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2.
Surg Neurol Int ; 15: 179, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38840593

RESUMO

Background: Colloid cysts are intracranial lesions originating from abnormalities in the primitive neuroepithelium folding of the third ventricle. Various surgical approaches have been explored for the management of colloid cysts, each carrying its own set of advantages and limitations. Tubular retractors developed recently alleviate retraction pressure through radial distribution, potentially offering benefits for colloid cyst resection. This study aims to introduce and assess a modified microsurgical method utilizing the tubular retractor for addressing colloid cysts. Methods: The study included a retrospective assessment of patients who had colloid cysts and who were treated between 2015 and 2023 by one experienced surgeon. The demographic, clinical, radiological, histological, and surgical data regarding these patients were evaluated. The patients were assessed using the colloid cyst risk score, indicating a risk for obstructive hydrocephalus. Results: The minimally invasive microsurgical approach was successfully applied to all 22 identified patients. No postoperative surgical complications were reported. Gross total resection was achieved in 21 (95.5%) patients. The early complication rate was 22.7% (n = 5). There were no postoperative seizures, permanent neurological deficits, or venous injuries. The average hospital stay was 3 days. There was no evidence of recurrence at an average follow-up length of 25.9 months. Conclusion: The transtubular approach is an effective, safe method for treating colloid cysts. It achieves complete cyst removal with minimal complications, offering the benefits of less invasiveness, improved visualization, and reduced tissue disruption, strengthening its role in colloid cyst surgery.

3.
Small ; : e2402920, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38864391

RESUMO

The controlled self-assembly of nanomaterials has been a great challenge in nanosynthesis, especially for hierarchical architectures with high complexity. Particularly, the structural design of Prussian blue (PB) series materials with robustness and fast nucleation is even more difficult. Herein, a self-sustained-release strategy based on the slow release of metal ions from coordination ions is proposed to guide the assembly of PB crystals. The key to this strategy is the slow release by ligand, which can create ultra-low concentrations of metal ions so as to provide the possibility to realize the surface charge manipulation of PB primary colloids. By adding electrolyte or changing the polarity of the solution, the surface charge regulation of PB colloid is realized, and the PB hierarchical structures with branch fractal structure (PB-BS), octahedral fractal structure, and spherical fractal structure are effectively constructed. This work not only achieves the designability of the PB structure, but also synchronizes the functionalization during the PB assembly growth process by in situ encapsulation of the effective catalytic active component L-Ascorbic acid. As a result, the assembled PB-BS exhibits greatly enhanced catalytic activity and selectivity in styrene oxidation with the selectivity of oxidized styrene increasing from 35.6% (PB) to 80.5% (PB-BS).

4.
Sci Total Environ ; 946: 174147, 2024 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-38909800

RESUMO

Environmental behaviors of heavy metal in soil are strongly influenced by seasonal freeze-thaw events at the mid-high altitudes. However, the potential impact mechanisms of freeze-thaw cycles on the vertical migration of heavy metal are still poor understood. This study aimed to explore how exogenous cadmium (Cd) migrated and remained in soil during the in-situ seasonal freeze-thaw action using rare earth elements (REEs) as tracers. As a comparison, soil which was incubated in the controlled laboratory (25 °C) was employed. Although there was no statistically significant difference in the Cd levels of different soil depths under different treatments, the original aggregate sources of Cd in the 5-10 cm and 10-15 cm soil layers differed. From the distributions of REEs in soil profile, it can be known that Cd in the subsurface of field incubated soil was mainly from the breakdown of >0.50 mm aggregates, while it was mainly from the <0.106 mm aggregates for the laboratory incubated soil. Furthermore, the dissolved and colloidal Cd concentrations were 0.47 µg L-1 and 0.62 µg L-1 in the leachates from field incubated soil than those from control soil (0.21 µg L-1 and 0.43 µg L-1). Additionally, the colloid-associated Cd in the leachate under field condition was mainly from the breakdown of >0.25 mm aggregates and the direct migration of <0.106 mm aggregates, while it was the breakdown of >0.50 mm and the direct migration of <0.106 mm aggregates for the soil under laboratory condition. Our results for the first time provided insights into the fate of exogenous contaminants in seasonal frozen regions using the rare earth element tracing method.

