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1.
Chemosphere ; 240: 124884, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31542586

RESUMO

Antibiotics and heavy metals are frequently detected simultaneously in water environment. In this study, the competitive adsorption behavior of tylosin (TYL) and sulfamethoxazole (SMX) on nano-hydroxyapatite modified biochar (nHAP@biochar) in accordance with Cu(II) in single, binary and ternary systems was investigated. The specific surface area of nHAP@biochar was 566.056 m2/g. The adsorption of TYL on nHAP@biochar reduced by 13.36%-41.04% or 9.92%-38.69% with Cu(II) and SMX in the solution, respectively. The suppression of SMX was stronger than Cu(II) on the adsorption of TYL when the SMX or Cu(II) was constant. The adsorption of SMX increased by 2.01-3.56 times in the present of Cu(II), while suppressed by TYL up to 42.30%. Due to the bridging of TYL or SMX between the nHAP@biochar and Cu(II) and destroying of bound water surrounded, the adsorption of Cu(II) increased to a greater extent. Electrostatic interaction and H-bond were the two main interactions between TYL, SMX and Cu(II) and nHAP@biochar. π-π interactions was also interaction between the SMX and nHAP@biochar.


Assuntos
Carvão Vegetal/química , Cobre/metabolismo , Durapatita/química , Nanopartículas/química , Sulfametoxazol/metabolismo , Tilosina/metabolismo , Poluentes Químicos da Água/metabolismo , Adsorção , Cobre/isolamento & purificação , Sulfametoxazol/isolamento & purificação , Tilosina/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos
2.
Chemosphere ; 240: 124889, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31563102

RESUMO

This study explores the use of an engineered char produced from the pyrolysis of anaerobically digested fiber (ADF) to adsorb phosphate from aqueous solutions. Two series of engineered chars were produced. The first series was a CO2 activated (CA) char produced via slow pyrolysis between 350 and 750 °C. The second series was a nitrogen doped (ND) char activated in the presence of ammonia at comparable temperatures. Proximate analysis, elemental composition, gas physisorption, Inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray powder diffraction (XRD) techniques were used to characterize properties of resulting products. The surface area of the carbon product increased after nitrogen doping through ammonization (166.6-463.1 m2/g) compared to CO2 activated chars (156.5-413.1 m2/g). Phosphate adsorption isotherms for both CO2 activated and nitrogen doped chars can be described by the Langmuir- Freundlich and Redlich Peterson adsorption models. Nitrogen doped carbon phosphate sorption capacity in aqueous solutions was twice compared to CO2 activated carbons. As carbonization/activation temperature increased the sorption capacity increased from 3.4 to 33.3 mg g-1 for CA char and 6.3-63.1 mg g-1 for nitrogen doped char.


Assuntos
Carvão Vegetal/química , Nitrogênio/química , Fosfatos/análise , Fosfatos/isolamento & purificação , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
3.
Chemosphere ; 238: 124559, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31446279

RESUMO

The adsorption of bisphenol-A (BPA) on ordered mesoporous carbon (CMK-3) and modified CMK-3 (MCMK-3) for decontamination of aqueous medium was investigated. The CMK-3 and MCMK-3 materials had uniform pore sizes of 3.60 and 3.70 nm and high Brunauer-Emmett-Teller (BET) surface areas of 751 and 564 m2 g-1, respectively. The maximum adsorption capacities of CMK-3 and MCMK-3 were 178.57 (0.24 mg m-2) and 238.01 (0.42 mg m-2) mg g-1, respectively at 298 K (pH 6.4). The difference in the adsorption capacities is attributed to the specific surface area and hydrophobicity of the adsorbents. The adsorption of BPA on CMK-3 and MCMK-3 may be influenced by π-π bonding and hydrophobic and electrostatic interactions, and the excellent adsorption capacity of MCMK-3 is attributed to its unique sp2-hybridized single-atom-layer structure. The kinetics and isotherm data were described by the pseudo-second order kinetic model and the Langmuir isotherm, respectively. This difference in the adsorption kinetics of CMK-3 and MCMK-3 is caused by the increase in the pore diameter of the latter. Further, CMK-3 and MCMK-3, with an open geometry consisting of interlinked nanorods, allow for faster intraparticle diffusion. Overall, CMK-3 and MCMK-3 could be promising adsorbents for the removal of chemicals containing benzene rings from wastewater.


