Peculiarities of U(VI) sorption on composites containing hydrated titanium dioxide and potassium-cobalt hexacyanoferrate(II)

As opposed to polymer sorbents, inorganic materials are stable against ionizing radiation. This gives a possibility to use them for the removal of radionuclides from water. As a rule, highly selective inorganic sorbents are obtained in a form of finely dispersive powder. This makes it difficult to use them in practice. Here the composites based on hydrated titanium dioxide containing K2Co[Fe(CN)6] have been developed. The modifier was inserted into partially (hydrogel) and fully (xerogel) formed oxide matrices. Modifying of hydrogel followed its transformation to xerogel provides the formation of potassium-cobalt hexacyanoferrate(II) nanoparticles (up to 10 nm), which are not washed out in aqueous media due to encapsulation in hydrated oxide. A number of the methods for sample characterization were used in this work: transmission electronic microscopy for vizualization of embedded nanoparticles, optical microscopy to measure granule size, FT-IR spectroscopy, X-ray fluorescence spectroscopy for chemical analysis of the samples, potentiometric titration to estimate ion exchange properties, and spectrophotometric analysis of the solution to determine U(VI) concentration. The features of U(VI) sorption from nitrate and sulfate solutions are considered: the effect of the sorbent dosage and solution composition was in a focus of attention. The influence of the modifier is the most pronounced at pH ³ 4, when U(VI) is in a form of one-charged cations (UO2OH+): the removal degree of U(VI) is close to 100 %. This positive effect of the selective constituent is expressed in a presence of an excess of NO3–, SO42– and Na+ ions. The model of chemical reaction of pseudo second order has been applied to sorption. Both pristine sorbent and composite are most completely regenerated with a 0.1 M KOH solution - the regeneration degree is 92 and 96 % respectively. In this case, the half-exchange time is minimal and equal to » 23 min (initial hydrated titanium dioxide) and 47 min (composite). Desorption obeys the model of particle diffusion: the diffusion coefficients for ions being exchanged are (1.7–7.6)´10–13 m2s–1.

Numerical Simulation of Enhancement of Superficial Tumor Laser Hyperthermia with Silicon Nanoparticles

Biodegradable and low-toxic silicon nanoparticles (SiNPs) have potential in different biomedical applications. Previous experimental studies revealed the efficiency of some types of SiNPs in tumor hyperthermia. To analyse the feasibility of employing SiNPs produced by the laser ablation of silicon nanowire arrays in water and ethanol as agents for laser tumor hyperthermia, we numerically simulated effects of heating a millimeter-size nodal basal-cell carcinoma with embedded nanoparticles by continuous-wave laser radiation at 633 nm. Based on scanning electron microscopy data for the synthesized SiNPs size distributions, we used Mie theory to calculate their optical properties and carried out Monte Carlo simulations of light absorption inside the tumor, with and without the embedded nanoparticles, followed by an evaluation of local temperature increase based on the bioheat transfer equation. Given the same mass concentration, SiNPs obtained by the laser ablation of silicon nanowires in ethanol (eSiNPs) are characterized by smaller absorption and scattering coefficients compared to those synthesized in water (wSiNPs). In contrast, wSiNPs embedded in the tumor provide a lower overall temperature increase than eSiNPs due to the effect of shielding the laser irradiation by the highly absorbing wSiNPs-containing region at the top of the tumor. Effective tumor hyperthermia (temperature increase above 42 °C) can be performed with eSiNPs at nanoparticle mass concentrations of 3 mg/mL and higher, provided that the neighboring healthy tissues remain underheated at the applied irradiation power. The use of a laser beam with the diameter fitting the size of the tumor allows to obtain a higher temperature contrast between the tumor and surrounding normal tissues compared to the case when the beam diameter exceeds the tumor size at the comparable power.

Polysaccharide-Based Organic Frameworks with Embedded Nanoparticles: Advanced SPR Study on the Antiviral Activity of Gold Composites Derived from Glucuronoxylomannan

The nanosized composites based on the natural polysaccharides and nanoparticles of noble metals are promising candidates for efficient antiviral drugs. However, the complexity of such objects, their diversity and novelty necessitate the development of new analytical methods for investigation of such supramolecular architectures. In this work, which was recently developed for SPR-based instrumentation, the concept of variative refraction (DViFA, density variations in fixed architectures) was used to elucidate the mechanism of the antiviral action of a polysaccharide with gold nanoparticles grown in it. The SPR data were confirmed by direct biological tests: the effect of the native polysaccharide glucuronoxylomannan (GXM) obtained from the fungus Ganoderma adspersum and gold nanocomposites thereon on the infection of Datura stramonium with tobacco mosaic virus (TMV) was investigated. Both drugs suppress the development of viral infections. However, if for high concentrations the characteristic activity of the composite is somewhat lower than for GXM, then with an increase in dilution, the effectiveness of the composite increases significantly, up to a twofold excess. It has been reasonably suggested that the mechanism of antiviral action is associated with the formation of clusters of viruses that are no longer capable of infecting cells.

