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1.
J Environ Manage ; 291: 112725, 2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-33962290

RESUMO

Riboflavin is commercially produced primarily by bio-fermentation. Nonetheless, purification and separation are particularly complex and costly. Adsorption from the fermentation liquor is an alternative riboflavin separation technology during which a cost-efficient adsorbent is highly desired. In this study, a low-cost activated algal biomass-derived biochar (AABB) was applied as an adsorbent to efficiently adsorb riboflavin from an aqueous solution. The adsorption capacity of riboflavin on AABB increased with the increase in pyrolysis temperature and initial riboflavin concentration. The adsorption isotherms were well described by the Freundlich and Langmuir models. The AABB displayed excellent adsorption performance and its maximum adsorption capacity was 476.9 mg/g, which was 6.8, 6.8, and 5.2 times higher than that of laboratory-prepared activated rape straw biochar, activated broadbean shell biochar and commercial activated carbon, respectively, which was mainly ascribed to its larger specific surface area and abundant functional groups. The mass transfer model results showed that mass transfer resistance was dependent on both the film mass transfer and porous diffusion. Raman and Fourier transform-infrared spectra confirmed the presence of π-π interactions and hydrogen bonding between riboflavin and the AABB. The adsorption of riboflavin onto AABB was a spontaneous process, which was dominated by van der Waals forces. These results will be beneficial for developing effective riboflavin recovery technologies and simultaneously utilizing waste algal blooms.

2.
Inorg Chem ; 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33793227

RESUMO

Easily producible sensors for harmful industrial waste compounds are of significant interest for both human health and the environment. Three novel coordination polymers, [Ag(µ-aca)(µ4-bztpy)1/2] (1), [Ag(µ-bza)(µ-bpa)] (2), and [Ag2(µ-aca)2(µ-bpa)2]·EtOH·2H2O (3), were assembled in this study by reactions using Ag+ as a node with the pyridyl ligand 1,2,4,5-tetrakis(4-pyridyl)benzene (bztpy) or 9,10-bis(4-pyridyl)anthracene (bpa) and an auxiliary chelating carboxylic ligand. Single-crystal X-ray structural analyses revealed that compound 1 has a 3D framework consisting of 1D [Ag(aca)]∞ chains and bztpy linkers, while 2 and 3 have 2D layered structures consisting of binuclear Ag-carboxylate units and bpa linkers, respectively. Topological studies revealed that 1 has a bbf topology, while 2 and 3 are 2D [4,4] rhombic grids. The compounds were further characterized by powder X-ray diffraction, IR, elemental analysis, thermogravimetric analysis, and a luminescence study. The solids of 1-3 exhibited intense photoluminescent emission with λemmax at ca. 493, 472, and 500 nm, respectively. Remarkably, due to their excellent framework stability, 1 and 2 can act as multiresponsive luminescent sensors for nitrobenzene, Fe3+, and Cr2O72- with a high selectivity and sensitivity ascribed to their quenching effect.

3.
Dalton Trans ; 50(12): 4152-4158, 2021 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-33688869

RESUMO

Two new two-dimensional (2D) coordination polymers, [FeII(L)2{PdII(SCN)4}] (L1 = 3-(9-anthracenyl)-pyridine (1) and L2 = 4-(9-anthracenyl)-pyridine (2)), were constructed by employing square-planar [Pd(SCN)4]2- building blocks. Compound 1 exhibits a complete spin-crossover (SCO) behaviour under normal atmospheric pressure, and represents the first SCO example in a 2D system containing [Pd(SCN)4]2- units. In contrast, compound 2 only shows paramagnetic behaviour at measured temperatures. It is clear that the fine-tuning of the monodentate ligand can modulate the ligand field and packing fashions, which sheds light on developing new SCO materials.

