Sulfathiazole-based novel UV-cured hydrogel sorbents for mercury removal from aqueous solutions

Sulfathiazole-based novel hydrogel sorbents P(Sulti/hydroxyethyl methacrylate (HEMA)/acrylic acid (AAc)) were prepared by UV irradiation and used for the removal of mercury(II) ion from aqueous media. Hydrogels have been characterized by SEM and thermogravimetric analysis (TGA) techniques. The influence of the uptake conditions was investigated; maximum Hg(II) ion adsorption capacity obtained was 13.46±1.15 mg g⁻¹ at pH 5.0. The hydrogels were tested several times without loss of adsorption capacity. The selectivity of the hydrogel towards to Hg(II), Cd(II) and Zn(II) ions tested was Hg>Cd>Zn.     

Chitosan based composite sorbents for arsenic removal

Russian Chemical Bulletin - The possibilities of using chitosan and its composites with transition metal oxides for arsenic removal from solutions with low concentrations are discussed. Methods for...     

The miniaturised process for lead removal from water samples using novel bioconjugated sorbents

ABSTRACT

In the present study, novel bioconjugated sorbents (peptide and oligo-nucleotide on the cobalt aluminate nanomaterials) were used to remove lead through miniaturised process and the concentration of lead was measured by inductively coupled plasma mass spectrometry. For this aim, lead was collected on sorbent in mini tube, and the influences of experimental conditions (e.g. pH of sample, amount of sorbent, concentration of eluent, foreign ions) and retention parameters on the recovery of the lead element were examined. After the optimisation of experimental parameters, a successful separation was obtained at pH 7.5 with high (>95%) quantitative recovery and high precision (<10% relative standard deviation). Using the proposed bioconjugated sorbents, the lead in sea water and tap water samples could be practically and easily removed with 95% confidence level. The detection limits of this method for lead using oligonucleotide and peptide on the cobalt aluminate nanomaterials were 0.14 and 0.12 µg/L (3σ, N = 10) with sample-matched blanks. This method can be widely used as promising and cost-effective nanomaterials to remove lead from water systems.     

Surface-layer composite sorbents for the rapid preconcentration of volatile organic substances from aqueous solutions and gas atmospheres

The regularities of the dynamic sorption of volatile organic substances from aqueous solutions and atmospheric air on surface-layer composite sorbents, in which a finely dispersed sorption-active material is retained due to adhesion on the surface of a relatively coarsely dispersed macroporous carrier, were determined. The analytical capabilities of such sorbents were studied, and they were found more effective than traditional porous bulk sorbents used for the concentration of volatile organic compounds from aqueous solutions and gas atmospheres.     

Application of inorganic sorbents for removal of Cs, Sr, Pu and Am from contaminated solutions

A sorption ability of titanium silicates (TiSi) and iron oxides towards Cs, Sr, Pu and Am was tested using the laboratory batch method. The obtained results are expressed as distribution coefficients (K_d). TiSi synthesised using TiOSO₄ revealed better sorption ability towards all studied radionuclides in comparison with TiSi produced on the basis of TiCl₄. The K_d values ranged from 3.9 × 10² to 1.6 × 10⁵ mL g⁻¹ for Sr, from 6 to 4.1 × 10⁴ mL g⁻¹ for Cs, from 2.2 × 10² to 2.6 × 10⁵ mL g⁻¹ for Pu and from 50 to 1.6 × 10⁴ mL g⁻¹ for Am. The highest Pu K_d values (9 × 10³–6.2 × 10⁴ mL g⁻¹) and better kinetics were found for iron oxides.     

Radiation removal of lead from aqueous solutions—effects of various sorbents and nitrous oxide

The influence of selected adsorbents (active carbon, bentonite and zeolite) on the radiation removal of lead from its aqueous solution using electron beam radiation was investigated. Both positive and negative effects on radiation reduction of Pb²⁺ ions depending on the dose applied were observed in presence of these solid modifiers. Besides deaeration with nitrogen, the efficiency of the process under study may be substantially increased by saturation of solution with nitrous oxide.     

Separation of curium from americium using composite sorbents and complexing agent solutions: part 2

TODGA–PAN composite sorbent and (PhSO₃H)₂–BTPhen in nitric acid solution were employed as a system for separation of curium from americium. The influence of aqueous phase composition (complexing agent and nitric acid concentrations) on weight distribution coefficients and Cm/Am separation factor was studied in batch experiments with trace amounts of ²⁴¹Am and ²⁴⁴Cm. Based on the results obtained, column experiment was designed and conducted. The Cm/Am separation factor of 3.8 ± 0.1 found in batch experiments with TODGA–PAN could be reproduced also in column experiment resulting in good separation of Cm from Am. The efficiency of Cm separation from Am in the TODGA–PAN system was compared with the analogous system with DGA resin (Triskem International). After separation on a 0.5 mL column (φ4.7 × 29 mm) the Cm fraction containing 93% of Cm(III) contained only 3% of Am(III) in optimum conditions.

