RESUMEN
Lignin-based carbon material can be utilized as carbonaceous adsorbents for the removal of toxic gaseous organic pollutants, while the poor heat-resistance limited its widely application. Here in, B-N co-doped lignin carbon (BN-C) with high thermal stability was synthesized, and the optimized BN-C (1:2) exhibited notably improved heat resistance with the decomposition temperature up to 505 °C, and excellent adsorption capacity for o-dichlorobenzene (o-DCB) (1510.0 mg/g) and toluene (947.3 mg/g), together with good cyclic stability over 10 cycles for o-dichlorobenzene. The existence of abundant hexagonal boron nitride (h-BN) with good thermal conductivity contributed to the superior heat-resistance of BN-C (1:2), and the high specific surface area (1764.5 m2/g), enriched hydroxyl functional groups and improved graphitization degree contributed to its enhanced adsorption performance. More importantly, BN-C (1:2) supported Ru could effectively remove o-DCB and toluene at wide temperature range (50-300 °C). The present work guided the development of heat-resistant lignin-derived adsorbent-catalyst for gaseous aromatic pollutants removal, which benefits both environmental protection and resource utilization.
Asunto(s)
Contaminantes Atmosféricos , Lignina , Nitrógeno , Adsorción , Lignina/química , Catálisis , Nitrógeno/química , Contaminantes Atmosféricos/química , Calor , Boro/química , Tolueno/química , Compuestos de Boro/química , Carbono/químicaRESUMEN
Lignocellulose is an abundant renewable bio-macromolecular complex, which can be used to produce biomethane and other high-value products. The lignin, presents in lignocellulose is typically regarded as an inhibitor of anaerobic digestion. Therefore, it is crucial to develop a novel selective separation strategy to achieve efficient biomethane production and all-component utilization of biomass. Hence, a combination of two-step pretreatment and solid-state anaerobic digestion was employed to enhance the production of biomethane and to generate valuable chemicals from poplar waste. Optimal conditions (4 % acetic acid, 170 °C, and 40 min) resulted in 70.85 % xylan removal, yielding 50.28 % xylo-oligosaccharides. The effect of a strong acid 4-CSA-based novel three-constituent DES on delignification was investigated from 80 °C to 100 °C; the cellulose content of DES pretreated poplar increased from 64.11 % to 80.92 %, and the delignification rate increased from 49.0 % to 90.4 %. However, high delignification of the pretreated poplar (DES-100 and DES-110) led to a rapid accumulation of volatile organic acids during the hydrolysis and acidogenesis stages, resulting in methanogenesis inhibition. The highest biomethane yield of 208 L/kg VS was achieved with DES-80 (49.0 % delignification), representing a 148 % improvement compared over untreated poplar. This approach demonstrates the potential for comprehensive utilization of all components of biomass waste.
Asunto(s)
Lignina , Metano , Populus , Lignina/química , Populus/química , Populus/metabolismo , Metano/química , Metano/metabolismo , Anaerobiosis , Hidrólisis , Oligosacáridos/química , Biomasa , Glucuronatos/química , ResiduosRESUMEN
Polymeric elastomers are extensively employed to fabricate implantable medical devices. However, implantation of the elastomers can induce a strong immune rejection known as the foreign body response (FBR), diminishing their efficacy. Herein, we present a group of immunocompatible elastomers, termed easy-to-synthesize vinyl-based anti-FBR dense elastomers (EVADE). EVADE materials effectively suppress the inflammation and capsule formation in subcutaneous models of rodents and non-human primates for at least one year and two months, respectively. Implantation of EVADE materials significantly reduces the expression of inflammation-related proteins S100A8/A9 in adjacent tissues compared to polydimethylsiloxane. We also show that inhibition or knockout of S100A8/A9 leads to substantial attenuation of fibrosis in mice, suggesting a target for fibrosis inhibition. Continuous subcutaneous insulin infusion (CSII) catheters constructed from EVADE elastomers demonstrate significantly improved longevity and performance compared to commercial catheters. The EVADE materials reported here may enhance and extend function in various medical devices by resisting the local immune responses.
