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1.
Harmful Algae ; 117: 102262, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35944948

RESUMO

One of the main symptoms of eutrophication is the proliferation of phytoplankton biomass, including nuisance cyanobacteria. Reduction of the external nutrient load is essential to control eutrophication, and in-lake interventions are suggested for mitigating cyanobacterial blooms to accelerate ecosystem recovery. Floc & Sink (F&S) is one such intervention technique that consists of applying a low dose of coagulants in combination with ballasts for removing cyanobacteria biomass. It is especially suitable for deep lakes with an external nutrient load that is higher than the internal load and suffers from perennial cyanobacterial bloom events. Studies showing the efficacy of the F&S technique have been published, but those testing its variation in efficacy with changes in the environmental conditions are still scarce. Therefore, we evaluated the efficiency of the F&S technique to remove cyanobacteria from water samples collected monthly from two different sites in a deep tropical reservoir (Funil Reservoir, Brazil) in the laboratory. We tested the efficacy of two coagulants, chitosan (CHI) and poly-aluminum chloride (PAC), alone and in combination with lanthanum-modified bentonite (LMB) in settling phytoplankton biomass. We hypothesized that: ⅰ) the combined treatments are more effective in removing the algal biomass and ⅱ) the efficiency of F&S treatments varies spatially and monthly due to changes in environmental conditions. The combined treatments (PAC + LMB or CHI + LMB) removed up to seven times more biomass than single treatments (PAC, CHI, or LMB). Only the treatments CHI and LMB + CHI differed in efficiency between the sites, although all treatments showed significant variation in efficiency over the months at both the sampling sites. The combined treatments exhibited lower removal efficacy during the warm-rainy months (October-March) than during the mild-cold dry months (April-September). At high pH (pH > 10), the efficiency of the CHI and LMB + CHI treatments decreased. CHI had lower removal efficiency when single-cell cyanobacteria were abundant, while the combined treatments were equally efficient regardless of the morphology of the cyanobacteria. Hence, the combination of PAC as a coagulant with a ballast LMB is the most effective technique to precipitate cyanobacteria under the conditions that are encountered around the year in this tropical reservoir.


Assuntos
Cianobactérias , Ecossistema , Bentonita/farmacologia , Eutrofização , Lagos , Fitoplâncton
2.
Molecules ; 27(15)2022 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-35956974

RESUMO

In this study, for the first time, a composite fluff pulp was produced based on the combination of softwood (i.e., long-length fiber), hardwood (i.e., short-length fiber), non-wooden pulps (i.e., bagasse) and bentonite, with specific amounts to be used in hygienic pads (e.g., baby diapers and sanitary napkins). After the defibration process, the manufactured fluff pulp was placed as an absorbent mass in diapers and sanitary napkins. Therefore, tests related to the fluff pulp, such as grammage, thickness, density, ash content, humidity percentage, pH and brightness, tests related to the manufactured baby diapers, such as absorption capacity, retention rate, retention capacity, absorption time and rewet, and tests related to the sanitary napkin, such as absorption capacity and rewet, were performed according to the related standards. The results demonstrated that increasing the amount of bagasse pulp led to increasing the ash content, pH and density of fluff pulp and decreasing the brightness. The addition of bentonite as a filler also increased ash content and pH of fluff pulp. The results also demonstrated that increasing of bagasse pulp up to 30% in combination with softwood pulp led to increasing absorption capacity, retention rate, retention capacity, absorption time and rewet of baby diapers and of sanitary napkins.


