Keggin型Ni-Mo-Zr杂多酸盐的合成、表征及催化超声降解性能

采用水热合成法制备了Keggin型结构的Ni-Mo-Zr杂多酸盐,并利用红外光谱（IR）和X射线衍射仪（XRD）对合成的产物进行了表征。以酸性绿B（AGB）为目标物,研究了在超声波辐射下,Ni-Mo-Zr杂多酸盐的投加量、染料废水初始浓度、pH值等因素对降解效果的影响。实验结果表明：新合成的杂多酸盐具有Keggin型结构,当催化剂的投加量为0.8 g/L,染料废水的初始浓度为10 mg/L,初始pH=5时,用 40 kHz超声频率辐射60 min,染料废水的降解率最高可达90.2%。通过动力学分析,降级反应符合一级反应动力学模型,降解速率随初始浓度的增加而减小。     

Keggin结构钼磷和钼硅杂多酸盐热稳定性研究

本文用ＴＧ－ＤＴＡ、ＤＳＣ热谱、变温红外光谱、Ｘ射线衍射和溶解性实验方法，对四十一种Ｋｅｇｇｉｎ结构钼磷和钼硅杂多酸的碱金属、碱土金属、过渡金属、希土元素以及有机阳离子盐的热稳定性进行了系统的研究，初步讨论了影响热稳定性的因素．得到了一些有意义的结论．     

新型杂多酸盐光催化降解亚甲基蓝染料废水

以水热自组装法合成的新型杂多酸盐[PMo₈V₆O₄₂][Co(Phen)₂][Him]₂·2H₃O·3H₂O(1),通过红外光谱、拉曼光谱、紫外-可见光谱、光电子能谱和X粉末衍射等技术手段进行表征。 以此物质为催化剂光催化降解亚甲基蓝染料废水。 分别讨论催化剂投加量、亚甲基蓝废水初始浓度、废水溶液酸度(pH)对亚甲基蓝降解率的影响。 实验结果表明:催化剂投加量为50 mg/L、亚甲基蓝初始浓度为4 mg/L、模拟废水溶液的初始pH=1、降解时间220 min时,废水降解率可达到99.2%。 光催化动力学分析显示,以合成杂多酸盐为催化剂光催化降解亚甲基蓝废水降解过程满足一级动力学方程,该一级方程反应速率常数为0.0144 min^-1,拟合常数为0.9918。 另外,此催化剂还表现出较好的重复使用性能,连续使用5 次后降解率仍为92.4%。     

可见光照射下取代型杂多酸盐对染料的催化降解

将杂多酸(GaWmFen)负载到阴离子交换树脂(Resin)上,得到GaWmFen/Resin(GaWmFenR)固相光催化剂,在可见光的照射下,以罗丹明B(RhB)为模型化合物,含镓的GaWmFen/Resin(GaWmFenR)催化剂可以有效地活化H2O2降解染料RhB,随着铁原子的取代数目的增多,RhB浓度比降低的趋势加快,GaW9Fe3最快,C/C0降低0.937.在光照300 min 以后,体系的总有机碳(TOC)的变化趋于平缓,减少了0.15 mg.L-1.催化剂的8次重复试验结果表明GaWmFenR固相光催化剂易于分离,并且具有良好的稳定性,可以重复利用.     

三缺位Keggin型磷钨杂多酸盐高选择性催化氧化环己烯

利用三缺位Keggin型杂多酸[A-α-PW9O34]9-和[(FeШ(OH2)2)3(A-α-PW9O34)2]9-的四丁基铵盐做为催化剂,H2O2做为氧化剂催化环己烯氧化反应. 考察了反应时间、H2O2与环己烯的摩尔比,催化剂的用量等因素对反应结果的影响. 结果表明：在1, 2-二氯乙烷为10 mL,H2O2 (30 %)与环己烯的摩尔比为2,反应温度为35 oC,反应时间为6 h,[(C4H9)4N]9[A-α-PW9O34]为催化剂的条件下,环己烯氧化反应的转化率为55 %,主要产物是环氧环己烷,其选择性 ≥ 99 %;而以[(C4H9)4N]9[(FeШ(OH2)2)3(A-α-PW9O34)2]为催化剂时环己烯氧化反应的转化率17 %,主要产物是2-环己烯-1-酮,选择性 ≥ 99 %.     