Asunto(s)
Elastómeros , Fibrosis , Reacción a Cuerpo Extraño , Animales , Reacción a Cuerpo Extraño/inmunología , Ratones , Materiales Biocompatibles , Masculino , Ratones Endogámicos C57BL , Femenino , Insulina/metabolismo , Ratas , Inflamación/inmunología , Inflamación/metabolismoRESUMEN
The foreign body response (FBR) to implanted biomaterials and biomedical devices can severely impede their functionality and even lead to failure. The discovery of effective anti-FBR materials remains a formidable challenge. Inspire by the enrichment of glutamic acid (E) and lysine (K) residues on human protein surfaces, a class of zwitterionic polypeptide (ZIP) hydrogels with alternating E and K sequences to mitigate the FBR is prepared. When subcutaneously implanted, the ZIP hydrogels caused minimal inflammation after 2 weeks and no obvious collagen capsulation after 6 months in mice. Importantly, these hydrogels effectively resisted the FBR in non-human primate models for at least 2 months. In addition, the enzymatic degradability of the gel can be controlled by adjusting the crosslinking degree or the optical isomerism of amino acid monomers. The long-term FBR resistance and controlled degradability of ZIP hydrogels open up new possibilities for a broad range of biomedical applications.
Asunto(s)
Reacción a Cuerpo Extraño , Hidrogeles , Animales , Hidrogeles/química , Ratones , Materiales Biocompatibles/química , Lisina/química , Primates , Roedores , Ácido Poliglutámico/químicaRESUMEN
In this study, a three-bore polyethersulfone (PES) hollow fiber ultrafiltration (UF) membrane with antibacterial properties was prepared by phase inversion, using PES as the membrane material, N,N-dimethylacetamide (DMAC) as solvent, polyvinylpyrrolidone (PVP) and AgNO3 as additives. The silver particles were detected by X-ray photoelectron spectroscopy. The effect of AgNO3 content on the antibacterial properties and separation performance was studied in detail. The membranes showed good antibacterial activity against Escherichia coli after adding AgNO3 and the antibacterial rate of PES/AgNO3 UF membrane with AgNO3 content of 1 wt% could reach 99.9% after running for 48 hours. Moreover, the bovine serum albumin solution filtration results indicated that the PES/AgNO3 membranes had a certain degree of antifouling performance. Therefore, three-bore PES/AgNO3 membranes have a potential application to reduce both bacterial and organic fouling in water treatment.
Asunto(s)
Incrustaciones Biológicas/prevención & control , Membranas Artificiales , Polímeros/química , Nitrato de Plata/química , Sulfonas/química , Ultrafiltración , Antibacterianos/química , Microscopía Electrónica de Rastreo , Espectroscopía de FotoelectronesRESUMEN
Surfactant-enhanced aquifer remediation has been proved successful to remove dense non-aqueous phase liquids (DNAPLs) from contaminated sites. However, the underlying mechanisms of the DNAPL mobilization and solubilization at the pore scale remains to be addressed for efficient application to the field remediation system. In this work, the emerging microfluidic and imaging technologies are applied to investigate the dynamics of DNAPL remediation. Visualized experiments of the evolution of DNAPL remediation are performed to study the role of surfactant type, concentration and injection rate. The DNAPL remediation is dominated by mobilization followed by solubilization for most surfactants. Mobilization occurs as soon as surfactants and DNAPL are in contact until forming a new stable phase structure, and the solubilization continues until the end of injection. We observe the breakup behavior of long droplets and ganglia during the mobilization, which is attributed to the surfactant-reduced interfacial tension and thus expedites DNAPL mobilization and redistribution. During the solubilization, the formation of micelles incorporating DNAPL fractions increases the DNAPL concentration gradient and thus enhances the mass transfer, but the rate-limited diffusion of micelles reduces the mass transfer rate coefficient. Increasing the surfactant content and decreasing the injection rate can promote mobilization and solubilization. The DNAPL mobilization ability of the surfactants SDS and SDBS is stronger than SAOS and Tween 80 regardless of the injection rates. Tween 80 may be considered an ideal surfactant of only solubilization but not mobilization is desired. This work elucidates the pore-scale mechanisms during surfactant-enhanced DNAPL remediation, which are beneficial for upscaling studies, predictive modeling, and operation optimization of DNAPL remediation in the field.
