A novel Z-scheme system of CeO2–Ag/AgBr heterostructure photocatalyst exhibits excellent ability to eliminate ciprofloxacin under visible light irradiation.
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•Novel Z-scheme ...CeO2–Ag/AgBr photocatalysts were prepared.•Superior photocatalytic activity for the degradation of ciprofloxacin (CIP) refractory pollutants was obtained.•The factors affecting the photocatalytic performance were investigated.•A plausible degradation pathway for CIP was proposed.•A Z-scheme photocatalytic mechanism was proposed.
In this study, CeO2–Ag/AgBr composite photocatalysts with a Z-scheme configuration were fabricated by in situ interspersal of AgBr on CeO2 and subsequent photoreduction process. The CeO2–Ag/AgBr composites exhibited enhanced photocatalytic activity for the photodegradation of ciprofloxacin (CIP) under visible light irradiation. The effects of initial CIP concentration and various inorganic salts were investigated in detail. Three-dimensional excitation–emission matrix fluorescence spectra were used to further monitor the CIP molecule degradation. Plausible degradation pathways for CIP were proposed based on LC-MS instruments. Photoluminescence, electrochemical impedance spectroscopy, and photocurrent tests indicated the rapid transfer and migration of electrons–holes can be achieved in this ternary photocatalytic system. The enhanced photocatalytic performances of CeO2–Ag/AgBr could be credited to the accelerated interfacial charge transfer process and the improved separation of the photogenerated electron–hole pairs. The existence of a small amount of metallic Ag is conducive to the formation of a stable Z-scheme photocatalytic system. This work would pave the route for the design of novel Z-scheme photocatalytic systems for application in solar-to-fuel conversion and photocatalytic water treatment.
Abstract
Currently, coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been reported in almost all countries globally. No effective ...therapy has been documented for COVID-19, and the role of convalescent plasma therapy is unknown. In the current study, 6 patients with COVID-19 and respiratory failure received convalescent plasma a median of 21.5 days after viral shedding was first detected, all tested negative for SARS-CoV-2 RNA within 3 days after infusion, and 5 eventually died. In conclusion, convalescent plasma treatment can end SARS-CoV-2 shedding but cannot reduce the mortality rate in critically ill patients with end-stage COVID-19, and treatment should be initiated earlier.
Six patients with coronavirus 2019 disease and respiratory failure received convalescent plasma a median of 21.5 days after first detected viral shedding, all tested negative for severe acute respiratory syndrome coronavirus 2 within 3 days after infusion, and 5 eventually died.
•Species of bacteria and fungi that dealt with PAHs and heavy metals were reviewed.•Factors affecting bioremediation of PAHs and heavy metals were discussed.•Bioremediation mechanisms of PAHs and ...heavy metals were elucidated.•Potential research needs for this field were discussed.
In recent years, knowledge in regard to bioremediation of combined pollution of polycyclic aromatic hydrocarbons (PAHs) and heavy metals by bacteria and fungi has been widely developed. This paper reviews the species of bacteria and fungi which can tackle with various types of PAHs and heavy metals entering into environment simultaneously or successively. Microbial activity, pollutants bioavailability and environmental factors (e.g. pH, temperature, low molecular weight organic acids and humic acids) can all affect the bioremediation of PAHs and heavy metals. Moreover, this paper summarizes the remediation mechanisms of PAHs and heavy metals by microbes via elucidating the interaction mechanisms of heavy metals with heavy metals, PAHs/PAHs metabolites with PAHs and PAHs with heavy metals. Based on the above reviews, this paper also discusses the potential research needs for this field.
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•Biochars are potential sustainable precursors for activated carbon production.•Physical activation and chemical activation are applied in the production process.•Production ...parameters affect the properties of resultant activated carbon.•Multiple applications in environmental protection and energy storage are reviewed.•Future perspectives about biochar activation and applications are highlighted.
