纳米二氧化钛-高锰酸钾协同光催化氧化体系快速测定化学需氧量

以纳米TiO2-KMnO4协同光催化氧化体系为基础,结合分光光度法建立了一种快速测定水样中化学需氧量(COD)的简便方法。本方法具有线性范围宽、抗氯离子干扰能力强等优点。在选定的最优条件下,线性范围为0.1~320mg/L;当氯离子含量在1500mg/L以内时,相对误差小于5%。此方法适用于污染程度低的自来水、地表水或中等污染程度的工业废水中COD值的快速测定。     

一种新的光催化氧化体系用于化学需氧量的测定研究

基于KMnO₄能获得光生电子从而提高半导体光催化氧化能力的原理,建立了一种用纳米ZnO-KMnO₄协同体系光催化测定化学需氧量(COD)的新方法,探讨了催化氧化测定COD的机理,考察了测定COD的最佳反应条件.COD值浓度在1.5～10mg/L范围内与信号呈良好的线性关系,检测限为0.5mg/L.用本方法测定实际水样,结果和标准高锰酸盐指数法(COD_Mn法)相符.     

二氧化钛纳米管阵列光电催化测定地表水化学需氧量

利用TiO2纳米管阵列(TNAs)TNAs和薄层反应器(TCR)体积小、传质快、反应时间短的特点,建立了光电催化测定地表水化学需氧量(COD)的新方法.本方法对于地表水COD值的测定呈线性关系,线性回归方程为Qnet=-0.18105ThCOD+0.15444,r=0.9903,检出限为0.30 mg/L;RSD<5%;分析时间<2 min,适宜pH范围是4～10,Cl-不干扰.通过地表水实际水样分析表明,本方法能够克服重铬酸钾法(CODCr)和高锰酸钾指数法(CODMn)的缺陷,测定结果可靠,稳定,重现性好,能够准确、快速地测定地表水的COD含量,是一种极值得推广应用的测定COD的新方法.     

光催化氧化法测定地表水化学需氧量的研究

用溶胶-凝胶法在石英管上制备了纳米TiO₂膜, 并采用光催化氧化法建立了一种测定地表水化学需氧量(COD)的新方法. 以Ce(IV)作为纳米TiO₂光生电子的接受体, 从而减少了纳米TiO₂光生电子和光生空穴的复合, 提高纳米TiO₂的光催化氧化能力. 以测定Ce(IV)的紫外吸收为手段探讨了光催化氧化测定COD的机理, 考察了测定COD的最佳反应条件. 实验结果表明, 该方法条件温和, 不会造成二次污染, 能够实现地表水等低COD值水样的快速准确测定. 在该实验所选择的条件下, 可准确地测定1.0～12 mg?L^－1之间的COD值, 检测限为0.4 mg?L^－1.     

TiO2光催化剂在COD测定中的应用研究

采用溶胶一凝胶法制备纳米TiO2薄膜电极,提出了一种简便、快速测量化学需氧量(COD)的方法.分别以葡萄糖、邻苯二甲酸氢钾(KHP)为COD检测的标准物,考察了TiO2薄膜的光催化行为,并与传统方法进行比较.实验结果表明,葡萄糖对紫外光几乎没有吸收,在葡萄糖的电解质溶液中,COD与光电流有很好的一元二次关系;KHP对紫外光有吸收,在KHP的电解质溶液中,当COD浓度大于50mg/L时,随着COD浓度的增加,光电流降低.引入了单位光强度引起的电流响应(E)这一变量,该传感器的单位光强度引起的电流响应E与COD值在15.0-300mg/L范围内有很好的一元二次关系,相关系数为0.9999,并且不同样品在薄膜电极上的E呈现很好的线性关系.该传感器对水样的测量结果与传统方法测量结果相吻合.     

专利

一种水体化学需氧量快速测定装置公开号:CN101900681A公开日:2010.12.01申请人:哈尔滨工业大学摘要一种水体化学需氧量快速测定装置,属于化学分析仪器,解决现有的光催化COD测定装置采用粉末TiO2和附着于反应器壁的TiO2薄膜做为催化剂,粉末TiO2易凝聚、难分离、易失     

桑色素修饰的纳米TiO_2分离富集铬和铝

建立了在表面活性剂十二烷基硫酸钠(SLS)的活化作用下,桑色素修饰的纳米TiO2分离富集,电感耦合等离子体原子发射光谱(ICP-AES)测定Cr3+和A l3+的新方法。考察了溶液pH、洗脱条件和干扰离子等因素对分析物分离富集的影响。结果表明,在pH 3.0时,Cr3+和A l3+可被桑色素修饰的纳米TiO2定量富集,吸附的金属离子可用1.5 mL 0.50 mol/L HC l溶液完全洗脱。在优化的实验条件下,纳米TiO2-桑色素对Cr3+和A l3+的吸附容量分别为9.69 mg/g和12.76 mg/g。本法对Cr3+和A l3+的检出限(3σ)分别为:0.21和0.49 ng/mL,相对标准偏差(RSD)分别为2.2%和1.6%(n=11,C=50 ng/mL)。本法应用于藏药和扇贝标准样品(GBW 10024)中Cr3+和A l3+的测定,测定值与标准值基本吻合,分析结果满意。     

纳米PbO2修饰电极安培检测器流动注射法快速测定化学需氧量

采用以纳米PbO₂修饰电极为工作电极的安培检测器,用流动注射法快速检测水体中的化学需氧量(COD).根据纳米PbO₂修饰电极催化氧化电流的大小测定样品的COD值,在50-1 200 mg/L COD的范围内,电流响应与标准水样中的COD_Cr值呈线性关系,检出限为20 mg/L.该法不需对水样进行预处理,不使用有毒试剂,无二次污染,具有快速、简便、进样量少及工作电极使用寿命长等优点,与COD_Cr国家标准分析法对比具有较好的相关性.     

化学发光-化学需氧量测定新方法

根据重铬酸钾消解废水后其最终还原产物Cr3+ 浓度与COD值成正比关系 ,以及在碱性条件下 ,Luminol H2 O2 Cr3+ 体系产生很强的化学发光的原理 ,提出了一种用光电二极管做检测器测定水体的化学需氧量的新方法。本方法线性范围为 2 .1～ 60 0mg L,r2 =0 .9974;检出限为 2 .1mg L ;回收率为 1 0 0 %± 1 0 % ;RSD≤ 5 % (n =6)。用于实际样品测定 ,结果满意。     

自掺杂改性Bi_4O_5X_2(X=Br,I)异质结催化剂的合成及在油田废液处理上的应用

通过调控原料中五水硝酸铋和卤源的比例制备了自掺杂改性Bi_4O_5X_2(X=Br, I)光催化材料,Bi_4O_5X_2(X=Br,I)光催化性能得到明显提升.分别用X射线衍射仪分析催化剂的晶体结构、环境扫描电子显微镜观测催化剂的形貌、紫外可见漫反射分光光度仪测试催化剂的光吸收性能、 ST-MP-9全自动比表面积测试仪测试催化剂的比表面积.通过测定光降解油田污染物丙烯酰胺的吸光度值和化学需氧量(COD)值的变化研究了催化剂的催化活性.结果表明,经过5 h的紫外可见光光降解反应,Bi_4O_5Br_2-Bi2.6降解丙烯酰胺的性能最好,降解率达到58.2%、 COD值降低87.1%.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.