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Surfactantes Pulmonares , Tensoactivos , Polisorbatos , Micelas , LipoproteínasRESUMEN
Microplastics are ubiquitous in the natural environment and have the potential to endanger the natural environment, ecology and even human health. A series of microfluidic experiments by using soft lithography technology were carried out to investigate the effect of flow rate, particle volume fraction, particle size and pore/throat ratio on microplastics migration and deposition at the pore scale. We discovered a range of deposition patterns of the spherical microplastics from no particle deposition, to discontinuous particle layer, and to continuous particle layers in the retained liquid in the pores, depending on the particle size and volume fraction. Several metrics, including air saturation, probability of particle detainment, expansion ratio and thickness of residual liquid, were quantified to examine the role of various parameters on particle migration and retention of microplastics. At low flow rate (Q = 0.05 µL/min), microplastics migration and deposition were sensitive to changes in particle volume fraction, particle size and pore/throat ratio. In contrast, at high flow rates (Q > 5 µL/min), the migration and retention of particles were mainly controlled by strongly channelized air invasion pattern, while the particle volume fraction, particle size and pore/throat size ratio have only secondary influence. At intermediate range of flow rates, microplastics migration and deposition were dramatically impacted by flow rate, particle volume fraction, particle size and pore/throat ratio. This work improves the understanding of the mechanisms of particle migration and retention in porous media and can provide a reference for more accurate assessment of the exposure levels and times of microplastics in soil and groundwater systems.
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Microplásticos , Plásticos , Humanos , Porosidad , Suelo , Tamaño de la PartículaRESUMEN
Forward osmosis (FO) technology is regarded as an alternative to wastewater treatment due to its high permeate flux, excellent solute selectivity and low fouling tendency. In this study, two novel aquaporin based biomimetic membranes (ABMs) were used for comparison in short-term experiments to investigate the impact of membrane surface properties on greywater treatment. The impact of feed solution (FS) temperature on the filtration performance and membrane fouling behavior of ABM was further analyzed in the sequential batch experiments. Results indicated that the membranes with rough surface morphology and low zeta potential (absolute value) facilitated the adsorption of linear alklybezene sulfonates (LAS), thus improving the water flux and the rejection of Ca2+ and Mg2+. The increase in FS temperature enhanced the diffusion of organic matter and the water flux. In addition, sequential batch experiments showed that the membrane fouling layer was mainly in the form of organic and inorganic composite fouling, which was mitigated at FS temperature of 40 °C. Microbial community analysis revealed that the increase in FS temperature affected the diversity of microbial communities. More heterotrophic nitrifying bacteria were enriched in the fouling layer at FS 40 °C than at FS 20 °C. This study provides a novel strategy for employing ABM FO in greywater treatment and reuse.
Asunto(s)
Biomimética , Purificación del Agua , Membranas Artificiales , Ósmosis , Purificación del Agua/métodos , AguaRESUMEN
Understanding of microplastics transport mechanism is highly important for soil contamination and remediation. The transport behaviors of microplastics in soils are complex and influenced by various factors including soil and particle properties, hydrodynamic conditions, and biota activities. Via a microfluidic experiments we study liquid film entrainment and microplastics transport and retention during two-phase displacement in microchannels with one end connected to the air and the other connected to the liquid with suspended particles. We discover three transport patterns of microplastic particles, ranging from no deposition to particle entrapment and to particle layering within liquid films, depending on the suspension withdrawal rates and the particle volume fraction in the suspension. The general behavior of particle motion is effectively captured by the film thickness evolution which is shown to be dependent on a modified capillary number Ca0 taking into account the effects of flow velocity, particle volume fraction, and channel shape. We also provide a theoretical prediction of the critical capillary number Ca0* for particle entrapment, consistent with the experimental results. In addition, the probability of microplastics being dragged into the trailing liquid film near the gas invading front is found to be proportional to both particle volume fraction and the capillary number. This work elucidates the microplastics transport mechanism during unsaturated flow, and therefore is of theoretical and practical importance to understand the contaminant migration in many natural and engineered systems spanning from groundwater sources to water treatment facilities.
Asunto(s)
Agua Subterránea , Microplásticos , Biota , Plásticos , SueloRESUMEN
The utilization of lignin as carbonaceous material for pollution adsorption provides an alternative way for lignocellulose valorization. Here in, lignin-based adsorbents (i.e., LC-A, LC-B, and LC-C) were prepared and used for the removal of o-DCB (a toxic gaseous pollutant). LC-B exhibited the best adsorption capacity (718.2 mg/g) when comparing with LC-A (93.1 mg/g), LC-C (10.2 mg/g), and activated carbon (72.7 mg/g). LC-B also demonstrated excellent recycling stability with the adsorption capacity of 710.8 mg/g after five runs. More importantly, LC-B supported Ru adsorbent catalyst could effectively remove o-DCB with removal rate >80% under a wide range of temperature (50-300°C). The excellent performance of lignin-based adsorbents could be attributed to its abundant pore structure, high specific surface area (1618.55 m2/g), enhanced graphitization degree as well as the abundant hydroxyl functional groups. The present work provided a cost-effective strategy for pollution control by lignin-based material.