4.
Huan Jing Ke Xue ; 42(2): 749-760, 2021 Feb 08.
Artigo em Chinês | MEDLINE | ID: mdl-33742869

RESUMO

Emerging contaminants including antibiotics and antibiotic resistance genes (ARGs) have been frequently detected in drinking water resources. In this study, the occurrence of antibiotics and ARGs in various environmental matrices in representative drinking water sources in Jiangsu Province and their influencing factors were explored. Five representative drinking water sources in northern, central, and southern Jiangsu were selected. Water, surface sediment, and epilithic biofilm samples were harvested near the water intakes of each water resource in December 2018 and June 2019. The concentrations and abundances of ten antibiotics, one integrase gene intl1, and seven common ARGs were measured. The results suggest that the concentrations of the target antibiotics and ARGs are relatively low compared to previously reported data in China and elsewhere in the world. The target antibiotics were detected in all of the water sources. The concentrations of sulfonamides in the water, surface sediment, and epilithic biofilm ranged from not found (NF) to 37.4 ng·L-1, NF to 47.3 ng·g-1, and NF to 3759.1 ng·g-1, respectively; the concentrations of quinolones in three matrices were NF-5.3 ng·L-1, 0.4-32.5 ng·g-1, and NF-4220.9 ng·g-1, respectively. The detection rates of the ARGs including sul 1, sul2, tetW, and tetQ were 100%, among which the sulfonamides sul1 and sul2 showed the highest abundance. The absolute abundances of sul1 in the three matrices were 2.48×106 copies·L-1, 3.54×107 copies·g-1, and 1.44×109 copies·g-1, respectively. The abundances of ARGs in the sediments and epilithic biofilms were comparable, and were much higher than in the water body. The phyla Bacteroidetes, Proteobacteris, Firmicutes, Verrucobacteria, and Actinomycetes have proven potential hosts for ARGs and might play an important role in the transmission and diffusion of resistance genes. This study offers baseline information on the presence of antibiotics and ARGs in the drinking water sources of Jiangsu Province, providing a significant theoretical basis for ARGs pollution control and safety guidelines for drinking water resources.


Assuntos
Antibacterianos , Água Potável , Antibacterianos/análise , China , Água Potável/análise , Resistência Microbiana a Medicamentos/genética , Genes Bacterianos/genética , Recursos Hídricos
5.
Int J Ophthalmol ; 13(4): 650-659, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32399419

RESUMO

AIM: To conduct a systematic review and Meta-analysis to examine the association between uveitis and psoriatic disease, and to evaluate whether one condition predisposes individuals to the other. METHODS: We performed a comprehensive search of PubMed and EMBASE to identify cohort studies examining the association between uveitis and psoriatic disease [psoriasis and/or psoriatic arthritis (PsA)]. We used a random-effects model to calculate the pooled relative risks (RRs) adjusted for confounders, along with the 95% confidence intervals (CIs). RESULTS: This Meta-analysis included a total of 6 studies and a maximum of 80 178 648 participants. Compared with non-psoriatic controls, uveitis risk was significantly elevated in patients with psoriasis (RR=1.49; 95%CI: 1.08-2.07), and PsA (RR=3.16; 95%CI: 2.16-4.63). Furthermore, pre-existing uveitis was associated with a significantly increased risk of psoriasis (RR=1.62; 95%CI: 1.44-1.83), and PsA (RR=4.44; 95%CI: 3.52-5.60). CONCLUSION: The results of this systematic review and Meta-analysis suggest an overall positive bidirectional association between uveitis and psoriatic disease (psoriasis and PsA), warranting increased awareness among clinicians involved in the management of these two conditions. Therefore, there remains a need for more detailed studies of the possible common pathogenesis of psoriatic disease and uveitis.

6.
Sci Total Environ ; 717: 137064, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32070890

RESUMO

Microplastics (MPs) have been gaining the attention of environmental researchers since the 1960s anecdotal reports of plastic entanglement and ingestion by marine creatures. Due to their increasing accretion in aquatic environments, as well as resistance towards degradation, marine litter research has focused on microplastics more recently. In the present study, a relatively new method of biodegradation was implemented for the biodegradation of three structurally different MPs i.e. polypropylene (PP), polyethylene (PE) and polyethylene terephthalate (PET). Periphytic biofilm was used for this purpose in various backgrounds of carbon sources (glucose, peptone, and glucose and peptone). Biodegradation of MPs was estimated in terms of weight loss. It was observed that the addition of glucose enhanced the biodegradation of MPs by periphyton biofilm for all MPs (from 9.52%-18.02%, 5.95%-14.02% and 13.24-19.72% for PP, PE and PET respectively) after 60 days compared to natural biofilm alone. To the contrary, peptone, and glucose and peptone together, were inhibitory. Biodegradation was further confirmed by morphological changes observed using SEM, FTIR spectra and GPC lent further support to the results whereby new peaks appeared along with reduction in old peaks and decrease in peak intensities. MiSeq sequencing shows that Deinococcus-thermus > Proteobacteria > Cyanobacteria are the dominant phyla in natural biofilms, and their relative abundances increase after the addition of glucose. However, the abundances shifted to Deinococcus-thermus > Cyanobacteria > Firmicutes > Bacteroidetes, when the biofilms were treated with either peptone alone, or with glucose and peptone together. Therefore, the change in biodegradation capability might also be due to the change in the microbial community structures after addition of the C-sources. These experiments provide an innovative approach towards effective biodegradation of MPs using a relatively new environment-friendly method.


