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1.
Heliyon ; 10(5): e27467, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38495140

RESUMO

This research provides an in-depth assessment of two paper yarn variants, examining their structural, functional, and performance characteristics. These yarns demonstrated favorable properties, including suitable linear density, twist, typical cellulosic functional groups as confirmed by Infrared spectroscopy, minimal hairiness, moisture transfer, and creditable mechanical strength. These yarns have flat layered cross-sections and grooved longitudinal surfaces. In addition, a low hairiness index (1.3-1.33) further acknowledged their smooth surface. Their remarkable evenness (15.86% and 7.08%) supported their effective wicking properties. Despite average breaking strength (0.77 cN/dTex and 1.05 cN/dTex) and moderate elongation, these yarns exhibited exceptional water-washing resistance and retained over 89% breaking strength after 15 washes. This study ranks these paper yarns as highly suitable for durable clothing fabrics, providing promising sustainable alternatives in the textile industry.

2.
J Hazard Mater ; 468: 133742, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38367436

RESUMO

Harmful algal blooms (HABs) significantly impact on water quality and ecological balance. Ultrasound irradiation has proven to be an effective method for algal control. Nevertheless, the molecular mechanisms underlying the inactivation of M. aeruginosa by ultrasound are still unknown. In this study, the physiological activity and molecular mechanism of algal cells exposed to different frequencies of ultrasound were studied. The results indicated a pronounced inhibition of algal cell growth by high-frequency, high-dose ultrasound. Moreover, with increasing ultrasound dosage, there was a higher percentage of algal cell membrane ruptures. SEM and TEM observed obvious disruptions in membrane structure and internal matrix. Hydroxyl radicals generated by high-frequency ultrasound inflicted substantial cell membrane damage, while increased antioxidant enzyme activities fortified cells against oxidative stress. Following 2 min of ultrasound irradiation at 740 kHz, significant differential gene expression occurred in various aspects, including energy metabolism, carbohydrate metabolism, and environmental information processing pathways. Moreover, ultrasound irradiation influenced DNA repair and cellular apoptosis, suggesting that the algal cells underwent biological stress to counteract the damage caused by ultrasound. These findings reveal that ultrasound irradiation inactivates algae by destroying their cell structures and metabolic pathways, thereby achieving the purpose of algal suppression.


Assuntos
Microcystis , Microcystis/metabolismo , Ondas Ultrassônicas , Antioxidantes/metabolismo , Proliferação Nociva de Algas , Estresse Oxidativo
3.
Chemosphere ; 349: 140914, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38092173

RESUMO

Magnetically modified carbon-based adsorbent (BC@γ-Fe2O3) was prepared through facile route using activated sludge biomass and evaluated for the simultaneous removal of Sb(III) and Pb(II). BC@γ-Fe2O3 exhibited outstanding Sb(III) and Pb(II) adsorption capacity when 200 mg of adsorbent was employed at pH 5.0 for 240 min, with the removal efficiency higher than 90%. The experiments demonstrated the excellent reusability and the potent anti-interference properties of the prepared absorbent. Freundlich and pseudo-second-order kinetic were prior to describe the adsorption process. The adsorption of Sb(III) and Pb(II) onto BC@γ-Fe2O3 was spontaneous and endothermic. BC@γ-Fe2O3 with high specific surface area revealed the exceptional competence to absorb Sb(III) and Pb(II) through pore filling, electrostatic adsorption and complexation. The adsorption mechanisms of Sb(III) and Pb(II) showed similarities with slight disparities. The removal of Sb(III) involved the Fe-O-Sb bond and π-π bond, while the adsorption of Pb(II) was closely related to ion exchange. Moreover, Sb(III) was oxidized to Sb(V) in a minor part during adsorption. The Fe-O-Cl active sites on BC allowed for the binding of γ-Fe2O3, guaranteeing the abundant adsorption sites and stability. BC@γ-Fe2O3 provides an efficient and green insight into the simultaneous removal of complex heavy metals with promising application in wastewater treatment.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Esgotos , Adsorção , Chumbo , Poluentes Químicos da Água/análise , Carvão Vegetal/química , Cinética , Fenômenos Magnéticos
4.
J Mater Chem B ; 11(40): 9757-9764, 2023 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-37807767