Asunto(s)
Carbón Orgánico , Lignina , Adsorción , Contaminación Ambiental , TemperaturaRESUMEN
While water chemistry (e.g., ionic strength, calcium concentration and organic foulants) is the primary property of surface water, its effects on membrane fouling in process of membrane-based water production and seawater pretreatment have not well investigated. In this study, fouling behaviors of alginate solutions in presence of different calcium ion concentration and ionic strength levels were investigated. It was found that alginate solutions complexing with 1.5 mM calcium possessed a remarkably high specific filtration resistance (SFR) (above 3.596 × 1015 m kg-1), and the SFR descended with calcium concentration and increased with ionic strength. A series of characterizations suggested that zeta potential, particle size, viscosity and morphology of alginate solutions were close related with foulant layer microstructure and these fouling behaviors. Based on these characterizations, the thermodynamics described by Flory-Huggins lattice theory was proposed to explain the remarkably high SFR of alginate gel for 1.5 mM calcium level. Meanwhile, preferential intermolecular coordination combined with Flory-Huggins lattice theory was suggested to be responsible for the descend trend of SFR with calcium concentration. Furthermore, electrostatic double layer compression effect together with Flory-Huggins lattice theory could well interpret the increase trend of SFR with ionic strength. This study provided the essential mechanisms underlying effects of ionic strength on alginate fouling in presence of calcium ions, and thus deepened understanding of membrane fouling.
Asunto(s)
Alginatos/química , Membranas Artificiales , Purificación del Agua , Calcio/química , Filtración , Iones , Concentración Osmolar , Electricidad Estática , TermodinámicaRESUMEN
Interfacial energy between sludge foulants and rough membrane surface critically determines adhesive fouling in membrane bioreactors (MBRs). As a current available method, the advanced extensive Derjaguin-Landau-Verwey-Overbeek (XDLVO) approach cannot efficiently quantify the interfacial energy. In this study, novel methods including back propagation (BP) artificial neural network (ANN) and generalized regression neural network (GRNN) were proposed to quantify the interfacial energy associated with the membrane fouling in an MBR. Different levels of 5 apparent input factors and the resulted interfacial energies were used as training and testing databases for establishment of ANN models. The established BP ANN and GRNN models exhibited high regression coefficients and accuracies, suggesting the high capacity of ANN models to capture the complicated non-linear mapping relations between interfacial energy and various factors. As compared with the advanced XDLVO approach, both BP ANN and GRNN showed remarkably improved quantification efficiency. Meanwhile, BP ANN showed better prediction performance than GRNN model. Case study further demonstrated the robustness and feasibility of BP ANN for interfacial energy quantification. This study provided a new approach to quantify interfacial energy associated with membrane fouling.
Asunto(s)
Redes Neurales de la Computación , Reactores Biológicos , Membranas Artificiales , Tamaño de la Partícula , Propiedades de Superficie , TermodinámicaRESUMEN
Molecular mechanisms responsible for the filtration behaviors of sodium alginate (SA) in presence of different iron(III) ion concentration were explored in this study. It was found that specific filtration resistance (SFR) of alginate mixtures (1.0 gSA/L) firstly increased and then decreased to a trough with iron(III) concentration increase from 0 to 2.5â¯mM. Alginate mixture interacting with 0.1â¯mM iron(III) possessed an SFR as high as 1.65â¯×â¯1014â¯mâ¯kg-1, which could be explained by Flory-Huggins lattice theory related with gel filtration. Optical observation showed significant morphology transition (from gel to granular solids) of foulant layers with iron(III) concentration increase. A series of characterizations indicated the change of microstructure, pH and surface charge of alginate mixture with iron(III) concentration. Density functional theory (DFT) simulation suggested that iron(III) ion preferentially forms coordination bonds with three terminal carboxyl groups of alginate chains, facilitating elongation and cross-linking of alginate chains. Such a coordination mode induces formation of a slime and homogeneous gel, corresponding to high SFR. Continuous increase in iron(III) concentration leads to non-terminal coordination, which makes alginate chains more clustered and coiled. This effect, together with effects of the reduced surface charge and electric double layer compression, significantly decrease SFR of alginate mixtures. This study provided deep molecular insights into effects of iron(III) ions on alginate fouling.