Assuntos
Biofilmes , Biodegradação Ambiental , Microplásticos , Polietileno , Poluentes Químicos da Água
7.
Chem Sci ; 10(32): 7496-7502, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31588302

RESUMO

This study reports the first modulation of spin-crossover (SCO) behavior via a photochemical [2 + 2] cycloaddition reaction. Here we construct two no-solvent Fe(ii)-Ag(i) bimetallic Hofmann-type frameworks, [Fe(4-spy)2{Ag(CN)2}2] (1) and [Fe(2,4-bpe)2{Ag(CN)2}2] (2) (4-spy = 4-styrylpyridine, 2,4-bpe = trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene). For 1, the dimerization of 4-spy results in a single-crystal to single-crystal (SCSC) transformation from 2D interdigitated layers to a 3D interpenetrated structure. Additionally, a 3D → 3D structural transformation accompanied with Ag(i)-N bond breaking is achieved via the photochemical cycloaddition reaction of 2,4-bpe in 2. More importantly, both the spin transition temperatures and the SCO character are effectively modulated; thus, this approach provides a new strategy for constructing photo-responsive SCO magnetic materials.

8.
Molecules ; 24(16)2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31426301

RESUMO

Two-dimensional aluminophosphate is an important precursor of phosphate-based zeolites; a new Sun Yat-sen University No. 6 (SYSU-6) with |Hada|2[Al2(HPO4)(PO4)2] has been synthesized in the hydrothermal synthesis with organic structure-directing agent (OSDA) of N,N,3,5-tetramethyladamantan-1-amine. In this paper, SYSU-6 is characterized by single-crystal/powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, transmission electron microscopy, infrared and UV Raman spectroscopy, solid-state 27Al, 31P and 13C magic angle spinning (MAS) NMR spectra, and elemental analysis. The single-crystal X-ray diffraction structure indicates that SYSU-6 crystallized in the space group P21/n, with a = 8.4119(3), b = 36.9876(12), c = 12.5674(3), α = 90°, ß = 108.6770(10)°, γ = 90°, V = 3704.3(2) Å3, Z = 4, R = 5.12%, for 8515 observed data (I > 2σ(I)). The structure has a new 4,12-ring layer framework topology linked by alternating AlO4 and PO4 tetrahedra. The organic molecules reside between the layers and are hydrogen-bonded to the inorganic framework. The new type of layer provides a greater opportunity to construct zeolite with novel topology.


Assuntos
Adamantano/química , Zeolitas/química , Adsorção , Catálise , Fracionamento Químico/métodos , Cristalografia por Raios X , Humanos , Microscopia Eletrônica de Varredura , Porosidade
9.
Chem Commun (Camb) ; 55(67): 9939-9942, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31369022

RESUMO

Herein we report a stable and high-performance Dy(iii) single-ion magnet (SIM) showing an energy barrier of 944 K under zero dc field, with an open hysteresis loop up to 6 K. To the best of our knowledge, this is the highest energy barrier for a square antiprism as well as phosphine oxide based Dy-SIMs, reported so far.