RESUMO

Stimuli-responsive/smart drug delivery systems (DDSs), particularly those that use temperature as a stimuli-response factor to activate drug release, are the subject of recent research. A phase change material (PCM) is a popular thermally responsive material that can be used as a drug carrier and only when the system temperature is above the phase change point is the drug released following the phase change material changing from solid to liquid. In this study, a novel NIR light-triggered temperature-sensitive drug delivery system is developed for controllable release of acyclovir (ACV). For this purpose, a mixture of a phase change material (T38) and an ACV compound is first emulsified with copper oxide nanoparticles (CuO NPs) as a Pickering stabilizer and a photothermal conversion material, and then encapsulated with SiO2 to form a photothermal stimuli-responsive delivery system. This system shows a uniform spherical shape with a well-distinct core-shell structure, and is further experimentally proven to be able to controllably release drugs with solid-liquid transition of the phase change carrier upon temperature change. These results indicate that cumulative release of ACV can reach 51.2% at 40 °C within 20 hours, which is much higher than 27.3% release achieved below the melting point of T38. In addition, CuO NPs with excellent photothermal conversion ability endow the system with precisely controllable drug delivery via NIR light stimulation, where the cumulative drug release can reach 83.6% after 7 cycles of light stimulation, allowing controlled release at a specific time or location.


Assuntos
Doxorrubicina , Dióxido de Silício , Temperatura , Cápsulas , Doxorrubicina/química , Sistemas de Liberação de Medicamentos/métodos
5.
Chemphyschem ; 24(19): e202300234, 2023 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-37428636

RESUMO

Phase change materials (PCMs) textiles have been developed for personal thermal management (PTM) while limited loading amount of PCMs in textiles reduced thermal buffering effect. In this work, we proposed a sandwich fibrous encapsulation to store polyethylene glycol (PEG) with PEG loading amount of 45 wt %, which consisted of polyester (PET) fabrics with hydrophobic coating as protection layers, polyurethane (PU) nanofibrous membranes as barrier layers and PEG-loaded viscose fabric as a PCM-loaded layer. The leakage was totally avoided by controlling weak interfacial adhesion between protection layer and melting PEG. The sandwich fibrous PEG encapsulations had an overall melting enthalpy value ranging from 50 J/g to 78 J/g and melting points ranging from 20 °C to 63 °C by using different PEGs. Besides, introduction of Fe microparticles in PCM-loaded layer enhanced thermal energy storage efficiency. We believe that the sandwich fibrous PEG encapsulation has a great potential in various fields.

6.
Chempluschem ; 88(4): e202300081, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36951444

RESUMO

Expanded graphite (EG) has been used to store phase change materials (PCM) to enhance thermal conductivity and avoid leakage. However, systematic investigation on physical structure of various embedded PCMs in EG is not reported. Besides, the effect of environment on thermal behavior of PCM/EG composites has not been investigated yet. In this work, three common PCMs (including myristic acid (MA), polyethylene glycol (PEG) and paraffin wax (PW)) were embedded in EG and three PCM/EG composites were obtained. As a result, capillary force between EG and PCMs supported encapsulation of PCMs in EG. PCM/EG composites had narrower phase change range while supercooling degree values were different when various PCMs were used. Besides, the hot and humid environment had a side effect on thermal energy storage of PCMs and PCM/EG composites. The inherent hydrophilicity of PCMs was essential for resistance against side effect of moisture on thermal energy storage.

