Trends in Sorption Recovery of Platinum Metals: A Critical Survey

The major trends in research into the sorption recovery and separation of platinum metals are critically surveyed. The advantages and disadvantages are described for ion-exchange and complexing sorbents based on organic polymers, chemically modified silicas, sorbents with applied macrocyclic compounds, hybrid organomineral sorbents with supported polymers, molecular imprinted sorbents, solid-phase extractants based on ionic liquids, biosorbents, and other types of sorbents. The technological potentials of these sorbents are evaluated.     

Separation of pharmacologically active nitrogen-containing compounds on silica gels modified with 6,10-ionene,dextran sulfate,and gold nanoparticles

New stationary phases for HPLC are obtained via layer-by-layer deposition of polyelectrolytes and studied: (1) silica gel modified layer-by-layer with 6,10-ionene and dextran sulfate (Sorbent 1); (2) silica gel twice subjected to the above modification (Sorbent 2); and (3) silica gel modified with 6,10-ionene, gold nanoparticles, and dextran sulfate (Sorbent 3). The effect the content of the organic solvent in the mobile phase and the concentration and pH of the buffer solution have on the chromatographic behavior of several pharmacologically active nitrogen-containing compounds is studied. The sorbents are stable during the process and allow the effective separation of beta-blockers, calcium channel blockers, alpha-agonists, and antihistamines. A mixture of caffeine, nadolol, tetrahydrozoline, pindolol, orphenadrine, doxylamine, carbinoxamine, and chlorphenamine is separated in 6.5 min on the silica gel modified with 6,10-ionene, gold nanoparticles, and dextran sulfate.

     

Sorption of arsenic onto inorganic sorbents modified with iron compounds

Granulated inorganic sorbents based on silica gel of KSKG grade and aluminum oxide and modified with Fe(III) compounds were developed for water treatment to remove As(V). The influence of the particle size of the modifying additive on the ability of silica gel to take up As(V) was examined. The KSKG-based sorbents modified with nanoparticles of Fe(III) compounds exhibit the highest sorption capacity. The capacity of silica gel based sorbents modified with nanoparticles of iron compounds for As(V) is higher than that of analogous sorbents modified with iron oxides prepared by thermal decomposition of Fe(III) nitrate.     

Magnetic nanomaterials for the removal,separation and preconcentration of organic and inorganic pollutants at trace levels and their practical applications: A review

The presence of organic and inorganic pollutants in nature even in very small concentrations threatens human and other living bodies health and makes it significant to remove, separate and preconcentrate these pollutants. Recently magnetic nano sorbents has been used frequently in the separation and preconcentration of these pollutants. The use of magnetic nano sorbents modified with inorganic and organic species has widespread applications in the solid phase extraction (SPE) studies due to its many unique properties. These modified nano sorbents are preferred due to their advantages such as high adsorption capacities and large surface areas. This review examined different types of magnetic materials such as magnetic carbon-based nano sorbents, inorganic nano sorbents with magnetic properties, magnetized biosorbents, magnetic metal-organic frameworks, and magnetized ionic liquids used in SPE studies. In this study, a comprehensive and systematic review of the separation and preconcentration of analytes such as heavy metal ions, drug active substances, pesticides, dyes, hormone disruptors, etc with SPE methods using magnetic nanomaterials has been revealed. Future aspects and challenges that may be encountered are discussed.     

Sorption of radionuclides on inorganic sorbents

Inorganic sorbents are often used in separation of metals and radionuclides in radioanalytical application and they were also used in technological scale for separation of radionuclides in cleanup of Three Mile Island NPP. Inorganic sorbents become popular in the last years because no problem with organic contamination, there are stable against radiation, sorption efficiency can be tailor made for selective separation of chosen metal. Contrary to the organic sorbents they have usually lower capacity and chemical stability is limited to narrower pH. Nevertheless of some problems, many good properties of inorganic sorbents make them very attractive for sorption study.     

Sorption in the chemistry of rare earth elements

Sorption methods for the concentration and separation of rare earth elements are reviewed. Sorbents based on organic polymers, specifically strongly and weakly acidic cation exchangers, anion exchangers, and complexing sorbents, are successively considered. Data on the use of inorganic sorbents and solid phase extractants in the rare earth chemistry are also given. Considerable attention is paid to hybrid organomineral materials constituting a promising class of sorbents. Advantages and disadvantages of using biosorbents, molecularly imprinted sorbents, and nanosorbents for the concentration and separation of rare earths are discussed.     

Regularities of the retention of aminopyridines by silica gel modified with gold nanoparticles

New sorbents based on silica gel and gold nanoparticles stabilized by L-cysteine and its methyl ester are synthesized. Regularities of the retention of various substituted aminopyridines by the synthesized sorbents are examined in the normal-phase mode of high-performance liquid chromatography upon elution by a binary mobile phase (hexane-isopropanol). Quantum-chemical simulations of L-cysteine and its derivative adsorptions on the surface of a gold cluster are performed, along with simulations of subsequent adsorptions of substituted pyridines on the modified gold surface. It is shown that the Snyder-Soczewinski and Scott-Kucera displacement models can be used to describe the experimental data on the synthesized sorbents.     

