Thin-layer chromatographic behavior of a number of metals on carboxymethyl-cellulose in sulfuric acid and ammonium sulfate media

Summary The thin-layer chromatographic behavior of 57 metals on a weakly acidic cation exchanger, carboxymethyl (CM) cellulose, has investigated systematically in sulfuric acid (0.01–1.0 M) and the acidic ammonium sulfate media. Thin-layer plates of a microcrystalline cellulose, Avicel SF, were also used to compare with the chromatographic behavior of the metals in the acidic sulfate system. The Rf values obtained for many metals tested on CM-cellulose plates increase with increasing concentration of sulfuric acid. Most of metals tested are distributed chromatographically on the CM-cellulose in the low acid concentration. The characteristic retention of many metals, including sulfato-complexes forming metals, on the CM-cellulose can be observed in ammonium sulfate solutions of a low concentration of the acid. Useful multicomponent separations of analytical interest on CM-cellulose layers are presented to demonstrate the use of Rf measurements for predicting separations in the acid and the acidic ammonium sulfate systems.     

改性膨润土催化乙醇流化床脱水制乙烯

以浸渍法制备的改性膨润土为催化剂,在自行设计的流化床装置上评价了乙醇脱水制乙烯的催化性能;采用X-射线衍射（XRD）、傅里叶变换红外（FT-IR）、扫描电镜（SEM）、比表面分析（BET）和热重分析（TG）等手段对催化剂的理化性能进行表征,同时考察了不同催化剂制备条件和催化反应条件等工艺因素对催化剂性能的影响。结果表明,当硫酸质量分数为44％,水洗至pH值为4～5,添加0．15g混合氯化稀土,反应温度为270℃,乙醇的进样流速为013mL／min,催化剂用量3g,催化反应的活性最佳,出口乙烯气体的体积分数可达8．56×10^-1。     

Retention behavior of carboyxlic acids on highly cross-linked poly(styrene-divinylbenzene)-based and silica-based cation exchangers

A highly cross-linked porous poly(styrene-divinylbenzene) resin was reacted with sulfuric acid to give strong cation-exchange resins with capacities from 0.2 to 1.9 mequiv./g. The retention behavior of mono- and dicar☐ylic acids on these resins was compared with results obtained from silica-based cation exchangers functionalized with alkylsulfonic acid or phenylsulfonic acid groups. The contribution of different retention mechanisms like ion exclusion, hydrophobic interaction and adsorption to the separation of the analytes on these chromatographic supports was discussed. Additionally the applicability of silica-based cation exchangers was tested in the field of silage analysis.     

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.     

Kinetic Regularities of the Kabachnik–Fields Reaction under Catalysis by Sulfonic Cation Exchangers Based on Petroleum Asphaltenes

Kinetics and Catalysis - Strongly acidic cation exchangers were obtained by the sulfonation and successive sulfonation and nitration of petroleum asphaltenes. The cation exchangers were...     

Isolation of transplutonium elements on ion exchangers from solutions of high salt concentration

The behaviour of transplutonium elements (TPE) on cation and anion exchangers in aqueous alcoholic solutions of chlorides and nitrates of some alkali and alkaline earth metals as depending on different factors: salt concentration, content of alcohol and of acid in the solution as well as the nature of a cation has been studied. The data obtained were used to determine the optimal conditions of concentration of TPE on ion exchangers from solutions containing great quantities of salts. The advantages of the use of aqueous alcoholic solutions of nitric acid in the isolation of TPE from such solutions have been shown.     

Ion-exchange high-performance liquid chromatography of nucleotides and polypeptides on new types of ion-exchange sorbents, based on polystyrene-coated silicas.

A novel type of ion exchanger was prepared by multipoint covalent binding of polystyrene chains onto the surface of porous silica followed by polymer-analogous modification of the bonded layer. Both anion and cation exchangers were synthesized and examined in the separation of nucleotides and proteins. Rapid and efficient separation of basic polypeptides on strong anion exchangers and that of acidic polypeptides on strong cation exchangers could be achieved. For the separation of complete mixtures of polypeptides the application of zwitter-ionic ion exchangers can be recommended.     

Vapor—phase Nitration of Benzene to Nitrobenzene over Supported Sulfuric Acid Catalyst

Nitrobenzene is an important chemical intermediate for producing dyestuffs. It is also used as a solvent. The industrial synthesis of nitrobenzene has been carried out in liquid phase with a mixture of nitric acid and concentrated sulfuric acid. This conventional nitration process still has some unsolved problems such as treatment of waste sulfuric acid and disposal of wastewater. The vapor-phase nitration of benzene to prepare nitrobenzene over the solid acidic catalysts in diluted nitric…     

ELECTRIC REGENERATION METHOD OF ION EXCHANGE RESIN IN THE MIXED BED

In this paper,the self-regeneration process of the mixed resins consisting of cation and anion ion exchangers in the electrolialyser of the packed bed is analyzed,and an electric regeneration method is put forward to supply the desalinated water by mixed bed.The electric regeneration technology is a new one used for regeneration of the exhausted ion exchangers in the mixed bed,instead of the traditional regenerating process by using acid and alkali liquor.Electric energy is consumed to regenerate the ion exchangers loaded by salts from water treatment without any chemicals-acid and alkali.The advantage of the electric regeneration process exhibited convenient operation,no discharge any waste,and therefore no pollution to the receiving water body and the environmental ground.     

Electrochemical reduction of oxygen at a porous flow-through electrode

The electrochemical reduction of oxygen at a porous flow-through electrode is described with emphasis on the effects of concentration, flow speed and surface area. On a packed bed copper electrode in sulfuric acid, it was found that oxygen undergoes a two electron reduction process giving rise to H₂O₂.     