There is a growing interest of the scientific community on production of activated carbon using biochar as potential sustainable precursors pyrolyzed from biomass wastes. Physical activation and chemical activation are the main methods applied in the activation process. These methods could have significantly beneficial effects on biochar chemical/physical properties, which make it suitable for multiple applications including water pollution treatment, CO2 capture, and energy storage. The feedstock with different compositions, pyrolysis conditions and activation parameters of biochar have significant influences on the properties of resultant activated carbon. Compared with traditional activated carbon, activated biochar appears to be a new potential cost-effective and environmentally-friendly carbon materials with great application prospect in many fields. This review not only summarizes information from the current analysis of activated biochar and their multiple applications for further optimization and understanding, but also offers new directions for development of activated biochar.
Due to their extensive application in human and veterinary medicine, antibiotics have been found worldwide and studied as new pollutants in the aquatic environment. In order to remove such ...pollutants, adsorption and photocatalysis have attracted tremendous attention because of their great potential in antibiotics removal from aqueous solutions. Graphene, as a novel two-dimensional nanomaterial, possesses unique structure and physicochemical properties, which can be used to efficiently adsorb and photodegrade antibiotics. This review provides an overview of the adsorptive and catalytic properties of graphene, and recent advances in adsorption and photodegradation of antibiotics by graphene and its derivatives. The factors that affect the adsorption and photodegradation of antibiotics are reviewed and discussed. Furthermore, the underlying mechanisms of adsorption and photodegradation are summarized and analyzed. Meanwhile, statistical analysis is conducted based on the number of papers and the maximum adsorption and photodegradation ability on various antibiotics removal. Finally, some unsolved problems together with major challenges that exist in the fabrication and application of graphene-based nanocomposites and the development for antibiotics removal is also proposed. This work provides theoretical guidance for subsequent research in the field of adsorption and photocatalytic removal of antibiotics from aqueous solution, especially on influence factors and mechanisms aspects.
•Recent studies on antibiotics removal from water by adsorption and photocatalysis.•Graphene and its derivatives as adsorbents and photocatalysts are reviewed.•Graphene properties and circumambient conditions influence the antibiotics removal.•The mechanisms of antibiotics removal via adsorption/photocatalysis are discussed.•Challenges and outlook are proposed to realize practical application.
As the largest container and resource of metals, sediment has a special role in the fate of metals. Factors influencing bioavailability of heavy metals in sediment have never been comprehensively ...considered and the sediment properties still fail to understand and even controversial. In this review, the mechanisms of sediment properties such as acid-volatile sulfides (AVS), organic matter, texture (clay, silt or sand) and geology, organism behaviors as well as those influencing the bioavailability of metals were analyzed. Under anoxic condition, AVS mainly reduce the solubility and toxicity of metals, while organic matters, Fe–Mn oxides, clay or silt can stabilize heavy metals in elevated oxidative–reductive potential (ORP). Other factors including the variation of pH, redox potential, aging as well as nutrition and the behavior of benthic organism in sediment also largely alter metals mobility and distribution. These factors are often inter-related, and various toxicity assessment methods used to evaluate the bioavailability of trace metals have been also discussed. Additionally, we expect that some novel synthetic materials like polysulfides, nano-materials, provide the substantial amendments for metals pollution in sediment.
•The influencing mechanisms of sediment geochemical properties on heavy metals bioavailability were analyzed.•AVS stabilize heavy metals in anoxic state but OM and Fe-Mn oxides immobilize metals under aerobic condition.•Considering the sediment geochemical properties is needed when establish the model of bioavailability.
Nowadays nanomaterials have been widely used to remove heavy metals from water/wastewater due to their large surface area and high reactivity. Humic acid (HA) and fulvic acid (FA) exist ubiquitously ...in aquatic environments and have a variety of functional groups which allow them to complex with metal ions and interact with nanomaterials. These interactions can not only alter the environmental behavior of nanomaterials, but also influence the removal and transportation of heavy metals by nanomaterials. Thus, the interactions and the underlying mechanisms involved warrant specific investigations. This review outlined the effects of HA/FA on the removal of heavy metals from aqueous solutions by various nanomaterials, mainly including carbon-based nanomaterials, iron-based nanomaterials and photocatalytic nanomaterials. Moreover, mechanisms involved in the interactions were discussed and potential environmental implications of HA/FA to nanomaterials and heavy metals were evaluated.
•The review outlined heavy metals' removal from water by nanomaterials affected by HA/FA.•Potential mechanisms involved in the interactions were discussed.•Environmental implications of HA/FA to nanomaterials and heavy metals were evaluated.•Outlook for further challenges and potential development was also offered.