Assuntos
Bentonita , Pele , Humanos , Indústrias , Lactente
3.
Water Res ; 221: 118788, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35777320

RESUMO

After disasters, such as forest fires and oil spills, high levels of benzene (> 1 ppm) can be detected in the water, soil, and air surrounding the disaster site, which poses a significant health risk to human, animal, and plant populations in the area. While remediation methods with activated carbons have been employed, these strategies are limited in their effectiveness due to benzene's inherent stability and limited retention to most surfaces. To address this problem, calcium and sodium montmorillonite clays were amended with a mixture of chlorophyll (a) and (b); their binding profile and ability to detoxify benzene were characterized using in vitro, in silico, and well-established ecotoxicological (ecotox) bioassay methods. The results of in vitro isothermal analyses indicated that chlorophyll-amended clays showed an improved binding profile in terms of an increased binding affinity (Kf = 668 vs 67), increased binding percentage (52% vs 11%), and decreased rates of desorption (28% vs 100%), compared to the parent clay. In silico simulation studies elucidated the adsorption mechanism and validated that the addition of the chlorophyll to the clays increased the adsorption of benzene through Van der Waals forces (i.e., aromatic π-π stacking and alkyl-π interactions). The sorbents were also assessed for their safety and ability to protect sensitive ecotox organisms (Lemna minor and Caenorhabditis elegans) from the toxicity of benzene. The inclusion of chlorophyll-amended clays in the culture medium significantly reduced benzene toxicity to both organisms, protecting C. elegans by 98-100% from benzene-induced mortality and enhancing the growth rates of L. minor. Isothermal analyses, in silico modeling, and independent bioassays all validated our proof of concept that benzene can be sequestered, tightly bound, and stabilized by chlorophyll-amended montmorillonite clays. These novel sorbents can be utilized during disasters and emergencies to decrease unintentional exposures from contaminated water, soil, and air.


Assuntos
Bentonita , Benzeno , Adsorção , Silicatos de Alumínio , Animais , Bentonita/química , Caenorhabditis elegans , Clorofila , Argila/química , Humanos , Solo , Água/química
4.
Langmuir ; 38(30): 9186-9194, 2022 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-35855632

RESUMO

The spike (S) protein of SARS-CoV-2 has been found to play a decisive role in the cell entry mechanism of the virus and has been the prime target of most vaccine development efforts. Although numerous vaccines are already in use and more than half of the world population has been fully vaccinated, the emergence of new variants of the virus poses a challenge to the existing vaccines. Hence, developing an effective drug therapy is a crucial step in ending the pandemic. Nanoparticles can play a crucial role as a drug or a drug carrier and help tackle the pandemic effectively. Here, we performed explicit all-atom molecular dynamics simulations to probe interactions between S protein and Montmorillonite (MMT) nano clay surface. We built two systems with different counterions (Na+ and Ca2+), namely Na-MMT and Ca-MMT, to investigate the effect of different ions on S protein-MMT interaction. Structural modification of S protein was observed in the presence of MMT surface, particularly the loss of helical content of S protein. We revealed that electrostatic and hydrophobic interactions synergistically govern the S protein-MMT interactions. However, hydrophobic interactions were more pronounced in the Na-MMT system than in Ca-MMT. We also revealed residues and glycans of S protein closely interacting with the MMT surface. Interestingly, N165 and N343, which we found to be closely interacting with MMT in our simulations, also have a critical role in cell entry and in thwarting the cell's immune response in recent studies. Overall, our work provides atomistic insights into S protein-MMT interaction and enriches our understanding of the nanoparticle-S protein interaction mechanism, which will help develop advanced therapeutic techniques in the future.


Assuntos
COVID-19 , Glicoproteína da Espícula de Coronavírus , Bentonita/química , Humanos , Íons , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus/metabolismo
5.
Biomed Res Int ; 2022: 4264466, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35880032