Sol-gel synthesis and sorption properties of calcium monoaluminate

Method for synthesis of calcium aluminate and sorbents based on this compound was developed on its basis of the sol-gel technology. The method makes it possible to obtain the target product with specific surface areas in the range from 7 to 120 m² g^–1. The compounds obtained were characterized by scanning electron microscopy, X-ray phase analysis, and X-ray fluorescence microanalysis. It was found that the main phase of the sorbents is rhombohedral calcium monoaluminate CaAl₂O₄. The method of Hammett indicator adsorption was used to determine the content of active centers on the surface of the sorbents and the distribution of these centers over ionization constants. It was shown that the surface characteristics of the sorbents depend on their synthesis method. The retention parameters, polarities, and thermodynamic characteristics were determined for organic compounds of various classes. The possibility of using calcium aluminate modified with sodium chloride for gas-chromatographic separation of aliphatic and aromatic hydrocarbons and carbonyl compounds was demonstrated.     

离子液体基磁性固相萃取技术的研究进展

磁性固相萃取(Magnetic solid-phase extraction,MSPE)是一种采用磁性材料作为吸附剂的新型样品前处理技术,发展新型的磁性材料作为吸附剂是MSPE领域的研究热点。用离子液体(Ionic liquid,IL)修饰磁性材料作为吸附剂既具有MSPE操作简单、萃取快速、基质干扰小的优点,又兼具IL结构的可设计性和易功能化的优点,在样品前处理领域引起了广泛关注。该文综述了IL修饰磁性吸附剂的制备方法(物理涂敷、化学键合和包埋法),IL-MSPE的萃取方式(传统的MSPE,混合半胶束-MSPE和分散液液微萃取-MSPE),以及IL-MSPE在有机污染物、金属离子和生物活性物质萃取分离中的应用,并对该技术的发展趋势进行了展望。     

New stationary phases for normal-phase HPLC based on silica gel modified with cobalt,nickel, zinc,and cadmium salts

Several new stationary phases for normal-phase high-performance liquid chromatography were synthesized by the modification of silica gel with cobalt, nickel, zinc, and cadmium salts and subsequent calcination at 700°C. These sorbents exhibit an increase in the retention of organic compounds of the basic character, an increase in the selectivity of separation, and an eightfold increase in efficiency in comparison with initial silica gel. The experimental results were explained on the basis of the interpretation of the IR spectra of pyridine adsorbed on the synthesized and initial silica gel. It was demonstrated that the surface of silica gel modified with cadmium ions exhibits the highest acidity. The advantage of the synthesized sorbents was demonstrated with the example of the separation of fullerenes containing diethylamino and hydroxy groups.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 4, 2005, pp. 412–416.Original Russian Text Copyright © 2005 by Pirogov, Kuzavlev, Shpigun.     

Synthesis and surface engineering of magnetic nanoparticles for environmental cleanup and pesticide residue analysis: A review

In recent years, water pollution and pesticide accumulation in the food chain have become a serious environmental and health hazard problem. Direct determination of these contaminants is a difficult task due to their low concentration level and the matrix interferences. Therefore, an efficient separation and preconcentration procedure is often required prior to the analysis. With the advancement in nanotechnology, various types of magnetic core–shell nanoparticles have successfully been synthesized and received considerable attention as sorbents for decontamination of diverse matrices. Magnetic core–shell nanoparticles with surface modifications have the advantages of large surface‐area‐to‐volume ratio, high number of surface active sites, no secondary pollutant, and high magnetic properties. Due to their physicochemical properties, surface‐modified magnetic core–shell nanoparticles exhibit high adsorption efficiency, high rate of removal of contaminants, and easy as well as rapid separation of adsorbent from solution via external magnetic field. Such facile separation is essential to improve the operation efficiency. In addition, reuse of nanoparticles would substantially reduce the treatment cost. In this review article, we have attempted to summarize recent studies that address the preconcentration methods of pesticide residue analysis and removal of toxic contaminants from aquatic systems using magnetic core–shell nanoparticles as adsorbents.     

Adsorption of Methylene Blue and Metanil Yellow Dyes by Modified Carbon Sorbents

Adsorption properties of carbon sorbents modified with glycolic and lactic acid oligomers and copolymers of these toward organic dyes of varied nature: Methylene Blue and Metanil Yellow were studied. Differences in the adsorption of the dyes by the modified sorbents, due to the nature of their surface, were found.     

磁性纳米粒子负载钯催化有机合成反应研究进展

磁性纳米粒子负载钯催化的有机合成反应,由于具有催化活性高,催化剂在外加磁场作用下即可快速分离和重复使用等特点,已引起了人们的广泛关注.综述了近年来磁性纳米粒子负载钯催化有机合成反应的研究进展,载体包括Fe3O4纳米粒子、有机小分子修饰的磁性纳米粒子、SiO2包覆的磁性纳米粒子、碳修饰磁性纳米粒子、羟基磷灰石包覆的磁性纳米粒子和有机高分子修饰的磁性纳米粒子等.     

