Determination of hydroxyl radical in Fenton system

Under visible light illumination,2,3-diaminophenazine(DAPN) was generated from the oxidation of o-phenylenediamine (OPDA) in Fe~(3+)/H_2O_2 solution.Hydroxyl radical(~·OH) produced in this system was determined by directly measuring the concentration of DAPN.In comparison with the traditional methods,the determination is more accurate and simple.     

Synthesis and properties of magnetic zeolite with good magnetic stability from fly ash

Magnetic fly ash-based zeolites (MFZ) with good magnetic stability were in situ synthesized from fly ash (FA) modified by Fe₃O₄ after alkali fusion, hydrothermal treatment, and followed by reduction. The effects of the synthesis parameters of MFZ, such as the loading amount of Fe₃O₄, NaOH/FA ratio, and SiO₂/Al₂O₃ molar ratio, were investigated as well as its adsorption capacity for Cu²⁺ ions. The results indicated that MFZ were composed of zeolite A and sodalite phases and possessed excellent magnetic property. Fe₃O₄ nanoparticles were encapsulated in or covered below the as-synthesized zeolites, resulting in a good magnetic stability of MFZ. The magnetic property and crystal type of MFZ could be adjusted by controlling the synthesis parameters. High loading amount of Fe₃O₄ hindered the leaching of active SiO₂ from FA and then limited the formation of zeolite A. MFZ exhibited a high adsorption capacity for Cu²⁺ ions and the latter increased with the amount and crystallinity of zeolite A in MFZ.

Open image in new window

     

Rapid synthesis of zeolitic imidazolate framework-8 (ZIF-8) nanocrystals in an aqueous system

We report here the first example of ZIF materials synthesized in aqueous solution. The synthesis was performed at room temperature and typically took several minutes compared to hours and days in non-aqueous conditions. The obtained product were ZIF-8 nanocrystals having size of ~85 nm and showed excellent thermal, hydrothermal and solvothermal stabilities.     

火焰原子吸收法同时测定地质样品中金和银

二氯化锡还原，二氯化汞共沉淀，火焰原子吸收法同时测定地质样品中金和银。对于原矿和尾矿样品，金含量为５．１５μｇ／ｇ，４．４５μｇ／ｇ和０．５４μｇ／ｇ时，相对标准偏差分别为６．２％，３．４％和４．１％。银含量为９．７８μｇ／ｇ和１．２２μｇ／ｇ时，相对标准偏差分别为４．４％，３．５％和１２．５％。金的分析结果与参考值基本一致。金和银的回收率分别为８８－１０２％和８５－１００％。方法具有干扰小，分离     

共沉淀分离富集-电感耦合等离子体原子发射光谱法测定高纯氧化钨中痕量金属杂质

提出了以Ｌａ（ＯＨ）３为共沉淀剂，对高纯氧化钨中的痕量金属杂质元素经共沉淀预分离富集后进行ＩＣＰ－ＡＥＳ测定的分析方法。探讨了影响杂质元素回收率和钨残留量的若干因素，确定了合适的分离富集条件。合成试样和标准样品的测试结果表明： Ｂｉ、Ｃａ、Ｃｄ、Ｃｏ、Ｃｕ、Ｆｅ、Ｍｇ、Ｍｎ、Ｎｉ、Ｐｂ、Ｓｂ、Ｓｎ、Ｔｉ等元素能被定量分离回收，回收率和精密度均令人满意。     

α-吡咯烷酮乙酸甲酯的H P LC测定

建立了测定α -吡咯烷酮乙酸甲酯的反相高效液相色谱法。采用的流动相为甲醇 -水 -四氢呋喃 (体积比30∶68∶2) ,流动相pH3.0,柱温45℃ ,流量梯度洗脱,检测波长208nm。在该条件下α -吡咯烷酮乙酸甲酯与相关物质的色谱峰分离完全,测定α -吡咯烷酮乙酸甲酯 ,含量为90 %～94 %时SD为0.59 %～0.72 % ,RSD为0.65 %～0.77 % ,与化学法相比 ,测定结果一致。     

Advances in the Synthesis of Crystalline Metallosilicate Zeolites via Interlayer Expansion

Given the numerous industrial applications of zeolites as adsorbents, catalysts, and ion-exchangers, the development of new zeolite structures is highly desired to expand their practical applications. Currently, a general route to develop new zeolite structures is to use interlayer expansion agents to connect layered silicates. In this review, we briefly summarize the novel zeolite structures constructed from the lamellar precursor zeolites MWW, RUB-36, PREFER, Nu-6(1), COK-5, and PLS-1 via interlayer expansion. The contents of the summary contain detailed experiments, physicochemical characterizations, possible expansion mechanisms, and catalytic properties. In addition, the insertion of metal heteroatoms (such as Ti, Fe, Sn) into the layered zeolite precursor through interlayer expansion, which could be helpful to modify the catalytic function, is discussed.     

Observer-based robust control for uncertain systems with time-varying delay

This paper is concerned with the function observer-based stabilizationfor time-varying delay systems with parameter uncertainties.The uncertain systems tackled in this paper involve uncertaintyin quadratic constrained form which includes the well-knownnorm-bounded time-varying uncertainty as a special case. Interms of Razumikhin-type stability theorem, we show that thefeasibility of several matrix inequalities guarantees the solvabilityof the addressed problem. Furthermore, we propose a parametricapproach for function observer-based robust stabilizer design.     

Chronology and origin of VMS deposits in Xinjiang, NW CHINA

VMS deposits in Xinjiang, NW China are widespread in the Altay, Tianshan and WestKunlun orogenic belt, mainly formed during the Proterozoic rifting and Phanerozoic post-orogenicextension and are related to the bimodal volcanism. The VMS deposits are middle and small inscale. According to assemblages of metallogenetic elements, they can be divided into four types(Cu-Zn, Cu-S, Pb-Zn-Cu and Pb-Zn types) with the Cu-Zn and Pb-Zn types being the most impor-tant ones. Research of isotopic chronology shows that the VMS deposits in Xinjiang were formedduring the Proterozoic, Ordovician, Deovonian, Carboniferous and Permian periods and usuallyunderwent multi-stage mineralization, especially the large-sized deposits usually have post-volcanic superimposed mineralization by tectonomagmatic or metamorphic hydrothermal metal-logenic fluids.     

对氨基苯甲酸的合成研究进展

综述了以对硝基苯甲酸为原料合成对氨基苯甲酸的近期研究进展。并从技术和经济角度讨论了各种合成方法的优点与不足。