Graphitic carbon nitride (g-C3N4) has recently emerged as a promising visible-light-responsive polymeric photocatalyst; however, a molecular-level understanding of material properties and its ...application for water purification were underexplored. In this study, we rationally designed nonmetal doped, supramolecule-based g-C3N4 with improved surface area and charge separation. Density functional theory (DFT) simulations indicated that carbon-doped g-C3N4 showed a thermodynamically stable structure, promoted charge separation, and had suitable energy levels of conduction and valence bands for photocatalytic oxidation compared to phosphorus-doped g-C3N4. The optimized carbon-doped, supramolecule-based g-C3N4 showed a reaction rate enhancement of 2.3–10.5-fold for the degradation of phenol and persistent organic micropollutants compared to that of conventional, melamine-based g-C3N4 in a model buffer system under the irradiation of simulated visible sunlight. Carbon-doping but not phosphorus-doping improved reactivity for contaminant degradation in agreement with DFT simulation results. Selective contaminant degradation was observed on g-C3N4, likely due to differences in reactive oxygen species production and/or contaminant-photocatalyst interfacial interactions on different g-C3N4 samples. Moreover, g-C3N4 is a robust photocatalyst for contaminant degradation in raw natural water and (partially) treated water and wastewater. In summary, DFT simulations are a viable tool to predict photocatalyst properties and oxidation performance for contaminant removal, and they guide the rational design, fabrication, and implementation of visible-light-responsive g-C3N4 for efficient, robust, and sustainable water treatment.
Microplastics (MPs) are ubiquitously spread in water environment and have raised global concerns due to their adverse effect to biological and ecological systems. Wastewater treatment plants have ...been reported to be an important route of releasing MPs into the environment. As a great source of MPs in number in wastewater, the characteristics of microbeads have hardly been studied. In this study, the variation of the characteristics of microbeads prior to and after incubating in wastewater samples has been identified. Reported digestion methods of acid, alkaline, enzymatic, and wet preoxidation digestion were subsequently applied to assess their efficacy for digesting microbeads from the wastewater, and enzymatic digestion has shown the optimal efficacy. Finally, enzymatic digestion was applied to evaluate microbeads and other MPs in real wastewater treatment plant samples. It is shown that the sequential treatment of fine screen, grit chamber, and improved sequencing batch reactor activated sludge processes were able to remove 72% pellets in number and 43% MPs in total, while a large portion was still remaining after the secondary treatment. This study set a base for understanding the characteristics and occurrence of MPs, especially microbeads in wastewater samples.
Efficiently exploring organic molecules through multi-step processes demands a transition from conventional laboratory synthesis to automated systems. Existing platforms for machine-assistant ...synthetic workflows compatible with multiple liquid-phases require substantial engineering investments for setup, thereby hindering quick customization and throughput increasement. Here we present a droplet-based chip that facilitates the self-organization of various liquid phases into stacked layers for conducting chemical transformations. The chip’s precision polymer printing capability, enabled by digital micromirror device (DMD)-maskless photolithography and dual post-chemical modifications, allows it to create customized, sub-10 µm featured patterns to confine diverse liquids, regardless of density, within each droplet. The robustness and open design of surface-templated liquid layers actualize machine-assistant droplet manipulation, synchronous reaction triggering, local oscillation, and real-time monitoring of individual layers into a reality. We propose that, with further integration of machine operation line and self-learning, this droplet-based platform holds the potential to become a valuable addition to the toolkit of chemistry process, operating autonomously and with high-throughput.Existing platforms for machine assistant synthetic workflows compatible with multiple liquid phases lack the possibility of easy customization and throughput increasement. Here, the authors report a droplet-based chip that allows self-organization of various liquid phases into stacked layers for conducting chemical transformations.
