层状双金属氢氧化物吸附性能的研究进展

面对日益严重的水污染,层状双金属氢氧化物(LDHs)可以作为一种良好的吸附剂。近年来,国内外在水污染方面针对其结构和吸附性能进行了深度的研究。LDHs由于具有良好的阴离子交换特性以及特殊的结构记忆效应,在水污染处理工作中逐渐得到重视。讲述了LDHs的结构与特性以及在吸附中的应用,对LDHs的发展方向进行了展望。

负载型NaOH/蒙脱石固体碱催化剂的制备及在生物柴油中的应用

多相催化生产生物柴油因其环境友好和经济效益突出而成为研究热点。以高纯蒙脱石为原料,用HCl酸化制得活性白土,再用Ca(OH)_2改性,制备出具有阴离子交换性的碱性蒙脱石,然后负载NaOH制备蒙脱石固体碱催化剂,并将其用于制备生物柴油的酯交换反应。结果表明,在m(NaOH):m(碱性蒙脱石)=0.7、负载时间18 h和碱性蒙脱石中OH含量为1.41 mmol·g^(-1)条件下,NaOH负载量可达4.1 mmol·g^(-1),催化大豆油醇解制备生物柴油的酯交换率可达91.8%,明显优于KOH,且催化剂易回收,污染小。

Identification of Fucans from Four Species of Sea Cucumber by High Temperature ~1H NMR

Acidic polysaccharide, which has various biological activities, is one of the most important components of sea cucumber. In the present study, crude polysaccharide was extracted from four species of sea cucumber from three different geographical zones, Pearsonothuria graeffei(Pg) from Indo-Pacific, Holothuria vagabunda(Hv) from Norwegian Coast, Stichopus tremulu(St) from Western Indian Ocean, and Isostichopus badionotu(Ib) from Western Atlantic. The polysaccharide extract was separated and purified with a cellulose DEAE anion-exchange column to obtain corresponding sea cucumber fucans(SC-Fucs). The chemical property of these SC-Fucs, including molecular weight, monosaccharide composition and sulfate content, was determined. Their structure was compared simply with fourier infrared spectrum analyzer and identified with high temperature 1H nuclear magnetic resonance spectrum analyzer(NMR) and room temperature 13 C NMR. The results indicated that Fuc-Pg obtained from the torrid zone mainly contained 2,4-O-disulfated and non-sulfated fucose residue, whereas Fuc-Ib from the temperate zone contained non-, 2-O- and 2,4-O-disulfated fucose residue; Fuc-St from the frigid zone and Fuc-Hv from the torrid zone contained mainly non-sulfated fucose residue. The proton of SC-Fucs was better resolved via high temperature 1H NMR than via room temperature 1H NMR. The fingerprint of sea cucumber in different sea regions was established based on the index of anomer hydrogen signal in SC-Fucs. Further work will help to understand whether there exists a close relationship between the geographical area of sea cucumber and the sulfation pattern of SC-Fucs.

Kinetic Model of Resin-Catalyzed Decomposition of Acetone Cyanohydrin in Organic Solvent

Decomposition of acetone cyanohydrin is the first-step reaction for preparing (S)-α-cyano-3-phenoxybenzyl alcohol (CPBA) by the one-pot method in organic media. Considering the compatibility of biocatalysts with chemical catalysts and the successive operation in the bioreactor, anion exchange resin (D301) was used as catalyst for this reaction. External diffusion limitation was excluded by raising rotational speed to higher than 190r·min^-1 in both solvents. Internal diffusion limitation was verified to be insignificant in this reaction system. The effect of acetone cyanohydrin concentration on the reaction was also investigated. An intrinsic kinetic model was proposed when the mass transfer limitation was excluded, and the average deviation of the model is 10.5%.

An advanced partitioning process for key elements separation from high level liquid waste

To separate MA （Am, Cm） and some fission product elements （FPs） such as Tc, Pd, Cs and Sr from high level liquid waste （HLLW） systematically, we have been studying an advanced aqueous partitioning process, which uses selective adsorption as the separation method. For this process, we prepared several novel adsorbents which were immobilized in a porous sili- c^polymer composite support （SiO2-P）. Adsorption and separation behavior of various elements was studied experimentally in detail. Small scale separation tests using simulated HLLW solutions were carried out. Pd（II） was strongly adsorbed by the AR-01 anion exchanger and effectively eluted off by using thiourea. Successful separation of Pd（ll） from simulated HLLW was achieved. Te（VII） also exhibited strong adsorption on AR-01 and could be eluted off by using U（IV） as a reductive eluent. Am（Ⅲ） presented significantly high adsorbability and selectivity onto R-BTP/SiOz-P adsorbents over various FPs including Ln（Ⅲ）. The R-BTP adsorbents were fairly stable in 3 M HNO3, but instable against 7-irradiation-3M HNO3. An advanced par- titioning process consisting of three separation columns for the target elements separation from HLLW was proposed and the obtained experiment results indicated that the proposed process is essentially feasible.