7.
Environ Technol ; 44(28): 4409-4423, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35731237

RESUMO

Filtration is one of the important technologies for separating suspended particles. Under the condition of gravity compression, the filtration density can be increased and the separation effect of suspended particles can be improved. Considering the complex composition and the difficulty in degrading dye in industrial wastewater, a gravity compression aeration system with a modified polyester fibre ball (denoted as MPFB) was evaluated for the separation of dye from water. Congo red azo dye solution (0-40 mg/L) was selected as the model treatment compound. The MPFB was prepared by adjusting the concentrations of alkali (Quality score 0-25%), ß-cyclodextrin (0∼80 g/L), reaction temperature (40-90°C), and silane coupler concentration (Concentration fractions 0-0.8%). We used Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) to characterise the MPFB. The separation was affected significantly by adsorption conditions such as MPFB dose and pH. The lower the MPFB dose, the higher the expected adsorption capacity. For the treatment of a dye solution at 500 mg/L, 100% removal was achieved with 48 g/L MPFB, at pH 8 during adsorption under non-circulation aeration. For 24 h of reaction, the system could reach the maximum adsorption capacity of 11.2 mg/g, which followed the pseudo-first order kinetics model and the intraparticle diffusion model. We discovered that circulation aeration provided the best adsorption and electrostatic and hydrogen bonding were the dominant components of adsorption. Overall, the system is a promising technology and has the potential to treat large volumes of dye wastewater.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Poluentes Químicos da Água/química , Concentração de Íons de Hidrogênio , Vermelho Congo , Temperatura , Adsorção , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Corantes/química
8.
Polymers (Basel) ; 14(9)2022 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-35567064

RESUMO

High thermostability of phase change materials is the critical factor for producing phase change thermoregulated fiber (PCTF) by melt spinning. To achieve the production of PCTF from melt spinning, a composite phase change material with high thermostability was developed, and a sheath-core structure of PCTF was also developed from bicomponent melt spinning. The sheath layer was polyamide 6, and the core layer was made from a composite of polyethylene and paraffin. The PCTF was characterized by scanning electron microscopy (SEM), thermal analysis (TG), Fourier Transform Infra-Red (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and fiber strength tester. The results showed that the core material had a very high thermostability at a volatilization temperature of 235 °C, the PCTF had an endothermic and exothermic process in the temperature range of 20-30 °C, and the maximum latent heat of the PCTF reached 20.11 J/g. The tenacity of the PCTF gradually decreased and then reached a stable state with the increase of temperature from -25 °C to 80 °C. The PCTF had a tenacity of 343.59 MPa at 0 °C, and of 254.63 MPa at 25 °C, which fully meets the application requirements of fiber in textiles.

9.
Materials (Basel) ; 14(13)2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-34209015

RESUMO

P-aminophenol is a hazardous environmental pollutant that can remain in water in the natural environment for long periods due to its resistance to microbiological degradation. In order to decompose p-aminophenol in water, manganese oxide/polytetrafluoroethylene (PTFE) hollow fiber membranes were prepared. MnO2 and Mn3O4 were synthesized and stored in PTFE hollow fiber membranes by injecting MnSO4·H2O, KMnO4, NaOH, and H2O2 solutions into the pores of the PTFE hollow fiber membrane. The resultant MnO2/PTFE and Mn3O4/PTFE hollow fiber membranes were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and thermal analysis (TG). The phenol catalytic degradation performance of the hollow fiber membranes was evaluated under various conditions, including flux, oxidant content, and pH. The results showed that a weak acid environment and a decrease in flux were beneficial to the catalytic degradation performance of manganese oxide/PTFE hollow fiber membranes. The catalytic degradation efficiencies of the MnO2/PTFE and Mn3O4/PTFE hollow fiber membranes were 70% and 37% when a certain concentration of potassium monopersulfate (PMS) was added, and the catalytic degradation efficiencies of MnO2/PTFE and Mn3O4/PTFE hollow fiber membranes were 50% and 35% when a certain concentration of H2O2 was added. Therefore, the manganese oxide/PTFE hollow fiber membranes represent a good solution for the decomposition of p-aminophenol.

