toward Grp94 in a fluorescence polarization-based assay. With improved physicochemical properties and suitable pharmacokinetic properties, compound 4 was advanced into in vivo bioactivity evaluation. In a dextran sulfate sodium (DSS)-induced mouse model of ulcerative colitis (UC), compound 4 showed anti-inflammatory property and reduced the levels of pro-inflammatory cytokines (TNF-α and IL-6). Together, these findings provide evidence that this approach may be promising for further Grp94 drug development efforts.

Catalyzed oxidative coupling reactions mediated by enzyme have been proposed as an effective remediation strategy to remove micropollutants, however, little is known about how the Mn(II) redox cycling affects the horseradish peroxidase (HRP)-mediated reactions in wastewater treatment. Here, we explored the removal of two pharmaceuticals and personal care products (PPCPs), methylparaben (MeP) and acetaminophen (AAP), in HRP-mediated reaction system with dissolved Mn (II). It was found that the conversion rate of AAP was about 284 times higher than that of MeP, and Mn (II) significantly inhibited HRP-catalyzed MeP removal but had little influence on that of AAP. X-ray photoelectron spectroscopy (XPS) and theoretical calculations demonstrated that HRP converted Mn(II) into Mn(III), and then generated MnO2 colloid, which inhibited the removal of the substrates. Moreover, the results of theoretical calculations also showed that the binding energy between HRP and Mn was 27.68 kcal/mol, which was higher than that of MeP (25.24 kcal/mol) and lower than that of AAP (30.19 kcal/mol). Therefore, when MeP and Mn (II) coexisted in the reaction system, HRP preferentially reacted with Mn(II), which explained the different impacts of Mn (II) on the removal of MeP and AAP. Additionally, Mn (II) significantly altered the product distribution by decreasing the amount of polymerization products. Overall, our work here revealed the roles of Mn (II) in the removal of MeP and AAP mediated by HRP, having strong implications for an accurate assessment of the influence of Mn(II) redox cycling on the removal of PPCPs in wastewater treatment.

Optics & laser technology 143, 107337 (2021). doi:10.1016/j.optlastec.2021.107337, Published by Elsevier Science, Amsterdam [u.a.]

The widespread occurrence of microplastics (MPLs) and nanoplastics (NPLs), collectively abbreviated as M/NPLs, has markedly affected the ecosystem and has become a global threat to human health. Multiple investigations have shown that the chronic ingestion of M/NPLs negatively affects gut barrier function but the mechanism remains unclear. Herein, this research has investigated the toxic effects of pristine polystyrene (PS) M/NPLs, negatively charged carboxylated polystyrene M/NPLs (PS-COOH) and positively charged aminated polystyrene M/NPLs (PS-NH2) of two sizes (70 nm and 5 μm in diameter) in mice. Gavage of these PS M/NPLs for 28 days caused obvious injuries to the gut tract, leading to the decreased expression of tight junction proteins. The toxicity of the M/NPLs was ranked as PS-NH2 > PS-COOH > pristine PS. Oral administration of these M/NPLs resulted in marked gut microbiota dysbiosis. The M/NPLs-enriched genera generally contained opportunistic pathogens which are accompanied by a deteriorated intestinal barrier function, while most M/NPLs-decreased bacteria were beneficial microbes with known tight junction-promoting functions, implicating an important indirect toxic effect of gut microbiota dysbiosis in M/NPLs-induced gut barrier dysfunction. In conclusion, this research highlights the importance of gut microbiota in the toxicity of M/NPLs exposure on gut barrier function, providing novel insights into the adverse effects of M/NPLs exposure on human health.

We study the Maxwell quasinormal spectrum on asymptotically anti-de Sitter black holes with a set of two Robin type boundary conditions, by requiring the energy flux to vanish at asymptotic infinity. Focusing, for illustrative purposes, on Schwarzschild-anti-de Sitter black holes both without and with a global monopole, we unveil that, on the one hand, the Maxwell quasinormal spectrum bifurcates as the black hole radius increases for both boundary conditions, which is termed the mode split effect; while on the other hand, with an appropriate fixed black hole radius but increasing the monopole parameter, the first (second) boundary condition may trigger (terminate) the mode split effect., Comment: 7 pages, published in Phys. Rev. D

We generalize our previous studies on the Maxwell quasinormal modes around Schwarzschild-anti-de-Sitter black holes with Robin type vanishing energy flux boundary conditions, by adding a global monopole on the background. We first formulate the Maxwell equations both in the Regge-Wheeler-Zerilli and in the Teukolsky formalisms and derive, based on the vanishing energy flux principle, two boundary conditions in each formalism. The Maxwell equations are then solved analytically in pure anti-de Sitter spacetimes with a global monopole, and two different normal modes are obtained due to the existence of the monopole parameter. In the small black hole and low frequency approximations, the Maxwell quasinormal modes are solved perturbatively on top of normal modes by using an asymptotic matching method, while beyond the aforementioned approximation, the Maxwell quasinormal modes are obtained numerically. We analyze the Maxwell quasinormal spectrum by varying the angular momentum quantum number $\ell$, the overtone number $N$, and in particular, the monopole parameter $8\pi\eta^2$. We show explicitly, through calculating quasinormal frequencies with both boundary conditions, that the global monopole produces the repulsive force., Comment: 10 pages, 5 figures, to appear in EPJC

