有机锡类农药——三唑锡液相色谱分析

用高效液相色谱分析农药三唑锡,采用强阳离子交换柱,甲醇、水、冰醋酸作流动相以及紫外检测器。结果表明,此法分离效果好,准确度和精密度高,可用于三唑锡生产控制及原药、各种制剂(粉剂、胶悬剂)产品分析。     

Recovery of metals from complexed solutions by electrodeposition

Electrolytic recovery of metals from aqueous solutions containing complexing chelating agents such as EDTA, NTA, and citrate was studied in a two-chamber cell separating with a commercial cation-exchange membrane (CEM). Equimolar solutions of metal and a chelating agent as a catholyte and NaNO₃ as an anolyte were used; the effect of current densities, initial catholyte and anolyte pH, metal concentration and the type of the CEM, chelating agent and metal on the recovery of metals was determined. The recovery of metal increased with higher initial anolyte pH, concentration and current density, whereas it decreased with lower initial catholyte pH. The results show that electrodeposition seems to be an applicable method for the recovery of metals under appropriate conditions.     

Preparation and characterization of polyacrylamide cryogels produced from a high‐molecular‐weight precursor. I. Influence of the reaction temperature and concentration of the crosslinking agent

A new type of cryogel was prepared through a reaction of high‐molecular‐weight polyacrylamide (viscosity‐average molecular weight ≈ 3 × 10⁶ Da) with glutaraldehyde in a moderately frozen aqueous medium. The influence of the crosslinking agent concentration and temperature of the reaction on the gel fraction yield, swelling characteristics, and morphology of the cryogels was investigated. The dependence of the gel fraction yield on the reaction temperature was bell‐shaped. The recognized regularities of the formation of this new type of polyacrylamide cryogel based on a high‐molecular‐weight precursor were very similar to those observed earlier for polyacrylamide cryogels synthesized through the cryopolymerization of monomeric precursors. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Praseodymium and copper cation-exchange capacities of neutral-detergent fibres relative to composition and fermentation kinetics

The cation-exchange capacity (CEC) of 12 neutral-detergent fibres (NDF) was measured using the elements praseodymium (Pr III) and copper (Cu II) at pH 3.5. CEC was positively correlated with lignin and nitrogen content as well as the lignin: acid-detergent fibre ratio of the NDF. CEC was also measured using Pr at pH 7.0. Increasing the pH of exchange from 3.5 to 7.0 significantly increased the CEC. Lignin had a higher correlation with CEC at pH 7.0. The relationship between CEC and the fermentation rates of NDF was non-significant. However, lag, i.e. the period of time before the initiation of fermentation, tended to decrease with increasing CEC. NDF influences the rumen ecosystem by buffering rumen pH, exchanging cations to influence osmotic pressure, and providing substrate and microenvironments for anaerobic microorganisms. Consequently, CEC needs to be measured at conditions which simulate the rumen. It is recommended that the Pr method should be used to measure CEC as it is a simple, yet robust technique that can be buffered to simulate conditions of the entire gastrointestinal tract ranging in pH from 2.0 to 7.0.     

乙酸甲酯的催化精馏水解实验研究

在自行设计的催化精馏塔中,以Amberlyst 35wet阳离子交换树脂为催化剂,全回流操作下,对乙酸甲酯催化精馏水解进行了研究。考察了空速、塔高度、回流进料比(体积比)以及进料中水酯物质的量比等操作条件对水解反应的影响。实验结果表明,在空速0.09 min-1,催化剂装填高度80 cm,提馏段7块塔板,回流进料比5∶1,进料中水酯物质的量比6.5∶1时,乙酸甲酯水解率达到83.5%。     

Super porous α-, β-, γ-cyclodextrin cryogels with high active agent loading and controllable release profiles

Cyclodextrins (CDs) are truncated cone-like structures that are natural cyclic oligosaccharides. Here, a simple preparation method for super porous poly(α-CD), poly(β-CD), and poly(γ-CD) cryogels crosslinking with divinyl sulfone at 150%, 100% and 125% mole ratios with respect to the α-CD, β-CD, and γ-CD molecules, respectively, under cryogenic conditions, is reported. The interconnected homogeneous pore distribution of CD-based cryogels with pore sizes in the range of 5–100 μm is confirmed by SEM analysis. The CD-based cryogels weighing 10 mg are determined as hemocompatible with <1% hemolysis ratios and >79% blood clotting indexes; whereas the same materials weighing 1 mg are biocompatible with >75% cell viability on L929 fibroblasts. Additionally, active agent adsorption/delivery efficiencies of CD-based cryogels utilizing two active agents, Bisphenol A (BPA, a carcinogenic compound) and Curcumin (CUR, a polyphenolic compound), are individually evaluated. It was revealed that p(γ-CD) cryogels exhibited the highest active agent loading capacity for BPA, 87 ± 13 mg/g, whereas p(α-CD) cryogels showed the highest loading capacity for CUR, 136 ± 4 mg/g. Moreover, the active agent release from p(α-CD), p(β-CD), and p(γ-CD) cryogel networks at pH 7.4 and 37°C were determined as 40.6 ± 2, 35.3 ± 2, and 34 ± 1 mg/g for BPA, and 1.07 ± 0.2, 1.27 ± 0.1, and 1.37 ± 0.1 mg/g for CUR, respectively, within 96 h.     