Assuntos
Compostos Benzidrílicos/isolamento & purificação , Carbono/química , Fenóis/isolamento & purificação , Águas Residuárias/análise , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Compostos Benzidrílicos/metabolismo , Cinética , Fenóis/metabolismo , Águas Residuárias/química , Poluentes Químicos da Água/metabolismo
4.
Chemosphere ; 238: 124543, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31450109

RESUMO

Nano micro-electrolysis materials (nMETs) have been used to degrade refractory pollutants in batch experiments. The reasonable formation mechanism of nMETs was given through DMXY digital biomicroscopy. Based on the kinetic data of Chlortetracycline (CTC) removal by nMETs in batch experiments, combined with the binomial distribution equation of CTC reduction by nano materials an experimental-scale fluidized bed (ESFB) was designed. The effects of CTC removal performance, pH and iron ion concentration were investigated. Under pure CTC solution environment, the experimental data showed that the average removal rates of CTC by nMET and nano micro-electrolysis material with loading copper (Cu-nMET) are 90.0% and 95.7% in ESFB, respectively. In the presence of nitrate, although the consumption of two kinds of nano-materials increased, their removal efficiencies of pollutants have 2.2%, 0.2% increase compared with the nitrate-free ESFB. At the same time, the CTC degradation pathway and the enhanced removal mechanism by Cu-nMET was proposed. Through microelectrolysis reaction, complexation reaction and the active substances produced, the intermediate products can be degraded completely to NH4+, CO2, H2O and so on. This study aims to provide a theoretical basis for the environmental application of nMETs.


Assuntos
Clortetraciclina/isolamento & purificação , Cobre/química , Eletrólise/métodos , Ferro/química , Nitratos/química , Poluentes Químicos da Água/isolamento & purificação , Clortetraciclina/análise , Clortetraciclina/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química
5.
Chemosphere ; 238: 124432, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31421464

RESUMO

This study investigated the adsorption of tetracycline (TC) on biochar (BC) derived from waste Auricularia auricula dregs obtained at different pyrolysis temperatures. The characterization of BC and batch experiment results showed that BC prepared at a higher temperature was more suitable for removing TC, where the maximum adsorption capacities of BC samples prepared at 300 °C, 500 °C, and 700 °C were 7.22 mg/g, 9.90 mg/g, and 11.90 mg/g, respectively. A pseudo-first order kinetics model and Freundlich, Temkin, and Dubinin-Radushkevich isotherm models fitted well to the adsorption data. Liquid film diffusion was the rate-controlling step. In addition, π-π electron donor-acceptor interactions may have played a dominant role in the adsorption mechanism between the enone structure of TC and aromatic C of BC. These results may facilitate further investigations of the adsorption mechanism and optimization of the process.


Assuntos
Basidiomycota , Carvão Vegetal/química , Resíduos Industriais , Tetraciclina/química , Tetraciclina/isolamento & purificação , Água/química , Adsorção , Indústria Alimentícia , Temperatura Alta , Concentração de Íons de Hidrogênio , Cinética , Soluções , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
6.
Chemosphere ; 238: 124539, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31470310

RESUMO

The performance and microbial community structure of anaerobic dynamic membrane bioreactor (AnDMBR) treating textile wastewater was investigated. The reactor showed excellent soluble COD and color removal of 98.5% and >97.5%, respectively. Dynamic membrane layer grown over the 3D printed dynamic membrane support showed decent rejection for high molecular weight compounds (>20 kDa); and the total suspended solid rejection by the dynamic layer was >98.8%. Gel permeation chromatography analysis of extracellular polymeric substance (EPS) and effluent samples revealed EPS accounted for more than 76.7% of low molecular weight fractions (<20 kDa) that end up in the effluent. Higher applied flux facilitated the rapid formation dynamic layer which enabled a satisfactory effluent quality. Microbial community analysis revealed that during the operation the archaeal community was relatively stable while obvious changes took place in the bacterial community. Introduction of dye Remazol Brilliant Blue R (RBBR) to the AnDMBR increased the abundances of phyla of Proteobacteria and Spirochaetae whereas fractions of Firmicutes and Euryarchaeota decreased obviously. Furthermore, relative stable abundances of phyla Aminicenantes, Bacteroidetes, Thermotogae and Chloroflexi among the top six phyla detected in the system ensured a healthy anaerobic degradation environment for RBBR wastewater treatment.


