5-Br-DMPAP 分光光度法测定食品中微量锌

研究了以５－Ｂｒ－ＤＭＰＡＰ分光光度法测定食品中微量锌，对实验条件和共存离子的干扰及掩蔽进行了探讨。在ＯＰ存在下，Ｚｎ（Ⅱ）和５－Ｂｒ－ＤＭＰＡＰ在ｐＨ８．０～１０．０氨性缓冲液中形成有色络合物；λｍａｘ＝５５５ｎｍ，ε＝８．８１×１０４Ｌｍｏｌ－１ｃｍ－１，Ｚｎ在０～５６０μｇ／Ｌ范围内符合比耳定律，变异系数和回收率分别在１．６％～４．６％和９１．１％～１０５％之间。     

Chlorophyll adsorption on acid-activated clay

An acid-activated clay (Çanakkale montmorillonite from Turkey) was used to adsorb chlorophyll from hexane solutions. The phenomenon seems to be mainly driven by the interaction of chlorophyll with acid sites. The adsorption of chlorophyll on Brönsted acid sites was indicated by a characteristic infrared band for the -OH group at 3671 cm^?1. The variations in the structure of clay mineral and chlorophyll during adsorption have been examined by differential thermal analysis, thermogravimetry and infrared spectroscopy of the activated clay before and after adsorption of chlorophyll. Oxidation of adsorbed chlorophyll was completed at quite a high temperature.     

1,2,3-三甲氧基苯的绿色合成工艺研究

采用碳酸二甲酯(DMC)代替传统的有毒有害试剂作为甲基化试剂和以廉价的焦性没食子酸(PA)为原料,在离子液体[ Bmim] Br催化作用下合成1,2,3-三甲氧基苯(TMB).通过单因素和正交试验考察了PA和DMC的摩尔比、催化剂的用量、反应温度以及反应时间等因素对甲基化反应的影响.结果表明:各因素的影响程度为反应温度...     

不锈钢在含有溴离子的醋酸溶液中的腐蚀

采用浸泡试验及电化学试验,对304、254 SMO和HastelloyC－276三种材料在醋酸和含有Br^-离子的醋酸溶液中的腐蚀行为进行了测试。用SEM和XPS分析点蚀形貌。结果发现材料表面所形成的钝化膜中含有Cr2O3和MoO2,对材料起保护作用。     

两种不同石墨电极上溴离子电氧化的研究

通过测定溴离子在两种不同石墨电极上的循环伏安曲线及电流效率,探索了溴离子在石墨电极上氧化的电解条件,比较了两种石墨电极对溴离子电氧化的影响。研究发现,由于电极材料的不同和析氧反应的存在,两种电极材料对溴离子氧化的催化作用有一定差别。溴离子在石墨电极上氧化的电流效率一般在80％以上,最高可达88.5％。     

Electrochemically induced hydrogenolysis of 1,1-dibromoalkenes to vinyl bromides

Vinyl bromides 2a-f, useful intermediates in organic synthesis, have been obtained under mild conditions and in good yields via electrochemical reduction of 1,1-dibromoalkenes 1a-f (readily available substrates). The reduction has been carried out in MeCN-tetraethylammonium perchlorate (TEAP) solutions, in the presence of a proton donor, at a Au, Hg, C or Ag cathode. The use of specific reducing agents, catalysts and bases, employed in the classical procedures, has been avoided. The isomeric E/Z ratio in vinyl bromides 2a-f is affected by the cathode material.     