10.
Water Res ; 163: 114873, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31326694

RESUMO

Dissolved organic matter (DOM) is widely present in aqueous environments and plays a significant role in pollutant mitigation and transformation. So far, excitation-emission matrix (EEM) fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC) has been widely applied to quantify fluorescent DOM. However, this approach fails to provide accurate concentration of DOM when fluorescent contaminants exist. In this work, a new method, prior linear decomposition (PLD), is developed to solve this problem by introducing prior information, i.e., EEMs of DOM, into data decomposition. First, EEM of humic acid (HA) with different numbers of random Gaussian peaks are tested to confirm the robustness of PLD. The percentages for the relative errors within 5% are found to be 97.7% and 69% using PLD and PARAFAC, respectively. Then, the determination of mixture of HA with several contaminants is performed, validating the feasibility of DOM quantification and capability of contaminant diagnosis using PLD for synthetic water samples. Finally, DOM-containing natural water samples collected from a polluted lake, river and wastewater treatment plant (WWTP) are measured. The testing results confirm that PLD provides an accurate result with less evaluated error than PARAFAC and the EEMs of the contaminants can be inferred precisely. This work clearly demonstrates that PLD offers a robust approach for quantifying fluorescent DOM, which is of great significance in both natural and engineered aqueous environments.


Assuntos
Substâncias Húmicas , Rios , Análise Fatorial , Lagos , Espectrometria de Fluorescência , Águas Residuárias
11.
Nat Prod Res ; 33(13): 1891-1896, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29798697

RESUMO

Gentisyl alcohol-type natural products, possessing various important biological properties, have been synthesized from 4-methoxyphenol by using a selective phenol monohydroxymethylation/monochlorination, a CAN oxidation and a sodium dithionite reduction as the key steps. The natural product synthesis is efficient, atom- and step-economical, and requires no protecting groups.


Assuntos
Álcoois Benzílicos/síntese química , Produtos Biológicos/síntese química , Anisóis/química , Halogenação , Metilação , Oxirredução
12.
Inorg Chem ; 57(7): 4070-4076, 2018 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-29553723

RESUMO

A chiral Co(II)-based coordination polymer, [Co3(pimda)2(H2O)5] (1, H3pimda = 2-propyl-1H-imidazole-4,5-dicarboxylic acid) with 3D hyperkagomé topology is reported. Upon heating/cooling, the water molecules which are coordinated to a pair of crystallographically symmetric Co(II) ions are removed/recovered discretely in two steps, giving [Co3(pimda)2(H2O)4] (2) and [Co3(pimda)2(H2O)3] (3), which is evidenced by the reversible single-crystal-to-single-crystal (SCSC) structural transformations. As the coordination geometry of the two Co(II) ions changes from octahedron to trigonal bipyramid, obvious color change from pink for 1 to dark violet for 2 and 3 is observed. Further magnetic measurements demonstrate the presence of a solvatomagnetic effect from paramagnets for 1 and 2 to weak ferromagnet for 3. Moreover, as revealed by the variable-temperature crystallographic measurements, the first and second dehydration temperatures could be controlled from 298 K (25 °C) and 383 K (110 °C) sealed in a capillary (high humidity) to 255 K (-18 °C) and 307 K (34 °C) in dry N2 (low humidity), indicating the strong humidity sensitivity of the structural dynamics.

13.
Sci Total Environ ; 633: 198-205, 2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-29573686

RESUMO

A large amount of excess waste activated sludge is produced in municipal wastewater treatment plants and should be further disposed to avoid environmental pollution. Ionic surfactants are being widely used for sludge conditioning, but how and to what extent ionic surfactants change the sludge properties remain unclear. In this work, the impacts of two typical ionic surfactants on the flocculability and stability of sludge were investigated by using experimental and theoretical analyses. The treatment of anionic sodium dodecyl sulfate (SDS) resulted in more detachment of extracellular materials and fluorophores from sludge compared to the treatment of cationic trimethyl ammonium bromide (DTAB). Fourier transform infrared spectra analysis indicates the promoted release of proteins and polysaccharides induced by the surfactants. Deteriorated flocculability of sludge was observed for the SDS-treated sludge, while treatment of DTAB slightly affected the overall sludge flocculability. The sludge floc structure became less stable after treatments of both surfactants, as confirmed by the elevated dispersed mass concentration of small particles in shearing tests. The relationship between the content of extracellular polymeric substances, surfactant dose and sludge properties were evaluated and the roles of released extracellular polymeric substances and surfactant dose in affecting sludge flocculability were examined. Extended DLVO approach was adopted to explore the stability of sludge. By using such an integrated approach, the impacts of ionic surfactants on sludge flocculability and stability were revealed, which is useful in understanding the mechanisms of sludge conditioning by surfactant treatment.