RESUMO

The impact of individual component, i.e., plant extract (Plagiochasma rupestre), biosynthesized silver nanoparticles (AgNPs), and healing clay (bentonite) as antimicrobial agent is reported but their combined effect as a ternary system is a new approach. This study is aimed at investigating the impact of the proposed ternary system against selected human pathogens. AgNPs were synthesized by using Plagiochasma rupestre extract (aqueous) as reducing agent and neutral polymer (PVP) as stabilizer. The morphology, size, and structural properties of synthesized AgNPs were determined with XRD and SEM analysis which showed spherical monomodal particles with an average particle size of 25.5 nm. The antibacterial and antifungal activities of the individual and nanoternary system were investigated. The phytochemical screening of plant extract showed the presence of alkaloids, flavonoids, phenol, and glycosides in methanol extract as compare to aqueous and acetone extract. The antimicrobial activities of crude extracts of Plagiochasma rupestre with AgNPs and bentonite clay were studied as an appropriate candidate for treatment of microbial infections, especially bacterial and fungal diseases. The antioxidant activity of Plagiochasma rupestre aqueous extract and nanoparticles was assessed by (DPPH) free radical, and absorbance was checked at 517 nm. Crude extract has inhibitory effect towards bacteria and fungi, and bentonite clay also showed some degree of antimicrobial resistance. Strategy can be efficiently applied for future engineering and medical. The nanoternary systems showed 3 and 3.5 times higher antibacterial and antifungal activity, respectively, in comparison to Plagiochasma rupestre and bentonite clay, individually.


Assuntos
Anti-Infecciosos , Nanopartículas Metálicas , Antibacterianos/química , Antibacterianos/farmacologia , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Antifúngicos/farmacologia , Bactérias , Bentonita/farmacologia , Argila , Humanos , Nanopartículas Metálicas/química , Testes de Sensibilidade Microbiana , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Prata/química , Prata/farmacologia
6.
Toxins (Basel) ; 14(7)2022 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-35878173

RESUMO

Aflatoxin B1 (AFB1) is a major food safety concern, threatening the health of humans and animals. Bentonite (BEN) is an aluminosilicate clay used as a feed additive to reduce AFB1 presence in contaminated feedstuff. So far, few studies have characterized BEN toxicity and efficacy in vitro. In this study, cytotoxicity (WST-1 test), the effects on cell permeability (trans-epithelial electrical resistance and lucifer yellow dye incorporation), and transcriptional changes (RNA-seq) caused by BEN, AFB1 and their combination (AFB1 + BEN) were investigated in Caco-2 cells. Up to 0.1 mg/mL, BEN did not affect cell viability and permeability, but it reduced AFB1 cytotoxicity; however, at higher concentrations, BEN was cytotoxic. As to RNA-seq, 0.1 mg/mL BEN did not show effects on cell transcriptome, confirming that the interaction between BEN and AFB1 occurs in the medium. Data from AFB1 and AFB1 + BEN suggested AFB1 provoked most of the transcriptional changes, whereas BEN was preventive. The most interesting AFB1-targeted pathways for which BEN was effective were cell integrity, xenobiotic metabolism and transporters, basal metabolism, inflammation and immune response, p53 biological network, apoptosis and carcinogenesis. To our knowledge, this is the first study assessing the in vitro toxicity and whole-transcriptomic effects of BEN, alone or in the presence of AFB1.


Assuntos
Aflatoxina B1 , Bentonita , Aflatoxina B1/metabolismo , Ração Animal/análise , Animais , Bentonita/metabolismo , Bentonita/toxicidade , Células CACO-2 , Enterócitos/metabolismo , Humanos , Transcriptoma
7.
Sci Rep ; 12(1): 9930, 2022 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-35705670

RESUMO

Cryogenic electron microscopy became a powerful tool to study biological objects. For non-biological objects (solutions, gels, dispersions, clays), the polemic about interpretation of cryogenic microscopy results is still in progress splitting on two contradictive trends: considering structure as a near-real state of the sample or as freezing artefacts. In this study, a microstructure of a range of stable aqueous solutions and dispersions (agar, kaolin, montmorillonite, nanoparticles) was investigated by means of cryo-SEM and confocal LSM in order to compare cryo-fixed and unfrozen structures. Noticed correlation between these two methods for studied systems (agar, kaolin, montmorillonite, NPs) allowed to state that ordered microstructure is an inherent feature of these systems. Some inconsistencies in microstructure dimensions were discussed and prescribed to the differences in the bulk and interface layers. Supposedly, NaCl solutions also possess dynamic (femtosecond level) microstructure of neat water clusters and solvated Na+ and Cl- ions that may have an impact on electrolyte abnormal properties.


