Self-assembly formation of Co quantum dot loaded N-doped porous carbon cathode for quinoline degradation in the electro-Fenton system.

Quinoline is high toxicity and difficult biodegradation in oil washing wastewater. Therefore, efficient removal of quinoline contaminant from water bodies poses a major challenge. Hence, Co quantum dot loaded N-doped porous carbon (CoNC) nanosheets grown in situ on carbon cloth were fabricated as cathode for the degradation of quinoline in electro-Fenton system. Under optimal conditions (c(Fe2+) = 0.5 mM, U = -0.3 V, pH = 3), quinoline was completely degraded within 15 min with superior apparent rate constant of 0.385 min-1, which was 19.6 times higher than that of the ZIF-L precursor, due to the abundance of Co QDs active sites and hydrophilicity and electrical conductivity of N-doped porous carbon. In addition, three reaction pathways for quinoline were deduced by combining Density Functional Theory (DFT) calculation and Liquid Chromatography-Mass Spectrometry (LC-MS). More importantly, in situ FTIR and free energy calculations were analyzed to reveal that pathway Ⅰ as spontaneous reaction was the main reaction pathway. Finally, the toxicity of the intermediates was assessed with ECOSAR software and E. coli experiments, and the overall toxicity decreased during the degradation reactions. This work provides novel perspectives on environmental protection by designing in-situ grown cathodes through self-assembly method, thereby effectively purifying pollutants from wastewater.

Construction of cellulose-degrading microbial consortium and evaluation of their ability to degrade spent mushroom substrate.

Introduction: Spent mushroom substrate (SMS) is a solid waste in agricultural production that contains abundant lignocellulosic fibers. The indiscriminate disposal of SMS will lead to significant resource waste and pollution of the surrounding environment.The isolation and screening of microorganisms with high cellulase degradation capacity is the key to improving SMS utilization. Methods: The cellulose-degrading microbial consortiums were constructed through antagonism and enzyme activity test. The effect of microbial consortiums on lignocellulose degradation was systematically evaluated by SMS liquid fermentation experiments. Results: In this study, four strains of cellulose-degrading bacteria were screened, and F16, F, and F7 were identified as B. amyloliquefaciens, PX1 identified as B. velezensis. At the same time, two groups of cellulose efficient degrading microbial consortiums (PX1 + F7 and F16 + F) were successfully constructed. When SMS was used as the sole carbon source, their carboxymethyl cellulase (CMCase) activities were 225.16 and 156.63 U/mL, respectively, and the filter paper enzyme (FPase) activities were 1.91 and 1.64 U/mL, respectively. PX1 + F7 had the highest degradation rate of hemicellulose and lignin, reaching 52.96% and 52.13%, respectively, and the degradation rate of F16 + F was as high as 56.30%. Field emission scanning electron microscopy (FESEM) analysis showed that the surface microstructure of SMS changed significantly after microbial consortiums treatment, and the change of absorption peak in Fourier transform infrared spectroscopy (FTIR) and the increase of crystallinity in X-ray diffraction (XRD) confirmed that the microbial consortiums had an actual degradation effect on SMS. The results showed that PX1 + F7 and F16 + F could effectively secrete cellulase and degrade cellulose, which had practical significance for the degradation of SMS. Discussion: In this study, the constructed PX1 + F7 and F16 + F strains can effectively secrete cellulase and degrade cellulose, which holds practical significance in the degradation of SMS. The results can provide technical support for treating high-cellulose solid waste and for the comprehensive utilization of biomass resources.

Iron complex regulated synergistic effect between the current and peroxymonosulfate enhanced ultrafast oxidation of perfluorooctanoic acid via free radical dominant electrochemical reaction.