Assuntos
Antraquinonas/isolamento & purificação , Antraquinonas/metabolismo , Reatores Biológicos/microbiologia , Membranas Artificiais , Têxteis , Águas Residuárias/química , Anaerobiose , Corantes/isolamento & purificação , Corantes/metabolismo , Matriz Extracelular de Substâncias Poliméricas/microbiologia , Proteobactérias/metabolismo , Spirochaeta/metabolismo , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/metabolismo
7.
Chemosphere ; 238: 124638, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31466006

RESUMO

In this study, we reported on the recycling of carbon materials from spent commercial supercapacitors and its application as low-cost adsorbent for high-efficiency removal of Ag(I) and Cr(VI) ions from aqueous solutions. Adsorption kinetics and isotherms, and effects of initial pH were carried out to investigate the adsorption performance of the recycled supercapacitor activated carbon (RSAC), whereas a series of characterizations such as SEM, EDX, BET, XPS, XRD and FTIR were employed to detailedly analyse the adsorption mechanism. The RSAC showed maximal adsorption capacity for Ag(I) and Cr(VI) of 104.0 and 96.3 mg g-1, respectively, with adsorbent dosage of 2 g L-1 and initial ions concentration of ∼2000 mg L-1 at room temperature (23 ±â€¯1 °C), and the adsorption was rapid and influenced by the initial pH value. The outstanding adsorption performance of RSAC was attributed to the high specific surface area (1403 m2 g-1) and abundant multifarious oxygenic groups which could participate in the electrostatic attraction and reduction reaction of Ag(I) and Cr(VI) during the adsorption process. Furthermore, the predominate species of the adsorbed toxic Ag(I) and Cr(VI) on the surface of RSAC was metallic silver particle (about 2 µm) and harmless Cr(III), respectively, thus it was possible for further recycling and disposal.


Assuntos
Carvão Vegetal/química , Cromo/isolamento & purificação , Reciclagem/métodos , Prata/isolamento & purificação , Águas Residuárias/química , Purificação da Água/métodos , Adsorção , Íons , Cinética , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
8.
Chemosphere ; 239: 124735, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499306

RESUMO

A key challenge in adsorption process of toxic organic and inorganic species is the design and development of adsorbent materials bearing an abundance of accessible adsorption sites with high affinity to achieve both fast adsorption kinetics and elevated adsorption capacity for toxic contaminants. Herein, a novel anion-exchange adsorbent based on fibrous silica nanospheres KCC-1 was synthesized by a facile hydrothermal-assisted post-grafting modification of KCC-1 with 1-methyl-3- (triethoxysilylpropyl)imidazolium chloride for the first time. Silica fibers with micro-mesoporous structure display the proper combination of features to serve as a potential scaffold for decorating adsorption sites to create desired ion-exchange adsorbent. The obtained N-methylimidazolium-functionalized KCC-1 (MI-Cl-KCC-1) with fibrous nanosphere morphology showed a high surface area (∼241 m2 g-1) and high pore volume (0.81 m2 g-1). The adsorption behaviors of toxic hexavalent chromium from aqueous media by the MI-Cl-KCC-1 were systematically studied using the batch method. The adsorption rate was relatively fast, and MI-Cl-KCC-1 possesses a high capacity for the adsorption of Cr(VI). The maximum Cr(VI) adsorption was obtained at pH 3.0-4.0. Different non-linear isotherm equations were tested for choosing an appropriate adorption isotherm behavior, and the adsorption data for MI-Cl-KCC-1 were consistent with the Langmuir model with a maximum adsorption capacity of 428 ±â€¯8 mg g-1.