10.
Chemosphere ; 282: 131068, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34107421

RESUMO

Metal organic framework (MOF) nanoparticles are recognized for their effective removal of metal ions from aqueous systems. However, the application of nanoparticles in a powder form as synthesized is not practical and recovery is not easy. We prepared a recyclable magnetic MOF nanoparticle phase and used a widely available waste biomass to generate biochar to support magnetic nanoparticles applied in the treatment of aqueous antimony pollution. A mushroom waste biochar was used to support a magnetic UIO-66-2COOH (denoted as BSMU). Adsorption of trivalent antimony (Sb (III)) onto the BSMU was evaluated. The results showed that optimum conditions for preparation of the BSMU were the mass ratio of MMOF to biochar 4:1, the temperature 70 °C, the time 4 h, and the initiator 4 mM. Under such conditions, sorption capacity reached 56.49 mg/g for treatment of Sb (III) solution at 100 mg/L and pH 9.1. Alkaline conditions (such as pH 9.1) are more favorable for adsorption than acidic conditions, and coexisting ions including NO3-, Cl-, SO42-, and PO43- had no significant negative effect in adsorption, and with the use of low dose, higher adsorption density achieved. The adsorption followed a pseudo second order kinetics model and Freundlich isotherm model. It resulted in a higher enthalpy changes (ΔHθ) and activation energy (Ea) of 97.56 and 8.772 kJ/mol, respectively, and enhanced the rate pf random contact between antimony and the BSMU, as indicated by a higher entropy change (ΔSθ) up to 360 J/mol·K. As a result, it readily absorbs antimony. These adsorption properties identified in this study would provide a valuable insights into the application of nanoparticles loaded biochar from abundant biomass in environmental remediation.


Assuntos
Estruturas Metalorgânicas , Poluentes Químicos da Água , Adsorção , Antimônio , Carvão Vegetal , Concentração de Íons de Hidrogênio , Cinética , Fenômenos Magnéticos , Termodinâmica , Poluentes Químicos da Água/análise
11.
Materials (Basel) ; 14(8)2021 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-33924470

RESUMO

COVID-19, classified as SARS-CoV-2, is causing an ongoing global pandemic. The pandemic has resulted in the loss of lives and has caused economic hardships. Most of the devices used to protect against the transmission of the novel COVID-19 disease are related to textile structures. Hence, the challenge for textile professionals is to design and develop suitable textile structures with multiple functionalities for capturing viruses, passivating them, and, at the same time, having no adverse effects on humans during the complete period of use. In addition to manufacturing efficient, biocompatible, and cost-effective protective face masks, it is also necessary to inform the public about the benefits and risks of protective face mask materials. The purpose of this article is to address the concerns of efficiency and efficacy of face masks by primarily reviewing the literature of research conducted at the Technical University of Liberec. The main focus is on the presentation of problems related to the specification of aims of face mask applications, mechanisms of capture, durability, and modes of sterilization. The recommendations, instead of conclusions, are addressed to the whole textile society because they should be leading players in the design, creation, and proper treatment of face masks due to their familiarity with the complex behavior of textile structures and targeted changes of structural hierarchy starting from polymeric chains (nano-level) and ending in planar textile structures (millimeter level) due to action by mechanical, physical and chemical fields. This becomes extremely critical to saving hundreds of thousands of lives from COVID-19.

12.
Chemosphere ; 262: 127723, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32799138

RESUMO

Removing dissolved organic matter (DOM) with polyaluminium chloride is one of the primary goals of drinking water treatment. In this study, a new HMW framework was proposed, which divided the factors affecting coagulation into three parts consisting of hydraulic condition (H), metal salt (M), and background water matrix (W). In this framework, H, M and W were assumed to be interacted with each other and combined to determine coagulation efficiency. We investigated the feasibility of the framework to determine the treatment efficiency through mathematical models. Results showed that non-linear artificial neural network (ANN) model was a better fit to the experimental data than the linear partial least squares (PLS) model: the ANN model could explain 76% of the total variations while the PLS could only explain 71%. The PLS did not follow the variations of observed values adequately. These experiments showed that the interaction between the HMW framework components were not simple linear relationships. The ANN model was able to optimize the composition of the HMW framework improving the efficiency of DOM removal through the components of HMW such as velocity gradient (G value), coagulant dosage, solution pH, and background water matrix. Overall, HMW framework is a new classification of factors affecting coagulation, leading to a better understanding of the coagulation process and sensitivity to influencing variables.