Iron complex regulated electrochemical reaction was triggered for revealing the reaction mechanism, degradation pathway, and applied potential of perfluorooctanoic acid (PFOA). The increased PMS concentrations, electrode spacing, and current density significantly enhanced PFOA elimination, with current density exhibiting a relatively strong interdependency to PFOA complete mineralization. The synergy between PMS and electrochemical reactions greatly accelerated PFOA decomposition by promoting the generation of key reaction sites, such as those for PMS activation and electrochemical processes, under various conditions. Furthermore, density functional theory calculations confirmed that the reciprocal transformation of Fe2+ and Fe3+ complexes was feasible under the electrochemical effect, further promoting the generation of active sites. The developed electrochemical oxidation with PMS reaction (EO/PMS) system can rapidly decompose and mineralize PFOA while maintaining strong tolerance to changing water matrices and organic and inorganic ions. Overall, it holds promise for use in treating and purifying wastewater containing PFOA.

Health risk assessment and potential sources of metals in riparian soils of the Wujiang River, China.

In order to understand the pollution status of metals in the riparian soils along the Wujiang River, 26 sampling sites in the mainstream and tributary streams were selected for investigation. The geo-accumulation index (Igeo), Nemerow integrated pollution index, and potential ecological risk index were applied to evaluate the contamination status and ecological risks of metals. Results revealed that the average concentrations of As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn were 12.20, 0.51, 84.01, 57.42, 922.57, 38.37, 38.06, and 127.82 mg/kg, respectively. The metal contamination degree and ecological risks in the upper reaches were significantly higher than those in the middle and lower reaches of the Wujiang River. Cd was the dominant contamination metal. Significant non-carcinogenic and carcinogenic risks of metals were found in children based on the hazard index and carcinogenic risk. As was the main non-carcinogenic and carcinogenic pollutant metal in both adults and children. According to principal component analysis, hierarchical clustering analysis, and absolute principal component scores-multiple linear regression, anthropogenic sources (mining and agricultural activities) contributed most to Zn, Pb, Cr, Cd, Cu, and Ni, with contribution rates of 89.14, 82.32, 74.46, 72.12, 68.52, and 61.02%, respectively. Natural sources contributed most to Mn, with a contribution rate of 83.07%. Unidentified sources contributed most to As, with a contribution rate of 47.27%.

Assessment of metal pollution and effects of physicochemical factors on soil microbial communities around a landfill.

The physicochemical properties, chemical fractions of six metals (Cu, Zn, Pb, Cd, Cr, and Mn), and microbial communities of soil around a typical sanitary landfill were analyzed. The results indicate that soils around the landfill were from neutral to weak alkalinity. The contents of organic matter (OM), total nitrogen (TN), total phosphorous (TP), and activities of catalase, cellulase, and urease were significantly higher in landfill soils than those in background soils. Negative correlations were found between pH and metals. Cr was the dominant metal. Cu, Pb, Cr, and Mn were accumulated in the nearby farmland soils. Cd had the highest percentage of exchangeable fraction (33.7%-51.8%) in landfill and farmland soils, suggesting a high bioavailability to the soil environment affected by the landfill. Pb, Cr, and Mn existed mostly in oxidable fraction, and Cu and Zn were dominant in residual fraction. There was a low risk of soil metals around the landfill based on the RI values, while according to RAC classification, Cd had high to very high environmental risk. The MisSeq sequencing results showed that Actinobacteria, Proteobacteria, Chloroflexi, and Acidobacteria were the dominant phyla of bacteria, and the most abundant phylum of fungi was Ascomycota. The NMDS analysis revealed that the landfill could influence soil fungal communities more intensely than bacterial communities. TN, cellulase, and bioavailable metals (Pb-Bio and Cr-Bio) were identified to have main influences on microbial communities. Pb-Bio was the most dominant driving factor for bacterial community structures. For fungi, Pb-Bio was significantly negatively related to Olpidiomycota and Cr-Bio had a significantly negative correlation with Ascomycota. It manifests that bioavailable metals play important roles in assessing environmental risks and microbial community structures of soil around landfill.

A comparative study on the influence of single and combined ultrasounds assisted flake graphite flotation.