We construct a family of solutions of the holographic insulator/superconductor phase transitions with the excited states in the AdS soliton background by using both the numerical and analytical methods. The interesting point is that the improved Sturm-Liouville method can not only analytically investigate the properties of the phase transition with the excited states, but also the distributions of the condensed fields in the vicinity of the critical point. We observe that, regardless of the type of the holographic model, the excited state has a higher critical chemical potential than the corresponding ground state, and the difference of the dimensionless critical chemical potential between the consecutive states is around 2.4, which is different from the finding of the metal/superconductor phase transition in the AdS black hole background. Furthermore, near the critical point, we find that the phase transition of the systems is of the second order and a linear relationship exists between the charge density and chemical potential for all the excited states in both s-wave and p-wave insulator/superconductor models., 23 pages, 8 figure, 6 tables

Reactive oxygen species (ROS) generated from light irradiation of microplastics (MPs) can potentially affect the environmental fate of organic contaminants when they coexist in the same environment. This study investigated the effect of polystyrene (PS) MPs with different aging degrees on the phototransformation of atorvastatin (ATV) under simulated sunlight. Results showed that the presence of PS MPs facilitated the phototransformation of ATV, and the degradation rate was linearly correlated with the aging degree (i.e., carbonyl index) of MPs. The enhanced effects mainly depended on the contents of oxygen-containing functional groups of PS MPs, which increased the absorption of light energy and the generation of ROS (e.g., singlet oxygen (1O2) and triplet-excited state PS (3PS*)). Quenching experiments indicated that 1O2 generated from photosensitization of PS was the major contributor to the increased phototransformation of ATV. Additionally, the role of 3PS* became more important in the photodegradation mediated by higher degree aged MPs because much more 1O2 was generated from the 3PS* . PS MPs also increased the types and yields of degradation products, especially for higher degree aged MPs, despite the low effect on leachate toxicity. The findings provide a novel insight into the critical role of MPs in the fate of organic contaminants in aquatic environments.

Since iron oxide minerals are ubiquitous in natural environments, the release of graphene oxide (GO) into environmental ecosystems can potentially interact with iron oxide particles and thus alter their surface properties, resulting in the change of their transport behaviors in subsurface systems. Column experiments were performed in this study to investigate the co-transport of GO nanoparticles and hematite colloids (a model representative of iron oxides) in saturated sand. The results demonstrated that the presence of hematite inhibited GO transport in quartz sand columns due to the formation of less negatively charged GO-hematite heteroaggregates and additional deposition sites provided by the adsorbed hematite on sand surfaces. Contrarily, GO co-present in suspensions significantly enhanced the transport of hematite colloids through different mechanisms such as the increase of electrostatic repulsion, decreased physical straining, GO-facilitated transport of hematite (i.e., highly mobile GO nanoparticles served as a mobile carrier for hematite). We also found that the co-transport behaviors of GO and hematite depended on solution chemistry (e.g., pH, ionic strength, and divalent cation (i.e., Ca2+)), which affected the electrostatic interaction as well as heteroaggregation behaviors between GO nanoparticles and hematite colloids. The findings provide an insight into the potential fate of carbon nanomaterials affected by mineral colloids existing in natural waters and soils.

In this study, batch and column tests were performed to investigate the co-transport of graphene oxide (GO) nanoparticles and tetracycline in saturated porous media under various solution chemistry conditions. Research indicated that GO and tetracycline had mutual promotion effect on their transport in the porous media under all the tested conditions, which was ascribed to the high adsorption capacity of tetracycline onto GO and the increased electrostatic repulsion as well as their competition for deposition sites on sand surfaces. Interestingly, the mutually promoting function of GO and tetracycline under acidic conditions was greater than that under alkaline conditions, the dominant mechanism was that the increased solution pH decreased the sorption of tetracycline onto GO and weakened the deposition site competition. Furthermore, the mutually promoting effect of GO and tetracycline was Na+ or Ca2+ concentration-dependent. Specially, increased Ca2+ concentration weakened the promoting effect of GO on tetracycline transport but magnified the promoting effect of tetracycline on GO transport. This is because higher Ca2+ concentration could cause a decrease in the adsorption of tetracycline on GO and facilitate more tetracycline molecules to occupy the deposition sites on sand surfaces. Additionally, sodium dodecyl sulfate had enhancement effect on co-transport of GO and tetracycline. Findings from this study clearly indicated that antibiotics and carbon based nanomaterials may transport together under various solution chemistry conditions, and consequently affect their fates in aquatic environments.

