Nanostructured materials, especially nanoparticles (NPs), of noble metal NPs such as silver (Ag) have been the focus of research in recent decades because of their distinct physical, chemical, and biological properties. These materials have attracted considerable attention because of their potential applications, such as catalysis, biosensing, drug delivery, and nanodevice fabrication. Previous studies on Ag NPs have clearly demonstrated that their electromagnetic, optical, and catalytic properties are strongly influenced by their shape, size, and size distribution, which can be varied by using different synthetic methods, reducing agents, and stabilizers. The valuable optical properties of Ag NPs have allowed for new approaches in sensing and imaging applications, offering a wide range of detection modes, such as colorimetric, scattering, and surface‐enhanced Raman scattering techniques, at extremely low detection limits. Here, an overview of the various chemical, physical, and biological properties of Ag NP fabrication approaches to obtain the various shapes and sizes is presented.
nophosphonic groups to sorb rare earth elements. • XPS, FTIR and molecular modeling were applied for characterizing metal binding. • Sorption isotherms and uptake kinetics are modeled for La(III) and Y (III) recovery. • Metal desorption and sorbent recycling are highly efficients. • The treatment of monazite leachate is discussed in terms of affinity for REEs.
Magnetic polymeric matrixces were synthesized from glycidyl methacrylate, N,N′-methylenebis(acrylamide) (MBA), and nanomagnetite particles. The obtained polymers were modified by ethylenediamine (DA) and diethylenetriamine (TA) to produce two amino-magnetic resins named R-DA and R-TA. The recovery of Th(IV) ions from their aqueous solutions by R-DA and R-TA were studied in the pH range 1−4. Maximum adsorption capacity values of 60 and 84 mg/g of Th(IV) ions on R-DA and R-TA, respectively, were obtained at pH 3.5 and 293 K. At a solid/liquid ratio (S/L) of 2 g/L, recovery efficiency values of 86 and 95% were achieved from initial thorium ion concentration of 100 mg/L using R-DA and R-TA, respectively. Adsorption isotherms and kinetic and thermodynamic parameters of the adsorption process were obtained and analyzed. Regeneration of the resins was tested by eluting the loaded Th(IV) ions on the spent resins using 0.2 M HNO 3 followed by washing with dilute NaOH.
High exposure to metals, such as cobalt (Co), copper (Cu) and cadmium (Cd), potentially has adverse effects, and can cause severe health problems, leading to a number of specific diseases. This study primarily aims to monitor, detect, separate, and remove the trace concentrations of Co(II), Cu(II), and Cd(II) ions in water, without a preconcentration process, using aluminosilica optical sensor (ASOS) monoliths. These monolithic scaffolds with advantageous physical features (i.e., large surface area-to-volume ratios of the scaffolds, active acid sites and uniform mesocage cubic pores) can strongly induce H-bonding and dispersive interactions with organic chelating agent, resulting in the formation of stable ASOS. In this engineering process, ASOS offers a simple and one-step sensing/capture procedure for the quantification and visual detection of the target elements from water, without requiring sophisticated instrumentation. The key result in this study is the ion selectivity exhibited by the designed ASOS toward the targets, Co(II), Cu(II), and Cd(II) ions, in environmental and waste disposal samples, as well as its reproducibility over a number of analysis/regeneration cycles. These findings can be useful in the fabrication of ASOS can be tailored to suit various applications.
The highly toxic properties, bioavailability, and adverse effects of Pb(2+) species on the environment and living organisms necessitate periodic monitoring and removal whenever possible of Pb(2+) concentrations in the environment. In this study, we designed a novel optical multi-shell nanosphere sensor that enables selective recognition, unrestrained accessibility, continuous monitoring, and efficient removal (on the order of minutes) of Pb(2+) ions from water and human blood, i.e., red blood cells (RBCs). The consequent decoration of the mesoporous core/double-shell silica nanospheres through a chemically responsive azo-chromophore with a long hydrophobic tail enabled us to create a unique hierarchical multi-shell sensor. We examined the efficiency of the multi-shell sensor in removing lead ions from the blood to ascertain the potential use of the sensor in medical applications. The lead-induced hemolysis of RBCs in the sensing/capture assay was inhibited by the ability of the hierarchical sensor to remove lead ions from blood. The results suggest the higher flux and diffusion of Pb(2+) ions into the mesopores of the core/multi-shell sensor than into the RBC membranes. These findings indicate that the sensor could be used in the prevention of health risks associated with elevated blood lead levels such as anemia.
A one-pot synthesis procedure is designed for preparing three α-aminophosphonates (R-H, R-COOH, and R-NH 2 ); through the reaction of amine precursors (aniline, anthranilic or o-phenylene diamine, respectively) with salicylaldehyde and triphenylphosphite, under controlled conditions. These materials are first characterized by elemental analysis, FTIR, 1 H NMR, 31 P NMR, BET, DLS, pH zpc , TGA and titration. In a second step, the sorption properties are compared for U(VI) recovery from mildly acidic solutions. At the optimum pH (i.e., pH 4) the sorbents can be ranked according the series: R-H (1.057 mmol U g − 1 ) > R-NH 2 (0.746 mmol U g − 1 ) > R-COOH (0.533 mmol U g − 1 ). The isotherms are fitted by the Langmuir equation. Uranium uptake is relatively fast: under selected experimental conditions, the equilibrium is reached within 90 min of contact. The kinetic profiles are indistinctly fitted by the model of resistance to intraparticle diffusion and the pseudo-first order rate equation.The study of sorption thermodynamics shows substantial changes between the sorbents: uranyl uptake is endothermic with R-H and R-NH 2 sorbents, while the reaction is exothermic with R-COOH sorbent. The diversity in functional groups and the speciation of uranyl in sulfuric acid solutions induce metal-binding through a combination of chelation and anion-exchange mechanisms (in function of pH). Sodium bicarbonate solutions achieve complete desorption of uranium from loaded-sorbents; the resins can be recycled for a minimum of 4-5 cycles with limited loss in efficiencies. The successful application of these resins for uranium recovery from acidic ore leachates demonstrates their promising properties for valorization of low-grade ores.
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