14.
Chemosphere ; 193: 472-478, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29156332

RESUMO

Mechanical harvest of massive harmful algal blooms is an effective measure for bloom mitigation. Yet subsequent processing of the resulting water from algae water separation after the harvesting becomes a new problem since individual algal cells or small algal aggregates are still present in the water. Here, we proposed a novel approach for effectively flocculating the cyanobacteria Microcystis aeruginosa with a removal efficiency of 97% in 6 h using hydrolyzed urine. Nitrogen and phosphorus were simultaneously reclaimed through struvite formation. The addition of Mg2+ promoted the flocculation efficiency and nutrient removal as well as the yield of struvite. Ca2+ could enhance the flocculation efficiency by forming calcium phosphate. During the flocculation process, no significant damage in algal cells was observed. This study provides a novel and sustainable potential for subsequent processing of the resulting water after algae water separation with simultaneous nutrient precipitation and reducing nutrient loads to wastewater treatment plants.


Assuntos
Floculação , Microcystis/química , Purificação da Água/métodos , Cianobactérias , Alimentos , Proliferação Nociva de Algas , Humanos , Hidrólise , Nitrogênio , Fósforo , Estruvita , Urina/química
15.
Sci Rep ; 7(1): 12787, 2017 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-28986570

RESUMO

Soluble microbial products (SMPs) are of significant concern in the natural environment and in engineered systems. In this work, poly-γ-glutamic acid (γ-PGA), which is predominantly produced by Bacillus sp., was investigated in terms of pH-induced conformational changes and molecular interactions in aqueous solutions; accordingly, its sedimentation coefficient distribution and viscosity were also elucidated. Experimental results indicate that pH has a significant impact on the structure and molecular interactions of γ-PGA. The conformation of the γ-PGA acid form (γ-PGA-H) is rod-like while that of the γ-PGA sodium form (γ-PGA-Na) is sphere-like. The transformation from α-helix to random coil in the γ-PGA secondary structure is primarily responsible for this shape variation. The intramolecular hydrogen bonds in the γ-PGA-H structure decrease and intramolecular electrostatic repulsion increases as pH increases; however, the sedimentation coefficient distributions of γ-PGA are dependent on intermolecular interactions rather than intramolecular interactions. Concentration has a more substantial effect on intermolecular electrostatic repulsion and chain entanglement at higher pH values. Consequently, the sedimentation coefficient distributions of γ-PGA shift significantly at pH 8.9 from 0.1 to 1.0 g/L, and the viscosity of γ-PGA (5% w/v) significantly increases as pH increases from 2.3 to 6.0.


Assuntos
Conformação Molecular , Ácido Poliglutâmico/análogos & derivados , Concentração de Íons de Hidrogênio , Microscopia de Força Atômica , Peso Molecular , Ácido Poliglutâmico/química , Sódio/química , Solubilidade , Soluções , Espectroscopia de Infravermelho com Transformada de Fourier , Viscosidade
16.
Environ Pollut ; 231(Pt 2): 1388-1392, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28911794

RESUMO

Sludge dewatering is an important process in municipal wastewater treatment and critically influences the subsequent transportation and disposal. Thermal treatment coupled with other chemical processes has been widely used to improve sludge dewaterability. However, information about the response of sludge extracellular polymeric substances (EPS) to thermal treatment and its role in sludge dewatering is still limited. In this work, the effects of thermal treatment on anaerobic and aerobic sludges were investigated with an emphasis on the colloid properties of released EPS in sludge dewatering process. The results indicate that sludge dewaterability became deteriorated with the increased temperature in the range of 30-170 °C, which was ascribed to the disintegration of sludge flocs and change of EPS characteristics. Disintegrated sludge induced the release of the negatively charged EPS, resulting in the weakened bridging interaction and lower compactness. After thermal treatment, the EPS with a higher average molecular weight and stretched coil configuration retained more water. In addition, difference in dewaterability between anaerobic and aerobic sludges was found to be attributed to their different contents and structures of EPS components. These results provide an insight into thermal-dependent sludge dewatering process and are useful to facilitate water-sludge separation.