Singlet oxygen (1O2) is well known to be formed through energy transfer from excited state organic matters to O2, playing an important role in the transformations of contaminants. However, the contribution of small oxidated aromatic compounds (OACs) to the production of 1O2 in surface water is unclear. In this study, 28 OACs were selected to investigate the correlations between their photochemical production abilities of 1O2 and molecular structures. Our results showed that the steady-state concentrations and quantum yields of 1O2 (Φ1O2) generated by OACs were in the range of 7.0 × 10−14–1.4 × 10−12 M and 2.2 × 10−4–4.7 × 10−2, respectively, indicating that the photochemical production abilities of 1O2 by OACs varied greatly with types and positions of functional groups on the molecule. More importantly, the observed photochemical production of 1O2 was most notable in cases of molecules containing –OCH3 group and benzoquinone. A good quantitative structure-property relationship model was established between 1O2 producing ability, energy of the lowest unoccupied molecular orbitals (ELUMO) and the most positive net charge of hydrogen atoms (qH+) of OACs. In addition, the role of 1O2 produced by 2, 6-dimethoxy-1, 4-benzoquinone, the OAC with the highest Φ1O2, in the photodegradation of organic contaminants was validated by the enhanced degradation of atorvastatin under simulated sunlight, suggesting that OACs ubiquitously existed in surface water may greatly affect the fate and ecological risks of organic contaminants.

We investigate the holographic p-wave superfluid in the background metric of the AdS soliton with $RF^{2}$ corrections. Two models, namely, the Maxwell complex vector field model and Yang-Mills theory, are studied in the above context by employing the Sturm-Liouville approach as well as the shooting method. When turning on the spatial components of the gauge field, one observes that, in the probe limit, the inclusion of $RF^{2}$ corrections hinders the superfluid phase transition. On the other hand, however, in the absence of the superfluid velocity, it is found that the $RF^2$ corrections lead to distinct effects for the two models. Regardless of either the $RF^2$ correction or the spatial component of the gauge field, the phase transition of the system is observed to be always of the second order. Moreover, a linear relationship between the charge density and chemical potential is largely established near the critical point in both holographic superfluid models., 20 pages, 2 figures, 3 tables

Antibiotics, a highly prevalent class of environmental organic pollutants, are becoming a matter of global concern. Clay minerals that are ubiquitous in subsurface environments may play an important role in the fate and transport of antibiotics. Taking ciprofloxacin (CIP) as a model antibiotic, this work explored the role of clay colloids (kaolinite and montmorillonite) on the adsorption and transport of CIP under different chemical solution conditions. The adsorption isotherms showed that montmorillonite colloids had a larger CIP sorption capacity than kaolinite colloids. The results of transport experiments indicated that montmorillonite colloids could promote CIP transport in saturated sand columns, but the addition of kaolinite colloids affected CIP mobility to a much smaller extent. The much stronger transport-enhancement effect of montmorillonite colloids was due to CIP adsorbed strongly to the colloids and desorption hysteresis of colloid-adsorbed CIP, likely stemming from the intercalation of this antibiotic in the interlayer of montmorillonite. Interestingly, transport of clay colloids increased with the increasing pH from 5.0 to 9.0; however, CIP transport decreased with the increasing pH in the presence of clay colloids. The observations were likely attributable to pH-dependent ciprofloxacin adsorption/desorption to clay minerals. Increasing the concentrations of NaCl and CaCl2 generally decreased the contaminant-mobilizing ability of montmorillonite colloids, mainly by increasing the aggregation of colloids and thus, decreasing the transport of colloid-adsorbed CIP. Moreover, under the test conditions (1 mM NaCl and pH 7.0), the presence of CIP inhibited the transport of clay colloids due to the increase in aggregate size of clay colloids with the addition of CIP. Overall, these findings suggest that clay colloids with high adsorption abilities for antibiotics in the subsurface environment may act as a carrier for certain antibiotic compounds.

Atorvastatin (ATV) has been widely detected in wastewater treatment plant and aquatic environment. Limited mineralization ratio of ATV in current wastewater treatment processes may result in the accumulation of its transformation intermediates in effluent and cause additional ecological risk to the environment. In this study effectiveness of peroxymonosulfate (PMS) activated by CuFe2O4 on the degradation of ATV in water were examined. Complete removal of ATV was achieved by using 40 ppm CuFe2O4 and 25 μ mol dm−3 PMS. Eight intermediates were identified and four degradation pathways were proposed. The distribution of major intermediates ATV lactone (P541), hydroxylated ATV lactone (P557) and the pyrrole ring-open intermediate (P416) were monitored with different PMS dosages. As PMS concentration increased from 25 to 150 μ mol dm−3, the main intermediates accumulated were evolved from P541 and P557 to P557 and P416, and all intermediates were completely degraded with 750 μ mol dm−3 PMS. 61.72% TOC removal was achieved at pH 7.0 with 100 ppm CuFe2O4 and 3 m mol dm−3 PMS, which indicated that ATV could be well mineralized if PMS and CuFe2O4 dosages were reasonably used. Overall, this study provided practical knowledge for ATV removal by CuFe2O4/PMS at ambient temperature.

Due to the growing needs of thermal management in modern electronics, high thermal conductive polymer composites are increasingly demanded. Boron nitride nanosheet (BNNS) was prepared through molten hydroxide assisted liquid exfoliation of hexagonal boron nitride (h-BN) powder and used as thermally conductive filler. The poly(vinylidene fluoride) (PVDF)/BNNS films were obtained through solution blend and hot pressing. With only 4 wt% BNNS, the in-plane thermal conductivity of PVDF/BNNS composite achieved 4.69 W/mK, with a thermal conductivity enhancement of 2297% compared to neat PVDF. However, the through-plane thermal conductivity of the composites is only 0.23 W/mK, which shows a high thermal conductive anisotropy over 20. The thermal conductive anisotropy and the high in-plane thermal conductivity can be attributed to the formation of thermally conductive network in PVDF matrix. Thus, the BNNS reinforced PVDF films are promising for use as an efficient heat spreader for electronic cooling applications.