     

钙基类吸附剂脱除烟气中气态汞的试验研究

用恒温水浴中汞渗透管的汞蒸气发生装置和其他烟气主要气体成分模拟烟气条件,在小型固定床试验台上开展钙基类物质作为吸附剂脱除单质汞的试验研究。结果表明,无SO2时,两种钙基吸附剂以及飞灰和熟石灰混合物对单质汞的吸附效率不高;当SO2存在时,对单质汞的脱除效率可增加15％～20％,30min时吸附量可增加50％以上,且吸附在较高温度下更有利。其原因在于SO2同钙基吸附剂之间的化学反应,在钙基物质表面产生了活性区域,有利于提高对Hg0的捕捉效率,化学吸附起到了促进吸附的作用。     

Mineral sorbents for the removal of oil products from waste water

Properties of filtering-sorption materials based on basalt fibers and bentonite clays intended for the removal of oil products from water were studied. Optimal parameters of a feed providing the maximal purification efficiency with the minimal power consumption were determined.     

Separation of actinides, cesium and strontium from marine samples using extraction chromatography and sorbents

Plutonium concentrations in seawater of the western North Pacific observed over the period from 1985 to 1997 are reported. In the 1990's, surface ^239,240Pu concentrations in the western North Pacific were relatively homogeneous (around 3 mBq/m³), although surface ^239,240Pu before the 1980's showed a latitudinal distribution with highs in mid-latitudes and lows in the Equatorial region. Temporal variations of surface ^239,240Pu in three different sea areas were examined. In mid-latitudes (21°–35°N), surface ^239,240Pu exponentially decreased with an apparent residence time of 9.9 years, whereas in the subtropical and Equatorial areas, decrease rates of surface ^239,240Pu were slower than in mid-latitudes. The vertical profiles of ^239,240Pu in mid-latitudes of the western North Pacific showed a surface minimum, a subsurface maximum and decreased with increasing depth. The water column inventory of ^239,240Pu at the station (27°48'N, 130°44'E) was calculated to be 113 Bq/m².     

Latest achievements in the analytical chemistry of actinides

New methods for separation and determination of actinides, widely used in analysis of actinides in technological and environmental samples are reviewed. Special attention is paid to obtaining and stabilizing transplutonium elements. (TPE) in extreme oxidation states. Their use in analytical practice resulted in expanding possibilities of methods for separation and determination of TPE. Solvent extraction, sorption and extraction chromatography are the basic methods for separation of TPE. Solvent extraction, sorption and extraction chromatography are the basic methods for separation of TPE. Methods of separation in gas phase and some other methods such as precipitation and coprecipitation are applied, however, to a lesser degree. Trends of development of these methods including those of various types of membrane extraction that succeeded in separation of TPE in both trivalent and other valence states have been shown. Attention is paid mainly to consideration of modern methods for determination of actinides, special distinction of such methods being low limits of determination, high precision and selectivity. Alpha- and beta-spectrometric methods with semiconductor detectors are the most advanced among various methods based on registration of nuclear radiation. Tremendous success has been achieved in development of emission-spectrometric methods for determination of trace amounts of actinides and various impure elements occurring in samples of actinides. Sensitive mass-spectrometric methods are widely used for determination of both isotope composition and content of elements in various samples including those which are highly radioactive. More simple and precise titrimetric methods based on using oxidizing-reducing or complexing agents are developed successfully. A large number of coulometric methods for determination of americium and berkelium, characterizing high precision and selectivity as well as luminescence methods have been developed.     

Development of a novel composite by coating polyacrylic fibres with hexacyanoferrates for the removal of Cs from radioactive liquid waste

Hexacyanoferrates (HCFs) are known to be efficient sorbents for the removal of Cs from aqueous solutions. But the powdery precipitate of HCF is unsuitable for use in columns. To make it amenable to column application, it has been coated on polyacrylic fibres by in situ precipitation. In batch and column experiments, the fibres coated with Cupric ferric hexacyanoferrate provided good removal of¹³⁷Cs from radioactive effluents. Leaching of Cs from the fibres was found to be only 14% in demineralised water medium. The Cs-loaded fibres could easily be incinerated to a smaller volume for further conditioning.     

Ozonated graphene oxides as high efficient sorbents for Sr(II) and U(VI) removal from aqueous solutions

Ozone was used to oxidize graphene oxides (GO) to generate ozonated graphene oxides (OGO) with higher oxygen-containing functional groups. The as-prepared OGO was characterized by Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Based on the results of potentiometric acid-base titrations, the total carboxylic acid concentration on OGO surface was calculated to be 3.92 mmol/g, which was much higher than that on GO surface. The results of adsorption experiments indicated that the adsorption capacities of OGO for Sr(II) and U(VI) removal were improved significantly after ozonization.     

