The reuse of waste polyethylene terephthalate for green and low-cost synthesis of fluorescent carbon dots for “on-off-on” sensing of ferric and pyrophosphate ions.
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The increasing ...production of waste polyethylene terephthalate (PET) is a growing problem worldwide. Environmentally benign conversion of waste PET to valuable materials remains a substantial challenge. In this paper, we developed a green route to reuse waste PET for low-cost synthesis of fluorescent carbon dots (CDs) via air oxidation followed by hydrothermal treatment in aqueous H2O2 solution. No expensive, corrosive, or toxic reagents, or severe conditions were required in the synthetic process. The resultant CDs possessed abundant oxygenous groups and unique photoluminescence (PL) properties, which showed a highly selective and sensitive detection of ferric ion (Fe3+) through a PL quenching effect (on-off). The fluorescence of CDs quenched by Fe3+ could be restored specifically with pyrophosphate anion (PPi), rendering the CDs/Fe3+ sensor promising for PPi detection (off-on). The linear ranges for Fe3+ and PPi detections were 0.5–400 and 2–600 μM, and the limit of detections (LODs) were 0.21 and 0.86 μM, respectively. The sensing system applied for Fe3+ and PPi assays in real water samples and human urine achieved good results. After detailed investigations, a possible electron transfer process was proposed for explaining the “on-off-on” sensing mechanism.
Porous organic framework (COF) nanomaterials have drawn increasing attention and showed promising potential in the applications of various fields. Nevertheless, its applications in biosensing or ...biomedical fields are still in the early stage. In this work, we designed and synthesized a series of nanohybrids of COF and Ce-based metal organic framework (Ce-MOF) for the first time as label-free bioplatforms for a sensitive electrochemical aptasensor to detect oxytetracycline (OTC). A novel kinds of Ce-MOF@COF hybrids were prepared by adding different dosages of COF, into the preparation system of Ce-MOF, for which COF was synthesized using melamine and cyanutic acidmonomers through polycondensation (represented by MCA). Basic characterizations revealed that Ce-MOF@MCA nanohybrids not only remained their orignal crystal and chemical structure and features, such as different Ce species containing in Ce-MOF (Ce3+ and Ce4+), various functional amino-groups of MCA, and individual frameworks, but also showed a large specific surface area and interpenetrated morphologies. As a result, the Ce-MOF@MCA hybrid with high content of MCA exhibited high bioaffinity toward the OTC-targeted aptamer, further leading to the incremental detection effect for OTC detection. Among different hybrid-based aptasensors, the Ce-MOF@MCA-based one with an MCA dosage of 500 mg exhibited the lowest limit of detection at 17.4 fg mL−1 within a wider linearity of the OTC concentration within 0.1–0.5 ng mL−1. Additionally, the fabricated aptasensor displayed excellent analytical performance with great reproducibility, high selectivity and stability, and acceptable applicability for detecting OTC in various aqueous solutions, including milk, wastewater, and urine samples. This new Ce-MOF@MCA hybrid will become an excellent aptasensors platform for detecting various analytes, such as antibiotics, heavy metal ions, or cancer markers, and it have shown the promissing application potentials in the fields of biomedicine, food safety and environmental monitoring.
•Novel nanohybrid of the covalent organic framework and Ce-based metal organic framework.•Highly electrochemical activity and bioaffinity performances.•High sensitivity, excellent selectivity, good stability, and acceptable applicability.
Destruction of pharmaceuticals excreted in urine can be an efficient approach to eliminate these environmental pollutants. However, urine contains high concentrations of chloride, ammonium, and ...bicarbonate, which may hinder treatment processes. This study evaluated the application of ferrate(VI) (FeVIO4 2–, Fe(VI)) to oxidize pharmaceuticals (carbamazepine (CBZ), naproxen (NAP), trimethoprim (TMP), and sulfonamide antibiotics (SAs)) in synthetic hydrolyzed human urine and uncovered new effects from urine’s major inorganic constituents. Chloride slightly decreased pharmaceuticals’ removal rate by Fe(VI) due to the ionic strength effect. Ammonium (0.5 M) in undiluted hydrolyzed urine posed a strong scavenging effect, but lower concentrations (≤0.25 M) of ammonium enhanced the pharmaceuticals’ degradation by 300 μM Fe(VI), likely due to the reactive ammonium complex form of Fe(V)/Fe(IV). For the first time, bicarbonate was found to significantly promote the oxidation of aniline-containing SAs by Fe(VI) and alter the reaction stoichiometry of Fe(VI) and SA from 4:1 to 3:1. In depth investigation indicated that bicarbonate not only changed the Fe(VI)/SA complexation ratio from 1:2 to 1:1 but provided a stabilizing effect for Fe(V) intermediate formed in situ, enabling its degradation of SAs. Overall, the results of this study suggested that Fe(VI) is a promising oxidant for the removal of pharmaceuticals in hydrolyzed urine.