METHYLENE BLUE REMOVAL THROUGH ADSORPTION OF WATER HYACINTH USING COBALT NANOPARTICLES SUPPORTED ON ACTIVE CARBON

In this research, active carbon-based catalyst synthesis and characterization were investigated for different applications in catalysis. The active carbon-based catalyst was combined with metal oxides to dye methylene blue (MB) removal. Water hyacinth is one of the major problems that facing society and especially in Egypt. One of the implications of industrial activities is environmental pollution. One of the major pollutants is dyes that are used in the production of textiles, paper, and clothes. The waste of those dyes discharged into water supplies without treatment, or ineffective treatment will harmfully impact the environment. In this research, the treatment is implemented using active carbon-based catalysts using embedded nanoparticles. That will lead to a huge increase in the surface area of the adsorbent to increase the adsorbent efficiency. The activated carbon was derived from water hyacinths that grow in the Nile River. Water hyacinth has many good uses as it can absorb heavy metals like lead and dyes. Water hyacinth was converted into activated carbon through carbonization. Different dyes were used with different contact times in fixed conditions.

Removal of Methylene Blue by Adsorption of Water Hyacinth Derived Active Carbon Embedded with Cobalt Nanoparticles

In this research, active carbon-based catalyst synthesis and characterization were tested for potential catalysts to be used in dye removal of methylene blue (MB). Water hyacinth is one of the major problems that is facing humankind and especially here in Egypt. One of the implications of industrial activities is environmental pollution. Dyes used in the production of textiles, paper, and clothes are one of the major pollutants. The waste of those dyes discharged into water supplies without treatment or with ineffective treatment harmfully impacts the environment. In this research, the treatment is implemented using active carbon-based catalysts using embedded nanoparticles. This leads to a huge increase in the adsorbent's surface area, also increasing the adsorbent efficiency. The activated carbon was derived from water hyacinth that grows near the Nile River. Water hyacinth has many practical uses as it can absorb heavy metals like lead and dyes. Water hyacinth was converted into activated carbon through carbonization. Different dyes were used with different contact times in fixed conditions.

A Parametric Study of Coupled Photo-Electro-Thermal Responses of Thin Film a-Si:H Solar Cell with Embedded Nanoparticles

A parametric investigation has been performed on a thin-film hydrogenated amorphous silicon (a-Si:H) solar cell that is enhanced with various light trapping schemes through a modelling approach. The proposed model contains a novel coupling approach and various feedback routines for a more holistic modelling treatment. The proposed optical model adopts a semi-coherent method, the electrical model extends the classical drift-diffusion model to incorporate the effects of thermal gradients, and the thermal model adopts energy conservation equations from the hydrodynamic model. Based on the simulation results, it is observed that the rise in cell temperature adversely affects the electrical performance but promotes more optical absorptions due to the unique optical properties of amorphous silicon. To obtain an optimum enhancement from the inclusion of nanoparticles, their dimensions and separation distances are essential factors. The thickness of the intrinsic active absorbing layer affects the optical performance directly which then leads to various variations in electrical and thermal responses.

Thermal Conductivity Calculations for Nanoparticles Embedded in a Base Fluid

The Prasher analytical model was used for calculating the thermal conductivity of the embedded nanoparticles of Al2O3, CuO, ZnO, and SiO2 in conventional fluids, such as water and ethylene glycol. The values that were obtained were used in the nanofluid theoretical models for comparison with experimental data, where good agreement was obtained. Liang and Li’s theoretical model was also used to calculate the thermal conductivity of these nanoparticles, where the results agreed with those obtained using the Prasher model. The effect of the liquid nanolayer thickness around the nanoparticles that was used to enhance the effective thermal conductivity of nanofluids was explained. The role of the nanoparticles’ surface specularity parameter, which was size-dependent, was clarified. This theoretical trend provides a simple method for estimating the thermal conductivity of nanoparticles and nanofluids.