Assuntos
Cromo/isolamento & purificação , Imidazóis/química , Nanoestruturas/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Ânions , Cromo/química , Imidazóis/síntese química , Troca Iônica , Cinética , Micro-Ondas , Dióxido de Silício/química , Poluentes Químicos da Água/química , Purificação da Água/métodos
9.
Chemosphere ; 239: 124714, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499309

RESUMO

Enhanced mineralization of phenol in brines with high chloride content was investigated by employing an electrochemical advanced oxidation treatment that couples anodic oxidation, electrochlorination and electro-Fenton in a single process. Experimental work was carried out in a pilot scale unit with an undivided plate-and-frame cell equipped with a boron-doped diamond anode and a carbon-PTFE gas diffusion electrode as cathode, in batch recirculation mode. The effects of operating conditions on phenol degradation, including current density, air flow rate, water feed flow rate, Fe2+ dosage and pH as well as of the water matrix, were evaluated. Applied current exhibited the greatest effect on phenol degradation/mineralization efficiency. Complete degradation of phenol (of initial concentration 50 mg L-1) was achieved under the near-optimum operating conditions (40 mA cm-2, pH 7, 0.4 m3 h-1 water circulation rate) within 30 min. Both air flow rate and Fe2+ dosage did not show a measurable impact on phenol removal. However, increasing the chloride content of water significantly improved the efficiency of treatment due to the enhanced indirect oxidation by the electrogenerated chlorine. Several trihalomethane intermediates (chloroform, bromodichloromethane) and chlorinated/brominated phenol byproducts forming during treatment, were eliminated after 60 min of processing time.


Assuntos
Técnicas Eletroquímicas/métodos , Fenol/isolamento & purificação , Salinidade , Poluentes Químicos da Água , Cloro/farmacologia , Eletrodos , Peróxido de Hidrogênio/química , Oxirredução , Projetos Piloto , Águas Salinas , Poluentes Químicos da Água/isolamento & purificação
10.
Chemosphere ; 239: 124728, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499314

RESUMO

Numerous of pollutants threaten our planet, for instance plastic wastes causes a huge potential risk on the environment in addition to many of emergened pollutants as pharmaceutical residue in aquatic environments which affecting ecological balance and in-turn affecting human health. Accordingly, this research proposed an innovative facile, one-step synthesis of functionalized magnetic fullerene nanocomposite (FMFN) via catalytic thermal decomposition of sustainable poly (ethylene terephthalate) bottle wastes as feedstock and ferrocene as a catalyst and precursor of magnetite. Growth mechanism of FMFN was discussed and batch experiments were achieved to examine its adsorption efficiency in relation to Ciprofloxacin antibiotic. Different adsorption parameters including time, initial Ciprofloxacin concentration, and solution temperature were investigated and optimized using Response Surface Methodology (RSM) model. In addition, a study on the antibiotic adsorption process impact on the organisms of an ecosystem was conducted using E. coli DH5α, and results validated method's efficiency in overcoming problem of appearance of antibiotic-resistant microbes.


Assuntos
Ciprofloxacino/isolamento & purificação , Fulerenos/química , Nanocompostos/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Ciprofloxacino/química , Ecossistema , Escherichia coli , Concentração de Íons de Hidrogênio , Cinética , Fenômenos Magnéticos , Modelos Estatísticos , Plásticos , Polietilenotereftalatos/química , Tomografia por Emissão de Pósitrons , Reciclagem , Temperatura Ambiente , Poluentes Químicos da Água/química , Purificação da Água/métodos , Purificação da Água/estatística & dados numéricos
11.
Chemosphere ; 239: 124708, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31505442

RESUMO

The discharge of phenol, a harmful pollutant, in the environment poses a threat to human health. With the rapid urbanization and industrialization of the land, there is a pressing need to find new technologies and efficient adsorption materials to address phenol contamination. As a potential adsorbent candidate, sepiolite (SEP) has garnered much interest owing to its large specific surface area, and excellent adsorption performance and biocompatibility. Herein, nanocomposite CESEP/ZIF-8, consisting of zeolite imidazole framework (ZIF-8) and hydrochloric acid-modified SEP (CESEP), was prepared and examined toward the adsorption of phenol. Adsorption equilibrium was achieved within 150 min at initial phenol solution concentrations of 10 and 20 mg/L. However, complete removal was not achieved. Accordingly, biodegradation was introduced. Microorganism Pseudomonas putida was immobilized onto CESEP/ZIF-8, which afforded synergistic adsorption and biodegradation action. Phenol at solution concentrations of 10 and 20 mg/L was effectively removed within 13 and 24 h, respectively (as opposed to 21 and 36 h when phenol was removed in the presence of free Pseudomonas putida solely). The synergistic physical-biological treatment presented herein is expected to have great potential in the field of wastewater treatment.