Assuntos
Modelos Teóricos , Redes Neurais de Computação , Purificação da Água/métodos , Hidróxido de Alumínio/química , Água Potável , Concentração de Íons de Hidrogênio , Metais/química
13.
Nanomaterials (Basel) ; 10(10)2020 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-33081151

RESUMO

This work is the first attempt to prepare microporous polytetrafluoroethylene (PTFE) fibrous layers embedded with aerogels/phase change materials. For preparation of this layer, the needle-less electrospray technology of water dispersion of individual components is used. Microstructure characteristics, including surface morphology and particle size distribution, and various properties of the prepared materials were investigated and explained. Transport performance of the fibrous layers embedded with aerogels/phase change materials, such as the transmission of heat, air, and water vapor was evaluated and discussed in details. It was found that the electro-sprayed materials composed by spherical particles with rough surface had compact disordered stacking structure. Aerogels and phase change materials (PCMs) play different roles in determining structural parameters and transport properties of the materials. Those parameters and properties could be flexibly adjusted by optimizing the spinning parameters, changing the content or proportion of the fillers to meet specific requirements.

14.
J Fluoresc ; 30(6): 1383-1396, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32997315

RESUMO

Fluorescence excitation-emission matrix spectroscopy (EEMs) has become a very popular technique in characterization of aquatic dissolved organic matter (DOM) coupled with a parallel factor (PARAFAC) model, denoted as (EEMs-PARAFAC). This research addresses the poorly researched relationship correlation between dissolved ions and fluorescence in a natural water environment. The relationship between the EEMs-PARAFAC components and ionic composition was studied in freshwater lakes, rivers, and seawater from locations in China. The natural water environment is different from a simulated environment having a fixed ionic composition. We used electrical conductivity (EC) to reflect the ionic strength as an indicator to evaluate the relationship in a series of water bodies. Results show that the EC generally had a positive correlation with DOM in natural water environment, but no correlation was found with water from the highly saline Yellow Sea. The Chaohu Lake samples contained one component having a significant negative correlation with EC, i.e., r > 0.6, p < 0.05, while other surface waters contained components having both positive and negative correlations (r > 0.5, p < 0.05). The negative correlation with EC also highlighted that humic acid-like components and protein-like materials (c1-c3) were positively correlated with DOM, while the protein-like component (c4) was negatively correlated with DOM. The EC equation proposed provided a good fit with the EC values of surface waters. The use of EC would be a useful and rapid method for analyzing the variation in the fluorescence component and its effect on water quality. This study highlights the need to account for variation in EC when assessing EEMs-PARAFAC of natural waters.

15.
J Fluoresc ; 30(5): 1271-1279, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32767189

RESUMO

Chemical oxidation is a key technique used in dye wastewater treatment via the formation of hydroxyl radicals. To obtain optimal treatment effects, it is critical to understand the interaction of the molecular structure of the dye with the hydroxyl radical. We evaluated fluorescence excitation-emission matrix spectroscopy to study the decay of an azo-dye (Procion Red MX-5B) by a hydroxyl radical generated from catalytic Fe (III) on H2O2. Results showed that fluorescence signal reliably indicated the variations of the chemical groups and components during degradation, and the degradation could be divided into three stages: initial degradation (decolorisation), rapid intermediate degradation, and final degradation. Under control of uncorrected matrix correlation, the fluorescence fractions could be fitted successfully by parallel factor model (PARAFAC) model: two fluorescence components in initial degradation including mono substituted benzene and mono substituted naphthalene, three components as multi substituted benzene in rapid degradation, and no components could be resolved in the final degradation. The results from the study demonstrate the utility fluorescence characterization of dye degradation mechanisms and enhance the understanding of the degradation mechanisms.