Ultrasound has emerged as a promising technique for improving the mineral flotation performance. However, limited research exists regarding the influence of different ultrasound types on the flotation process. Specifically, the impact of combined ultrasound and the comparison of horn- and bath-type ultrasounds on flotation have not been fully investigated. To address this knowledge gap, a comprehensive study to explore the effects of different ultrasonic pretreatments on the flotation of flake graphite was conducted. A Box-Behnken design is employed to analyze the effects of combined ultrasound on graphite flotation. By characterizing the properties of graphite samples before and after the ultrasonic treatment, the aim is to elucidate the mechanism underlying the impact of ultrasound on graphite flotation. The experimental results indicated that the ultrasonic cavitation intensity exerted a significant influence on the graphite flotation recovery. Both horn- and bath- type ultrasounds contributed to flotation, but horn-type ultrasound demonstrated a more pronounced effect, leading to a 7% increase in flotation recovery, whereas bath-type ultrasound resulted in only a 2% increase. Furthermore, the cavitation intensity of combined ultrasound was found to be higher than that of single-frequency ultrasound in the same duration. However, the performance of graphite flotation was better with short duration combined ultrasound pretreatment, while the opposite trend was observed for a long duration ultrasound pretreatment. These findings may inform the development of more efficient and effective ultrasonic pretreatments for flotation separation processes.

Geochemical fractionation, bioaccessibility and ecological risk of metallic elements in the weathering profiles of typical skarn-type copper tailings from Tongling, China.

Nonferrous metal tailings have long posed a significant threat to the surrounding environment and population. Previous studies have primarily focused on heavy metal pollution in the vicinity of sulfide tailings, while little attention was given to metal mobility and bioavailability within skarn-type tailings profile during weathering. Therefore, this study aimed to investigate the fractionation, bioaccessibility, and ecological risk associated with metallic elements (MEs, including Pb, Cd, Cr, Zn, and Cu) in two representative weathering copper-tailings profiles of Tongling mine (China). This was achieved through the use of mineralogical analyses, BCR extractions (F1: exchangeable, F2: reducible, F3: oxidizable, F4: residual fraction), in-vitro gastrointestinal simulation test (PBET) and risk assessment models. The mineral compositions of two weathering profiles were similar, with quartz and calcite being the dominant minerals, along with minor amounts of siderite, hematite and spangolite. The mean concentration in the tailings profile was approximately 0.31 (Cr), 1.8 (Pb), 12 (Zn), 33 (Cd) or 34 (Cu) times of the local background values (LBVs). The mean content of the bottom weakly-weathering layer in profile was about 0.36 (Cr), 0.91 (Pb), 1.91 (Cd), 2.73 (Zn) or 2.68 (Cu) times of the surface oxide layer, indicating a strong weathering-leaching effect. The average proportion of BCR-F1 fraction for Cd (30.94 %) was the highest among the five MEs, possibly due to its association with calcite. The PBET-extracted fractions for Cd, Zn and Cu were significantly positively correlated with the F1, F2 and F3 fractions of BCR, suggesting that these elements have higher bioavailability/bioaccessibility. The assessment results indicated that Cd posed a higher health risk, while the risk of Cu, Zn, and Pb is relatively low and Cr is safe. In conclusion, this study provides valuable insights into the environmental geochemical behavior and potential risks of MEs in skarn-type non-ferrous metal tailings ponds.

Qualitative and quantitative analysis for Cd2+ removal mechanisms by biochar composites from co-pyrolysis of corn straw and fly ash.

Removal of heavy metals (e.g., Cd) from contaminated water using waste-converted adsorbents is promising, but the efficiency still needs to be improved. Here, we prepared a functional biochar composite as novel Cd adsorbents by co-pyrolysis of two typical solid wastes, i.e., agricultural corn straw and industrial fly ash. The adsorption behavior and mechanism were investigated using batch and column adsorption experiments and modern characterization techniques. Results showed that alkali-modified fly ash (AMFA) was loaded onto the surface of the corn straw biochar as some fine particle forms, with quartz (SiO2) and silicate being the main mineral phases on the surface. The maximum sorption capacity fitted by Langmuir model for functionalized biochar composite (FBC700) was up to 137.1 mg g-1, which was 7.7 times higher than that of the original corn straw biochar (BC700). Spectroscopic analysis revealed that adsorption mechanisms of Cd onto the FBC700 included mainly precipitation and ion exchange, with complexation and Cd-π interaction also contributing. The AMFA could effectively improve the mineral precipitation with Cd. The adsorption columns filled with FBC700 exhibited a longer breakthrough time than that filled with BC700. The adsorption capacity calculated by Thomas model for FBC700 was also approximately 6.0 times higher than that for BC700, showing that FBC700 was more suited to practical applications. This study provided a novel perspective for recycling solid wastes and treating Cd-contaminated water.