Assuntos
Polissacarídeos Bacterianos/química , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Dessecação , Polímeros/química , Esgotos/química , Temperatura , Água/química
17.
Inorg Chem ; 56(15): 8730-8734, 2017 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-28692252

RESUMO

A bifunctional dysprosium(III) dimer, [Dy2(HTPEIPOMe)2(OAc)4(NO3)2] (1), comprising an AIE-active (AIE = aggregation-induced emission) ligand of 2-methoxy-6-[[[4-(1,2,2-triphenylvinyl)phenyl]imino]methyl]phenol (HTPEIPOMe), was successfully synthesized. It not only behaves as a single-molecule magnet (SMM) with an energy barrier of 168(15) K at zero field but also exhibits piezochromism during the pressing-fuming cycle with switchable color, photoluminescence, and magnetic response.

18.
Inorg Chem ; 56(15): 8829-8836, 2017 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-28714676

RESUMO

The dimeric molecule [Dy2(acac)6(MeOH)2(bpe)]·bpe·2MeOH (1, acac = acetylacetonate, bpe = 1,2-bis(4-pyridyl)ethylene) undergoes a solid-state ligand substitution reaction upon heating, leading to the one-dimensional chain [Dy(acac)3(bpe)]n (2). This structural transformation takes advantage of the potential coordination of the guest bpe molecules present in 1. In both complexes the Dy(III) ions adopt similar octacoordinated D4d geometries. However, the different arrangement of the negatively charged and neutral ligands alters the direction of magnetic anisotropy axis and the energy states, thus resulting in largely distinct magnetization dynamics, as revealed by the CASSCF/RASSI calculations.

19.
Anal Chem ; 89(7): 4264-4271, 2017 04 04.
Artigo em Inglês | MEDLINE | ID: mdl-28252936

RESUMO

Excitation-emission matrix (EEM) fluorescence spectroscopy coupled with parallel factor (PARAFAC) analysis has been widely applied to characterize dissolved organic matter (DOM) in aquatic and terrestrial systems. However, its application in environmental samples is limited because PARAFAC is not able to handle nontrilinear EEM data, leading to the overestimated number of components and incorrect decomposition results. In this work, a new method, parallel factor framework-clustering analysis (PFFCA), is proposed to resolve this problem. First, simulated data with different signal-to-noise ratios and intensities of nontrilinear structure were tested to confirm the robustness of PFFCA. The residual sum of squares (RSS) of PARAFAC was significantly higher than that of PFFCA (p < 0.037). Second, a set of data originating from a synthetic mixture of humic acid and bovine serum albumin was applied to compare with PARAFAC with known samples. PFFCA provided an estimation (R2 > 0.92) closer to actual EEM than PARAFAC (R2 > 0.81). Finally, to confirm the feasibility of PFFCA in analyzing natural samples, DOM-containing samples collected from both a polluted lake and river were tested, indicating that PFFCA provides a more precise estimation than PARAFAC. The results clearly indicate that PFFCA offers a robust approach for the unique decomposition of complex synthetic and natural samples, which is of great significance in understanding the characteristics of DOM in aqueous systems.

20.
Water Res ; 113: 89-96, 2017 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-28199866

RESUMO

Polyvinylidene fluoride (PVDF) membrane has been widely applied in water and wastewater treatment because of its high mechanical strength, thermal stability and chemical resistance. However, the hydrophobic nature of PVDF membrane makes it readily fouled, substantially reducing water flux and overall membrane rejection ability. In this work, an in-situ blending modifier, i.e., extracellular polymeric substances (EPS) from activated sludge, was used to enhance the anti-fouling ability of PVDF membrane. Results indicate that the pure water flux of the membrane and its anti-fouling performance were substantially improved by blending 8% EPS into the membrane. By introducing EPS, the membrane hydrophilicity was increased and the cross section morphology was changed when it interacted with polyvinl pyrrolidone, resulting in the formation of large cavities below the finger-like pores. In addition, the fraction of pores with a size of 100-500 nm increased, which was also beneficial to improving membrane performance. Surface thermodynamic calculations indicate the EPS-functionalized membrane had a higher cohesion free energy, implying its good pollutant rejection and anti-fouling ability. This work provides a simple, efficient and cost-effective method to improve membrane performance and also extends the applications of EPS.


Assuntos
Reatores Biológicos , Esgotos/química , Biopolímeros/química , Membranas Artificiais , Polímeros
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