络合滴定铁矿中铝的新指示剂

在ＰＨ４．５－６．５条件下，Ｚｎ与３，５－ｄｉＢｒ－ＰＡＤＡＰ及ＳＤＳ形成可溶性紫红色络合物，利用此体系以３，５－ｄｉＢｒ－ＰＡＤＡＰ为指示剂，锌盐回滴法测定铁矿中的Ａｌ２Ｏ３溶液颜色由亮黄变为紫红，络点突跃敏锐，Ｆｅ＾３＋的黄色不影响终点观察。     

The application of potentiometric techniques to study complexation reactions at the mineral/water interface

The most widely used technique to characterize the acid/base and complexing properties of hydrous particle surfaces is based on potentiometric titrations. Properly applied it provides accurate data over wide concentration ranges and, with help of automatic measuring and data collecting systems, it has become possible to collect large amounts of data within a reasonably short time period. However, collection and interpretation of experimental data is beset with difficulties. Some of these difficulties are identified and discussed with special reference to some goethite systems.     

库仑法和电化学阻抗法测量LiFePO4锂离子扩散系数

库仑法和电化学阻抗法是测量锂离子扩散系数有效的测量手段。以实验室自制的LiFePO4为实验电池正极材料,介绍如何用库仑法和阻抗法测试并计算电极材料的锂离子扩散系数。库仑法计算得到锂离子扩散系数由Li1-xFePO4(x=0)的9.6×10-9cm2.s-1变化为Li1-xFePO4(x=0.7)的1.1×10-11cm2.s-1。用阻抗法的两种模型,分别计算了Li1-xFePO4(x=0.65)的电池材料的锂离子扩散系数,结果分别是8.5×10-11cm2.s-1和3.1×10-12cm2.s-1。三种方法的计算结果接近。     

测定矿物颗粒表面积的改进酸-碱滴定法

实验研究改进了测定矿物颗粒表面积的酸—碱滴定法,即应用改进ＢＥＴ方程求矿物颗粒的最大表面酸量（｛Ｍ＋｝Ｔ）和碱量（｛Ｍ－｝Ｔ）,并分别用改进酸—碱滴定法和Ｎ２—ＢＥＴ方法测定了１２种矿物颗粒（３种粘土,８种氧化物和１种碳酸钙）的比表面积。结果表明,应用酸—碱滴定法不仅可得到合理的｛Ｍ＋｝Ｔ和｛Ｍ－｝Ｔ值,而且提高了测定表面积和相应酸度常数的准确性,由改进酸—碱滴定法得到的表面积平均比用Ｎ２－ＢＥＴ方法测得的表面积大一个数量级,且二者有显著的相关性。     

Surface Acidity of Amorphous Aluminum Hydroxide

The surface acidity of synthetic amorphous AI hydroxide was determined by acid/base titration with several complementary methods including solution analyses of the reacted solutions and XRD characterization of the reacted solids. The synthetic specimen was characterized to be the amorphous material showing four broad peaks in XRD pattern. XRD analyses of reacted solids after the titration experiments showed that amorphous AI hydroxide rapidly transformed to crystalline bayerite at the alkaline condition （pH〉10）. The solution analyses after and during the titration Ksp=^aAl^3＋/aH^＋^3 ,was 10^10.3. The amount of consumption of added acid or base during the titration experiment was attributed to both the protonation/deprotonation of dissolved AI species and surface hydroxyl group. The surface acidity constants, surface hydroxyl density and specific surface area were estimated by FITEQL 4.0.     

泥沙颗粒表面电荷特性及其对干容重影响试验研究

采用黄河及长江中的沙样在不同Ca2+浓度下分别进行电位滴定试验和干容重试验,得到以下结论:①随Ca2+浓度的增加,泥沙颗粒表面负电荷先不断减少然后趋于不变。②Ca2+对泥沙淤积干容重的影响可分为三个阶段:第一阶段干容重减小;第二阶段增加并达到最大值;第三阶段减小最后趋于不变。③在Ca2+浓度相同条件下,泥沙浓度对淤积干容重的影响根据所加Ca2+浓度不同也呈现不同的变化。④Ca2+浓度、泥沙浓度相同时,中值粒径越大干容重越大,且中值粒径大的泥沙干容重达到最大值所需Ca2+少。⑤在不同Ca2+浓度下泥沙颗粒由于表面电荷不同造成静电斥力不同,同时表面水膜作用力也不同,二者共同作用使得干容重体现不同的变化。     