Epoxy composites with ZnO powders characterized by different structures as inclusion are prepared and their thermal properties are studied. The experimental results demonstrate that the epoxy resins filled by tetrapod-shaped ZnO (T-ZnO) whiskers have the superior thermal transport property in comparison to ZnO micron particles (ZnO MPs). The thermal conductivity of ZnO/epoxy and T-ZnO/epoxy composites in different mass fraction (10, 20, 30, 40, 50 wt%) are respectively investigated and the suitable models are compared to explain the enhancement effect of thermal conductivity. The thermal conductivity of T-ZnO/epoxy composites with 50 wt% filler reaches 4.38 W m−1 K−1, approximately 1816% enhancement as compared to neat epoxy. In contrast, the same mass fraction of ZnO MPs are incorporated into epoxy matrix showed less improvement on thermal conduction properties. This is because T-ZnO whiskers act as a thermal conductance bridge in the epoxy matrix. In addition, the other thermal properties of T-ZnO/epoxy composites are also improved. Furthermore, the T-ZnO/epoxy composite also presents a much reduced coefficient of thermal expansion (∼28.1 ppm K−1) and increased glass transition temperature (215.7 °C). This strategy meets the requirement for the rapid development of advanced electronic packaging.

Materials with superior thermal conduction, stable electrical insulation, and excellent mechanical strength that can be obtained at low cost are desirable for electronic packaging and thermal management in electrical engineering systems. There is therefore relentless interest in developing highly robust thermally conductive and electrically insulating polymer-based composites. Herein, a facile and environmentally friendly method to construct three-dimensional thermal transport channels in a poly(vinyl alcohol) (PVA) matrix composite is reported. The formation of thermal transport highways improves the thermal conductivity up to 4.79 W m−1 K−1 for alumina (Al2O3) loading of 45.4 vol% in the composites. The thermal conductivity achieved is the highest value for this Al2O3 content range compared with reported work, and is 1700% compared with that of pure PVA. In the meantime, the composites still retain outstanding electrical insulation properties and excellent mechanical strength. The heat-conducting and electrically insulating composites not only have promising applications in electronic packaging and electrical engineering systems, but the technically facile vacuum-assisted infiltration method is a new avenue for the mass production of spherical filler/polymer composites.

It is difficult for traditional cooling liquids to meet equipment requirements due to the high power and high integration they demand. Nanofluids are nanoparticle dispersions with high thermal conductivities, thus they have been proposed for heat transfer applications. Boron nitride nanosheets (BNNSs) possess high thermal conductivities and excellent insulation properties. Here, we fabricated BNNS nanofluids and investigated their effects on thermal conductivity enhancements. We find that BNNSs can effectively enhance the thermal conductivity of water. The thermal conductivity of the BNNS nanofluids reached 2.39 W mK-1 at 24 vol% loading. The surface temperature changes of the nanofluids and water were observed during the heating process using an infrared camera. The results show that the nanofluids transfer heat much faster than water, indicating that the fabricated BNNS nanofluids have excellent thermal transfer properties.

Herein, a cigarette filter-templated graphene/epoxy composite was prepared with enhanced thermal conductive properties. The through-plane thermal conductivity of the epoxy composite was up to 1.2 W mK−1, which was 4 times that of it in the in-plane (0.298 W mK−1) after only 5 filtration cycles. The thermal conductive anisotropy and improvement in the through-plane thermal conductivity of the epoxy composite were attributed to the particular structure of cigarette filter-templated graphene in the epoxy matrix. The unique structure formed effective conductive pathways in the composite to improve the thermal transportation properties. The excellent thermal transportation properties allow the epoxy composite to be used as an efficient heat dissipation material for thermal management applications.

The effects of multi-walled carbon nanotubes (MWCNTs) on the removal of contaminants mediated by Fenton reactions and how the functional groups on MWCNTs cooperate to modulate the cycling of Fe(III)/Fe(II) remain unclear. Here, we showed that MWCNTs significantly enhanced the removal of atenolol (ATL) in Fenton-like system by facilitating the generation of ·OH and O2·–, in which ·OH directly attacked ATL, while O2·– promoted the cycling of Fe(III)/Fe(II). Moreover, we found that in addition to –COOH, –OH on MWCNTs played an important role in ATL removal, that is, Fe(III) was likely to interact with –OH by H-bond and O–H···π interactions, which significantly reduced the reduction potential of Fe(III)/Fe(II), thus promoting the removal of ATL. Our findings revealed the role of –OH and –COOH on MWCNTs in promoting the removal of ATL in Fe(III)/H2O2 system, which is helpful to rationally design the CNTs-based materials applied for wastewater treatment.