5.
Carbohydr Polym ; 340: 122244, 2024 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-38858017

RESUMO

This study introduces a novel multi-functional double-layer intelligent packaging. It focuses on developing a dual-function system capable of real-time monitoring and freshness preservation. Specifically, cellulose nanocrystalline (CNC) was obtained through acid hydrolysis, and then CNC/soybean protein isolate (CNC/SPI) complex colloid particles were prepared via antisolvent method. These particles served as stabilizers to prepare oil-in-water (O/W) cinnamon essential oil Pickering emulsion (CSCEO). The CSCEO was then integrated into the emulsified hydrophobic layer of a konjac glucomannan (Kgm) matrix through intermolecular hydrogen bonding. Finally, alginate (Alg) matrix containing alizarin (Al) as an indicator was added to construct the bilayer structure using a layer-by-layer casting strategy. The inner layer Alg/Al was the pH/NH3-responsive indicator layer, while the outer layer Kgm/CSCEO acted as the high-barrier bacteriostatic layer. The obtained dual-function, double-layer film (Alg/Al-Kgm/CSCEO), which possesses a sensitive, reversible and rapid response towards pH/NH3, shows exceptional antibacterial and antioxidant properties, as well as excellent mechanical property, light-blocking capability and hydrophobicity. For monitoring and maintaining the actual freshness of shrimp, such a bilayer packaging displays smallest change of ∆E and TVB-N (18.65 mg/100 g) even after 72 h, which further highlighting its potential in enhancing food safety and extending shelf life.


Assuntos
Alginatos , Antibacterianos , Embalagem de Alimentos , Mananas , Alimentos Marinhos , Alginatos/química , Embalagem de Alimentos/métodos , Mananas/química , Antibacterianos/química , Animais , Antioxidantes/química , Conservação de Alimentos/métodos , Interações Hidrofóbicas e Hidrofílicas , Penaeidae/química , Proteínas de Soja/química , Concentração de Íons de Hidrogênio , Escherichia coli/efeitos dos fármacos
6.
Small ; : e2402531, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38727180

RESUMO

The efficacy of electron transport layers (ETLs) is pivotal for optimizing the device performance of perovskite photovoltaic applications. However, colloidal dispersions of SnO2 are prone to aggregation and possess structural defects, such as terminal-hydroxyls (OHT) and oxygen vacancies (VOs), which can degrade the quality of ETLs, impede charge extraction and transport, and affect the nucleation and growth processes of the perovskite layer. In this study, the Sb(OH)4 - ions hydrolyzed from SbCl3 in colloidal dispersion can bind to defect sites and effectively stabilize the SnO2 nanocrystals are demonstrated. Upon oxidative annealing, a Sb2O5@SnO2 composite film is formed, in which the Sb2O5 not only mitigates the aforementioned defects but also broadens the energy range of unoccupied states through its dispersed conduction band. The increased electron affinity (EA) facilitates more efficient capture of photoexcited electrons from the perovskite layer, thus augmenting electron extraction and minimizing electron-hole recombination. As a result, a significant improvement in power conversion efficiency (PCE) from 22.60% to 24.54% is achieved, with an open circuit voltage (VOC) of up to 1.195 V, along with excellent stability of unsealed devices under various conditions. This study provides valuable insights for the understanding and design of ETLs in perovskite photovoltaic applications.

7.
J Contam Hydrol ; 264: 104369, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38810412

RESUMO

A conceptual equilibrium-based mathematical model for colloid-associated contaminant transport has been developed to study the impact of the subsurface environment on contaminant transport through a three-dimensional, saturated, and homogeneous groundwater flow system with uniform flow. The kinetic model's critical limitation is dealing with the more significant number of parameters utilized upon application to larger scales in three-dimensional regions when a series of transport mechanisms are incorporated. Therefore, the present study is the first attempt to study the equilibrium approach in three-dimensional regions to avoid complexities in the model. The current study, however, shows that the mere existence of colloids does not indicate that contaminants will move more quickly; rather, it also depends on how the aqueous phase interacts with the static solid matrix, captured colloid particles, and mobile colloids as well as how colloids interact with stationary solid matrix phase. We noticed that the affinity of contaminants to immobile sorbents (stationary solid matrix and captured colloids) can reduce the transport even in the presence of colloids. Three-dimensional numerical experiments reveal that contaminants infiltrate more in the downward direction in the absence of colloids and can be distributed more in the longitudinal direction and less in the downward direction when colloids are present. The dual nature of colloids is espied here: first, colloids can remove pollutants from a specific area more quickly, and second, in a similar manner, colloids can pollute a specific region more quickly.


