EDTA络合溶胶-凝胶法制备Y2O3:Eu纳米晶

以金属硝酸盐和EDTA为原料,用EDTA络合溶胶-凝胶法制备出Y₂O₃:Eu纳米晶,并对合成条件进行了优化.分别用TG-DTA、FTIR、XRD、SEM、荧光分光光度计等手段对凝胶的热分解机理,Y₂O₃:Eu的形成过程以及纳米晶的性质进行了研究.结果表明:硝酸根离子可以加速EDTA凝胶的热分解,仅在600℃焙烧即可得到颗粒细小、组分均匀,纯立方相的’Y₂O₃:Eu纳米晶,颗粒基本呈球形,粒径随温度升高逐渐长大,600℃时,约为20nm,1000℃时,约为70nm.     

液相混合法合成Ba2Ti9O20研究

以EDTA为络合剂,乙二醇为酯化剂,利用液相混合法,合成了单相的Ba2Ti9O20。利用DTA、TG、XRD和Raman光谱等技术表征了树脂中间体和由此得到的氧化物粉末。Ba2Ti9O20相在1000℃开始出现,在1100℃变成主相。在1200℃可得到单相的Ba2Ti9O20。该方法简单易行,不需要低温条件或保护性气氛,也不需要长时间热处理。     

Effect of complexing agent on growth process and properties of nanostructured Bi2S3 thin films deposited by chemical bath deposition method

Nanostructured Bi₂S₃ thin films have been prepared onto amorphous glass substrates by chemical bath deposition method at room temperature using bismuth nitrate and sodium thiosulphate as cationic and anionic precursors with EDTA as complexing agent in aqueous medium. The X-ray diffraction study reveals that the films deposited without the complexing agent are amorphous in nature and becomes nanocrystalline in the presence of EDTA. The resistivity for the films prepared from EDTA complexed bath is decreased due to the improvement in grain structure. The decrease in optical bandgap and activation energy is observed as the thickness of the film varies from 45 to 211 nm on account of the variation of the volume of complexing agent in reaction bath. Studies reveal that the growth mechanism of Bi₂S₃ gets affected in the presence of complexing agent EDTA and shows impact on structural, electrical and optical properties.     

Copper(II)-EDTA sorption onto chitosan and its regeneration applying electrolysis

Cu(II)-EDTA (ethylendiaminetetraacetate) complexes are widely used in the manufacture of printed circuit boards. In order to avoid the outlet into the environment the sorption of complexes onto chitosan is proposed. The uptake of both Cu(II) and EDTA proceeds in weakly acidic (pH 3-5) and strongly alkaline (pH > 12) solutions. In acidic solutions EDTA sorption prevails. FT-IR investigations have shown that in acidic solutions the amide bonds between -COOH groups of EDTA and -NH2 groups of chitosan were formed. In alkaline solutions the single EDTA sorption does not proceed. In this media the sorption is enhanced by Cu(II) ions. The possible sorption mechanisms are discussed. The uptake of both Cu(II) and EDTA by chitosan depends on the ratio between them in solutions. EDTA sorption in acidic solutions increases with increase in its concentration while that of Cu(II) decreases. In alkaline solutions the sorption of both Cu(II) and EDTA increases with increase in Cu(II) concentration. The use of electrolysis enables to regenerate chitosan and to reuse it. During electrolysis copper is deposited onto the cathode and EDTA is oxidized onto the anode. The current efficiency depends on the current intensity, the load of chitosan and the pH of the background electrolyte. Electrolysis under the most favorable conditions ensures the 10-cycles regeneration without considerable changes in the sorption properties of chitosan. FT-IR spectra of the initial and regenerated chitosans are similar.     

In situ ATR-IR spectroscopic and electron microscopic analyses of settlement secretions of Undaria pinnatifida kelp spores

Knowledge about the settlement of marine organisms on substrates is important for the development of environmentally benign new methods for control of marine biofouling. The adhesion to substrates by spores of Undaria pinnatifida, a kelp species that is invasive to several countries, was studied by scanning electron and transmission electron microscopies (SEM/TEM) as well as by in situ attenuated total reflection infrared (ATR-IR) spectroscopy. The IR spectra showed that adhesive secretion began approximately 15 min after initial settlement and that the adhesive bulk material contained protein and anionic polysaccharides. Energy dispersive X-ray microanalysis of the adhesive identified sulphur and phosphorus as well as calcium and magnesium ions, which facilitate the gelation of the anionic polysaccharides in the sea water. The adhesive may be secreted from Golgi bodies in the spore, which were imaged by TEM of spore thin sections. Additionally, an in situ settlement study on TiO₂ particle film by ATR-IR spectroscopy revealed the presence of phosphorylated moieties directly binding the substrate. The presence of anionic groups dominating the adhesive suggests that inhibition of spore adhesion will be favoured by negatively charged surfaces.     

滴定法连续测定铅锌矿中铅锌铜

铅锌矿样经盐酸和硝酸溶解后,以硫酸为沉淀剂,使铅与硫酸形成硫酸铅沉淀,锌和铜留在溶液中。过滤后,用乙酸-乙酸铵缓冲溶液溶解硫酸铅沉淀,以二甲酚橙为指示剂,EDTA标准溶液滴定铅。分取两份滤液,一份用于测定锌,另一份用于测定铜。测定锌时以氢氧化物沉淀分离铁、锰等金属离子后,在pH 5.5乙酸-乙酸钠缓冲液中,硫脲存在下,以二甲酚橙为指示剂,用EDTA标准溶液滴定锌。另一份滤液中铜采用碘化钾-硫代硫酸钠滴定法测定。方法用于铅锌矿样品中铅、锌和铜的测定,测定值与国家标准方法的测定值一致,测定结果的相对标准偏差在0.042%～0.088%之间。     

加权平均法测定RH炉顶渣改质剂中的金属铝

RH炉顶渣改质剂中细颗粒铝经硫酸铁溶液进行浸取,以二苯胺磺酸钠为指示剂,用重铬酸钾标准溶液滴定,计算出筛下试样金属铝的含量;粗颗粒铝用氢氧化钠溶解,用苦杏仁酸掩蔽钛,以二甲酚橙为指示剂,先用乙酸锌标准溶液滴定过量的EDTA,再用氟盐取代法计算出筛上试样金属铝的含量,运用加权平均法求出金属铝总量.     

氢氟酸分离-EDTA容量法测定钕铁硼废料中稀土总量

试验用烘烧的手段去除钕铁硼废料中水分或油分的方法,使基体金属转化为有脆性的氧化物,便于研磨混合,从而解决了分析样品的均匀性问题.研究氢氟酸分离杂质、EDTA容量法测定稀土总量的方法,两次消除杂质离子干扰,提高了分析结果的准确度.样品分析结果的相对标准偏差为1.41%,方法重现性好.