Safety assessments of nanoparticles (NPs) in food are essential for safeguarding supervision and maintaining public health. However, there are still no safety assessment procedures for NPs established at the national level in China and no specific toxicology and safety assessment procedures concerning NPs in food. Current methods of evaluating the safety of NPs mainly rely on traditional toxicological assessments that are extrapolated based on animal experiments from high doses to low doses and from animals to humans. This leads to uncertainties which restrict the accuracy of safety assessments for NPs, and limit the development of scientific and effective evaluation procedures and regulatory measures. This review summarizes relevant research on the application and toxicity of NPs in food as well as current administrative and regulatory issues concerning NPs in food in China and some developed countries. As such, a scientific basis is provided for the future development of evaluation procedures for NPs in food.

Electronic packaging materials and thermal interface materials (TIMs) are widely used in thermal management. In this study, the epoxy composites with core-shell structure SiC@SiO(2) nanowires (SiC@SiO(2) NWs) as fillers could effectively enhance the thermal conductivity of epoxy composites. The unique structure of fillers results in a high thermal conductivity of epoxy composites, which is attributed to good interfacial compatibility epoxy matrix and bridging connections of SiC@SiO(2) NWs. From neat epoxy to 2.5 wt% loading of SiC@SiO(2) NWs, the thermal conductivity is significantly increased from 0.218 to 0.391 W m^−1 K^−1, increased by 79.4%. In addition, the composite with 2.5 wt% filler possess lower coefficient of thermal expansion and better thermal stability than that of neat epoxy. All these outstanding properties imply that epoxy/SiC@SiO(2) NWs composites could be the ideal candidate for TIM.

High thermal conductive polymer composites have recently attracted much attention, along with the quick development to the electronic devices toward higher speed. The addition of high thermal conductive fillers is an efficient method to solve this problem. Here, we introduced superfullerene (SF), a novel zero-dimensional carbon-based filler, and incorporated into PVDF by a solution method. The effects of SF filler on the thermal conductivity of PVDF composites were systematically investigated. It was found that PVDF composites exhibited an improvement in thermal conductivity at a low SF loading. PVDF composites with only 5 wt% SF filler present the thermal conductivity value of 0.365 Wm-1K-1, which is as much as 121 % enhancement in comparison with that of neat PVDF. In view of the excellent thermal transport performance, the composites may enable some applications in thermal management in the future.

Land-use change, particularly urban expansion, can greatly affect the carbon balance, both from the aspects of terrestrial ecosystems and anthropogenic carbon emissions. Coastal China is a typical region of rapid urban expansion, and obvious spatial heterogeneity exists from the north to south. However, the different urban change characteristics and the effect on carbon balance remain undetermined. By unifying the spatial-temporal resolution of carbon source and sink data, we effectively compared the carbon budgets of three coastal urban agglomerations in China. The results show that all of the three urban agglomerations have undergone an obvious urban expansion process, with the built-up area increasing from 1.03 &times, 104 km2 in 2000 to 3.06 &times, 104 km2 in 2013. For Beijing&ndash, Tianjin&ndash, Hebei (BTH), the built-up area gradually expanded. The built-up area in the Yangtze River Delta (YRD) gradually changed before 2007 but rapidly grew thereafter. The built-up expansion of the Pearl River Delta (PRD) passed through three growing stages and showed the largest mean patch size. Carbon emission spatial patterns in the three urban agglomerations are consistent with their economic development, from which the net ecosystem production (NEP) spatial patterns are very different. Compared to carbon emissions, NEP has a carbon sink effect and can absorb some carbon emissions, but the amounts were all much lower than the carbon emissions in the three urban agglomerations. The carbon sink effect in the Yangtze River Delta is the most obvious, with the Pearl River Delta following, and the lowest effect is in Beijing&ndash, Hebei. Finally, a scientific basis for policy-making is provided for viable CO2 emission mitigation policies.

Acetaminophen (AAP) is one of the most commonly prescribed over-the-counter drugs with wide distribution in surface water, which has attracted great attention around the world. Photodegradation and enzymatic transformation are important processes for the removal of AAP in water. The influence of natural organic matter (NOM) from different sources on the transformation of AAP by horseradish peroxidase (HRP) in sunlit water was systematically studied. NOM can effectively promote the combined degradation rate of AAP in photo-enzyme coupling system (PECS), and the promotion extents of different NOMs were dependent on their aromaticity and average molecular weights. NOM with low aromaticity and low average molecular weight is more effective. In order to disclose the underlying effects of NOM clearly, the reaction mechanism was clarified through the determination of the photodegradation constant and enzymatic reaction constant. The effect of NOM structure on the photo-enzymatic transformation of AAP was quantified, which showed significant positive correlation with the SUVA254 and E2/E3 of NOM. Further investigation revealed that the amount of H2O2 generated by NOM from different sources was also closely related to SUVA254 and E2/E3 of NOM. The findings will facilitate understanding the environmental fate of AAP and other pharmaceutical products in natural water.

Reciprocating sliding friction tests were conducted on pure magnesium using a UMT-II tester. The tribo-chemical behavior was characterized using X-ray photoelectron spectroscopy (XPS) and electron probe micro-analyzer (EPMA), which showed that the tribo-chemical behavior of pure magnesium was due to a tribo-oxidation reaction. At room temperature, the debris layer on the worn surface contained Mg(OH)2, MgO, and MgCO3. According to the reciprocating sliding friction mechanism, the decomposition of MgCO3 into MgO should occur. XPS results revealed that the surface oxide layer, containing Mg(OH)2, and MgO, acted as a third layer to protect the surface. Apparently, Mg(OH)2&middot, nH2O was the main tribo-chemical product of pure magnesium under sliding friction.