Stable ZnO/ionic liquid hybrid materials: novel dual-responsive superhydrophobic layers to light and anions

Novel dual-responsive superhydrophobic hybrid materials, ZnO/SAMs （self-assembled monolayers） of ionic liquids （ILs） with different counter-anions （I^-, BF4^-, PF6^- and Tf2N^-）, were synthesized and characterized. ZnO nanoparticles were first deposited on glass surfaces to produce roughness. Next, SAMs of fluorinated-alkyl-3-（3-triethoxysilylpropyl）-4,5-dihydro-imidazoliumiodide （abb. [C8Ftespim]I） were grafted onto these surfaces via -Si-O- covalent bonds using self-assembly technique. The I- ion could be subsequently exchanged with BF4, PF6-or Tf2N- through a simple aqueous anion-exchange reaction. The ZnO/ILs hybrid layers were characterized by atomic-force microscopy （AFM）, scanning-electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS）. Their wettability was estimated through the measurements of static and dynamic contact angles （CAs）. Compared to corresponding films of ZnO/[CsFtespim]I with CAs 140.7° ±2.0°, films of ZnO/[CsFtespim]PF6 and ZnO/[CsFtespim]Tf2N showed CAs with 154.0° ± 2.0° and 152.0° ± 2.0°, respectively that remained for a long time. This result suggests that anion-exchange can afford superhydrophobic materials. In addition, the wettability of ZnO/[CsFtespim]X hybrid layers can be reversibly switched by altering ultraviolet （UV） irradiation and dark storage, which shows a photo-induced reversible switch of wettability. The synergistic action of ZnO nanoparticles and SAMs of ILs produced light-anion dual-responsive superhydrophobic materials with ideal stability.

Anion exchange membranes based on long side-chain quaternary ammonium-functionalized poly(arylene piperidinium)s for vanadium redox flow batteries

A new series of poly(arylene piperidinium)-based anion exchange membranes(AEMs)are proposed for vanadium redox flow batteries(VRFBs).The AEMs are fabricated via the Menshutkin reaction between poly(arylene piperidine)without ether bonds in the backbone and various quaternizing agents,including iodomethane,1-bromopentane,and(5-bromopentyl)-trimethylammonium bromide.The properties of the AEMs are investigated in terms of sulfuric acid doping content,swelling,vanadium permeability,ion selectivity,area-specific resistance,mechanical properties,VRFB performance,and cyclic testing.Particularly,a method of measuring the H^(+) permeability of the AEM is developed.It demonstrates that the poly(p-terphenyl-N-methylpiperidine)-quaternary ammonium(PTP-QA)membrane with a QA cation-tethered alkyl chain exhibits high H^(+) permeability,resulting in low area resistance.Combined with its low vanadium permeance,the PTP-QA membrane achieves nearly 370 times higher ion selectivity than Nafion 115.The VRFB based on PTP-QA-based AEM displays high Coulombic efficiencies above 99% at current densities of 80-160 mA cm^(-2).The higher energy efficiency of 89.8% is achieved at 100 mA cm^(-2)(vs.73.6% for Nafion 115).Meanwhile,the PTPQA-based AEM shows good cycling stability and capacity retention,proving great potential as the ion exchange membrane for VRFB applications.

Highly conductive and robust composite anion exchange membranes by incorporating quaternized MIL-101(Cr)

With well-defined channels and tunable functionality, metal-organic frameworks （MOFs） have inspired the design of a new class of ion-conductive compounds. In contrast to the extensive studies on proton- conductive MOFs and related membranes attractive for fuel cells, rare reports focus on MOFs in preparation of anion exchange membranes. In this study, chloromethylated MIL-101 （Cr） was prepared and incor- porated into chloromethylated poly （ether ether ketone） （PEEK） as a multifunctional filler to prepare imidazolium PEEK/imidazolium MIL-101（Cr） （ImPEEK/ImMIL-101（Cr）） anion exchange membrane after synchronous quaternization. The successful synthesis and chloromethylation of MIL-101（Cr） were veri- fied by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy while the enhanced performance of composite membranes in hydroxide conductivity, mechanical strength and dimensional stability were evaluated by alternating-current impedance, electronic stretching machine and measurement of swelling ratio. Specifically, incorporating 5.0wt% ImMIL-101（Cr） afforded a 71.4% increase in hydroxide conductivity at 20℃, 100% RH. Besides, the composite membranes exhibited enhanced dimensional stability and mechanical strength due to the rigid framework of ImMIL- 101（Cr）. At room temperature and the ImM1L-101（Cr） content of 10wt%, the swelling ratio of the ImPEEK/lmMIL-101（Cr） was 70.04% lower while the tensile strength was 47.5% higher than that of the pure membrane.

Facial synthesis of highly stable and bright CsPbX(X=Cl,Br,I)perovskite nanocrystals via an anion exchange at the water-oil interface

Cesium lead halide perovskite nanocrystals(NCs)have attracted unprecedented attention owing to their compelling properties for optoelectronic applications.Compared with the classical hot-injection method,the roomtemperature(RT)synthetic strategy is more facile and tender,but it is hard to obtain stable CsPbI3 NCs and it usually uses polar solvents that sometimes reduce the stability and properties of NCs.Here,we reported a simple approach to synthesize highly efficient and stable CsPbI3 as well as other colortunable CsPbX3 NCs with high quantum efficiency at room temperature via an anion exchange at the water-oil interface,in which the as-synthesized pristine CsPbBr3 NCs in toluene were treated in aqueous solutions of HX(X=Cl,Br,and I)and protonated oleylamine(OAm)acted as a carrier.The synthesized CsPbI3 NCs had an emission at 680 nm and even showed excellent colloidal stability after being stored for 32 d.The high efficiency and stability of the obtained CsPbX3 NCs were ascribed to the facts that:(ⅰ)the polar reagents were almost removed from the surface of NCs;(ⅱ)the defect-related nonradiative recombination was suppressed efficiently by surface passivation.