Phosphate-Solubilizing Capacity of Paecilomyces lilacinus PSF7 and Optimization Using Response Surface Methodology.

Phosphorus-solubilizing microorganisms release organic acids that can chelate mineral ions or reduce the pH to solubilize insoluble phosphates for use by plants; it is important to study potential phosphorus-solubilizing microorganisms for use in agriculture. In this study, PSF7 was isolated from the soil of the Wengfu Phosphorus Tailings Dump in Fuquan City, Guizhou Province, China. PSF7 was identified as Paecilomyces lilacinus, based on morphological characterization and ITS sequencing analysis. The relationship between the phosphorus-solubilizing capacity and pH variation of PSF7 under liquid fermentation was studied. The results showed that there was a significant negative correlation (-0.784) between the soluble phosphorus content of PSF7 and the pH value. When PSF7 was placed under low phosphorus stress, eight organic acids were determined from fermentation broth using HPLC, of which tartaric acid and formic acid were the main organic acids. Different optimization parameters of medium components were analyzed using response surface methodology. The optimized medium components were 23.50 g/L sucrose, 1.64 g/L ammonium sulfate and soybean residue, 1.07 g/L inorganic salts, and 9.16 g/L tricalcium phosphate, with a predicted soluble phosphorus content of 123.89 mg/L. Under the optimum medium composition, the actual phosphorus-solubilizing content of PSF7 reached 122.17 mg/L. Moreover, scanning electron microscopy analysis of the sample was carried out to characterize the phosphate-solubilizing efficiency of PSF7 on mineral phosphate. The results provide useful information for the future application of PSF7 as a biological fertilizer.

Comparative study on metal concentrations in water, sediments, and two fish species (Cyprinus carpio and Pelteobagrus fulvidraco) from the Wujiang River, China.

In order to assess the metal pollution in the Wujiang River, concentrations of Cu, Zn, Fe, Mn, Pb, Cd, As, and Hg in the water, sediments, and two fish species Cyprinus carpio and Pelteobagrus fulvidraco from the middle reaches (Tuomugang, TMG) and lower reaches (Wulong, WL) of the Wujiang River were examined. The results indicated that all metal concentrations were lower than the values for grade one water quality according to the Environment Quality Standard for Surface Water of China (GB 3838-2002). The bioavailable fraction concentrations of Zn, Fe, Mn, Pb, and Hg in WL were significantly higher than those in TMG (p < 0.05), indicating that these metals in sediments of WL have higher bioavailability and mobility. The Cu, Zn, Fe, Pb, As, and Hg were mainly related to the residual fraction, while the Mn and Cd were mainly associated with the non-residual fraction. The risk assessment code (RAC) and the secondary phase to the primary phase (RSP) values indicated that Mn and Cd have a high risk of secondary release. The mean metal concentrations in the liver of the two fish species were higher than those in muscle. The higher metal concentrations of fish in WL suggested that bioaccumulation of metals in fish could be influenced by metal bioavailability. No identical relationships between metal concentrations and fish length were manifested in the present study. The values of target hazard quotient (THQ) and hazard index (HI), and carcinogenic risk (CR) of metals for the consumption of C. carpio and P. fulvidraco indicated that the anglers would likely not experience significant non-carcinogenic risk, but the carcinogenic risk of As cannot be ignored. Thanks to prohibited commercial fishing in the Wujiang River, the metal pollution will probably not pose a health risk to the general public for wild fish consumption.

Spatiotemporal variation in the blood lead levels of Chinese children with the environmental Kuznets curve trend.