The holographic entanglement entropy (HEE) of field theories dual to 4-dimensional black strings with both the infinity boundary and near the horizon is investigated. It is shown that, with the infinity boundary, the main contribution of the HEE is divergent and it comes from the AdS background. If we remove this contribution, the remaining part is finite and proportional to the mass and charge densities. Near the horizon, we find that the HEE equals the Bekenstein–Hawking entropy if the subsystem covers the whole conformal boundary, for both charged and uncharged cases. In particular, the minimal surface (Ryu–Takayanagi surface) always stays in the bulk region for uncharged and non-extremal charged cases, while it is immersed inside the boundary for extremal black string.

Chloride ion (Cl−) widely presents in natural water and wastewater, which can significantly affect the performance of sulfate radical-based advanced oxidation processes (SR-AOPs). However, few studies are available now on the generation of chlorinated by-products in the peroxymonosulfate (PMS) based systems. Here a novel catalyst (cobalt/carbon nanotubes, Co/CNTs) was synthesized and used as a PMS activator to remove methylparaben (MeP) with and without Cl−. The morphology and chemical composition of the fresh and used Co/CNTs were characterized by TEM, SEM, XRD, BET, and XPS. Results revealed that Co/CNTs exhibited significant catalytic activity toward MeP removal, and the removal efficiency increased with the augment of reaction temperature and concentrations of Co/CNTs and PMS. In the absence of Cl−, 83.2% of 10 μM MeP was degraded within 60 min by using 2 mg/L Co/CNTs and 100 μM PMS at 25 °C with pH 7.0. However, complete removal of MeP was achieved within 20 min in the presence of 100 mM Cl−, which enhanced the apparent rate constant by a factor of 4.3. Consequently, TOC removal was enhanced from 8.1% to 19.2% within 60 min. Through the quenching experiments, both SO4 − and OH were found responsible for MeP degradation without Cl−, while Cl2− was the main reactive oxygen species (ROS) with 100 mM Cl−. Based on the intermediates identified via TOF-LC-MS, four potential reaction pathways were proposed, including hydrogen abstraction coupling reaction, hydroxylation, OH attack, and Cl2− attack. The intermediates also exhibited decreased toxicity compared to the parent compound based on the ecotoxicity evaluation. In addition, Co/CNTs + PMS system achieved over 60% MeP removal from real wastewater with elevated PMS concentration, indicating the process applicability. These findings provide valuable information of SR-AOPs to facilitate organic contaminants removal in Cl−-containing water.

Cerium and titanium oxides are considered as promising alternative catalysts for selective catalytic reduction with NH3 (NH3-SCR) to remove NOx. However, the poor SO2 or H2O tolerance and stability limit their practical applications. Herein, CeTiOx with nanotube structure (CeTiOx-T) was prepared by hydrothermal method and used for NH3-SCR reaction. CeTiOx-T shows the excellent catalytic activity, SO2 and H2O tolerance and stability, in which more than 98 % NO conversion can be achieved in the range of 180−390 °C with 100 % N2 selectivity. The characterizations verify that CeTiOx-T exhibits amorphous structure due to the strong interaction between Ce and Ti to form short-range ordered Ce-O-Ti species. As results, CeTiOx-T displays the larger BET surface area, more surface Bronsted acid amounts and chemisorbed oxygen, leading to its higher NH3-SCR performance. In situ DRIFTS results suggest the SCR reaction mainly follow L-H and E-R mechanisms at low and high temperature for over CeTiOx-T, respectively.

Fabrication of porous carbon supported plasmonic photocatalysts with the low-cost carbon waste is a promising strategy for resource utilization. Herein, a sewage sludge was chosen for the synthesis of the sewage sludge activated carbon (SSC) supported Bi3+-doped TiO2 and Bi0 (SSCTB) photocatalysts. Through the pyrolytic carbonization, the sewage sludge was simultaneously displayed as the carbon precursor and reduction agent for the formation of SSC and Bi0, respectively. The results showed that the monodispersed Bi3+-doped TiO2 nanoparticles embedded with Bi0 were in-situ formed on the porous SSC. The synergistic effect of the localized surface plasmon resonance (LSPR) of Bi0, Bi3+ doping in TiO2, and the carbon of SSC greatly improved the light response ability and charge separation efficiency of the SSCTB samples. Under UV–Vis-NIR light irradiation for 60 min, the SSCTB sample with 5% of Bi (SSCTB5) possessed higher degradation rate of 47% for methyl orange compared with those of other samples. The photocatalytic mechanism was proposed based on the LSPR effect and the charge transfer process, where SSCTB5 was able to yield the highest numbers of OH and O2 − radicals. The fabrication of the SSC supported plasmonic photocatalysts provides a cost-efficient strategy for the resource utilization of sewage sludge.

