连续滴定法测定矿石及合金中砷锑含量

用浓硫酸溶样,在一定温度下,先用硫酸铈滴定,再用溴酸钾滴定,可分别计算出Sb和As的含量.该法操作简单、测定快速,相对标准偏差小于1.5%,适用于常规的矿石和合金中砷锑的测定.     

The chemistry of heavy metals in digested sewage sludge—II. Heavy metal complexation with soluble organic matter

Characterisitcs of copper-binding, in the soluble fraction of a digested sewage sludge, were determined using ion-selective electrodes. Results showed that ion exchange with protons is a principal component in copper binding and that the soluble organic matter has a cation exchange capacity of 8.86 m-equiv g⁻¹ at pH 6.5. A pH-dependent exchange constant, defined in terms of mole fractions of exchange components, describes the data in the pH range 2–8 and is independent of both pH and the extent of exchange in the range 5.5–8. Supplementary data include acid/base titration curves and simple kinetic measurements. Anion uptake is insignificant in the pH range 2.5–7. A model of the aqueous phase of a sewage sludge, containing soluble organic matter with only copper and protons as competing ions, predicts that at pH 7 over 99% of the copper present will be bound to the soluble organic matter.     

Applications and limitations of the colloid titration method for measuring activated sludge surface charges

Surface charge quantification of polymer solutions and sludge suspensions were investigated by the colloid titration technique and compared to charge densities obtained by pH-titration. The colloid titration technique worked well for polymer samples. The charge quantity of humic acid and activated sludge extracellular polymers (EPS) was estimated to be -1.51 and -0.42 meq/g, respectively. These values are reasonable when compared to pH-titration results. The surface charge of activated sludge particles appears to be below the limit of detection. However, surface charge estimates are obtained, when the reactant doses and sample concentration are increased. It is suggested that such estimates are not correct, but artefacts of the non-stoichiometric precipitation of the polymeric reactants at high doses. It appears that the colloid titration method is limited to conditions of low reactant doses and valid for charge determination of extracted sludge polymers, whereas the method is not valid for charge determination of whole sludge.     

电位滴定法测定107胶游离甲醛含量

提出了用电位滴定法测定１０７建筑胶中游离甲醛含量的方法。该法快速简便,条件易控制;与差减式碘量法进行比较,结果令人满意。     

New biosorbent materials for heavy metal removal: product development guided by active site characterization

Olive pomace wastes were used as precursors for the development of new biosorbents for heavy metals. Thermal and/or chemical treatments were addressed in terms of their effects on functional group properties and copper removal. Product development was guided by experimental characterization (potentiometric titrations, IR spectra, copper biosorption, total surface area) and theoretical modeling of acid-base properties. Olive pomace was characterized by negative charge due to dissociation of two weakly acidic sites (carboxylic and phenolic). After thermal treatment, a char-like material was obtained, characterized by basic sites with positive charge in the acidic pH range. Copper biosorption properties of this material were improved with respect to olive pomace due to the binding ability of pyrone-like sites. Both native and carbonized olive pomace samples were chemically treated by HNO(3). Experimental tests were performed according to factorial designs and analysis of variance was used to evaluate significant effects on copper removal of both oxidant concentration and temperature. Chemical treatment by HNO(3) of carbonized material developed negatively charged groups in the acidic pH range (carboxylic groups), but presented a decreased copper removal. Chemical treatment by HNO(3) of olive pomace without carbonization gave biosorbents with acid-base properties similar to those of native olive pomace, but with a significant increase of copper biosorption. Specific carboxylic-copper interactions indicated by IR spectra and increased surface area due to chemical treatment were simultaneously responsible for such improvement.     

碳酰肼和过碳酸钠反应的化学动力学和反应工艺(英)

高氯酸三碳酰肼合锌(GTX)是一种大量使用的安全环保型高能起爆药,其母液中溶解有过量的碳酰肼和GTX起爆药,为了最大限度地消除母液中溶解的碳酰肼,运用容量滴定分析法和控制变量法研究了过碳酸钠(SPC)与碳酰肼(CHZ)的反应过程和影响因素,获得二者在80℃下的最佳反应工艺条件为:CHZ(0.1 mol·L~(-1))和SPC(0.15 mol·L~(-1))溶液的体积比为1∶4,反应时间不少于90 min时,CHZ的去除率可高达68%。应用最小二乘法对获得的反应时间与剩余CHZ浓度的数据进行一级动力学和二级动力学拟合,结果表明CHZ和SPC的反应过程符合二级动力学模型。     

微波消解-丁二酮肟沉淀分离-EDTA返滴定法测定含镍生铁中镍

含镍生铁是不锈钢冶炼重要原材料,准确快速检测含镍生铁中镍含量对不锈钢冶炼质量控制及成本控制至关重要,而使用丁二酮肟重量法测定含镍生铁中镍需使用大量酸溶解样品,有时还需要对不溶性残渣进行熔融处理,过程繁琐。实验利用微波消解法处理含镍生铁样品,并通过丁二酮肟沉淀分离法使含镍生铁中镍与钴、铜有效分离,再使用EDTA返滴定法测定镍,最终建立了含镍生铁中镍含量的测定方法。使用5个含镍生铁标准样品进行验证,当镍质量分数为5%～20% 时,测定结果的相对标准偏差(RSD,n=7)为0.14%～0.33%;通过t检验法进行显著性检验,测定结果与标准值之间无显著性差异。分别按照实验方法和国标方法GB/T 31924—2015《含镍生铁 镍含量的测定 丁二酮肟重量法》对同一个含镍生铁样品进行检验,使用t检验对两种方法得到的结果进行统计分析,结果表明两种方法检验结果无显著性差异。     

添加剂对全钒液流电池电解液稳定性的影响

为获得更高浓度、更稳定的钒电池阳极电解液,在钒离子硫酸溶液中分别加入了硫酸钾、硫酸钠、硫酸锌、尿素、柠檬酸、柠檬酸钠、柠檬酸三钠和EDTA,并恒温在43℃保存。利用电位滴定分别测定钒离子硫酸溶液恒温保存1和30 d后的钒离子浓度。结果表明,硫酸钾、硫酸钠、硫酸锌、尿素等添加剂可以使钒离子硫酸溶液更稳定,而柠檬酸、柠檬酸钠、柠檬酸三钠和EDTA不适合做添加剂。     

灰吹留铅—硫氰酸钾滴定联合原子吸收测定铅精矿银量

本方法适合于铅精矿银含量在1000~2000g/t。此方法采用灰吹留铅1~2g左右,用硫氰酸钾滴定银量w1与灰渣配料二次试金,灰吹留铅0.5g左右,硝酸溶解定容,原子吸收测定渣中银量w2,两者之和即为最终测定值。实验中用与试样等量银粉和纯铅混合滴定,验证回收率及留铅干扰程度。     

阴极电泳漆槽液MEQ值的容量法检测

介绍了乙醇法测阴极电泳漆槽液MEQ值的方法。用乙醇对阴极电泳漆槽液进行溶解,通过人工滴定法记录氢氧化钠标准溶液的用量,得到槽液p H与氢氧化钠消耗量的函数。利用相关软件绘图并进行数据处理,再根据公式便可计算出槽液MEQ值。此外还对四氢呋喃法和乙醇法测MEQ值的准确性和难易程度等进行了比较。