With the increasing promotion of new energy vehicles and the rapid popularization of digital electronic products, there is a growing demand for lithium-ion and lithium-sulfur batteries. These ...batteries have gained widespread attention due to their excellent electrochemical performance. However, with the continued demand for high-power applications in new energy vehicles and digital electronics, the safety and stability of the batteries have become critical. TiO
2
is commonly utilized in battery separators owing to its capacity to enhance the thermal stability, mechanical properties, and electrochemical stability. It can inhibit the “shuttle effect” of polysulphides in lithium-sulfur batteries through physical and chemical methods to improve the cycling performance of lithium-sulfur batteries. This review will outline three methods for modifying TiO
2
separators: blending (utilizing electrostatic spinning and phase conversion), coating (involving the coating method, immersion fabrication method, and vacuum filtration method), and grafting. Finally, the prospective evolution of battery separators and the concomitant challenges they confront will be contemplated.
Background
Most particulate organic matter (POM) cannot be directly degraded in the conventional wastewater treatment, which should be transformed into dissolved organic matter (DOM) through a ...hydrolysis process. However, non-hydrolyzed POM in the biological treatment can limit treated efficiencies for the wastewater treatment plants (WWTPs) facilities. Hence an operational tool is indispensable for insight into removals of DOM and POM factions in the WWTP. In this study, excitation-emission matrix fluorescence spectroscopy (EEM) combined parallel factor analysis (PARAFAC), two-dimensional correlation (2D-COS) and structural equation modeling (SEM) was employed to evaluate removals of DOM and POM in a wastewater treatment plant.
Results
Four fluorescence components were identified in DOM and POM substances from the WWTP by EEM combined with PARAFAC, i.e., tyrosine-like (TYLF), tryptophan-like (TRLF), microbial byproduct-like (MBLF), and fulvic acid-like (FALF). In A
2
/O process, the TYLF and TRLF of DOM were removed to a larger extent than those of MBLF and FALF in anaerobic tank, while TYLF and MBLF of POM were removed to a great extent than those of TRLF and FALF in primary sedimentation and aerobic tanks. By the 2D-COS, a decreasing variation order of DOM fractions in the wastewater treatment process was UV-FALF → MBLF2 → Vis-FALF → TRLF → TYLF, while the decreasing order of POM fractions was Vis-FALF → UV-FALF → MBLF2 → TYLF → MBLF1 → TRLF. SEM revealed that TRLF and TYLF of DOM were degraded by anaerobic microorganism, and TRLF could be transformed partially into FALF. However, TRFL and TYLF of POM were discomposed by aerobic microorganism.
Conclusions
The 2D-COS and SEM can be practicable tools as EEM-PARAFAC for monitoring DOM and POM in the WWTP. The study could present a theoretical support to improving the retrofit of WWTP and formulating emission standards for organic pollutants.
Abstract
This study investigated the efficacy of using micro-flocculation as a pretreatment approach in alleviating ultrafiltration (UF) membrane fouling caused by organic matter in treated ...wastewater. Three typical model dissolved organic matters (DOM), humic acid, fulvic acid, and sodium alginate, were employed to simulate membrane fouling. The results showed that micro-flocculation using poly aluminum chloride (PAC) or polymerized ferric sulfate (PFS) as flocculant could effectively enhance the treatment performance of the UF process on DOM. With 6 mg/L PAC, the removal efficiency of humic acid, fulvic acid, and sodium alginate by micro-flocculation combined UF process reached 79.95%, 63.25%, and 51.14%, respectively. Specifically, after micro-flocculation, micromolecular hydrophilic organic matter (e.g., fulvic acid) tended to form a compact cake layer. The macromolecular hydrophobic organic matter (e.g., humic acid) and macromolecular hydrophilic organic matter (e.g., sodium alginate) generally led to a loose cake layer. At PAC dosage of 6 mg/L, the membrane specific flux (J/J0) at the end was improved by 11.71%, 10.27%, and 2.2% for humic acid, sodium alginate and fulvic acid solutions, respectively, compared with the UF process alone. It could be inferred that micro-flocculation pretreatment can effectively mitigate the membrane fouling when treating wastewater containing humic acid, sodium alginate, or fulvic acid.