EDTA-铅滴定法测定水中硫酸根条件试验

测定水中硫酸根的方法有重量法、容量法、硫酸钡比浊法和间接极谱法等。常用硫酸钡比浊法和容量法来测定。EDTA 铅滴定法测定水中硫酸根的含量是一种经典的容量法,通过对该法滴定条件———溶液酸度、沉淀放置时间、缓冲溶液的加入量等进行较详细的试验。提出了测定时应控制的实验条件,验证了该法的可行性,且测定结果更精确。进一步氯离子的干扰试验表明:此方法适用于氯离子含量小于600mg·L-1的水样测定。     

湖泊沉积物碳酸盐含量3种测定方法的比较

湖泊沉积物中碳酸盐含量是指示气候和环境变化的常用指标之一,其测定方法多样,但缺乏不同测定方法结果之间的比较,尤其是对同一沉积序列样品的比较.选择新疆天山大龙池DLC12孔110 cm岩芯沉积物,按1 cm间隔取样,利用烧失量法、酸碱滴定法和气量法分别进行碳酸盐含量分析,并比较3种分析方法在表达湖泊沉积物碳酸盐含量时的差异性.结果表明:3种方法测定的碳酸盐含量随岩芯深度的变化趋势并无太大差别,其中烧失量法测定的结果较滴定法和气量法测定的结果平均分别偏高5%和3%,气量法结果与滴定法结果较为接近,平均差值不到2%,表明烧失量测定过程中有其他矿物分解导致碳酸盐含量被高估.将3种方法测定的结果与岩芯中20个样品的X衍射(XRD)得到的碳酸盐含量对比,发现气量法的测定结果与XRD测定结果的相关性最高.通过比较各种方法的优缺点,考虑到分析精度、操作技巧和分析费用,认为气量法比较适合湖泊沉积物的碳酸盐含量分析.     

Measurement of dissolved oxygen using optodes in a FerryBox system

Optode sensors can provide detailed information on concentrations of dissolved oxygen, which in turn may be used to quantify variations in net primary productivity. Throughout 2005 and 2006 the performance of commercially available oxygen optodes was examined, one in each year. The optode was part of an autonomous measurement system (FerryBox) on a ferry operating between Portsmouth (UK) and Bilbao (Spain). On crossings during which water samples were collected manually, the optode outputs were compared to measurements of dissolved oxygen made by Winkler titrations. The optodes maintained good stability with no evidence of instrumental drift during the course of a year. Over the observed concentration range (230–330 mM m⁻³) the optode data were approximately 2% low in both years. By fitting the optode data to the Winkler data the median difference between the optode and Winkler measurements is reduced to less than 1 mM m⁻³ (0.3%) in both years. The most appropriate calibration factor for 2005 was corrected O₂ = Optode O₂ × 1.018 and for 2006 the corresponding equation is corrected O₂ = Optode O₂ × 0.884 + 36.8. The standard deviation (95%) of the difference between the individual Winkler measurements was 5 mM m⁻³ and 3 mM m⁻³ in 2005 and 2006 respectively.Calculation of the oxygen saturation anomaly is required for calculation of the air sea exchange of oxygen and net biological production. This calculation requires the use of both salinity and temperature data. Salinity is measured to better than 0.1 so the corresponding error in anomaly is less than 0.2 mM m⁻³. Distortion of the temperature data is present due to warming of the water pumped to the optode. In winter this warming at the optode may be as great as 0.4 °C. The difference in the pumped water temperature can be corrected for by reference to other measurements of sea surface temperature reducing the error to less than 1 mM m⁻³.     

金属矿中铜含量滴碘法快速测定

通过调节pH值,加入氟化氢铵消除铁的干扰,用硫代硫酸钠滴定碘,淀粉溶液做指示剂等方法。探讨了快速滴碘法在金属矿中铜含量分析的应用,方法快速易掌握,结果准确。适用于金属矿中铜的测定。