Assuntos
Caulim , Nanopartículas , Ágar , Bentonita , Argila , Géis , Íons , Nanopartículas/química , Água/química
8.
Sci Rep ; 12(1): 10259, 2022 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-35715426

RESUMO

This in vitro study synthetized hybrid composite nanoparticles of graphene oxide (GO) and montmorillonite MMt (GO-MMt) by ultrasound treatments. Samples were characterized by X-ray diffraction, FT-Raman, FTIR, TEM and SEM. The effect of their incorporation (0.3% and 0.5%) on the mechanical properties in a resin-based composite (RBC) and their bioactivity potential were evaluated. The specimens were characterized by evaluating their 3-point flexural strength (n = 6), modulus of elasticity (n = 6), degree of conversion (n = 6), microhardness (n = 6), contact angle (n = 3) and SEM analysis (n = 3). In vitro test in SBF were conducted in the RBCs modified by the hybrid. Overall, the synthetized hybrid composite demonstrated that GO was intercalated with MMt, showing a more stable compound. ANOVA and Tukey test showed that RBC + 0.3% GO-MMt demonstrated superior values of flexural strength, followed by RBC + 0.5% GO-MMt (p < 0.05) and both materials showed higher values of microhardness. All groups presented a contact angle below 90°, characterizing hydrophilic materials. RBCs modified by the hybrid showed Ca and P deposition after 14 days in SBF. In conclusion, RBCs composed by the hybrid showed promising results in terms of mechanical properties and bioactive potential, extending the application of GO in dental materials.


Assuntos
Bentonita , Grafite , Resinas Compostas , Grafite/farmacologia , Teste de Materiais , Propriedades de Superfície
9.
Molecules ; 27(11)2022 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-35684417

RESUMO

To improve the phenolic extraction and color stability of red wine made from cold-hardy grapes, two winemaking practices, saignée and bentonite, were applied separately and in combination on Marquette grapes at crushing. The effects of these winemaking strategies on Marquette wine's basic chemical properties, monomeric and polymeric phenolic compounds were studied, as well as the development of color characteristics from crushing to 5 months of aging. The saignée (9% juice run-off) treatment showed little impact on the phenolic content of the finished wine, but showed an increase in color intensity. A hue shift towards an orange-yellow tone was observed in the bentonite-treated wines, which was associated with a loss of monomeric anthocyanins. The combination of saignée and bentonite showed less impact on removing anthocyanins and wine color, and increased phenolics content, therefore improving the extraction of non-anthocyanins monomeric phenolics. Although this combination treatment led to the highest concentration of tannin content after pressing, this difference between the control and other treatments disappeared over time. These results suggested that the interactions between tannins and other wine compounds still occur after removing proteins in Marquette wines.


Assuntos
Vitis , Vinho , Antocianinas/química , Bentonita , Cor , Frutas/química , Fenóis/análise , Taninos/química , Vitis/química , Vinho/análise
10.
Eur J Pharm Sci ; 175: 106222, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35649471

RESUMO

The drug delivery systems are an important strategy of pharmaceutical technology to modulate undesirable properties, increasing efficacy, and reducing the side effects of active pharmaceutical ingredients (API). The sustained release is a type of controlled-release system that provides a suitable drug level in the blood through a slow release rate. An interesting alternative to achieve a controlled release is the application of carrier materials such as polymers, cyclodextrins, and clays. Sodium montmorillonite (Na-MMT) is a biocompatible natural clay that allows the insertion of organic compounds in interlamellar space, owing to its high cation exchange capacity and large internal surface area. Bromopride (BPD) is an aminated compound with antiemetic properties classified as class II (low solubility, high permeability) of the Biopharmaceutical Classification System (BCS). Herein, the aim of the study was the development and investigation of a drug delivery system formed by intercalation of BPD with Na-MMT. The results indicate the successful intercalation of this API with the lamellar silicate, meanwhile, there was no evidence of BPD intercalation in organic montmorillonite. The Na-MMT/BPD molecular complex exhibits a sustained release in performed assays. Molecular dynamics simulations suggested that BPD molecules interact with the montmorillonite layer through ion-dipole interactions and also between BPD molecules, forming hydrogen bonds web into montmorillonite interlayer space. The new drug delivery system showed an alternative to achieve the BPD sustained release, which may improve its pharmacological performance in therapeutic applications.