Asunto(s)
Alginatos/química , Hierro/farmacología , Membranas Artificiales , Alginatos/farmacología , Incrustaciones Biológicas , Filtración , Geles/química , Iones , Estructura Molecular , Electricidad Estática , Relación Estructura-Actividad , Propiedades de SuperficieRESUMEN
Though sludge foaming often occurs and thus causes serious membrane fouling in membrane bioreactors (MBRs), the fouling mechanisms related with the foaming phenomenon have not been well addressed, hindering better understanding and solving foaming problem. In this work, it was interestingly found that, the foulants during the foaming period possessed extremely high specific filtration resistance (SFR) (over 1016 m kg-1) and strong adhesion ability to membrane surface. Chemical characterization showed that the proteins (178.57 mg/L) and polysaccharides (209.21 mg/L) in the foaming sample were about 6.4 times and 5.4 times of those in the supernatant sample, suggesting existence of a mechanism permitting continuous production of these foulants in the MBR during the foaming period. It was revealed that the fouling caused by foams was associated with gel layer filtration process, and the extremely high SFR can be interpreted by chemical potential change in the gel filtration process depicted in Flory-Huggins theory. Meanwhile, analyses by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory showed that the strong adhesion ability stemmed from the high interaction energy between the foaming foulants and membrane surface. In addition, 16S rDNA gene sequencing identified that the abundance of the foaming related bacteria species in the sludge suspension during the foaming period was more than 10 times of that during the non-foaming period. This study offered new mechanism insights into foaming fouling in MBRs.
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Reactores Biológicos , Membranas Artificiales , Bacterias , Filtración , Aguas del AlcantarilladoRESUMEN
While molecular weight distribution (MWD) is one of the most important properties of soluble microbial products (SMPs), mechanisms underlying effects of MWD of SMPs on membrane fouling have not well unveiled. In this study, it was found that, the supernatant of sludge suspension in a membrane bioreactor (MBR) for wastewater treatment can be fractionated into a series of SMPs samples with different molecular weight (MW) fraction. The real gel sample mainly formed by the rejected SMPs on membrane surface had a high specific filtration resistance (SFR) of 1.21 × 1016 m-1 kg-1. The SFR of SMPs samples and the model foulants of polyethylene glycol (PEG) increased with their MW. The change trend of SFR with MW cannot be sufficiently explained by three-dimensional excitation-emission matrix (EMM) and chemical compositions. Tyndall effect analysis indicated that gelating ability of SMPs and PEG in the solution increased with their MW. Scanning electron microscope (SEM) confirmed gel structure changes with the PEG MW. Accordingly, mechanisms based on Carman-Kozeny equation and Flory-Huggins lattice theory were proposed to interpret SFR of SMPs with low and high MW, respectively. Simulating these two mechanistic models on PEG samples resulted in the comparable SFR data to the experimental ones, indicating the correctness and feasibility of the proposed mechanisms. The proposed mechanisms provided in-depth understanding of membrane fouling regarding MW, facilitating to develop effective membrane fouling mitigation strategies.
Asunto(s)
Membranas Artificiales , Eliminación de Residuos Líquidos/métodos , Reactores Biológicos/microbiología , Filtración , Geles , Peso Molecular , Aguas del Alcantarillado/química , Aguas ResidualesRESUMEN
Efficient quantification of interfacial energy related with membrane fouling represents the primary interest in membrane bioreactors (MBRs) as interfacial energy determines foulant layer formation. In this study, radial basis function (RBF) artificial neural networks (ANNs) with five related factors as input variables were applied to quantify interfacial energy with randomly rough membrane surface. It was found that, RBF ANNs could well capture the complex non-linear relationships between the related factors and interfacial energy. RBF ANN quantification showed high regression coefficient and accuracy, suggesting its high capacity to quantify interfacial energy. Compared to at least one-week time consumption of the advanced extensive Derjaguin-Landau-Verwey-Overbeek (XDLVO) approach, quantification by RBF ANNs only took several seconds for a same case, indicating the high efficiency of RBF ANNs. Moreover, the abilities of RBF ANNs can be further improved. The robust RBF ANNs proposed paved a new way to study membrane fouling in MBRs.
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Reactores Biológicos , Membranas Artificiales , Redes Neurales de la Computación , Fenómenos Físicos , Programas InformáticosRESUMEN
This article presents an original work aiming at rationally designing a molecularly imprinted polymer (MIP) towards high selective recognition. Assembled with (S)-naproxen as a template and 4-vinylpyridine as a functional monomer, a certain amount of cobalt, as pivot, is added for the preparation of MIP. The result indicates that the use of pivot plays obviously a positive role in increasing the specificity of MIP, so as to adsorb more for the template and less for its enantiomer. Related information indicates that this, in logic, can be a result of increasing match between binding sites and the templates, which makes the polymer capable of selectively recognizing the imprint species.