Allylacetylenes and their derivatives as inhibitors of steel corrosion in sulfuric acid

New functionalized derivatives of allylacetylenes were prepared, and their ability to inhibit corrosion of St.3 low-carbon steel in 5 N sulfuric acid was studied. The effectiveness of inhibition of steel corrosion was studied in relation to the structure of acetylene derivatives, their concentration, and temperature of acidic medium.     

Ion-exchange recovery of nickel(II) and cobalt(II) from sulfuric acid solutions

Sorption recovery of nickel(II) and cobalt(II) in their joint presence in sulfuric acid solutions was studied on new samples of domestic ion exchangers of CYBBER brand. It was shown that the ion exchangers under study have a high sorption capacity for ions of both nonferrous metals, depending on the structure of a sorbent and on the acidity of a contacting solution. It was found that, after Co(II) and Ni(II) ions are extracted from weak or strong sulfuric acid solutions, they can be effectively eluted from the ion exchangers under study with a 2 M hydrochloric acid solution to an extent of 85–95% (nickel) and 87–95% (cobalt).     

双功能聚合物基质阳离子交换固定相的制备及其在离子色谱中的应用

离子色谱是分离分析阳离子型化合物的重要手段之一。高效阳离子交换固定相的制备研究对离子色谱技术的发展具有重要的意义。该文以丙烯酸和顺丁烯二酸酐为单体,2-巯基乙基磺酸钠为巯基改性剂,提出了聚合物基质微球巯基改性自由基聚合修饰方法,用以制备新型双功能的阳离子交换固定相。该固定相以羧基和磺酸基为功能基,仅用简单的强酸淋洗液便可以实现常规阳离子的基线分离。利用色谱学模型,对金属离子和有机胺的保留行为进行了研究。采用梯度淋洗模式,可在24 min内实现10种阳离子的分离,表明固定相具有优异的色谱性能。"巯基-烯"修饰方法简单、高效。此外,通过调节巯基改性剂的比例能够实现对固定相交换能力的调控。     

Reaction kinetics of lactic acid with methanol catalyzed by acid resins

The esterification of aqueous lactic acid solution with methanol and its reverse reaction catalyzed by acidic cation exchange resins in the H⁺ form were carried out in a batch system. The inhibiting effects of water and methanol on the resins were evaluated. The experimental data were correlated by a kinetic model that the inhibition by methanol and water was included. The reaction rate constants and the adsorption coefficients were determined from the experiments. The activity of acidic resin was compared with that of sulfuric acid as catalyst. © 1996 John Wiley & Sons, Inc.     

Extraction of mercury by inert solvents from pure and mixed acids

The extraction of mercury by inert solvents has been investigated as a function of the hydrochloric and sulfuric acid concentration in the aqueous phase. It was found that the extraction of mercury with kerosene is adequate at low hydrochloric acid concentrations but decreases with the increasing acid concentration. In the case of sulfuric acid a maximum and/or a minimum are noticed. The presence of trace halides in the aqueous phase changes the shape of the relation between the distribution of mercury and the sulfuric acid concentration in the aqueous phase. The extraction of mercury by neutral, anion and cation exchange reagents was also investigated.     

Characterization of Nitro-Substituted Polybenzimidazole Synthesized by the Reaction with Nitric Acid

Abstract

Nitro-substituted poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole]s (PBIs) were synthesized by the reaction of PBI with nitric acid in sulfuric acid under various conditions. The number of nitro groups substituted on the aromatic ring of PBI per polymeric unit varied from 1.44 to 3.55 according to the reaction conditions. An increase in reaction temperature and concentration of the nitric acid increased the degree of substitution. The inherent viscosity of the substituted polymer increased as the reaction temperature decreased. When the reaction temperature was 30°C, the inherent viscosity of the polymer increased as the concentration of nitric acid increased. The nitro-substituted PBI exhibited polyelectrolyte behavior in formic acid. The nitro groups substituted on PBI were dissociated when the polymer was heated to 450°C, displaying exothermic behavior, and the decomposition of polymer was proportional to its nitro group content. All nitro-substituted PBIs showed better solubilities in polar aprotic and acidic solvents, such as dimethylacetamide, dimethylsulfoxide, dimethylformamide, N-methylpyrrolidone, formic acid, sulfuric acid, and trifluoromethanesulfonic acid.     

New phosphorus-containing sorbents based on wheat straw and glycidyl methacrylate for Hg<Superscript>2+</Superscript> removal

The possibility of preparing new phosphoric acid cation exchangers based on wheat straw and glycidyl methacrylate was explored. The mercury(II) ion sorption properties of the prepared cation exchangers were studied.     

Synthesis and properties of noncyclic polyether compounds. Part V : The influence of acid and concentration of cations on the uphill transport rates of cations and selectivities through liquid membranes by synthetic,noncyclic polyether ionophores

The effects of acid and cation concentration on the uphill transport rates of cations and selectivities through chloroform liquid membrane by noncyclic polyether ionophores, which are pentaethylene glycol derivatives containing both 8-quinolyt and o-carboxylphenyl terminal groups, have been demonstrated. Using sulfuric, oxalic, or polyphosphoric acid in aqueous solution, the initial transport rates and the amount of cation transported by the ionophores after two days were larger than those using hydrochloric or nitric acid. Using picric acid, the amount of cation transported decreased greatly. It was confirmed that it decreased where an acid could easily be counter-transported by the ionophore through liquid membranes. On the other hand, it was found that the rates, amounts of cation transported, and selectivities, change with the changing of the cation concentration in the aqueous solutions. When the cation concentration in both aqueous solutions is high enough compared with the pH gradient between the two aqueous solutions, the rate, amount, and selectivity of the ionophore for potassium ion increases compared with when the cation concentration is low.