Assuntos
Bentonita , Metoclopramida , Bentonita/química , Argila , Preparações de Ação Retardada , Metoclopramida/análogos & derivados
11.
Int J Biol Macromol ; 213: 123-133, 2022 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-35643153

RESUMO

To promote the controlled release efficacy of nanocomposites based on alginate and bentonite, (3-chloro-2-hydroxypropyl)trimethyl ammonium grafted starch was prepared and used as modifying agent of the clay. The nanocomposites were characterized by FTIR, XRD, SEM and TG analysis, to reveal the structural effects on the swelling property of the matrix and the release of alachlor, the model compound. Thermodynamics study indicated that the adsorption of alachlor on the bentonite was dominated by hydrophobic interaction with the siloxane surface of the clay and enhanced by the binding of the cationic starch. The electrostatic attraction between alginate and cationic starch bound on the surface also decreased the aggregation of bentonite platelets, leading to a more compact structure of the nanocomposites. The higher adsorption capability and lower permeability of the matrix resulted in a slower release of alachlor, which was dominated by Fickian diffusion mechanism. The release of alachlor first decreased and then increased with increasing content of bentonite and cationic starch modified bentonite in the nanocomposites, reaching a minimum around weight percentage 10%, at which the time taken for 50% of active ingredient to be released were 4.4 and 7.3 times that for the release from pure alginate hydrogel.


Assuntos
Nanocompostos , Praguicidas , Adsorção , Alginatos/química , Bentonita/química , Argila , Nanocompostos/química , Amido
12.
Environ Res ; 213: 113633, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35700766

RESUMO

The bentonite colloid produced in the deep geological repository of high-level radioactive waste can directly affect the migration of radionuclide strontium when it acts on claystone. The adsorption characteristics of strontium were investigated on claystone with the presence or absence of bentonite colloids from the Suhongtu area of China. The effects of different influencing factors, such as pH and solid content, on the adsorption process were investigated by batch adsorption experiments, and spectroscopic techniques were used to characterize the samples before and after adsorption of strontium. The results show that the presence of bentonite colloids can promote the adsorption of strontium on claystone under alkaline conditions. and the general order kinetic model provided the best fit to the experimental data. Strontium is adsorbed on the surface of claystone and bentonite colloid by ion exchange and surface complexation. Most of the Sr2+ formed SrCO3 with CO32- after ion exchange with Ca2+ and Mg2+ in plagioclase and dolomite, and a small amount of Sr2+ was adsorbed by complexation with -OH, Al-O and Si-O. These results provide a scientific basis for predicting the migration of strontium in subsurface porous media and the siting of high-level radioactive waste repositories.


Assuntos
Resíduos Radioativos , Adsorção , Bentonita/química , Coloides/química , Resíduos Radioativos/análise , Estrôncio/química
13.
Bioresour Technol ; 360: 127519, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35760244

RESUMO

This study systematically evaluated the effects of bentonite as a possible additive to alleviate the "inhibited steady-state" induced by ammonia and acid accumulation during anaerobic digestion. Continuous stirred tank reactors fed with poultry manure were operated at 35 ± 1 °C either with bentonite or not. The results demonstrate that bentonite amendment increased average specific methane production by 35% as suffered from steady-state at an organic loading rate of 6.25 g VS/L·d. 16S rRNA gene amplicon sequencing revealed that the relative abundance of electron-donating Sedimentibacter and Syntrophomonas, and electrophilic Methanosarcina was increased by 110%, 91%, and 49%, respectively. The genera were identified as crucial for alleviating "inhibited steady-state", through establishment of a more robust syntrophic pathway of methanogenic acetate degradation. The enhancement might result from the accelerated electron transfer by bentonite, which is qualified for serving as an exogenetic electron mediator due to containing abundant redox-active metal elements.