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•Recent studies on synthesis of biochar-based nano-composites are reviewed.•Biochar-based nano-composites combine the advantages of biochar with nano-materials.•Nano-particles improve ...biochar’s physicochemical properties and serve as active sites.•Multiple mechanisms are involved in contaminants removal.•Knowledge gaps in the future development should be studied.
Synthesizing biochar-based nano-composites can obtain new composites and combine the advantages of biochar with nano-materials. The resulting composites usually exhibit great improvement in functional groups, pore properties, surface active sites, catalytic degradation ability and easy to separation. These composites have excellent abilities to adsorb a range of contaminants from aqueous solutions. Particularly, catalytic material-coated biochar can exert simultaneous adsorption and catalytic degradation function for organic contaminants removal. Synthesizing biochar-based nano-composites has become an important practice for expanding the environmental applications of biochar and nanotechnology. This paper aims to review and summarize the various synthesis techniques for biochar-based nano-composites and their effects on the decontamination of wastewater. The characteristic and advantages of existing synthesis methods are summarized and discussed. Application of biochar-based nano-composites for different contaminants removal and the underlying mechanisms are reviewed. Furthermore, knowledge gaps that exist in the fabrication and application of biochar-based nano-composites are also identified.
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•DCQN showed fast, sensitive and specific NIR fluorescence turn-on response to sulfite.•Sulfite in food could be visually detected by DCQN in term of chromogenic reaction.•DCQN could ...be used for tracking and imaging of sulfite in cells and zebrafish.•DCQN-incorporated agar hydrogel as a portable device could on-site detect sulfite.
Excessive sulfite is harmful to human health. To monitor the sulfite level in food, living cells, and organisms, we herein present a high-performance near-infrared (NIR) fluorescent probe DCQN that exhibits chromogenic and NIR fluorescence turn-on response towards sulfite with a rapid response time of 4.5 s, unique specificity, a low detection limit of 24 nM, and a large Stokes shift. DCQN was used for the facile and accurate determination of the sulfite level in real food with high sensitivity and good recoveries (93–105%). In particular, the sulfite present in food samples can be in situ visually detected by DCQN in terms of chromogenic reaction along with fluorescence turn-on indicator. Moreover, DCQN was incorporated into agar hydrogel to serve as a convenient, cheap and portable device for the fast and visual on-site detection of sulfite in food. Furthermore, DCQN was used to achieve in situ tracking and imaging of sulfite in MCF-7 cells and zebrafish with a high contrast ratio and high sensitivity.
SrTiO3/BiOI heterostructure photocatalysts were successfully fabricated through a facile chemical bath method with assistant of the ethylene glycol, which exhibit an efficient charge separation and ...excellent catalytic ability in removing different refractory pollutants.
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•Novel SrTiO3/BiOI heterojunction photocatalysts were fabricated.•A wider application in the degradation of refractory pollutants.•The factors affecting the photocatalytic performance were investigated.•The degradation process of MO and OTTCH was monitor by 3D EEMs.•The in-depth mechanisms insight of charge separation.
Novel SrTiO3/BiOI heterostructure photocatalysts were successfully fabricated through a facile chemical bath method with assistant of the ethylene glycol. The photocatalysts were applied to minimize methyl orange (MO), bisphenol A (BPA), antibiotic oxytetracycline hydrochloride (OTTCH) under visible light irradiation. The SrTiO3/BiOI composites exhibited excellent photocatalytic performance towards the different refractory pollutants. Especially, the sample of STB-22.12 possessed the best photocatalytic performance in all the obtained catalysts. Several reaction parameters affecting degradation such as initial concentration, ion species were investigated systematically. Three-dimensional excitation–emission matrix fluorescence spectroscopy (3D EEMs) was used to further investigate the MO and OTTCH molecule degradation process. The photocatalytic mechanism over composite photocatalyst is systematically investigated by active species trapping experiments, ESR technique and Mott–Schottky measurements. Moreover, the energy band alignments of SrTiO3/BiOI heterostructure were confirmed via combining DRS and XPS analysis, which provided strong support for the proposed mechanism. This work could provide a deeper insight for the heterojunction catalyst.
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