Assuntos
Biodegradação Ambiental , Imidazóis/química , Nanocompostos/química , Fenol/isolamento & purificação , Pseudomonas putida/metabolismo , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Zeolitas , Adsorção , Cinética , Fenol/metabolismo , Fenóis/isolamento & purificação , Fenóis/metabolismo , Águas Residuárias/química , Poluentes Químicos da Água/metabolismo , Purificação da Água/normas
12.
Chemosphere ; 238: 124640, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524609

RESUMO

Triclosan (TCS) is a kind of chronic toxicity to aquatic organisms. Due to its highly effective antimicrobial, TCS has been widely applied in personal-care products, which naturally poses a potential risk to the ecological system and human health since its release into water-ecological environment. Therefore, it urgently demands a selective, easily separated, recyclable, and low-cost adsorbent to remove the residues of TCS from aquatic environments. In this study, a novel magnetic molecularly imprinted nano-polymers (TMIPs) were prepared for selective adsorption and convenient collection of TCS in aquatic samples, based on a core-shell technique using TCS as template molecule and SiO2-coated Fe3O4 nanoparticles as the support substrate. The functional groups, particle size, morphology and magnetic property of TMIPs were characterized by Fourier-transform infrared spectroscopy, scanning electron microscope, transmission electron microscopy and vibrating sample magnetometer, respectively. The obtained TMIPs possessed excellent adsorption capacity (Qe = 53.12 mg g-1), speedy adsorption equilibrium time (2 min) and high selectivity (k' = 6.321) for TCS. Moreover, the pH-tolerance and stability tests manifested that the adsorption capacity of TMIPs for TCS was acid-resistance and could retain 94.2% of the maximum Qe after 5 times removal-regeneration cycles. The feature of magnetically susceptibility can simplify the procedures of sample handling in TCS determination, because the TMIPs of TCS are easy to be recycled from aquatic samples. As an application demonstration, the toxicity test in microalgae confirmed that a tiny amount of TMIPs could significantly eliminate the toxic effect of TCS on Chlamydomonas reinhardtii via the efficient binding with TCS.


Assuntos
Magnetismo/métodos , Impressão Molecular , Nanopartículas/química , Triclosan/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Antibacterianos/isolamento & purificação , Antibacterianos/toxicidade , Cosméticos/química , Cosméticos/toxicidade , Impressão Molecular/métodos , Tamanho da Partícula , Polímeros/química , Dióxido de Silício/química , Triclosan/toxicidade
13.
Chemosphere ; 239: 124831, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31526986

RESUMO

The overuse of antibiotics, including tetracycline hydrochloride (TC), seriously threatens human health and ecosystems. In this work, magnetic carbon-coated cobalt oxide nanoparticles (CoO@C) were prepared by one-step annealing method and used as an adsorbent for efficient removal of TC from aqueous solution. The characteristic of the materials was studied by SEM, TEM, and XRD, revealing CoO nanoparticles (≤10 nm) were coated by carbon layer. Several influencial parameters, such as annealing temperature and pH on adsorption of TC, were explored, and found that the maximum adsorption capacity of CoO@C on TC reached as high as 769.43 mg g-1. Furthermore, CoO@C displayed excellent stability and reusability. After four repeated use of the adsorbent, the adsorption capacity still remained at 90% of the initial capacity. The pseudo-second order model and Temkin model proved that it was an exothermic chemical adsorption process. Furthermore, after analysis of FT-IR, Zeta-potential, XPS, the positive charge on the surface of CoO@C forms a strong electrostatic interaction with TC, and in addition, a surface bond is formed between the adsorbent and the TC molecule. This work provides a novel and efficient adsorbent for the purification of TC-containing wastewater.