Assuntos
Esterco , Aves Domésticas , Anaerobiose , Animais , Bentonita , Reatores Biológicos , Metano/metabolismo , Aves Domésticas/genética , Aves Domésticas/metabolismo , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo
14.
Environ Res ; 213: 113724, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35732201

RESUMO

Thermal and flame-retardant properties of traditional composites have limitations that are not satisfied for the various applications. Multilayered materials have great potential to improve material properties. The present paper focused on designing new multilayering approach to fabricate flame retardant multilayered materials with a very basic instrument and several simple steps. Montmorillonite nanoparticles filled maleic anhydride grafted polypropylene composites were prepared by the melt-blending method, and the multilayered composites with polypropylene alternating multilayers were fabricated by the quadruple-layering approach. The multilayer structure was characterized by the scanning electron microscopy/energy dispersive spectrometer. The influence of layer structure on the thermal stability, thermal conductivity and flame-retardant properties was investigated by the comparison with the conventional composites. Multilayered composites showed enhanced flame-retardant properties with lower peak heat release rate and better char formation compared to conventional composites with the same mass fraction of montmorillonite. Multilayered composites had higher mass fraction of montmorillonite in filled layers and no fillers in other layers, which caused the unequal distribution of montmorillonite, resulting in changes of thermal and flame-retardant properties of the materials especially in the perpendicular direction to the film surface. This study demonstrates a unique multilayering approach that has potential to be used in variety applications such as food and medical packaging.


Assuntos
Retardadores de Chama , Bentonita , Temperatura Alta , Microscopia Eletrônica de Varredura , Polipropilenos
15.
J Hazard Mater ; 437: 129295, 2022 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-35717817

RESUMO

Pyrolytic treatment of crude-oil contaminated soils offers great potential for rapid remediation without destroying soil fertility with lower energy requirements than incineration. Here, we show that clays impregnated with non-toxic transition metals (iron or copper) can be used as an amendment to decrease the required pyrolytic treatment temperature and time. Amending a weathered crude-oil contaminated soil with 10 % (by weight) of bentonite modified via ion-exchange with Fe or Cu, achieved 99 % removal of residual total petroleum hydrocarbons (TPH) at a pyrolysis temperature of 370 °C with 15-min contact time. Pyrolytic treatment of amended soils at the unprecedentedly low pyrolysis temperature of 300 °C resulted in 87 % TPH removal efficiency with Cu-bentonite and a 93 % with Fe-bentonite. We postulate that the transition metals catalyzed the pyrolysis reactions at lower onset temperatures. This hypothesis is supported by thermogravimetric analysis coupled with mass spectrometry, which revealed the release of hydrogen, methyl and propyl ion fragments (markers of pyrolytic degradation products of crude oil) at lower temperatures than those observed for unamended soil. Overall, this work shows proof of concept that metal-impregnated clays can enhance rapid pyro-catalytic treatment of crude-oil contaminated soils and encourages further work to understand the detailed reaction mechanisms and inform process design.


Assuntos
Petróleo , Poluentes do Solo , Bentonita , Biodegradação Ambiental , Catálise , Argila , Hidrocarbonetos/química , Petróleo/metabolismo , Pirólise , Solo/química , Microbiologia do Solo , Poluentes do Solo/metabolismo
16.
J Hazard Mater ; 437: 129366, 2022 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-35728313

