氰离子选择电极测定水中氰离子方法研究

氰化物是环境监测和工业卫生的重要分析指标之一。氰化物的分析方法有硝酸银滴定法、吡啶联苯胺比色法和硫化氰酸汞法。这些化学法虽能测定“总氰化物”,但一般比较麻烦、费时,有些化学试剂具有毒性等。随着电化学理论的发展和应用,离子选择电极应用日趋广泛。它虽存在着只能测定氰离子的缺点,但它具有简便快速,测定范围大等优点,易于大批量样品测定。因而,本文对应用氰离子选择电极测定水中氰离子的方法作了一些探讨研究。

急性硫化氢中毒角膜病变的临床观察

急性硫化氢中毒可致人数秒钟内死亡,可造成多脏器的严重损害.其眼部的并发症表现在结膜、角膜、视网膜、视神经,角膜的病变尤为突出.本文收集的病例均为在腐败的鱼仓内作业的渔民.我院共抢救6起29例急性硫化氢中毒,以及散发病例8例,计37例.死亡4例,其中3例进入鱼仓内当场死亡,1例入院后死于肾功能衰竭.现将33例角膜病变的临床观察报告如下:

鱼舱内急性硫化氢中毒眼部损害临床分析

近几年来,沿海地区渔民在鱼舱内作业因鱼类腐败产生硫化氢气体而致急性中毒时有发生,但眼部损害报道较少,现将我院接诊的96例鱼舱内急性硫化氢中毒眼部损害分析如下.

Efficient in-situ end-functionalization of polydienes by isothiocyanate via neodymium mediated coordinative chain transfer polymerization system

End-functionalization of polydiene rubbers can not only improve its compatibility with inorganic fillers,but also enhance the overall mechanical properties.Nevertheless,for traditional neodymium(Nd)diene polymerization systems,it is highly challenging to achieve such end-functionalizations,because most of polydienyl chains are capped withη3-allyl-Nd moiety during the end of polymerization,which shows very poor reactivity with nucleophile compounds.We launched a new diene polymerization strategy calling coordinative chain transfer polymerization(CCTP)[1].In such a system,all the polydienyl chains are capped withη1-allyl-Al moieties,which reveal greater reactivity with cyclic esters and epoxide compounds,providing an effective manner to prepare polydiene-polyester amphiphilic block copolymers.Inspired by such findings,we now show herein how such types of chain-ends react with isot-hiocyanate to demonstrate an efficient in-situ manner to access end-functionalized polydienes by using CCTP.

对炼化企业防空袭的几点思考

作为我国最重要的能源基地的大庆,在未来防空作战中将面临极为严峻的形势。特别是作为防护能力、抗摧毁能力极弱的炼化企业,在正常生产状态下一旦遭敌空袭,必将引发骤燃、爆炸、泄毒等难以估量其损失的灾难性后果。因此,提早做好防空袭准备,尽最大努力最大限度地减少外敌空袭造成的损失,并力争坚持战时生产,对于支持在现代化战争中“打得赢”,乃至外敌空袭后尽快恢复生产,具有十分重要的战略意义。

Mechanism of sodium sulfide on flotation of cyanide-depressed pyrite

The mechanism of sodium sulfide(Na2S)on the flotation of cyanide-depressed pyrite using potassium amyl xanthate(PAX)as collector was investigated by flotation test and electrochemical measurements.The flotation results show that both PAX and Na2S can promote the flotation recovery of cyanide-depressed pyrite and their combination can further improve the pyrite flotation recovery.Electrochemical measurements show that PAX and Na2S interacted with cyanide-depressed pyrite through different mechanisms.PAX competed with cyanide and was adsorbed on the pyrite surface in the form of dixanthogen,thus enhancing the hydrophobicity and flotation of cyanide-depressed pyrite.Unlike PAX,Na2S rendered the pyrite surface hydrophobic through the reduction of ferricyanide species and the formation of elemental sulfur S0 and polysulfide Sn2-.The combined application of PAX and Na2S induced superior pyrite flotation recovery because of a synergistic effect between PAX and Na2S.