Assuntos
Cobalto/química , Nanopartículas/química , Óxidos/química , Tetraciclina/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Antibacterianos/química , Carbono , Magnetismo , Reciclagem , Tetraciclina/isolamento & purificação , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos
14.
Chemosphere ; 239: 124833, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31526990

RESUMO

A facile and effective method has been developed to prepare hierarchical porous carbon nanofibers (PCNFs), carbon nanofibers supported nickel nanoparticles (PCNFs-Ni) and carbon nanofibers encapsulating gold nanoparticles (PCNFs-Au). PCNFs or PCNFs-Au were obtained by embedding metal-organic frameworks (e.g. ZIF-8 or ZIF-8-Au) into polyacrylonitrile via electrospinning and subsequent carbonization. In addition, PCNFs-Ni were obtained by impregnating PAN/ZIF-8 nanofibers in Ni(NO3)2·6H2O followed by carbonization. Both PCNF and PCNF-Ni exhibited excellent adsorption activities for methylene blue (MB) and congo red (CR). Especially, PCNF-Ni could be removed and separated via a magnet. PCNFs-Au showed excellent catalytic properties in the reduction reaction of 4-nitrophenol (4-NP).


Assuntos
Resinas Acrílicas/química , Carbono/química , Estruturas Metalorgânicas/química , Nanofibras/química , Poluentes Químicos da Água/química , Adsorção , Catálise , Vermelho Congo/química , Vermelho Congo/isolamento & purificação , Nanopartículas Metálicas/química , Azul de Metileno/química , Azul de Metileno/isolamento & purificação , Nitrofenóis/química , Nitrofenóis/isolamento & purificação , Porosidade , Poluentes Químicos da Água/isolamento & purificação
15.
Chemosphere ; 239: 124733, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31526991

RESUMO

Lignin, natural aromatic polymer derived from plant dry matter, is second abundant biopolymer. Recently, interest in applications of lignin, especially as an adsorbent material is increasing. However, the physicochemical complexity of lignin significantly reduces access to practical environmental remediation processes. Also, there is a limitation because the adsorption performance of the pristine lignin materials is not superior to that of commercial adsorbent and ion exchange resin material. In this study, spherical lignin particles with high physicochemical stability and excellent Cr(VI) adsorption capacity are prepared using a polyethylenimine (PEI) modification strategy. This modification process significantly improves the mechanical properties and water stability of lignin by complementing the instability of lignin particles. In addition, the PEI-lignin particles exhibit a superior Cr(VI) removal capability (657.9 mg/g, the highest value for a PEI-modified natural adsorbent), which is attributed to their structural stability and introduced amine functional groups. The Cr(VI) removal with PEI-lignin particles is performed via intra-particle diffusion and adsorption followed by covalent bonding combined with a reduction process. Moreover, the PEI-lignin particles exhibit excellent reusability, which sustains their high adsorption efficiency over a long and repeated adsorption period. The results herein strongly support the potential use of PEI-lignin particles as a high performance bio-sorption material for heavy metal removal and its detoxification in aqueous wastewater streams. Evidently, this lignin-based bio-sorbent manufacturing system can provide sustainable bio-resource recycling and cost efficiency.


Assuntos
Cromo/isolamento & purificação , Lignina/química , Adsorção , Cromo/química , Recuperação e Remediação Ambiental , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia Fotoeletrônica , Polietilenoimina/química , Espectroscopia de Infravermelho com Transformada de Fourier , Eliminação de Resíduos Líquidos/métodos , Água/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
16.
Chemosphere ; 239: 124840, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31526996

RESUMO

Organic-magnetic bentonites (OMBts), i.e., amphoteric modified MBt (BS-MBt), amphoteric-cationic modified MBt (BS-CT-MBt) and amphoteric-anionic modified MBt (BS-SDS-MBt), obtained by modifying magnetic bentonite (MBt) with amphoteric surfactant (BS), cationic surfactant (CT) and anionic surfactant (SDS) were investigated with the aim to remove cadmium (Cd2+). The modifier contents, surface charge and Cd2+ adsorption performances of OMBts were compared, and the influences of pH, temperature and ionic strength on Cd2+ removal were evaluated. Results showed that modifier contents of OMBts increased in the order: BS-CT-MBt > BS-MBt > BS-SDS-MBt. Although CEC of adsorbents increased in the order: MBt > BS-MBt > BS-SDS-MBt > BS-CT-MBt. The BS-MBt exhibited the highest Cd2+ adsorption capacity (233.19 mmol kg-1) than other adsorbents. The adsorption isotherms could be well described by Langmuir model. The Cd2+ adsorption capacities on MBt and OMBts increased with an increase in pH, temperature and with a decrease of ionic strength. According to characterizations (FT-IR and XPS) and experiments, Cd2+ adsorption on MBt and OMBts most possibly involved electrostatic interaction, ion exchange, and surface complexation. Furthermore, the adsorption of Cd2+ on BS-MBt was also attributed to the chelation. The amidocyanogen group of BS-CT-MBt inhibited adsorption of Cd2+ due to electrostatic repulsion, while Cd2+ was adsorbed on BS-SDS-MBt through electrostatic attraction induced by the sulfo group.