Keggin结构钼系杂多蓝的离析和性质研究

本文报道了八种1:12系列钼系杂多蓝KyHzXMo_(12)O_(40)·nHp(X=Si,P,As,Ge)的制备和离析方法,并通过元素分析、电位滴定、极谱、循环伏安、红外光谱、可见-紫外光谱、X射线粉末衍射、XPS和~(31)PNMR对产物进行了表征。测定了四电子钼硅杂多蓝的单晶结构,确定了还原钼原子的位置是第三位、七位、八位、十位。实验结果表明,杂多蓝仍基本保持了Keggin结构。首次系统研究了八种杂多蓝固体的ESR谱,发现二电子、四电子杂多蓝比一电子杂多蓝具有更小的电子离域程度;热性质研究表明,固体杂多蓝随还原程度增大,热稳定性增强;研究其氧化还原性质发现,在不同介质中,杂多蓝的氧化序发生变化,极谱半波电位与杂原子电负性线性相关。并发现P和As的杂多蓝具有极强的抗酸解能力。     

新奇的双帽Keggin型铬钒磷杂多化合物的合成

用水热合成方法首次合成了一种用低价过渡金属元素Cr(Ⅲ )取代的高钒杂多化合物M13 PV12 Cr2 O4 2 ·2 1H2 O(M =K或H) ,通过元素分析、UV、IR以及XRD谱等对其进行了表征 ,认为其阴离子具有双帽Keggin结构     

单空位Keggin结构杂多化合物的相转移化学研究(英文)

利用相转移试剂四庚基溴化铵将含过渡金属单空位Ｋｅｇｇｉｎ结构杂多化合物［ＸＷ１１Ｏ３９Ｚ（Ｈ２Ｏ）］ｎ－（Ｘ＝Ｃｒ，Ｍｎ，Ｆｅ；Ｚ＝Ｃｏ，Ｚｎ，Ｃｒ；ｎ＝６，７），从水相转移至非极性溶剂有机相苯中．并根据电子光谱、ＩＲ谱、ＥＳＲ谱的变化，进一步考察了它们在有机相苯中的配位水脱去，形成配位不饱和杂多阴离子的情况，同时详细研究了该类杂多阴离子所含表面配位水与若干无机阴离子及有机配体的取代反应．实验表明，杂多阴离子由水相转移至有机相苯后，较易脱去配位水形成溶剂配位不饱和离子．当加入Ｌｅｗｉｓ碱时，可迅速恢复饱和配位．ＥＳＲ测定给出某些含过渡金属单空位Ｋｅｇｇｉｎ结构杂多阴离子相转移前后价态变化及电子转移情况．     

α—Keggin结构钼硅酸两电子还原杂多蓝的合成及晶体结构

用电解还原法制得标题化合物H6SiMoγ2Moи10O10·10H2O,该晶体为深蓝色,属三斜晶系,P1空间群,晶胞参数:a=1.4077(3)nm,b=1.4176(3)nm,c=1.3752(2)nm;α=111.04(1)°;β=93.99(1)°,γ=119.09(1)°;Z=2,R=0.52.分析结果表明,钼硅酸还原后八面体有所畸变.     

Keggin结构多金属含氧酸盐的热解性质

用变温XRD、变温IR以及TG-DTA、溶解性实验等方法研究了具有Keggin结构的18种化合物YmHnXM12O40(X=P,Si,Ge;M=W,Mo;Y=NH4+,K+,Cu2+,m和n为抗衡离子数,YmHnXM12)的热解性质.得到了较为准确的热分解温度,探讨了其热分解过程,对其主要的热分解产物作了初步鉴定.对多金属含氧酸盐热分解的判断方法进行了系统研究,提出了新的见解.讨论了影响多金属含氧酸盐热解性质的一些主要因素及其变化规律.     