The ability of constructed wetlands with different plants in nitrate removal were investigated. The factors promoting the rates of denitrification including organic carbon, nitrate load, plants in ...wetlands, pH and water temperature in field were systematically investigated. The results showed that the additional carbon source （glucose） can remarkably improve the nitrate removal ability of the constructed wetland. It demonstrated that the nitrate removal rate can increase from 20% to more than 50% in summer and from 10% to 30% in winter, when the nitrate concentration was 30-40 rag/L, the retention time was 24 h and 25 mg/L dissolved organic carbon （DOC） was ploughed into the constructed wetland. However, the nitrite in the constructed wetland accumulated a little with the supply of the additional carbon source in summer and winter, and it increased from 0.15 to 2 mg/L in the effluent. It was also found that the abilities of plant in adjusting pH and temperature can result in an increase of denitrification in wetlands. The seasonal change may also impact the denitrification.
The ever-increasing production and processing of textiles will lead to greater risks of releasing pollutants into the environment. Textile wastewater treatment plants (TWTPs) effluent are an ...important source of persistent toxic pollutants in receiving water bodies. The effects of specific pollutants on organisms are usually studied under laboratory conditions, and therefore, comprehensive results are not obtained regarding the chronic combined effects of pollutants under aquatic environmental conditions. Thus, this study aimed to determine the combined effects of TWTP effluents on the growth performance, oxidative stress, inflammatory response, and intestinal microbiota of adult zebrafish (
). Exposure to TWTP effluents significantly inhibited growth, exacerbated the condition factor, and increased the mortality of adult zebrafish. Moreover, markedly decreases were observed in the activities of antioxidant enzymes, such as CAT, GSH, GSH-Px, MDA, SOD, and T-AOC, mostly in the intestine and muscle tissues of zebrafish after 1 and 4 months of exposure. In addition, the results demonstrated that TWTP effluent exposure affected the intestinal microbial community composition and decreased community diversity. Slight changes were found in the relative abundance of probiotic
,
, and
in zebrafish guts after chronic TWTP effluent exposure. The chronic toxic effects of slight increases in opportunistic pathogens, such as
,
, and
, deserve further attention. Our results reveal that TWTP effluent exposure poses potential health risks to aquatic organisms through growth inhibition, oxidative stress impairment of the intestine and muscles, and intestinal microbial community alterations.
Tumor recurrence in patients after surgery severely reduces the survival rate of surgical patients. Targeting and killing recurrent tumor cells and tissues is extremely important for the cancer ...treatment.
Herein, we designed a nano-biomimetic photothermal-controlled drug-loading platform HepM-TSL with good targeting ability and immunocompatibility for the treatment of recurrent hepatocellular carcinoma. HepM-TSL can accurately target the recurrent tumor area with the aid of the cloaked homotypic cell membrane and release the chemotherapy drugs in a controlled manner. In vivo results have confirmed that HepM-TSL loaded with drugs and photosensitizer achieves the synergistic treatment of recurrent hepatocellular carcinoma with good therapeutic effect and slight side effects.
Accordingly, HepM-TSL provides a sound photothermal-chemotherapy synergistic strategy for the treatment of other recurrent cancers besides of recurrent hepatocellular carcinoma.
Sites in a gene showing the nonsynonymous/synonymous rate ratio (ω) >1 have been frequently identified to be under positive selection. To examine the performance of such analysis, sites of the ω ...ratio >1 in the HA1 gene of H3N2 subtype human influenza viruses were identified from seven overlapping sequence data sets in this study. Our results showed that the sites of the ω ratio >1 were of significant variation among the data sets even though they targeted similar clusters, indicating that the analysis is likely to be either of low sensitivity or of low specificity in identifying sites under positive selection. Most (43/45) of the sites showing ω >1 calculated from at least one data set are involved in B-cell epitopes which cover less than a half sites in the protein, suggesting that the analysis is likely to be of low sensitivity rather than of low specificity. It was further found that the analysis sensitivity could not be enhanced by including more sequences or covering longer time intervals. Previously some reports also likely identified only a portion of the sites under positive selection in the viral gene using the ω ratio. Low sensitivity of the analysis may result from that some sites under positive selection in the gene are also under negative (purifying) selection simultaneously for functional constrains, and so their ω ratios could be <1. Theoretically, the sites under the two opposite selection forces at the same time favor only certain nonsynonymous changes, e.g. those changing the antigenicity of the gene and maintaining the gene function. This study also suggested that sometimes we can identify more sites under positive selection using the ω ratio by integrating the positively selected sites estimated from multiple data sets.
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