Assuntos
Bentonita/química , Cádmio/isolamento & purificação , Tensoativos/química , Adsorção , Ânions , Cádmio/química , Cátions , Concentração de Íons de Hidrogênio , Fenômenos Magnéticos , Concentração Osmolar , Eletricidade Estática , Temperatura Ambiente , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
17.
Chemosphere ; 240: 124860, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31542578

RESUMO

In order to increase the adsorption properties of sodium alginate gel beads, a series of SA@PF-beads (sodium alginate-based beads with different amount of pore-forming agent) were prepared with calcium carbonate as the pore forming agent. The experimental results showed that the adsorption capacity of Cu(Ⅱ) increased by at least two times (from 13.69 mg/g to 33.88 mg/g, treated with SA@PF-0 and SA@PF-2.0, respectively) with proper amount of calcium carbonate added, which is economical and effective. In the experiment, SEM was used to measure the morphology of gel beads with different amount of pore-forming agent. FTIR and XPS were used to analyze the variation of functional groups and bond energies in the adsorption process. Adsorption isotherms and kinetics were conducted and showed that the adsorption process was consistent with Langmuir model and Elovich kinetic model. The maximum Langmuir adsorption 229.746 mg/g. The effects of pH, temperature and solid-liquid ratio on adsorption capacity were also investigated. In brief, calcium carbonate is an efficient and convenient pore-forming agent, which can be used to improve the adsorption properties of alginate gel materials.


Assuntos
Alginatos/química , Cobre/isolamento & purificação , Microesferas , Adsorção , Carbonato de Cálcio/química , Concentração de Íons de Hidrogênio , Cinética , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura Ambiente , Poluentes Químicos da Água/isolamento & purificação
18.
Ecotoxicol Environ Saf ; 188: 109887, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31706237

RESUMO

To investigate the removal mechanisms of cadmium (Cd) by Zn-layer double hydroxides-modified zeolites substrates in constructed rapid infiltration systems (CRIS), the ZnAl-LDHs and ZnFe-LDHs were synthesized and in-situ coated on the original zeolites through co-precipitation method. The prepared Zn-LDHs-modified and original zeolites were characterized by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) methods, whose results provided the evidences that the Zn-LDHs were successfully coated on the original zeolites. From the results of purification experiments, the average Cd removal rates of ZnAl-LDHs-modified, ZnFe-LDHs-modified and original zeolites were 88.40, 86.00 and 32.52%, respectively; demonstrating that the removal rates of zeolites could significantly improve. Additionally, the modification of Zn-LDHS could enhance the theoretical adsorption ability. According to the results of isothermal adsorption and desorption tests, the desorption rates of Zn-LDHs-modified zeolites were higher than that of original zeolites. Cd adsorption capacity of ZnFe-LDHs-modified zeolites was 1428.57 mg kg-1 and original zeolites was 434.783 mg kg-1. In the adsorption kinetic studies, the pseudo-second-order models were used to well describe the experimental results of Zn-LDHs-modified zeolites, indicating that their adsorption types were attributed to be more stable chemisorption. Besides, the relevant microbial tests also confirmed that microbial enzymatic activity and extracellular polymeric substances (EPS) were significantly promoted on surface of Zn-LDHs-modified zeolites. The contents of EPS on the surface of zeolites were as following: ZnAl-LDHs-modified zeolites (78.58128 µg/g) > ZnFe-LDHs-modified zeolites (71.85445 µg/g) > original zeolites (68.69904 µg/g). Meanwhile, the results of high-throughput sequencing showed that modification by Zn-LDHs improved microbial diversity and relative abundance. The Proteobacteria was the dominant phylum and the Acidobacteria was conducive to Cd removal. Overall, it could be concluded that ZnAl-LDHs-modified zeolites might be applied as an efficient substrate for Cd removal in CRIS.