Impact of nanomaterials on high-throughput separation methodologies

Due to the unique properties, such as their large surface to volume ratio and easy modification, nanomaterials have recently been studied as effective sorbents in the field of separation science. It has proven to be more effective and efficient to use nanoparticles (NPs) as a stationary phase in solid-phase extraction separation. In addition, NPs can be also used as buffer additives in capillary electrophoresis separation. This review highlights recent developments in high-throughput separation methodologies employing nanomaterials such as carbon nanotubes, gold nanoparticles and magnetic NPs etc.     

Emerging materials for sample preparation

This review provides an update on the implementation of emerging materials as sorbents for sample preparation in combination with chromatographic separation. We have focused on recent applications of metal–organic frameworks, layered double hydroxides, porous carbons obtained from polymers or biomass precursors, and silicates (clays and zeolites). The review is directed toward the strategies followed by the authors to engineer suitable supports enabling the application of materials with unconventional size and shape as high‐performance sorbents to explore new boundaries in sample pretreatment in manual or automated modes.     

色素的纳米纸色谱分离分析

采用SiO2纳米粒子结合硅烷化处理对滤纸进行改性,以罗丹明B、苏丹红Ⅰ及苏丹红Ⅳ为模型化合物,考察了改性滤纸在分离特性上的差异,对不同粒径纳米粒子、不同硅烷化试剂及不同展开剂的极性进行比较、优化后发现,在同等展开条件下,经改性纳米粒子修饰后的滤纸分离色素的效果得到明显改善,且纳米粒子越小、烷基碳链越长、硅烷化越完全,则...     

Poly(styrene‐co‐N‐methacryloyl‐l‐phenylalanine methyl ester)‐functionalized magnetic nanoparticles as sorbents for the analysis of sodium benzoate in beverages

In this study, poly(styrene‐co‐N‐methacryloyl‐l ‐phenylalanine methyl ester)‐functionalized magnetic nanoparticles were constructed and used as magnetic solid‐phase extraction sorbents for analysis of food preservatives in beverages. To prepare the poly(amino acid)‐based sorbents, N‐methacryloyl‐l ‐phenylalanine methyl ester, and styrene served as the functional monomers and modified onto the magnetic nanoparticles via free radical polymerization. Interestingly, compared with propylparaben and potassium sorbate, the proposed poly(amino acid)‐based sorbents showed a good selectivity to sodium benzoate. The adsorption capacity of the sorbents to sodium benzoate was 6.08 ± 0.31 mg/g. Moreover, the fast adsorption equilibrium could be reached within 5 min. Further, the resultant poly(amino acid)‐based sorbents were applied in the analysis of sodium benzoate in real beverage samples. The results proved that the proposed magnetic solid‐phase extraction sorbents have a great potential for the analysis of preservatives in food samples.     

Optimization of working conditions for polyelectrolyte sorbents

Matters affecting the working stability of polyelectrolyte sorbents are considered. The decrease in retention time during exploitation is found not to relate to desorption of the modifying polymer. It is found that dissociation of surface silanol groups influences significantly the extra retention of ionene on the surface of silica-based sorbents. Sorption of heavy metals and microbial contamination of the sorbent are identified as causes of decreased efficiency of polyectrolyte sorbents. The influence of organic additives on the chromatography behavior of a number of inorganic anions is studied. Finally, exploitational conditions for chromatography polyelectrolyte-containing columns are elaborated, allowing the initial parameters of separation to be maintained for a period of 1.5 months or longer.     

Solid–liquid phase diagrams of binary mixtures

This study investigates the sorption of toluene and naphthalene by a sodium bentonite (BFN), an organoclay (WS35) and by their respective iron oxide hydrate composites Mag_BFN and Mag_S35. The organic matter content of WS35 and Mag_S35, determined by thermogravimetry, was used to obtain their organic matter sorption coefficients, which show that they are effective sorbents to remove organic contaminants from water, with a higher selectivity for naphthalene than for toluene sorption. The main iron oxide phase present in Mag_BFN and Mag_S35 is maghemite (γ-Fe₂O₃), which allows these sorbents to be separated from the effluent by a magnetic separation process after use.     

Nanosorbents as Materials for Extraction Processes of Environmental Contaminants and Others

The aim of this work focuses on the application of nanomaterials (NMs) in different sorptive extraction techniques for the analysis of organic contaminants from environmental samples of distinct matrix compositions. Without any doubt, the integration of specific NMs such as carbonaceous nanomaterials, magnetic nanoparticles (MNPs), metal–organic frameworks (MOFs), silica nanoparticles, and ion-imprinted NPs with solid-phase extraction techniques counting d-SPE, solid-phase microextraction (SPME), and stir bar sorptive extraction (SBSE) impact on the improvements in analytical performance. The application of NMs as sorbents in the extraction of organic pollutants in environmental samples allows for providing better sensitivity, repeatability, reproducibility, and reusability.