用六价铬还原产物电镀铬

研究了不同还原剂与六价铬的还原反应和各种反应条件对还原率的影响。讨论了反应历程,确定了最佳反应条件。这种还原产物可以做为无毒性电镀铬的铬源。使用这种三价铬化合物进行了电镀试验,获得了厚度超过100μm的镀层。     

三价铬离子在电沉积过程中的形态

研究证明三价铬离子在HCl体系中适应电活性物质是[Cr(H₂O)₆]³⁺,不同pH通过溶液中的存在形态而影响Cr³⁺电沉积过程。同时证实了Cr³⁺在HCOOH或(NH₂)₂CO存在时不与三价铬形成配位化合物。     

碳化钨掺钒掺铬粉末中铬的测定

碳化钨掺钒掺铬粉末经过灼烧后转化为氧化钨,氧化钒与三氧化二铬的混合物,采用氢氧化钠溶解,过滤,分离钨和钒。将沉淀灰化后,氢氧化钠熔融,在酸性条件下用过硫酸铵将三价铬氧化成六价铬,用标准硫酸亚铁铵溶液滴定。     

Acetylsalicylate and salicylates in foods

Acetylsalicylic acid is effective in the prevention of cardiovascular disease. It was suggested that fruits and vegetables provide unknown amounts of acetylsalicylic acid. We could not find any acetylsalicylic acid in 30 foods using HPLC with fluorescence detection (detection limits: 0.02 mg/kg for fresh, and 0.2 mg/kg for dried products). We showed that urinary excretion of salicylates is a valid indicator for intake, and found a median salicylate excretion of 10 micromol (1.4 mg) in 24 h urine of 17 volunteers eating a variety of diets. Our data suggest that the content of (acetyl)salicylic acid of diets may be too low to affect disease risk.     

Chromium Redox Chemistry in Drinking Water Systems

In order to understand the redox chemistry of chromium at low concentrations (100?μg/L) under conditions typically found in drinking water systems, three reductants and four oxidants were tested in three different waters at pH 5, 7, and 9. In the absence of any oxidant or reductant, Cr(VI) was stable at all three pHs, while Cr(III) precipitated out of solution at pH 9 and greatly impacted the reduction reactions. Stannous chloride was more effective than sodium sulfite or sodium sulfide for reducing Cr(VI) to Cr(III). Sulfide is not likely to be used as a reductant due to the long reaction time (120?h) to achieve the same reduction as SnCl2, while sulfite may be effective at higher doses. The oxidation of Cr(III) by dissolved oxygen and chloramine was very slow, while Cl2 and KMnO4 were effective oxidants under many conditions. A Cl2 residual in a drinking water distribution system may oxidize any soluble Cr(III) to Cr(VI) because of the long contact time, so Cr treatment strategies will need to remove both Cr(III) and Cr(VI).     

铬矿石中三氧化二铝测定的研究

于5％硫酸介质中用过硫酸铵将铬矿石中的铬（Ⅱ）氧化为铬（Ⅵ），在氨性溶液中，铝以氢氧化物沉淀的形式与铬分离，用EDTA容量法分析三氧化二铝的含量，消除了大量铬对分析三氧化二铝的影响。方法简单，准确，快速。     

Cr在金刚石工具胎体材料中的作用

采用金相显微镜、SEM、EPMA及XRD等手段分析了Cr在常用胎体材料中的扩散反应及Cr对胎体材料粘结金刚石的影响。结果发现：在82℃短时热压条件下,Cr在钴-青铜系和Fe-青铜系胎材料中分别形成了8-20μm和4-10μm厚的扩散层;成分分析表明Cr在α-Fe、γ-Co和α-Cu中的溶解度依次减少;Cr显著强化了胎体材料,但它并没有明显改善胎体材料与金刚石的粘结状态。     

The occurrence of BVD virus infections in lower Austrian dairy farms

Bulk tank milk samples from 5,024 dairy herds in Lower Austria were tested by ELISA for antibodies to bovine virus diarrhoea virus (BVDV). Approximately 54 per cent of the herds had a low level of bulk tank antibody unsuspected of recent infection with BVDV. In 512 herds, which had a high level of bulk tank antibody suggestive of recent infection with BVDV, milk samples from 5-10 primiparous cows, respectively were tested by ELISA for antibodies to BVDV. In 287 (56.1%) of these 512 herds only antibody-negative primiparous cows were detected. In 759 herds blood samples from 8-10 young stock, respectively were tested by ELISA for antibodies to BVDV. The majority of the tested animals was seronegative in 583 (76.8%) herds. The whole stock from 154 herds was tested for persistent BVDV infections. From 51 herds in all 149 cattle persistently infected with BVDV were detected. Because of the low prevalence of BVDV infections it seems possible to control BVDV without vaccination in Lower Austrian dairy farms.     

电感耦合等离子体原子发射光谱法同时测定铬铁矿中铬和铁

利用电感耦合等离子体发射光谱法,建立了一种快速测定铬铁矿中铬和铁量的一种方法。样品利用高铝坩埚和过氧化钠进行熔融后,用热水浸取后再用硝酸酸化,在选定铬(267.716{97})和铁(238.204{107})作为测定波长的条件下,进行电感耦合等离子体发射光谱法测定。干扰试验表明,一般铬铁矿中存在的其他杂质元素均不干扰测定。按照实验方法应用于2个铬铁矿样品中进行铬和铁的测定,相对标准偏差(RSD,n=10)小于0.350%,回收率为101%~103%。并与标准样品的认定值比较,结果吻合。     

三正辛胺—CHCl3萃取Cr（Ⅵ）的研究

研究了三正辛胺－ＣＨＣｌ３从Ｈ２ＳＯ４溶液中萃取Ｃｒ（Ⅵ）。考察了各种影响萃取的因素,用多种方法联合确定萃合物的组成和萃取平衡机理,表明萃取过程属阴离子交换机理理,提示了Ｄｅｐｔｕｔａ等对Ｃｒ（Ⅵ）萃取型体的异论。