The environmental Kuznets curve (EKC) is often used to analyze the relationship between environmental pollution health indicators and economic development level in different regions. In developed countries, the blood lead levels (BLLs) of children have been declining fitting the EKC since the 1970s. However, such figures in China have remained at relatively high levels, without any obvious decline, since 2010. We explored spatial variations and graded countermeasures using reported data on BLLs including the lead poisoning rates (LPRs) of children. We found that there were prefectures where either the mean BLLs of the children had reached 100.00 µg/L or the LPRs of more than 40% of the children had reached 100 µg/L. When we reduced the average BLLs to 50 µg/L or lowered the proportion of children with a lead poisoning rate (LPR) above 100 µg/L to 10.00%, the EKC trend decreased, and the linear slope after 2010 became -0.202. If the areas where children's BLLs exceeded 50.00 µg/L or the proportion of children with an LPR above 100 µg/L was more than 10.00% will be controlled, the linear slope of the EKC decrease trend after 2010 will became -0.989, and the national average of children's BLLs would decline by 22.17%. The study concluded that children's BLLs in different regions of China are situated at different EKC stages, and urgent prevention and control strategies must be put in place for undeveloped areas.

Solar-Assisted Superhydrophobic MoS2/PDMS/MS Sponge for the Efficient Cleanup of Viscous Oil.

Industrialization releases many high-viscosity oil pollutants into the environment, requiring a hydrophobic recyclable oil-absorbing material. Therefore, a self-heating and superhydrophobic melamine sponge (MS) by connecting polydimethylsiloxane (PDMS) was coated with functionalized molybdenum disulfide (MoS2) nanosheets on a three-dimensional microstructure of a commercial MS (MoS2/PDMS/MS) via a simple and low-cost dip-coating method. The prepared sponge showed a water contact angle of 151.8°, indicating that the modified sponge exhibited superhydrophobicity. Due to the addition of MoS2, the modified sponge can convert light into heat, and its surface could be heated to 59.7 °C within 30 s. Because of the excellent MoS2/PDMS/MS photothermal performance, the sponge could decrease the viscosity of the high-viscosity oil, absorbing the high-viscosity oil efficiently. After simultaneous thermal analysis and repeated compression tests, the modified sponge exhibited high thermochemical stability, mechanical property, and reusability. This superhydrophobic multifunctional sponge shows excellent potential for high-viscosity oil absorption.

Enhanced removal of Cd2+ from water by AHP-pretreated biochar: Adsorption performance and mechanism.

The sesame straw-derived biochar was successfully prepared via alkaline hydrogen peroxide (AHP) pretreatment in this study. Systematic experimental characterizations, 15 relevant batch and column adsorption models, combined with density functional theory (DFT) calculation were used to investigate the performances and micro-mechanisms of Cd2+ adsorption onto biochar. We found AHP-pretreatment could greatly improve the adsorption performance of biochar for Cd2+. The maximum Cd2+ adsorption capacity of AHP-pretreated biochar (87.13 mg g-1) was much larger than that of unpretreated biochar. Cd2+ adsorption was mainly dominated by the chemisorption of the homogeneous surface monolayer. The hydroxyl and carboxyl groups on the surface of biochar provided preferential adsorption sites, and liquid film diffusion and intra-particle diffusion were two dominant rate-controlling steps. Our results showed that ion exchange, co-precipitation, surface complexation, and Cd2+-π interaction were the dominant adsorption mechanisms. Especially, DFT calculations well-identified that lone-pair electrons during complexation and π electrons during coordination were provided by oxygen-containing functional groups and aromatic rings, respectively. The experimental breakthrough curves fitted better with the theoretical value of the BJP model, compared to Thomas, Yoon-Nelson, and EXY models. Overall, our study provides a promising method for Cd2+ removal from wastewater and resource utilization of agricultural wastes.

Differentiated strategies of animal-derived and plant-derived biochar to reduce nitrogen loss during paper mill sludge composting.

This work aimed to reveal the differences of nitrogen (N) transformation between animal-derived and plant-derived biochar during paper mill sludge composting. Three treatments were established, including CK (no biochar), ABC (animal-derived biochar), and PBC (plant-derived biochar). Results showed that N loss was reduced by 24.43% and 35.50% in ABC and PBC, respectively, compared with CK. Moreover, the contents of acid-insoluble N (AIN) in ABC and bioavailable organic N (BON) in PBC were 6.180 g/kg and 9.269 g/kg higher than in CK (2.602 g/kg and 8.988 g/kg). The protease activity and bacterial abundance associated with the generation of humic N-containing precursors increased in ABC. Low urease activity and a more complex bacterial N-cycling network were found in PBC. Structural equation model confirmed that AIN formation and BON retention were the dominant strategies for animal-derived and plant-derived biochar, respectively. The findings provided multiple pathways to produce N-enriched compost products.