Assuntos
Corantes/química , Catálise , Compostos Férricos/química , Peróxido de Hidrogênio/química , Radical Hidroxila/síntese química , Radical Hidroxila/química , Estrutura Molecular , Oxirredução , Espectrometria de Fluorescência , Águas Residuárias/química
16.
Polymers (Basel) ; 12(6)2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32549395

RESUMO

Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer known for its excellent hydrophobic properties. In this work, samples from PTFE dispersions with different combinations of water and carbon microparticles were prepared using an electrospraying method. The morphologies and sizes of carbon particles were investigated and the properties of layers including roughness, hydrophobicity and electrical resistivity were investigated. The non-conductive carbon microparticles were selected as a model particle to check the compatibility and electrospraying ability, and it had no effect on the hydrophobic and electrical properties. Carbon microparticles in polymer solution increased the degree of ionization and was found to be beneficial for the shape control of materials. The results showed that PTFE dispersion with the composition of water and carbon microparticles produced fine sphere particles and the layer fabricated with increased roughness. It was also found that the electrical resistivity and hydrophobicity of all the layers comparatively increased. The fabricated microporous layers can be used in various applications like interlining layer in multilayer textile sandwiches.

17.
Chemosphere ; 247: 125921, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31972494

RESUMO

Dissolved organic matter (DOM) is not only a vector for the migration of aquatic environmental pollutants, but is also key to the control of water pollution. Economic and effective DOM removal through coagulation is essential in water treatment processes. This work investigated the role of carboxylated magnetic metal organic frameworks (MMOFs) nanoparticles in polymeric iron-based coagulation for the removal of aquatic DOM using a MMOFs-doped polyferric iron-based coagulant (MMOF-PIC). Analytical methodologies and tools used in this research included scanning electron microscopy (SEM), zeta potential, molecular weight cut off (MWCO), vibrating sample magnetometer (VSM) measurement, excitation emission matrix spectroscopy (EEMs), and X-ray photoelectron spectroscopy (XPS). The results showed that MMOF-PIC had the potential to change the structure of the polyferric iron-based coagulant (PIC) and charge, as determined by a porous surface morphology, a higher medium polymeric species distribution, and a more positive zeta potential. The MMOFs consequently enhanced PIC action on the removal of UV254 exposed DOM species with molecular weight <30 kDa, including aromatic CC based compounds, org-N as primary amines and amide/peptide bound species, water containing microbial metabolites and protein-like materials. The coagulation of DOM was enhanced by improving charge neutralization, adsorption-bridging and sweep-flocculation in the presence of MMOFs nanoparticles. This was due to hydrogen bonds, π-π bonds and covalent bonds resulting from actions of nanoparticles and pollutants. These results indicate that magnetic MOF nanoparticles can improve PIC coagulation for DOM, enhancing future removal of target pollutants.


Assuntos
Substâncias Húmicas/análise , Estruturas Metalorgânicas/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Floculação , Ferro/química , Fenômenos Magnéticos , Nanopartículas , Compostos Orgânicos/química , Poluentes Químicos da Água/análise
18.
Materials (Basel) ; 12(17)2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31480702

RESUMO

A novel composite was synthesized by using flocculant polyaluminum titanium silicate chloride (PATC) and poly(diallyldimethylammonium chloride) (PDMDAAC) monomers to treat low-temperature and low-turbidity water. The structure and physicochemical properties of PATC-PDMDAAC were analyzed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis/differential scanning calorimetry (TG/DSC), X-ray diffraction spectroscopy (XRD), and scanning electron microscopy-energy dispersion spectrum (SEM-EDS). The compound flocculant produced new functional groups exhibiting great thermal stability, and the complex chemical reaction between the two monomers generated new substances with reticular structures. Coagulation performance results showed that the PATC-PDMDAAC had an organic and inorganic ratio of 0.15 and exhibited excellent removal efficiency at pH 9.0, dosage of 1.80 mg/L, sedimentation time of 40 min, and a stirring speed of 110 r/min. The optimal treatment efficiency reduced the turbidity to 0.56 NTU (Nephelometric Turbidity Unit). The removal rates of TOC (Total Organic Carbon) and UV254 (Ultraviolet 254) were 62.18% (from 7.23 mg/L to 2.734 mg/L) and 99.99% (from 10 mg/L to 0.001 mg/L). The 3D fluorescence, zeta potential and kinetic analysis in the flocculation process indicated that coagulant electroneutralization and adsorption bridge in a slightly alkaline environment played a dominant role, and a sufficient and effective collision occurred between the coagulant and particulate matter under the optimal dosage. Lastly, PATC-PDMDAAC has more advantage than conventional flocculants in the treatment of low-temperature and low-turbidity water in the Xiangjiang River.