Sustainability in waste and wastewater treatment is currently drawing extensive attention. This study employed magnesium-oxides-modified biochar (Mg-biochar) yielded from wood waste to recover ...ammonium and phosphate from human urine. The Mg-biochar demonstrated high removal capacities of ammonium and phosphate, reaching 47.5 mgN/g and 116.4 mgP/g, respectively. Particularly, the removal capacity of ammonium was higher than those of many other carbon-based absorbents. Process mechanisms were discussed by analyzing the chemical composition of nutrient-enriched biochar (NBC), and the adsorption kinetics and isotherms. The struvite precipitation on the biochar surface was the dominant mechanism in the removal of both ammonium and phosphate, whereas the surface adsorption of phosphate also played a role in phosphate removal. The NBC presented competitive effects on growths of maize and ryegrass as a commercial fertilizer diammonium phosphate in pot experiments. However, the relatively low concentration of phosphate in the urine limited the removal efficiency of ammonium to only 1%, although most phosphates were removed. As such, another treatment unit should be combined for the complete removal of ammonium. Results indicated that Mg-biochar from wood waste can effectively remove phosphate from urine while recovering ammonium and phosphate as a biochar-based nutrient-enriched fertilizer.
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•Nutrient removal from urine reached 48 mgN/g and 116 mgP/g using Mg-biochar.•The removal capacity of NH4+ was higher than many other carbon-based absorbents.•Struvite precipitation was main mechanism to remove N and P instead of adsorption.•Adsorption on the Mg oxides contributed to about 30% of the phosphate removal.•The nutrient-enriched biochar showed competitive effect on plant growth as (NH4)2HPO4.
Liquid absorption and recycling play a crucial role in many industrial and environmental applications, such as oil spill cleanup and recovery, hemostasis, astronauts' urine recycling, and so on. ...Although many liquid absorbing materials have been developed, it still remains a grand challenge to achieve both fast absorption and efficient recycling in a cost‐effective and energy‐saving manner, especially for viscous liquids such as crude oil. A smart polyurethane‐based porous sponge with aligned channel structure is prepared by directional freezing. Compared to common sponges with random porous structure, the as‐prepared smart sponge has larger liquid absorption speed due to its lower tortuosity and stronger capillary (“tortuosity effect”). More importantly, the absorbed liquid can be remotely squeezed out due to a thermally responsive shape memory effect when the sponge is heated up. Such smart sponges with well‐defined porous structure and thermal responsive self‐squeezing capability have great potential in efficient liquid absorption and recycling.
A smart porous sponge with aligned channel structure is fabricated by directional freezing. Compared to sponges with random porous structure, the as‐prepared sponge has larger liquid absorption speed due to its lower tortuosity. The absorbed liquid can be remotely squeezed out due to thermally responsive shape memory effect. Such sponges have great potential in efficient liquid absorption and recycling.
The German Human Biomonitoring Commission (HBM Commission) derives health-related guidance values (Human Biomonitoring assessment values, HBM values) according to the procedures described in the HBM ...Commission’s position papers. Since the last adaption of the methodology in 2014, the HBM Commission has established a series of new HBM values, mainly on the basis of internationally agreed TDI/RfD values, or of toxicologically well- founded points of departure observed in animal studies. The derivation of these new HBM values for HBCDD, triclosan, 2-MBT, PFOA and PFOS as well as for the metabolites of glycol ethers, of Hexamoll® DINCH®, DPHP, DEHTP, NMP, NEP, and 4-MBC is specified, and the HBM values are presented together with already established HBM values for other substances. Furthermore, the HBM Commission has defined provisional reference values for 2-methoxyacetic acid and for several parabens in the urine of the German population. It has also updated provisional reference values for PCB in the blood of the German population. An overview of all available reference values is given.
A Au-Cu2O/rGO nanocomposite based electrochemical sensor for selective and simultaneous detection of dopamine and uric acid was developed. The nanocomposite was prepared by a one-pot synthesis method ...and the resulted product was characterized by transmission electron microscope (TEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) patterns and X-ray photoelectron spectroscopy (XPS). From TEM image, the presence of Au-Cu2O supported on rGO sheets were identified. The XRD analysis reveals the face centered cubic (FCC) structure of Au-Cu2O nanoparticles and the XPS spectrum showed the presence of the constituent elements in the nanocomposite. The electrochemical studies on the Au-Cu2O/rGO nanocomposite towards dopamine (DA) and Uric Acid (UA) were tested using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The CV studies showed enhanced catalytic activity for dopamine due to the synergistic effect of the ternary nanocomposite which was also further supported by the increased surface roughness of the material. From DPV, the detection limit of 3.9 μM and 6.5 μM and linear range of 10–90 μM and 100–900 μM was estimated for DA and UA. The selective and simultaneous detection of DA and UA was demonstrated. The sensor shows long term stability and reproducibility. Quantification of DA and UA in biological fluid samples (ie human serum and urine) has also been carried out to prove the practical applicability of the sensor.