Blending Electrostatic Spinning Fabrication of Superhydrophilic/Underwater Superoleophobic Polysulfonamide/Polyvinylpyrrolidone Nanofibrous Membranes for Efficient Oil-Water Emulsion Separation.

The scarcity of water resources has led to widespread interest in the treatment of oily wastewater. This study prepared a novel superhydrophilic/underwater superoleophobic polysulfonamide (PSA)/polyvinylpyrrolidone (PVP) nanofibrous membrane through electrostatic spinning for efficient oil-water emulsion separation. The surface morphology, fiber diameter distribution, wettability properties, and oil-water emulsion separation performance of the membranes were investigated. Results showed that the addition of PVP increases the diameter of the fibers, which led to a loose, large, porous structure and improved the permeability of the membranes. A high pure-water flux of 2057 L·m-2·h-1 was obtained for membranes with PVP addition of 3 wt%, providing an 835% increase in pure-water flux compared with a pure PSA nanofibrous membrane (220 L·m-2·h-1). For n-hexane-in-water emulsions, the optimum membrane obtained a high separation efficiency of 99.7%, in which flux was 1.5 times greater than that of the pure PSA nanofibrous membrane. Moreover, the optimum membrane exhibited good recycling stability and solvent resistance. The as-prepared PSA/PVP nanofibrous membrane displayed high permeability, an outstanding rejection rate, resistance to organic solvents, and reusability for oil-water separation, providing great potential in practical membrane separation applications.

Efficient decomposition of perfluorooctane sulfonate by electrochemical activation of peroxymonosulfate in aqueous solution: Efficacy, reaction mechanism, active sites, and application potential.

The electrochemical oxidation method is a promising technology for the degradation of perfluorooctane sulfonate (PFOS). However, the elimination processes of PFOS are still unknown, including the electron transfer pathway, key reactive sites, and degradation mechanism. Here, we fabricated diatomite and cerium (Ce) co-modified Sb2O3 (D-Ce/Sb2O3) anode to realize efficient degradation of PFOS via peroxymonosulfate (PMS) activation. The transferred electron and the generated hydroxyl radical (•OH) can high-effectively decompose PFOS. The electron can be rapidly transferred from the highest occupied molecular orbital of the PFOS to the lowest unoccupied molecular orbital of the PMS via the D-Ce/Sb2O3 driven by a potential energy difference under electrochemical process. The active site of Ce-O in the D-Ce/Sb2O3 can greatly reduce the migration distance of the electron and the •OH, and thus improving the catalytic activity for degrading various organic micropollutants with high stability. In addition, the electrochemical process shows strong resistance and tolerance to the changing pH, inorganic ions, and organic matter. This study offers insights into the electron transfer pathway and PMS activation mechanism in PFOS removal via electrochemical oxidation, paving the way for its potential application in water purification.

Exploration of perfluorooctane sulfonate degradation properties and mechanism via electron-transfer dominated radical process.

Polyfluoroalkyl and perfluoroalkyl chemicals (PFCs) widely used in lubricants, surfactant, textiles, paper coatings, cosmetics, and fire-fighting foams can release a large deal of organics contaminants into wastewater and pose great risks to the health of humans and eco-environments. Although advanced oxidation processes can effectively deconstruct various organic contaminants via reactive radicals, the stable structure of PFCs makes it difficult to be degraded. Here, we confirm that electrochemical oxidation process coupled with peroxymonosulfate (PMS) reaction can efficiently destroy stable structure of PFCs via electron transfer and meanwhile completely degrade PFCs via generated active radicals. We further studies via capturing and scavenging radicals, and DFT calculations find that electron hydroxyl radials play a dominant role in degrading PFCs. Based on the calculations of adsorption energy and molecular orbital energy we further demonstrate that many active sites on the surface of Ti4O7 (1 0 4) plane can rapidly take part in electrochemical reaction for generating radials and removing organic contaminants. These results give a promising insight towards high-effective and deep degradation of PFCs via electrochemical reaction coupled with advanced oxidation processes, as well as providing guidance and technical support for the remove of multiple organic contaminants.