用于三价锕镧分离的萃取剂的合成与表征

以6,6'-二氰-2,2'-联吡啶为原料,经两步反应,合成了6,6'二(5,6二乙基-1,2,4-三嗪-3-基)-2,2'-联吡啶.第一步改变条件使反应时间由17d缩短到3d,得到的中间体和目标产物经元素分析、IR,1 HNMR和MS等表征确认.此外,对反应机理进行了初步探讨.     

Removal of pentachlorophenol from aqueous solutions by dolomitic sorbents

The partial decomposition of dolomite carried out within the temperature range 600-1000 degrees C provides new sorbents, called dolomitic sorbents. Their surface properties and identification by X-ray diffraction are discussed. The lowest specific surface area value was found for the raw dolomite, while the highest value was achieved by the D-1000 sample. The adsorption equilibrium of pentachlorophenol from aqueous solutions on the examined sorbents was investigated at 30, 40, and 50 degrees C via a bath process. Langmuir, Freundlich, Langmuir-Freundlich, and Redlich-Petersen models were fitted to experimental equilibrium data, and their goodnesses of fit are compared. The adjustable parameters of Langmuir-Freundlich and Redlich-Petersen isotherms were estimated by nonlinear least-squares analysis. Langmuir and Freundlich models were found insufficient to explain the adsorption equilibrium, while Langmuir-Freundlich and Redlich-Petersen isotherms provide the best correlation of the pentachlorophenol adsorption onto dolomitic sorbents.     

Synthesis of magnetic graphene oxide nanoribbons composite for the removal of Th(IV) from aqueous solutions

Journal of Radioanalytical and Nuclear Chemistry - Functionalized magnetic graphene oxide nanoribbons (MGONRs) composite material was synthesized by hydrothermal treatment method using graphene...     

Granulated sulfur-containing sorbents for recovery of heavy metal ions from aqueous solutions

Granulated sorbents that can recover zinc salts from aqueous solutions were produced by poly-condensation of organochlorine wastes from manufacture of epichlorohydrin with sodium polysulfide on the surface of ash-and-slag particles formed at thermal power plants in the system constituted by aqueous hydrazine and an alkali.     

Use of actinides in uncommon oxidation states for their extraction and separation from alkaline solutions

The extraction behavior of Am(IV–VI) from high pH solutions in the presence of carbonates, pyrophosphates or polyphosphates of alkali metals and of Np(VI–VII) from alkaline solutions with acylpyrazolones (1-phenyl-3-methyl-4-benzoylpyrazolone-5, PMBP) and extractants of the phenol type [bis(2-oxy-4-alkyl-benzoil)amin, CAAF] has been studied. The extraction ability of phenolic extractants with respects to Np(VII) is determined generally by its state in the alkaline solution. Maximum extraction is observed when Np(VII) is present as hydroxo complex and minimum extraction, when the solution contains oxo-ions. During the extraction the reduction of Np(VII) to Np(VI) is possible. Hexavalent neptunium can be extracted by phenol extractants too, but more slowly and with smaller distribution coefficients in comparison with Np(VII). The stabilization of transplutonium elements (TPE) in the highest oxidation states in alkaline solutions contaning carbonate and pyrophosphate ions, in combination with extraction by PMBP and CAAF, allows to realize the separation of transplutonium elements which are very similar in their properties. Methods of separation for americium and curium have been developed. They are based on the ability of trivalent curium to be extracted quantitatively from 0.1M sodium pyrophosphate solution (pH 10) and 1.0M potassium carbonate solution (ph 13.4) by PMBP in chloroform and by CAAF in carbon tetrachloride, respectively, with high distribution coefficients, whereas americium which is electrochemically oxidized to Am(VI) in these media, remains in the aqueous phase, since it reduces only to Am(V) when contacting the extractant. The separation factor of the couple Cm(III) Am(VI) is about 10³.     

Composite carbon-fluoroplastic surface-layer sorbents for the rapid preconcentration of organic substances from aqueous solutions

The regularities of the dynamic solid-phase extraction of organic substances (exemplified by chloroform, butyl acetate, and diethyl ether) from aqueous solutions on composite surface-layer sorbents, in which a finely dispersed sorption-active carbon material (active carbon or nanocarbon) was supported onto the surface of porous polytetrafluoroethylene, were found. It was demonstrated that the efficiency of the sorbents developed was higher than that of traditional bulk porous sorbents used for the preconcentration of volatile organic substances from aqueous solutions.