Keggin结构杂多酸热性质研究

本文利用DSC, TG-DTA, X射线衍射, 变温红外光谱和溶解性试验方法, 系统地研究了Keggin结构杂多酸HnXM12O40(X=Si, P, Ge; M=Mo, W)的热稳定性, 提出杂多化合物热分解的新判据, 给出了Keggin结构杂多酸的热分解过程, 推导出预测热分解温度的半经验公式。     

Racemization on thermal degradation of poly( -lactide) with calcium salt end structure

Poly( -lactide) with calcium salt end structure (PLLA-Ca) is a promising material for PLLA recycling because of the ease of lactide recovery through the unzipping depolymerization process. However, the pyrolysis of PLLA-Ca also causes meso-lactide to form. In this article, the racemization in PLLA-Ca pyrolysis was analyzed in detail with Py-MS, Py-GC/MS, and a glass tube oven. The results suggested that at a temperature lower than 250 °C, nucleophilic attack by a carboxylate anion end on an asymmetrical methyne carbon in a penultimate lactate unit occurred, resulting in the predominant formation of meso-lactide. On the other hand, also at temperatures over 320 °C, by-reactions, such as enolization reactions, caused the meso-lactide to form, but not dominantly. In the temperature range of 250–320 °C, -lactide was produced exclusively, because unzipping depolymerization proceeded as the main reaction. This is a very significant result for PLLA recycling, because PLLA-Ca is an easily recyclable material, which depolymerizes based on the 1st-order weight loss process.     

杂多蓝的研究 I. 具有Dawson结构的钼砷杂多蓝的制备及性质

本文详细地研究了具有Dawson结构的钼砷杂多酸(H6As2Mo18O62)的两电子、四电子、六电子还原杂多蓝的制备条件, 离析出了它们的钾盐、铵盐及四丁基胺盐。找到了合适的电解电位。通过电位滴定、极谱、电子光谱、红外光谱、X射线粉末衍射和光电子能谱的研究, 确证了所希望得到的产物。研究表明, 杂多蓝的结构与还原前相比未发生明显变化。水溶液稳定性的研究指出, 杂多蓝要比还原前的杂多阴离子稳定, 存在的PH范围加宽, 指认了可见-红外区出现的谱带。     

Preparation of BiVO4/MIL‐125(Ti) composite with enhanced visible‐light photocatalytic activity for dye degradation

Because of their desired features, including very specific surface areas and designable framework architecture together with their possibility to be functionalized, Metal Framework (MOF) is a promising platform for supporting varied materials in respect of catalytic applications in water treatment. In this work, a novel visible‐light‐responsive photocatalyst that comprised BiVO₄ together with MIL‐125(Ti), was synthesized by a two‐step hydrothermal approach. The characterization of as‐obtained samples as performed by X‐ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscope, X‐ray photoelectron spectroscopy and ultraviolet‐visible diffuse reflection spectra. Rhodamine B was selected being a target for the evaluation of the photocatalytic function of as‐developed photocatalyst. The photocatalytic reaction parameters, for example, the content of BiVO₄ as well as initial concentration of Rhodamine B was researched. The composite photocatalyst possessing Bi:Ti molar ratio of 3:2 brought to light the fact that the greatest photocatalytic activity had the ability to degrade 92% of Rhodamine B in 180 min. In addition to that, the BiVO₄/MIL‐125(Ti) composite could keep its photocatalytic activity during the recycling test. The phenomenon of disintegration of the photo‐generated charges in the BiVO₄/MIL‐125(Ti) composite was brought to discussion as well.     