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•One-pot synthesis of Au-Cu2O/rGO nanocomposite was prepared by a simple wet chemical method.•The nanocomposite exhibited enhanced catalytic activity towards DA.•The increased activity is attributed to the synergistic effect and the increased surface roughness of the nanocomposite.•The selective and simultaneous detection of DA and UA was accomplished using the proposed sensor.
We have previously described a novel flow-electrode capacitive deionization (FCDI) unit combined with a hydrophobic gas-permeable hollow fiber membrane contactor (designated “CapAmm”) and presented ...results showing efficient recovery of ammonia from dilute synthetic wastewaters (Zhang et al., Environ. Sci. Technol. Lett. 2018, 5, 43–49). We extend this earlier study here with description of an FCDI system with integrated flat sheet gas permeable membrane with comprehensive assessment of ammonia recovery performance from both dilute and concentrated wastewaters. The integrated CapAmm cell exhibited excellent ammonia removal and recovery efficiencies (up to ∼90% and ∼80% respectively). The energy consumptions for ammonia recovery from low-strength (i.e., domestic) and high-strength (i.e., synthetic urine) wastewaters were 20.4 kWh kg–1 N and 7.8 kWh kg–1 N, respectively, with these values comparable to those of more conventional alternatives. Stable ammonia recovery and salt removal performance was achieved over more than two days of continuous operation with ammonia concentrated by ∼80 times that of the feed stream. These results demonstrate that the integrated CapAmm system described here could be a cost-effective technology capable of treating wastewaters and realizing both nutrient recovery and water reclamation in a sustainable manner.
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•Only the variable Mg:P molar ratio had a significant influence on P recovery.•99% of P was recovered with MgO as Mg2+ source, 2:1 molar ratio and 30rpm.•Struvite crystals with ...50–100μm size were obtained.•XRD patterns were coherent with the standard model for struvite crystals.•Only the variable stirring speed had a significant effect on crystal size.
Phosphorus recycling and recovery has received special attention due to its non-replaceable and non-renewability. Phosphorus recovery from human urine in the form of struvite crystals is a potential alternative source. In this work, the efficiency of struvite precipitation from source separated human urine and struvite crystals size were analyzed using three different Mg2+ sources (MgCl2, Mg(OH)2 and MgO), individually evaluated using a statistical design of experiments to assess the combined effect of Mg2+:P molar ratio (1:1, 1.5:1 and 2:1) and stirring speed (30, 45 and 60rpm). Formation of struvite crystals was confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with an energy dispersive spectrometer (EDS). Using the optimal conditions determined, MgO as Mg2+ source at 2:1 molar ratio and a stirring speed of 30rpm, 99% of P was recovered as struvite crystals with a size of 50–100μm.
Urine metabolites are used in many clinical and biomedical studies but usually only for a few classic compounds. Metabolomics detects vastly more metabolic signals that may be used to precisely ...define the health status of individuals. However, many compounds remain unidentified, hampering biochemical conclusions. Here, we annotate all metabolites detected by two untargeted metabolomic assays, hydrophilic interaction chromatography (HILIC)-Q Exactive HF mass spectrometry and charged surface hybrid (CSH)-Q Exactive HF mass spectrometry. Over 9,000 unique metabolite signals were detected, of which 42% triggered MS/MS fragmentations in data-dependent mode. On the highest Metabolomics Standards Initiative (MSI) confidence level 1, we identified 175 compounds using authentic standards with precursor mass, retention time, and MS/MS matching. An additional 578 compounds were annotated by precursor accurate mass and MS/MS matching alone, MSI level 2, including a novel library specifically geared at acylcarnitines (CarniBlast). The rest of the metabolome is usually left unannotated. To fill this gap, we used the in silico fragmentation tool CSI:FingerID and the new NIST hybrid search to annotate all further compounds (MSI level 3). Testing the top-ranked metabolites in CSI:Finger ID annotations yielded 40% accuracy when applied to the MSI level 1 identified compounds. We classified all MSI level 3 annotations by the NIST hybrid search using the ClassyFire ontology into 21 superclasses that were further distinguished into 184 chemical classes. ClassyFire annotations showed that the previously unannotated urine metabolome consists of 28% derivatives of organic acids, 16% heterocyclics, and 16% lipids as major classes.
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