Humic acid (HA), a naturally occurring and widely distributed natural organic matter in the environment, is one of the most important factors controlling the transport and fate of mineral colloids. This study examined the influence of HA (0–10 mg/L) on the transport of goethite and hematite colloids in saturated quartz sand-packed columns under various solution chemistry conditions (including ionic strength and pH). We found that the transport-enhancement effect of HA on goethite colloids was greater than that on hematite colloids because the steric hindrance and electrostatic repulsion between HA-bound goethite colloids and sand stronger than those between HA-bound hematite colloids and sand. Besides, Ca2+ could be a bridging agent between HA and sand; and consequently, enhanced the steric hindrance between iron oxide colloids and sand, which was an important mechanism for the transport-enhancement effect of HA in the presence of Ca2+. Interestingly, with increasing HA concentration from 3 to 10 mg/L, the transport-enhancement effect of HA at higher ionic strength (i.e., 20 mM NaCl) was to a larger extent than that at lower ionic strength (i.e., 5 mM NaCl); meanwhile, the enhancement effect of HA at lower pH (i.e., 5.0) was to a larger extent than that at higher pH (i.e., 9.0). The observations were attributable to the surface charge and aggregation properties of HA-bound iron oxide colloids affected by solution chemistry coupled with HA concentration. Furthermore, DLVO theory extended by steric repulsion (XDLVO) could explain the observed trend of colloid transport under the test conditions.

With the broadly application of antibiotics to treat infectious diseases in humans and animals, antibiotic contaminants such as tetracycline (TC) and ciprofloxacin (CIP) have been detected in soil environments, where iron oxide minerals and phosphate are ubiquitous. To date, the influence of phosphate on the adsorption behaviors of TC/CIP onto iron oxides is still poorly understood. In this study, the effects of phosphate on the adsorptions of TC and CIP onto iron oxide minerals were investigated. Adsorption isotherms showed that the adsorption affinities of TC and CIP onto the three iron oxide minerals were in the order of goethite > hematite > magnetite with or without phosphate, the trend was dominated by different surface area and amount of surface hydroxyl groups of iron oxide minerals. Meanwhile, TC contains more functional groups than CIP for bonding, which resulted in greater adsorption affinity of three iron oxides to TC than that to CIP. Interestingly, phosphate weakened TC adsorption, while enhanced CIP adsorption, on the three iron oxides. This observation was ascribed to that phosphate anion enhanced the surface negative charge of iron oxides, which reinforced the electrostatic repulsion between iron oxides and negatively charged TC, also reinforced the electrostatic attraction between iron oxides and positively charged CIP. Furthermore, the inhibitory effect of phosphate on TC adsorption was dramatically enhanced at high pH, while the promoting effect of phosphate on CIP adsorption was slightly changed with various pH. Our results highlight the importance of phosphate in exploring the environmental fate of antibiotics in natural environment.

High-momentum synthetic jets have been used to enhance the mixing of a subsonic round jet with ambient air. The enhanced mixing processes are studied numerically to reveal jet mixing enhancement mechanisms. A parametric study has been carried out focusing on the effects of synthetic jet nozzle outlet diameter and maximum blowing jet momentum on penetration depth, interaction area, and counter-rotating vortices pair vorticity. Results show that high-momentum synthetic jets significantly affect the subsonic round jet. The centerline length of the primary jet high-temperature zone is reduced by up to 75% with the presence of synthetic jets. The induced streamwise vortices and the primary jet flapping resulting from synthetic jets are the key mixing mechanism. Jet mixing enhancement is related to the interaction area and the synthetic jet maximum momentum, which is the key parameter in jet mixing.

Previous time series methods have difficulties in simultaneous characterization of seasonal, gradual, and abrupt changes of remotely sensed land surface temperature (LST). This study proposed a model to decompose LST time series into trend, seasonal, and noise components. The trend component indicates long-term climate change and land development and is described as a piecewise linear function with iterative breakpoint detection. The seasonal component illustrates annual insolation variations and is modeled as a sinusoidal function on the detrended data. This model is able to separate the seasonal variation in LST from the long-term (including gradual and abrupt) change. Model application to nighttime Moderate Resolution Imaging Spectroradiometer (MODIS)/LST time series during 2000-2012 over Beijing yielded an overall root-mean-square error of 1.62K between the combination of the decomposed trend and seasonal components and the actual MODIS/LSTs. LST decreased (similar to -0.086K/yr, p

Sintered in a reducing atmosphere, the dielectric properties of Ba4.5(Nd0.7Sm0.3)9Ti18O54 (BNST) ceramics are deteriorated because of the ionized oxygen vacancies and conduction electrons. The feasibility of reduction resistance in BNST ceramics sintered in a reducing atmosphere was investigated in this work. Prompted by the example of BaTiO3 ceramics used in base-metal electrode multilayer ceramics capacitor, the effects of acceptor dopant MnCO3 on the microstructure, insulation resistivity (IR) and dielectric properties of BNST ceramics doped with 1 wt% BaCuB2O5 (BCB) sintered under a reducing atmosphere of moist N2-1%H2 were investigated. Results showed that MnCO3 effectively rendered BNST-BCB ceramics resistant to reduction. Mn ions completely substituted into the Ti4+ site of BNST at 1.5 wt% MnCO3, and the dielectric constant (e r ) of BNST-BCB was not obviously modified by the presence of additive. Moreover, 2 wt% MnCO3-doped BNST-1wt% BCB ceramics sintered in a reducing atmosphere exhibited attractive properties with e r = 75.1, tanδ = 0.00115, TCC = −42.3 ppm/°C and IR = 4.56×1012 Ω cm.