退火温度对碳基全无机钙钛矿太阳能电池性能的影响

碳基全无机钙钛矿太阳能电池(carbon-based all-inorganic perovskite solar cells, C-PSCs)由于成本低、热稳定性好等优点逐渐引起人们的广泛关注,然而其效率要远低于传统的钙钛矿太阳能电池(perovskite solar cells, PSCs)。通过调控CsPbI₂Br薄膜的退火温度,改善薄膜质量。利用SEM、XRD表征分析了钙钛矿薄膜微观形貌以及物相结构,发现升高退火温度可有效提高CsPbI₂Br薄膜的结晶性从而减少其表面的孔洞。升高钙钛矿薄膜的退火温度,器件的光伏性能有显著提高,短路电流密度(J_sc)从8.84 mA·cm^-2提高至12.14 mA·cm^-2,开路电压(V_oc)从0.93 V提高至1.06 V,最终能量转换效率(PCE)从2.75%提高至7.63%。研究结果表明,优化钙钛矿太阳能电池的制备工艺可以有效提高其光伏性能。     

采用质子酸离子液体反应萃取精馏制备醋酸甲酯

以醋酸、甲醇为原料,以质子酸离子液体为催化剂和萃取剂,采用反应萃取精馏法制备了醋酸甲酯。考察了质子酸离子液体和配料比、回流比及反应时间对反应萃取精馏的影响。实验结果表明,质子酸离子液体是制备醋酸甲酯的良好催化剂和萃取剂,能消除醋酸甲酯与水或甲醇的共沸点,提高醋酸甲酯的纯度和收率;在3种质子酸离子液体[Hmim]CF3COO,[Hmim]BF4,[Hmim]HSO4中,[Hmim]HSO4(Hmim为N-甲基咪唑)的催化活性最高。反应萃取精馏的最佳工艺条件是:m(HOAc)∶m(CH3OH)∶m([Hmim]HSO4)=100∶50∶1,回流比2.5,反应时间30min。在此条件下,醋酸甲酯的纯度可达99.84%,收率可达98.65%。采用闪蒸的方法可回收醋酸、甲醇及质子酸离子液体,质子酸离子液体可重复使用8次。     

Doping manganese into CsPb(Cl/Br)3 quantum dots glasses: Dual-color emission and super thermal stability

CsPbX₃ (X = Cl, Br, I) perovskite quantum dots (QDs) represent bright and tunable photoluminescence, it is regrettable that the air instability and poor water resistant properties prevent their application in optoelectronic devices. At the same time, the toxicity of lead is also a major factor restricting its development. As a consequence, we demonstrate the partial replacement of Pb with Mn through conventional melt-quenching and heat-treatment method preparation of Mn-doped CsPb(Cl/Br)₃ QD glass. Mn-doped CsPb(Cl/Br)₃ QD glass exhibits high luminescent intensity like QDs. It is important that Mn-doped CsPb(Cl/Br)₃ QD glass with Dual-Color maintained the same lattice structure like Mn-doped CsPb(Cl/Br)₃ QDs, and highly homogeneous spectral characteristics of Mn luminescence. The intensity and position of this Mn-related emission are also tunable by altering the experimental parameters, such as the Pb-to-Mn feed ratio, annealing temperature. More importantly, the as-prepared orange Mn-doped CsPb(Cl/Br)₃ QD glass was employed to fabricate white LEDs combined with a commercial Ce³⁺:Y₃Al₅O₁₂ phosphor-in-glass (Ce-PiG) on top of a InGaN blue chip. And the constructed WLEDs generate a warm white with an optimal luminous efficacy (LE) of 67.00 lm/W, a high CRI of 81.4, and a low CCT of 4902 K.     

Epoxidation of n-hexene and cyclohexene over titanium-containing catalysts

TS-1, Ti-beta and Ti-MCM-41 molecular sieves have been prepared by direct hydrothermal synthesis method and applied to the epoxidation of n-hexene and cyclohexene with H₂O₂ under mild conditions. Ti-beta with extremely low Al content was synthesized by using a seed method to suppress the formation of diol produced by Brønsted acid sites present in Ti-beta. It was also found that a large amount of by-products (1-ol and 1-one) formed over hydrophilic Ti-MCM-41. We further modified Ti-MCM-41 by silylation with bis(trimethylsilyl) trifluoroacetamide (BSTFA). Among these catalysts, the Ti-beta with low content of Al enhanced the yield of epoxide and suppressed the formation of diol markedly. The silylated Ti-MCM-41 reduced the formation of by-products and promoted the yields of epoxide significantly. Based on experimental results, a reaction mechanism with two parallel and competitive reactions was proposed.