Assuntos
Coloides , Água Subterrânea , Modelos Teóricos , Movimentos da Água , Poluentes Químicos da Água , Coloides/química , Água Subterrânea/química , Adsorção , Poluentes Químicos da Água/química , Cinética , Modelos Químicos
8.
Adv Colloid Interface Sci ; 329: 103162, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38761601

RESUMO

This paper reviews the recent progress of small angle scattering (SAS) techniques, mainly including X-ray small angle scattering technique (SAXS) and neutron small angle scattering (SANS) technique, in the study of metal-organic framework (MOF) colloidal materials (CMOFs). First, we introduce the application research of SAXS technique in pristine MOFs materials, and review the studies on synthesis mechanism of MOF materials, the pore structures and fractal characteristics, as well as the spatial distribution and morphological evolution of foreign molecules in MOF composites and MOF-derived materials. Then, the applications of SANS technique in MOFs are summarized, with emphasis on SANS data processing method, structure modeling and quantitative structural information extraction. Finally, the characteristics and developments of SAS techniques are commented and prospected. It can be found that most studies on MOF materials with SAS techniques focus mainly on nanoporous structure characterization and the evolution of pore structures, or the spatial distribution of other foreign molecules loaded in MOFs. Indeed, SAS techniques take an irreplaceable role in revealing the structure and evolution of nanopores in CMOFs. We expect that this paper will help to understand the research status of SAS techniques on MOF materials and better to apply SAS techniques to conduct further research on MOF and related materials.

9.
Adv Sci (Weinh) ; 11(26): e2400147, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38704677

RESUMO

Crystallization of alloys from a molten state is a fundamental process underpinning metallurgy. Here the direct imaging of an intermetallic precipitation reaction at equilibrium in a liquid-metal environment is demonstrated. It is shown that the outer layers of a solidified intermetallic are surprisingly unstable to the depths of several nanometers, fluctuating between a crystalline and a liquid state. This effect, referred to herein as crystal interface liquefaction, is observed at remarkably low temperatures and results in highly unstable crystal interfaces at temperatures exceeding 200 K below the bulk melting point of the solid. In general, any liquefaction process would occur at or close to the formal melting point of a solid, thus differentiating the observed liquefaction phenomenon from other processes such as surface pre-melting or conventional bulk melting. Crystal interface liquefaction is observed in a variety of binary alloy systems and as such, the findings may impact the understanding of crystallization and solidification processes in metallic systems and alloys more generally.

11.
J Colloid Interface Sci ; 668: 599-606, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-38691968

RESUMO

HYPOTHESIS: The formation of soft colloidal crystals, which are nonclose-packed ordered arrays of colloidal particles suspended in a solvent, is dictated by a single physical factor that yields a fixed threshold at order-disorder boundaries for different experimental conditions such as ion concentration, solvent type, and particle size. Identifying the determinant factor and its threshold value should enable the prediction of the critical concentrations of colloidal particles to form soft colloidal crystals. EXPERIMENTS: Soft colloidal crystals were fabricated using a series of monohydric alcohols as dispersion media and reflectance spectra were measured to locate order-disorder boundaries. The interaction forces acting between particles were also measured by employing atomic force microscopy. FINDINGS: The interparticle forces at the order-disorder boundaries exhibited a universal threshold that was independent of the solvent types including alcohols and water. Therefore, the determinant factor for the formation of soft colloidal crystals was determined to be the force acting between the particles. Furthermore, a priori calculation of this critical force and consequently the critical particle concentration in colloidal systems was demonstrated by referring to the pressure at the liquid-to-solid transition in a hard sphere system (Alder transition).

12.
Materials (Basel) ; 17(9)2024 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-38730840

RESUMO

Attapulgite (APT) is widely used in wastewater treatment due to its exceptional adsorption and colloidal properties, as well as its cost-effectiveness and eco-friendliness. However, low-grade APT generally limits its performance. Here, a colloid mill-assisted ultrasonic-fractional centrifugal purification method was developed to refine low-grade APT. This process successfully separated and removed impurity minerals such as quartz and dolomite from the raw ore, resulting in a refined APT purity increase from 16.9% to 60% with a specific surface area of 135.5 m2∙g-1. Further modifying of the refined APT was carried out through the hydrothermal method using varying dosages of cetyltrimethylammonium chloride (CTAC), resulting in the production of four different APT adsorbents denoted as QAPT-n (n = CTAC mole number) ranging from 0.5 to 5 mmol. Using Congo red (CR) as the target pollutant, the QAPT-5 sample exhibited the best adsorption capacity with the maximum quantity of 1652.2 mg∙g-1 in a neutral solution at 30 °C due to the highest surface charge (zeta potential = 8.25 mV). Moreover, the QAPT-5 pellets (~2.0 g adsorbent) shaped by the alginate-assisted molding method removed more than 96% of 200 mL aqueous solution containing 200 mg∙L-1 CR and maintained this efficiency in 10 adsorption-elution cycles, which exhibited the promising practical application.