Assuntos
Cádmio/isolamento & purificação , Hidróxidos/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Zeolitas/química , Zinco/química , Acidobacteria/química , Acidobacteria/metabolismo , Adsorção , Proteínas de Bactérias/metabolismo , Cádmio/química , Cinética , Poluentes Químicos da Água/química , Purificação da Água/instrumentação , Purificação da Água/normas
19.
Chemosphere ; 238: 124617, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31450108

RESUMO

Perfluorooctanoic acid (PFOA) in environmental media contains numerous isomers/enantiomers because of the PFOA manufacturing process and biological degradation of PFOA precursors. Few methods for analyzing PFOA enantiomers have been described. A simple derivatization method using (S)-1-phenethyl chloride that was developed to allow PFOA isomers/enantiomers to be separated by gas chromatography and analyzed by electron-capture negative ionization mass spectrometry is described here. PFOA standards were analyzed, and enantiomers of the chiral isomers perfluoro-3-methyl-heptanoic acid, perfluoro-4-methyl-heptanoic acid, and perfluoro-3,5-dimethyl-hexanoic acid were separated using an HP-5MS column. Linear PFOA and perfluoro-6-methyl-heptanoic acid were chromatographically separated from these enantiomers. The linear ranges (giving correlation coefficients r > 0.997) of the calibration curves for the isomers were 0.010-3.00 ng/mL. PFOA isomer/enantiomer concentrations in river water were determined using the method. The method separated the enantiomers of perfluoro-3-methyl-heptanoic acid and perfluoro-4-methyl-heptanoic acid, the isomers of perfluoro-6-methyl-heptanoic acid, and linear PFOA in river water. No significant differences were found between the PFOA enantiomer/isomer compositions of the sample and technical PFOA. Enantiomer ratios can provide information about the sources and transport of pollutant isomers/enantiomers in the environment. Enantiomeric separation requires effective separation techniques. Our method achieved chiral separation using a non-chiral GC column that is often used in general analytical laboratories. The method could be used to investigate the sources and fates of PFOA and the isomers/enantiomers of other potentially toxic persistent pollutants in the environment and the risks posed to humans.


Assuntos
Caprilatos/química , Fluorcarbonetos/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Rios/química , Poluentes Químicos da Água/química , Caprilatos/análise , Caprilatos/isolamento & purificação , Fluorcarbonetos/análise , Fluorcarbonetos/isolamento & purificação , Humanos , Estereoisomerismo , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
20.
Chemosphere ; 238: 124621, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31454740

RESUMO

Present study prepared a new magnetic and thermo dual-responsive core-shell nanomaterial (Fe@SiO2@poly(N-isopropylacrymide-co-methacrylic acid, Fe@SiO2@PNIPAM-co-MAA), which was characterized by transmission electron microscopy and X-ray diffraction techniques. The new nanomaterials integrated with the magnetism of nanoscale zero valent iron material and thermo-response of the copolymers, and were utilized to investigate the adsorption capacity for typical phenols such as bisphenol A, phenol and hydroquinone from water samples, and the results showed that the magnetic and thermo dual-responsive core-shell nanomaterial exhibited good adsorption ability to typical phenols. Based on these, a sensitive method was developed for the determination of bisphenol A, phenol and hydroquinone using as-prepared magnetic nanoparticles as the magnetic solid phase extraction sorbent prior to high performance liquid chromatography coupled with variable wavelength detection. Under the optimal conditions, linear linearity was obtained over the range of 0.1-500 µg L-1 with the correlation coefficients (r2) above 0.996. The detection limits of three analytes were in the range of 0.019-0.031 µg L-1, and the precisions were all less than 4.8% (n = 6). The developed method was evaluated with real water samples and excellent spiked recoveries in the range of 94.0-105.4% were achieved. These results indicated that the proposed method was a robust analytical tool and a useful alternative for routine analysis of such pollutants.


Assuntos
Compostos Benzidrílicos/isolamento & purificação , Hidroquinonas/isolamento & purificação , Magnetismo , Nanoestruturas/química , Fenol/isolamento & purificação , Fenóis/isolamento & purificação , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/isolamento & purificação , Compostos Benzidrílicos/análise , Hidroquinonas/análise , Fenol/análise , Fenóis/análise , Temperatura Ambiente , Poluentes Químicos da Água/análise
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