19.
Environ Sci Pollut Res Int ; 25(26): 25955-25966, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29968210

RESUMO

A novel magnetic flocculant (CPAMF) was synthesized by using Fe3O4 coated with cationic polyacrylamide (CPAM) for flocculation of high turbid water. The surface morphology and chemical structures of CPAMF were confirmed by Fourier transform infrared spectroscopy (FTIR) and thermo-gravimetric analysis (TGA). X-ray diffraction (XRD) was employed to verify the crystal structure of CPAMF. The magnetic property of CPAMF was compared with Fe3O4 in this study. The flocculation performance by using flocculants CPAMF was evaluated in high turbid water treatment. The maximum transmittance 92.4% of kaolin suspension was achieved at corresponding optimal flocculation conditions. The result indicated that CPAMF was efficient in high turbid water flocculation. Analysis of FTIR, XRD of flocs, and zeta potential (ZP) of supernatant were accomplished for flocculation mechanism investigation. Because of low recovery factor in reflocculation under the effect of shear force on flocs, the bridging effect was found to be dominant in both acidic and alkaline conditions. Sedimentation experiments under the role of permanent magnet indicated that nano-Fe3O4 could effectively improve the settling property of CPAM. Graphical abstract ᅟ.


Assuntos
Resinas Acrílicas/química , Purificação da Água/métodos , Água/química , Cátions , Floculação , Caulim , Magnetismo , Espectroscopia de Infravermelho com Transformada de Fourier , Suspensões , Termogravimetria , Difração de Raios X
20.
Chemosphere ; 201: 708-715, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29547859

RESUMO

Characterization of dissolved organic matter/nitrogen (DOM/DON) is critical in water quality assessment and nutrient management in watershed or ecosystem. This study was to investigate the link between DOM/DON and its source using fluorescence excitation-emission matrix (EEM) spectroscopy coupled with parallel factor analysis (PARAFAC). Water samples were collected from various aquatic systems in a watershed located in central Missouri, including rural watershed with various land use and land cover (LULC), landfill, and constructed wetland. PARAFAC results based on EEM spectroscopy revealed four DOM components: two humic/fulvic acid-like components, one xenobioic-like component, and one protein-like component (f4). The f4 score was found highly correlated to LULC, indicating its distinctive EEM structure in relation to source. It is believed that the f4 score could be used as a surrogate for DOM/DON source-tracking in complex ecosystems. The nitrogen 1s X-ray photoelectron spectroscopy (XPS) of the solid DOM showed a close relationship between N oxidation state and its origin. The classification of the sample origins by the N oxidation state confirmed the grouping by the f4 score of EEM/PARAFAC. This study demonstrated that EEM/PARAFAC could be used as a tool for DOM/DON source tracking, point or non-point source pollution control, and understanding of DOM/DON fate and transport in complex aquatic ecosystems.


Assuntos
Monitoramento Ambiental/métodos , Substâncias Húmicas/análise , Nitrogênio/análise , Rios/química , Poluentes Químicos da Água/análise , Áreas Alagadas , Ecossistema , Análise Fatorial , Missouri , Espectroscopia Fotoeletrônica/métodos , Espectrometria de Fluorescência/métodos , Qualidade da Água
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