Enhancements in sugar immobilization in polymeric macroporous matrices for affinity capture

The use of macroporous monolithic matrices in the purification of biocompounds is constantly growing and developing. In this work, the objective was to optimize the quantity of N-acetyl-D-glucosamine (D-GlcNAc) immobilized on the surface of macroporous polymeric cryogels for capture of lectins from less clarified solutions. Surface response methodology was applied and it was observed that the immobilization temperature of the glutaraldehyde (GLU) and the D-GlcNAc concentration influenced the amount of sugar immobilized. The matrices produced with 1.1% of allyl glycidyl ether were functionalized by GLU. Optimal maximum condition was obtained with mean value of 160.39 ± 26.38 mg of D-GlcNAc immobilized per gram of dry cryogel. Characterization analyses of the matrices showed that the activation process was effective, maintaining the macroporous structure and physical characteristics. The adsorbents produced were tested for capture of lectins from a crude protein solution of barley. At tested conditions, adsorbent capture around 11% of protein in solution but reduce the hemaglutinating capacity in 40%, demonstrating its selectivity. The cryogels functionalized with D-GlcNAc present potential for use in capture compounds by affinity with carbohydrates, such as lectins. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47956.     

Preparation of polyacrylamide-based supermacroporous monolithic cryogel beds under freezing-temperature variation conditions

Continuous supermacroporous monolithic cryogel is a novel sponge-like chromatographic adsorbent for bioseparation in downstream process and it is always prepared under a constant freezing-temperature condition. In this work, polyacrylamide-based supermacroporous monolithic cryogel beds in different inner diameter glass columns (I.D. 10, 16 and 26 mm) have been prepared by radical cryogenic copolymerization process under the condition of freezing-temperature variation. The matrix microstructure morphologies of these cryogels were analyzed by scanning electron microscopy (SEM) and the axial liquid dispersion characteristics in these cryogel beds were also analyzed by measuring the residence time distributions (RTDs). The formation of cryogel bed under the present situation has been considered as a coinstantaneous process of solvent crystal growth and polymeric monomer copolymerization. Effects of freezing-temperature variation route, cooling rate and redox initiator concentration on the cryogel microstructure and the liquid dispersion characteristics were investigated experimentally to reveal the cooperative mechanisms of these two processes on the formation of cryogel bed. The results showed that the cryogel pore-structures and the axial liquid dispersion coefficients in the cryogel beds depended strongly on the cooling condition, which controls the solvent crystallization process, and the redox initiator concentration, which influences the monomer polymerization.     

PDMA cryogel beads as a catalyst for hydrogen generation from NaBH4 alcoholysis

Poly[2-(dimethylamino)ethyl methacrylate] cryogel beads were prepared under cryogenic conditions via free radical polymerization and used as a catalyst in the production hydrogen (H₂) from NaBH₄ by alcoholysis. The efficiency of the catalyst was investigated in the range of 0–40 °C by both methanolysis and ethylene glycolysis reactions, and its reuse was tested. Accordingly, it was observed that the methanolysis reaction was faster than the ethylene glycolysis reaction. When the hydrogen generation rate (HGR) values between 0 and 40 °C were compared, it was concluded that the methanolysis reaction rate increased from 1550 to 4800 mL.min⁻¹g⁻¹ and the ethylene glycolysis reaction rate increased from 923 to 3551 mL.min⁻¹g⁻¹. In the alcoholysis reaction catalyzed by PDMA cryogel beads, the activation energy was calculated as 19.34 and 22.77 kJ.mol⁻¹ for the methanolysis and ethylene glycolysis reactions, respectively. After six repetitions, the catalyst activity was calculated over 50% for NaBH₄ methanolysis and ethylene glycolysis.     

Electrochemical synthesis of 2,2′-dichlorohydrazobenzene from o-chloronitrobenzene on a porous Ni/Fe electrode

We develop a novel method of synthesizing 2,2′-dichlorohydrazobenzene (DHB) from o-chlornitrobenzene (o-CNB) in a membrane-separated cell on a porous Ni/Fe-combined electrode. PbO particles are used as a catalyst and are dispersed finely over and in the electrode surface. The morphology and microstructure characteristics of electrode materials are characterized by SEM and XRD analyses. The influences of the cathodic surface morphology, electrolyte temperature, and initial concentration of o-CNB are investigated by liquid chromatography and electrochemistry. A moderate current density (e.g., 5.2 A/dm²) and temperature (70 °C) are beneficial to improving hydrogenation reduction, current efficiency, and yield, which could reach 85% when density is adjusted and 91% when the temperature is adjusted.