Antioxidant Activity of Isothiocyanate Extracts from Broccoli

Isothiocyanates(ITCs) extracts were prepared from fresh broccoli.Their antioxidant properties were evaluated by using the in vitro bioassays,including superoxide anion radical( 2 O·-) ,hydroxyl radical(HO·-) and 2,2-diphenyl-1-picrylhydracyl(DPPH·) radical-scavenging methods,lipid peroxidation assay,and reducing power assay.The ITCs extracts exhibited significant dose-dependent antioxidant activities(P<0.01) .Its antioxidant-stability was affected by temperature and storage condition,although it was more stable than vitamin C(Vc) .GC-MS iden-tified sulforaphane in the ITCs extracts.The antioxidant activity of sulforaphane was approximately one tenth to one fifth of that of Vc.Sulforaphane was experimented to be one of dominating contributors to antioxidant capacity of ITCs extracts.However,there was no direct antioxidant activity found for benzyl isothiocyanate(BITC) in vitro. Therefore,it could be concluded that the general group(-N=C=S) was not the essential part for the antioxidant activity of sulforaphane.It is suggested that the ITCs extracts from broccoli can be developed into a promising food additive for healthy food.

Cyanide removal for ultrafine gold cyanide residues by chemical oxidation methods

Because of the highly toxic cyanide in the gold cyanide residues,cyanide must be removed for environmental protection.The process mineralogy of residues was studied firstly,and then cyanide removal was carried out by three chemical methods.The results showed that the residue mainly contained Si,S and Fe.Pyrite was the main metallic mineral,and the iron-complex cyanides make cyanide removal difficult.The minerals in residues were in ultrafine particle size with high monomer dissociation degrees.In H_(2)O_(2)oxidation process,the self-decomposition and side reactions resulted in high consumption of H_(2)O_(2).In Na_(2)S_(2)O_(5)-air oxidation process,the time for complete process was long because of the reactions between Na_(2)S_(2)O_(5)and O_(2).Na_(2)SO_(3)oxidation method was found to be a new method for cyanide removal without air inflation device.The cyanide content was reduced to the national standard level in 90 min at pH 9.0 with optimum Na_(2)SO_(3)dose of 2.0 g/L.

Synthesis and characterization of PMoV/Fe_3O_4/g-C_3N_4 from melamine:An industrial green nanocatalyst for deep oxidative desulfurization

A facile approach to the preparation of a novel magnetically separable H_5PMo_（10）V_2O_（40）/Fe_3O_4/g-C_3N_4（PMoV/Fe_3O_4/g-C_3N_4） nanocomposite by chemical impregnation is demonstrated.The prepared nanocomposite was characterized and its acidity was measured by potentiometric titration.PMoV/Fe_3O_4/g-C_3N_4 showed high catalytic activity in the selective oxidative desulfurization of sulfides to their corresponding sulfoxides or sulfones.The catalytic oxidation of a dibenzothiophene（DBT）-containing model oil and that of real oil were also studied under optimized conditions.In addition,the effects of various nitrogen compounds,as well as the use of one- and two-ring aromatic hydrocarbons as co-solvents,on the catalytic removal of sulfur from DBT were investigated.The catalyst was easily separated and could be recovered from the reaction mixture by using an external magnetic field.Additionally,the remaining reactants could be separated from the products by simple decantation if an appropriate solvent was chosen for the extraction.The advantages of this nanocatalyst are its high catalytic activity and reusability;it can be used at least four times without considerable loss of activity.

Synthesis of ethoxycarbonyl isothiocyanate by orthogonal design

Using Schiff base as a phase transfer catalyst, ethoxycarbonyl isothiocyanate was synthesized by reacting ethyl chloroformate with sodium thiocyanate. In order to get the best synthetic technology, an orthogonal test （L9（34）） was applied. The results show that reaction temperature, reaction time, content of catalyst and molar ratio of sodium thiocyanate to ethyl chloroformate are the main factors influencing the yield. The four factors chosen for the present investigation are based on the results of a single-factor test. The optimum synthetic technology is determined as follows： reaction temperature 35 ℃, reaction time 3 h, the content of catalyst （molar fraction based on ethyl chloroformate） 1.5% and molar ratio of sodium thiocyanate to ethyl chloroformate 1.1. Under the optimized synthetic technology, the experimental yield reaches 96.8%.

Efficient synthesis of thiohydantoin derivatives from amino acid esters and isothiocyanates in alkaline Al_2O_3

Various amino acid esters were reacted with different isothiocyanates in alkaline Al2O3 at room temperature for 1 h affording thiohydantoins in moderate to excellent yields.