13.
Chemosphere ; 359: 142200, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38697565

RESUMO

Mg(OH)2 dissolves slowly and can provide a long-term source of alkalinity, thus a promising alternative reagent for the in situ remediation of heavy metal polluted groundwater. Unfortunately, it exhibits a relatively poor stabilization effect on heavy metal Cd due to the higher solubility of the resulting stabilized product, Cd(OH)2. To overcome this limitation, we investigated the use of MgCO3/Mg(OH)2 colloid modified by sodium polyacrylate (PAAS) to remove Cd from groundwater. Through ultrasonic dispersion, the molecular chains of PAAS are broken, causing a transformation from flocculation to surface modification, resulting in the production of a stable colloid. The colloidal particles of MgCO3/Mg(OH)2 have a smaller size and a negatively charged surface, which significantly enhances their migration ability in aquifers. The combination of MgCO3 and Mg(OH)2 provides a complementary effect, where MgCO3 effectively precipitates Cd in the aquifer while Mg(OH)2 maintains the required pH level for stabilization. The optimal compounding ratio of MgCO3 to Mg(OH)2 for achieving the best stabilization effect on Cd is found to be 1:1. Column experiments demonstrate that the injection of MgCO3/Mg(OH)2 colloid substantially enhances Cd stability, reducing the exchangeable fraction of Cd in aquifer media from 88.61% to a range of 22.50-34.38%. Based on these results, the MgCO3/Mg(OH)2 colloid shows great potential as a reactive medium for remediating Cd-contaminated groundwater.


Assuntos
Cádmio , Coloides , Recuperação e Remediação Ambiental , Água Subterrânea , Poluentes Químicos da Água , Água Subterrânea/química , Poluentes Químicos da Água/química , Cádmio/química , Coloides/química , Recuperação e Remediação Ambiental/métodos , Concentração de Íons de Hidrogênio , Floculação , Resinas Acrílicas/química
14.
Intensive Care Med ; 50(6): 813-831, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38771364

RESUMO

PURPOSE: This is the first of three parts of the clinical practice guideline from the European Society of Intensive Care Medicine (ESICM) on resuscitation fluids in adult critically ill patients. This part addresses fluid choice and the other two will separately address fluid amount and fluid removal. METHODS: This guideline was formulated by an international panel of clinical experts and methodologists. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology was applied to evaluate the certainty of evidence and to move from evidence to decision. RESULTS: For volume expansion, the guideline provides conditional recommendations for using crystalloids rather than albumin in critically ill patients in general (moderate certainty of evidence), in patients with sepsis (moderate certainty of evidence), in patients with acute respiratory failure (very low certainty of evidence) and in patients in the perioperative period and patients at risk for bleeding (very low certainty of evidence). There is a conditional recommendation for using isotonic saline rather than albumin in patients with traumatic brain injury (very low certainty of evidence). There is a conditional recommendation for using albumin rather than crystalloids in patients with cirrhosis (very low certainty of evidence). The guideline provides conditional recommendations for using balanced crystalloids rather than isotonic saline in critically ill patients in general (low certainty of evidence), in patients with sepsis (low certainty of evidence) and in patients with kidney injury (very low certainty of evidence). There is a conditional recommendation for using isotonic saline rather than balanced crystalloids in patients with traumatic brain injury (very low certainty of evidence). There is a conditional recommendation for using isotonic crystalloids rather than small-volume hypertonic crystalloids in critically ill patients in general (very low certainty of evidence). CONCLUSIONS: This guideline provides eleven recommendations to inform clinicians on resuscitation fluid choice in critically ill patients.