RESUMO

Contact with trace heavy metal contaminants will also lead to extremely bad health influence on human body and aquatic life. Although various adsorbents have been synthesized for the recovery of heavy metal ions, most of them shows deficient adsorption capacity, sluggish uptake rate and low selectivity. In this study, a montmorillonite/polypyrrole (MMT/PPy) film was successfully synthesized by intercalating polymers PPy into the interlayer of MMT nanosheets for selective and rapid capture of Pb2+. The electroactive film has ultrahigh uptake capacity (1373.29 mg⋅g-1), which is much higher than most conventional Pb2+ adsorbents. Meanwhile, it had an extreme selectivity towards Pb2+ due to the MMT/PPy film can accurately identified Pb2+. Through characterization testing and data analysis, the selective and rapid uptake/release of Pb2+ should be realized through three ways: (1) negatively-charged laminates of MMT can generate electrostatic attraction to Pb2+; (2) -OH on the surface of MMT laminates can accurately identified and bonded with Pb2+ (M-O-H↔ M-O-Pb); (3) PPy doped by PSSn- and protic acid can rapidly catch Pb2+ (PPy+·PSSn-+Pb2++e-→ PPy·PSSn-·Pb2+). Therefore, such a novel MMT/PPy nanocomposite film could has evident application prospect to remove Pb2+ from various water bodies.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Adsorção , Bentonita , Humanos , Troca Iônica , Íons , Chumbo , Polímeros , Pirróis , Poluentes Químicos da Água/análise
17.
Nat Commun ; 13(1): 3408, 2022 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-35729107

RESUMO

Ionic conductive hydrogels prepared from naturally abundant cellulose are ideal candidates for constructing flexible electronics from the perspective of commercialization and environmental sustainability. However, cellulosic hydrogels featuring both high mechanical strength and ionic conductivity remain extremely challenging to achieve because the ionic charge carriers tend to destroy the hydrogen-bonding network among cellulose. Here we propose a supramolecular engineering strategy to boost the mechanical performance and ionic conductivity of cellulosic hydrogels by incorporating bentonite (BT) via the strong cellulose-BT coordination interaction and the ion regulation capability of the nanoconfined cellulose-BT intercalated nanostructure. A strong (compressive strength up to 3.2 MPa), tough (fracture energy up to 0.45 MJ m-3), yet highly ionic conductive and freezing tolerant (high ionic conductivities of 89.9 and 25.8 mS cm-1 at 25 and -20 °C, respectively) all-natural cellulose-BT hydrogel is successfully realized. These findings open up new perspectives for the design of cellulosic hydrogels and beyond.


Assuntos
Celulose , Hidrogéis , Bentonita , Condutividade Elétrica , Congelamento , Hidrogéis/química , Íons/química
18.
Sci Total Environ ; 840: 156577, 2022 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-35688243

RESUMO

Fe(III) may be reasonably considered as one of the most important electron acceptors in petroleum reservoir ecosystems. The microbial mineralization of clay minerals, especially montmorillonite, is also of great significance to the exploration of petroleum and gas reservoirs. The bioreduction mechanisms of iron-poor minerals in petroleum reservoirs have been poorly investigated. This study investigated the bioreduction of montmorillonite by dissimilatory iron-reducing bacteria (DIRB) in petroleum reservoirs based on culture-independent and culture-dependent methods. Microbial diversity analysis revealed that Halolactibacillus, Bacillus, Alkaliphilus, Shewanella, Clostridium, and Pseudomonas were the key genera involved in the bioreduction of Fe(III). Through the traditional culture-dependent method, most of the key genera were isolated from the samples collected from petroleum reservoirs. Traditional culture-dependent methods can be used to reveal the metabolic characteristics of microorganisms (such as iron-reduction efficiency) to further elucidate the roles of different species (B. subtilis and B. alkalitelluris) in the environment. Moreover, many species with high iron-reduction efficiencies and relatively low abundances in the samples, such as Tessaracoccus and Flaviflexus, were isolated from petroleum reservoirs for the first time. The combination of culture-dependent and culture-independent methods can be used to further the understanding of the microbial communities and the metabolic characteristics of DIRB in petroleum reservoirs. Structural alterations that occurred during the interactions of microorganisms and montmorillonite were revealed through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD). The physical and chemical analysis results demonstrated that microorganisms from petroleum reservoirs can dissolve iron-poor montmorillonite and promote the release of interlayer water. The secondary minerals illite and clinoptilolite were observed in bioreduced smectite. The formation of secondary minerals was closely related to the dissolution degrees of minerals based on iron reduction.