Oxovanadium(IV) based hypocrellin B complexes with enhanced photodynamic activity

Hypocrellin B (HB), a naturally occurring photosensitizer, has been extensively and intensively studied as a promising photodynamic therapy (PDT) agent. In this work, three new oxovanadium(IV) complexes were designed and synthesized with HB as a bridging ligand and phen (1,10-phenanthroline, complex 1), tmp (3,4,7,8-tetramethyl-1,10-phenanthroline, complex 2) and dpq (dipyrido[3,2-f:2'3'-h]quinoxaline, complex 3) as terminal ligands. The use of a diimine terminal ligand avoids the formation of polymeric complexes and ensures the three VO(2+)-HB complexes possess a definite molecular formula and molecular weight to meet the single component requirement for an ideal PDT agent. Compared to HB, the VO(2+)-HB complexes exhibit improved water solubility, enhanced absorptivity in the phototherapeutic window, increased binding affinity toward dsDNA, and similar singlet oxygen quantum yield, therefore advanced DNA photocleavage activity. Both the DNA binding constants and photo nuclease activities of the complexes follow the order 2 (tmp) > 3 (dpq) > 1 (phen), demonstrating the importance of the binding affinity to biomolecules, which improves the bioavailability of reactive oxygen species. Our work opens a new avenue for the development of HB-based PDT agents.     

Cyclic Ti9 keggin trimers with tetrahedral (PO4) or octahedral (TiO6) capping groups

We have synthesized the cyclic Ti 9 Keggin trimers [(alpha-Ti 3PW 9O 38) 3(PO 4)] (18-) ( 1) and [(alpha-Ti 3SiW 9O 37OH) 3(TiO 3(OH 2) 3)] (17-) ( 2), which are both composed of three (Ti 3XW 9O 37) units (X = P or Si) linked via three Ti-O-Ti bridges and a capping group, which is either tetrahedral PO 4 ( 1) or octahedral TiO 6 ( 2). Polyanions 1 and 2 were fully characterized in the solid state (IR, X-ray diffraction, thermogravimetric and elemental analyses) and in solution ( (31)P or (183)W NMR).     

A general, one-step and template-free synthesis of sphere-like zinc ferrite nanostructures with enhanced photocatalytic activity for dye degradation

Spinel zinc ferrite nanospheres with diameters of about 212 nm were synthesized in high yield via a general, one-step and template-free solvothermal route. The prepared nanospheres had cubic spinel structure and exhibited good size uniformity and regularity. The absorption edge of ZnFe(2)O(4) nanospheres shifted to a higher energy in the UV-Vis absorption spectrum compared with that of ZnFe(2)O(4) nanoparticles. The ZnFe(2)O(4) nanospheres exhibited remarkably high surface photovoltage response in the UV and visible region, suggesting the enhanced separation ability of photogenerated electrons and holes. The dramatically enhanced photocatalytic activity of the ZnFe(2)O(4) nanospheres was evaluated in the decomposition of rhodamine B under Xe lamp irradiation. Hydroxyl radicals on the surface of photoilluminated ZnFe(2)O(4) nanospheres were detected by the photoluminescence technique, which suggested that hydroxyl radicals played an important role in the photocatalytic reaction. This study provided new insight into the design and preparation of functional nanomaterials with sphere structure in high yield, and the as-grown architectures demonstrated an excellent ability to remove organic pollutants in wastewater.     

Al(III)- CTMAB增敏酸性降解荧光法测定土霉素

The fluorescence characteristics of acid degraded product of oxytetracycline with aluminium(III) in micellar system has been studied.The experiment indicated that oxytetracycline reacts with hydrochloric acid and produces more strong fluorescent species.After CTMAB and aluminium(III)are added in this species,its fluorescence intensity can be enhanced greatly in pH 7.20 Na2HPO4-KH2PO4 buffer solution.Based on this,a new fluorimetric method involving acidic degradation and enhancement by surfactant and aluminium(III)is proposed for the determination of oxytetracyline.The maximum excitation and emission wavelengths are 392nm and 492nm,respectively.The fluorescence intensity is proportional to the concentration of oxytetracycline over the range of 2.01×10-8mol/L～2.10×10-6mol/L with the detection limit of 1.0×10-8 mol/L.The method has been used to the determination of oxytetracycline in tablets with satisfacoty results.