Assuntos
Cuidados Críticos , Estado Terminal , Soluções Cristaloides , Hidratação , Ressuscitação , Humanos , Hidratação/métodos , Hidratação/normas , Estado Terminal/terapia , Adulto , Cuidados Críticos/métodos , Cuidados Críticos/normas , Soluções Cristaloides/administração & dosagem , Soluções Cristaloides/uso terapêutico , Ressuscitação/métodos , Ressuscitação/normas , Europa (Continente) , Albuminas/uso terapêutico , Albuminas/administração & dosagem , Sepse/terapia
15.
World Neurosurg ; 187: e63-e76, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38599374

RESUMO

BACKGROUND: This research discusses colloid cyst surgical concerns, with an emphasis on the value of a novel surgical classification based on anatomical sites. In the study, 59 patients who underwent surgical intervention between 2009 and 2022 and were diagnosed with colloid cysts via computed tomography scan and magnetic resonance imaging participated. METHODS: There were more male cases than female ones (57.6%). The majority of patients presented with headache (79%), followed by abnormal gait (12%), visual blurring (5%), and seizures (4%). RESULTS: In this study, we present a new surgical classification based on anatomical locations, distinguishing 4 types: open Monro type (50.84%), closed Monro type (23.72%), retroforaminal type (13.55%), and interforniceal type (11.86%). CONCLUSIONS: In summary, the surgical classification that has been suggested provides significant insights into the varied anatomical sites where colloid cysts might be found. Microneurosurgeons significantly need to be oriented about the possible sites of colloid cysts through this classification to achieve complete and curative resection and reduce the likelihood of recurrence.


Assuntos
Cistos Coloides , Imageamento por Ressonância Magnética , Humanos , Cistos Coloides/cirurgia , Cistos Coloides/diagnóstico por imagem , Feminino , Masculino , Adulto , Pessoa de Meia-Idade , Adulto Jovem , Adolescente , Procedimentos Neurocirúrgicos/métodos , Idoso , Terceiro Ventrículo/cirurgia , Terceiro Ventrículo/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Criança
16.
Iran J Basic Med Sci ; 27(6): 695-705, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38645499

RESUMO

Objectives: Basal cell carcinoma (BCC) is the most common form of skin cancer and the most frequently occurring form of all cancers, affecting sun-exposed areas like the face. Surgery is the main treatment, focusing on safe and minimally invasive methods for better outcomes. Technology has enabled the development of artificial skin substitutes for tissue repair. Tissue engineering uses scaffolds to create functional replacements. This project aims to create an alginate-based hydrogel with PEG-coated gold nanoparticles. Materials and Methods: The project extensively explored the modification of alginate hydrogels with PEG-coated gold nanoparticles, involving the synthesis of gold nanoparticles, their integration with the polymer, and the subsequent preparation of the concentrated hybrid hydrogel. Utilizing various physicochemical techniques, such as UV-visible spectroscopy, transmission electron microscopy, dynamic light scattering, zeta potential analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy, the fabrication process was optimized and characterized. Results: The successful synthesis of the hybrid biomaterial was achieved through robust and highly reproducible methods. The MTT assay results offered valuable insights into the biocompatibility and safety of the PEG-coated gold nanoparticle-loaded alginate-based films. The incorporation of PEG-coated gold nanoparticles allowed for potential drug loading on the nanoparticle surface and, consequently, within the hydrogel. Cellular assays were conducted to assess the potential applications of this novel biomaterial. Conclusion: The addition of polyethylene glycol made it possible to load different drugs onto the gold nanoparticles and also within the hydrogel. This makes it a promising choice for potential uses in tissue engineering.

17.
Gels ; 10(4)2024 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-38667668

RESUMO

Raman spectroscopy is a non-destructive analytical technique for characterizing organic and inorganic materials with spatial resolution in the micrometer range. This makes it a method of choice for space-mission sample characterization, whether on return or in situ. To enhance its sensitivity, we use signal amplification via interaction with plasmonic silver-based colloids, which corresponds to surface-enhanced Raman scattering (SERS). In this study, we focus on the analysis of biomolecules of prebiotic interest on extraterrestrial dust trapped in silica aerogel, jointly with the Japanese Tanpopo mission. The aim is twofold: to prepare samples as close as possible to the real ones, and to optimize analysis by SERS for this specific context. Serpentinite was chosen as the inorganic matrix and adenine as the target biomolecule. The dust was projected at high velocity into the trapping aerogel and then mechanically extracted. A quantitative study shows effective detection even for adenine doping from a 5·10-9mol/L solution. After the dust has been expelled from the aerogel using a solvent, SERS mapping enables unambiguous adenine detection over the entire dust surface. This study shows the potential of SERS as a key technique not only for return samples, but also for upcoming new explorations.