Assuntos
Petróleo , Shewanella , Bentonita , Argila , Ecossistema , Compostos Férricos/química , Ferro/química , Minerais/metabolismo , Campos de Petróleo e Gás , Oxirredução , Petróleo/metabolismo , Shewanella/metabolismo
19.
Sci Rep ; 12(1): 8716, 2022 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-35610357

RESUMO

The use of inorganic binder for briquetting of subbituminous coal and torrefied biomass for energy generation is scarce. The present study focuses on the physicomechanical durability and energy content of briquettes produced from subbituminous coal (SubC) and torrefied biomass (TM) using bentonite as binder. Briquettes were produced using 95% SubC and 5% TM. Bentonite was varied at 2-10% of the total SubC and TM weight. The briquettes were produced with a constant pressure (28 MPa) in a hydraulic press. The briquettes were primarily cured at room temperature and then at 300 [Formula: see text] in a tubular furnace under an inert condition for 60 min. The density and water resistance (WRI) of the briquettes were evaluated. Drop to fracture (DF), impact resistance index (IRI), cold crushing strength (CCS) and tumbling strength index (TSI+3 mm) of the briquette were obtained. The reactivity index (RI), proximate, ultimate and calorific values analyses were assessed based on different ASTM standards. Microstructural studies and elemental mapping were carried out using scanning electron microscope equipped with EDS and electron probe microanalyzer. The density increased with increment in bentonite content. The WRI decreased with increase in bentonite while the least (95.21%) was obtained at 10% binder content. The DF and IRI ranges from 100 to 150 and 2000-3000, respectively. The CCS were in the range of 19.71 to 40.23 MPa. The RI varies from 34 to 50%. Fixed carbon, carbon and calorific values were impaired as the bentonite content in the briquette increases. Oxygen and silica bridges with mechanical interlocking were observed on the micrographs of the briquettes. The briquettes produced with 2% bentonite content have better physicomechanical durability with equivalent energy content. It is recommended as feedstock for thermal and metallurgical applications.


Assuntos
Bentonita , Carvão Mineral , Biomassa , Carbono , Água
20.
Sci Rep ; 12(1): 8412, 2022 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-35589942

RESUMO

A sol-gel method was utilized to prepare a novel nanocomposite adsorbent (nMgO/bentonite) and was tested for Pb(II) removal from aqueous solutions. The produced nanocomposite was investigated using, SEM-EDX, XRD, and FTIR analyses before and after Pb adsorption. Adsorption equilibrium and kinetic experiments were run in batch system under different conditions of pH, adsorbent dose, competitive cations, contact time and temperature. The results exhibited rapid Pb(II) adsorption by the nanocomposite in the first five min. Experimental lead adsorption equilibrium and kinetics data fitted well to Langmuir and power function models, respectively as indicated from the lowest standard error (SE) values. The calculated Langmuir maximum adsorption capacity (qmax) value of nanocomposite (75 mg g-1) was 4.5 times higher than that of bentonite (16.66 mg g-1). Moreover, the highest quantity of Pb(II) uptake was achieved at temperature of 307 K and pH 9. The Langmuir sorption capacity of the nanocomposite for Pb(II) increased from 75 to 145 mg g-1 with increasing temperature from 287 to 307 K. The thermodynamic parameters of Pb(II) adsorption by the nanocomposite affirm the spontaneous and endothermic nature of the adsorption process. Lead adsorption mechanisms by the nanocomposite were proposed and discussed.


Assuntos
Nanocompostos , Poluentes Químicos da Água , Adsorção , Bentonita , Concentração de Íons de Hidrogênio , Cinética , Chumbo/análise , Termodinâmica , Águas Residuárias/análise , Poluentes Químicos da Água/análise
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