The effect of preparation time and aeration rate on the properties of bulk micro-nanobubble water using hydrodynamic cavitation.

Fundamental research on bulk micro-nanobubbles (BMNBs) has grown rapidly due to the demand for their industrial applications and potential role in interfacial sciences. This work focuses on examining properties of such bubbles, including the number, concentration, zeta potential, and surface tension in water. For this purpose, BMNBs were generated by the hydrodynamic cavitation (HC) mechanism. Distilled water and air in the experiments were the liquid and gas phases, respectively. The characterization of bulk microbubbles (BMBs) and bulk nanobubbles (BNBs) were performed through focused beam reflectance measurement (FBRM) and nanoparticle tracking analysis (NTA) techniques, respectively. Zeta potential and surface tension of aqueous solutions were measured at different time and aeration rates. The results showed that aeration rate and preparation time had an important role in the properties of BNBs (concentration, bubble size, and surface charge) and BMBs (number, and bubble size). The instability of BMBs led to the rapid changes in the dissolved oxygen (DO) content in the water. The number of BMBs decreased when preparation time and aeration rate increased, but their size remained constant. By enhancing the preparation time and aeration rate, the concentration of BNBs improved first and then reduced. Additionally, the surface tension of an aqueous solution containing BNBs was significantly lower than that of pure water.

Facile one-step fabrication of superhydrophobic melamine sponges by poly(phenol-amine) modification method for effective oil-water separation.

Although polydopamine (PDA)-related modification is widely studied in the fabrication of superhydrophobic sponges, the high cost of dopamine limits its widespread application. To imitate PDA modification, a low-cost and facile one-step poly(phenol-amine) modification was performed on melamine sponges in this study. Low-cost catechol and diethylenetriamine (DETA) were used as the monomers, and n-dodecanethiol was used as an additive in the one-step modification. The results confirmed that the poly(phenol-amine) aggregations were successfully anchored on the sponge skeleton surface and that the aggregations were formed via the Schiff base reaction and the Michael addition reaction. Furthermore, the as-prepared sponges still showed excellent mechanical properties after modification. Additionally, the optimally modified sponge (MS-0.5) exhibited superhydrophobic properties with a contact angle value above 150° under various environments, high oil-absorption capacity for various oils and organic solvents, high continuous oil-water separation performance with efficiency greater than 98.8% in 30 cycles, outstanding demulsification performance with 99.52% toward oil-in-water emulsion, and excellent recoverability and long-term stability. Thus, this work provides a feasible facile one-step modification method that can be used in place of PDA-related modification.

Heavy metals speciation and distribution of microbial communities in sediments from the abandoned Mo-Ni polymetallic mines, southwest of China.

Chemical fractions of heavy metals (Mo, Ni, Cu, Zn, Fe, Mn, Pb, Cd, and Cr) and compositions of bacteria and fungi in surface sediments from the Mo-Ni polymetallic mine area were analyzed. The results indicated that the mean concentrations of Mo, Ni, Cu, Zn, and Cd were higher than their background values. The mean percentage of Cr in residual fraction was much higher than that of other heavy metals. Mo, Cu, Zn, Fe, and Pb were mainly associated with oxidizable fraction. The dominant proportions of Mn and Cd were found in exchangeable fraction with mean percentages of 93.46% and 54.50%, respectively. According to RAC classification and potential ecological risk index (PERI), the Cd with high bioavailability had a very high environmental risk. The MisSeq sequencing results of bacteria and fungi revealed that microbial communities discrepantly respond to different sampling sites. The most abundant phylum of bacteria and fungi were Proteobacteria and Ascomycota, respectively. The bioavailable heavy metals including Mo-B, Pb-B, and Cd-B were recognized to have important influences on both dominant bacterial and fungal communities. The present study manifested that the bioavailability of heavy metal is very important to assess the potential environmental risk and plays a key role in shaping microbial structure.