18.
Artigo em Inglês | MEDLINE | ID: mdl-38588802

RESUMO

An extremely rare complication of endoscopic colloid cyst removal is presented. Terson's syndrome related to endoscopic resection of a colloid cyst has been reported only twice before in the literature and it could be explained by intracranial hypertension related to rinsing during the procedure. The case is described and the complications in the neuroendoscopic removal of colloid cyst are reviewed from the literature.

19.
Talanta ; 274: 126008, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38599117

RESUMO

Flexible and transparent surface-enhanced Raman scattering (SERS) substrates have gained great attention in analysis field as they offer a fast, non-destructive, and highly sensitive platform for in-situ detection. In this work, we present a facile one-pot strategy for synthesizing gold-cored silver shell nanoparticles (Au@Ag NPs) in the polyvinyl alcohol (PVA) colloid. With no other reducing agents, PVA can serve as both reducing and stabilizing agents for forming Au@Ag NPs. Besides, PVA acts as a scaffold to maintain SERS "hot-spots" by preventing nanoparticle aggregation. By using this flexible Au@Ag NPs/PVA colloid, the analytes can be extracted from rough surfaces for SERS measurements with excellent sensitivity, repeatability and stability. The SERS activity of the Au@Ag NPs/PVA remained at 89.8% even after 120 days of storage at room temperature in sealed air atmosphere. The selective detection of thiram residues on the surface of fruits and vegetables was successfully achieved. The limits of detection for thiram residues on apple and tomato surfaces were measured to be 0.58 and 0.56 ng cm-2, respectively, with recovery rate ranging from 91% to 107%. This work demonstrates the immense application potential of SERS colloid platform in the fields of food safety and environmental analysis.

20.
J Environ Radioact ; 275: 107430, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38615506

RESUMO

Clay colloids in the subsurface environment have a strong adsorption capacity for radionuclides, and the mobile colloids will carry the nuclides for migration, which would promote the movability of radionuclides in the groundwater environment and pose a threat to the ecosphere. The investigations of the adsorption/desorption behaviors of radionuclides in colloids and porous media are significant for the evaluation of the geological disposal of radioactive wastes. To illustrate the adsorption/desorption behaviors of 241Am(Ⅲ) in Na-montmorillonite colloid and/or quartz sand systems at different pH (5, 7 and 9), ionic strengths (0, 0.1 and 5 mM), colloid concentrations (300 and 900 mg/L), nuclide concentrations (500, 800, 1100 and 1400 Bq/mL) and grain sizes (40 and 60 mesh), a series of batch sorption-desorption experiments were conducted. Combining the analysis of the physical and chemical properties of Na-montmorillonite with the Freundlich model, the influencing mechanism of different controlling factors is discussed. The experimental results show that the adsorption/desorption behaviors of 241Am(Ⅲ) in Na-montmorillonite colloid and/or quartz sand strongly are influenced by the pH value and ionic strength of a solution, the colloid concentration as well as quartz sand grain size. The adsorption and desorption isotherms within all the experimental conditions could be well-fitted by the Freundlich model and the correlation coefficients (R2) are bigger than 0.9. With the increase in pH, the adsorption partition coefficient (Kd) at 241Am(Ⅲ)-Na-montmorillonite colloid two-phase system and 241Am(Ⅲ)-Na-montmorillonite colloid-quartz sand three-phase system presents a trend which increases firstly followed by decreasing, due to the changes in the morphology of Am with pH. The Kd of 241Am(Ⅲ) adsorption on montmorillonite colloid and quartz sand decreases with increasing in ionic strength, which is mainly attributed to the competitive adsorption, surface complexation and the reduction of surface zeta potential. Additionally, the Kd increases with increasing colloid concentrations because of the increase in adsorption sites. When the mean grain diameter changes from 0.45 to 0.3 mm, the adsorption variation trends of 241Am(Ⅲ) remain basically unchanged. The research results obtained in this work are meaningful and helpful in understanding the migration behaviors of radionuclides in the underground environment.


Assuntos
Amerício , Bentonita , Coloides , Quartzo , Bentonita/química , Concentração Osmolar , Adsorção , Concentração de Íons de Hidrogênio , Coloides/química , Quartzo/química , Amerício/química , Amerício/análise , Poluentes Radioativos da Água/química , Poluentes Radioativos da Água/análise , Poluentes Radioativos do Solo/análise , Poluentes Radioativos do Solo/química , Modelos Químicos , Tamanho da Partícula , Areia/química
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