Polymeric composites with the advantages of easy process, light weight and good chemical resistance were employed in thermal management. The construction of a new type thermal conductive filler has become an efficient method for improving the thermal transportation performance of polymer composite. In this work, a barnacle-like nano-crystalline diamond@silicon carbide (ND@SiC) is prepared through depositing ND on SiC powders in a hot filament chemical vapor deposition (HFCVD). ND@SiC/PVDF composite was prepared and their thermal transportation properties were investigated. The obtained composites with 70 wt% ND@SiC loading exhibit a high thermal conductivity of 2.39 W m−1 K−1, which increased by 1132% in comparison with the pure polymer. It is also much higher than that of the composite adding 70 wt% SiC powders (1.48 W m−1 K−1). The high thermal conductivity of polymer composites by adding the ND@SiC filler is mainly attributed to the novel barnacle-like structure. This work provides a new idea to significantly enhance thermal transportation properties of composites as used in advanced packaging materials.

The hydroxide precipitation with CaO or Ca(OH)2 is frequently applied in the ferrite formation process of electroplating wastewater, but the excess Ca2+ ions present often weaken the quality of the resultant mixed-ferrite (M−Fe3O4) precipitates. In this work, for resource utilization of the M−Fe3O4 and the Ca2+ sources introduced from Ca(OH)2 in the hydroxide precipitate process, the upconversion assisted magnetite near-infrared (NIR) photocatalysts of M−Fe3O4/Tm3+/Yb3+-doped CaF2/TiO2 (FCT) are synthesized. The M−Fe3O4 phases possess the advantages of magnetic separation, broadband spectrum absorption, and the heterostructure with TiO2, and absorb the strong upconversion luminescence emitted from Tm3+/Yb3+-CaF2 for photocatalysis. The TiO2 phase contributes to the large improvement of upconversion luminescence and photocatalytic activity. Because of the stronger UV–Vis-NIR absorption, upconversion luminescence, and electron-hole pair separation for the FCT sample with Ti: Ca molar ratio of 3: 1 (FCT3), higher yields of OH and O2 − radicals are generated, which enable FCT3 to possess much enhanced degradation rate (87.3%) of ciprofloxacin compared with those of other FCT samples under UV–Vis-NIR light irradiation. The fabrication of the upconversion magnetite NIR photocatalysts from electroplating wastewater is a promising strategy for its resource utilization and the environmental remediation.

Biochar, a cost-effective carbonaceous material, has shown great promise in many applications such as soil remediation and wastewater treatment. Citric acid in soil and water environments may affect interactions between biochar and organic contaminants (e.g., tetracycline). To evaluate the effect of citric acid on the adsorption of tetracycline onto biochars, this study investigated the adsorption behavior of tetracycline onto biochars of two different pyrolysis temperatures (300 and 450 °C, referred to as BC_300 and BC_450) in the present of citric acid, accompanying with the effects of solution pH and Cu2+. The results indicated that citric acid significantly inhibited the adsorption of tetracycline onto both biochars, that was mainly due to the multi-mechanisms including pore blocking effect, surface adsorption sites competition, and steric hindrance induced by citric acid. Moreover, citric acid more significantly suppressed the adsorption of tetracycline onto the two biochars at pH 9.0 than at pH 5.0 and 7.0. Because increasing pH could promote electrostatic repulsion between the negative tetracycline and the negatively charged surface of biochars. Cu2+ had greater enhancing effect on the sorption of tetracycline onto BC_300 than BC_450 via cation-bridging effect. Meanwhile, citric acid inhibited the adsorption of tetracycline onto BC_300 to a larger extent than the adsorption onto BC_450 in the presence of Cu2+. That is possibly due to BC_300 has more surface oxygen-containing functional groups than BC_450. Thus, the effect of coexisting citric acid needs to be taken into account when biochar is increasingly used as an amendment in soil and water systems.

Phenol and its derivatives have received a great deal of attention due to their ubiquitous existence in surface water and recognized to be the main constituents in humic substance. However, few relevant studies concerned whether and how phenolic acids affect the fate of endocrine disrupting chemicals in surface water. In this study, the effect of 3, 5-dihydroxybenzoic acid (DHBA) on the phototransformation of 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) under simulated sunlight were systematically investigated. The results showed that DHBA significantly promoted the photolysis of estrogen mainly by producing triplet-excited state and superoxide anion based on density functional theory calculation and quenching experiments for reactive oxygen species (ROS). Interestingly, the intermediates of DHBA could compete with estrogen for reactive species to reduce the enhancing effect on E2 degradation, indicating that the changes on the structure and functional groups of phenolic compounds in photochemical process could further affect the photolysis of contaminants. Photodegradation pathways of E2 in the presence of DHBA were speculated as hydroxylation, oxidation, and coupling reactions. The study provided new insights for better understanding the effects of phenolic compounds on the natural attenuation of emerging organic contaminants in surface water.