催化动力学光度法测定痕量钒(Ⅴ)

在硫酸介质中，以抗坏血酸为活化剂，对钒催化溴酸钾氧化中性红的反应进行了研究，建立了一种测定痕量钒的新方法.对波长、介质、增敏剂、反应温度及时间进行了测试，得出了最佳试验条件：试剂加入分别为1.00×10 ^-3 mol/L中性红溶液0.50 mL；5×10 ^-2 mol/L的硫酸溶液1.2 mL；5×10^-3 mol/L的抗坏血酸溶液0.2 mL；1.00×10^-2 mol/L溴酸钾溶液1.2 mL及适量钒；在沸水浴中加热16 min，在525 nm波长处测定.该方法的线性范围为0～0.6 μg/L,检出限为1.42×10^-11 g/mL，最大相对标准偏差为0.82%.该方法用于湖水中痕量钒的测定，回收率在96.0%～104.5%之间.     

甲基橙退色光度法测定饮水中溴酸根离子

在三氯乙酸介质中,以溴化钾为催化剂,研究了BrO3-氧化甲基橙退色的最佳条件.以510 nm为甲基橙退色溶液的测定波长,KBrO3在0.01-0.2μg/mL范围内,甲基橙退色溶液的吸光度值与溴酸钾含量显著相关,相关系数R2=0.9993,检测限为3.8×10-3μg/mL,试样测定结果的相对标准偏差(RSD)为<8%,试样加标回收率为86.9%-99.5%.     

氧化褪色光度法测定微量硒(IV)

在近中性溶液中,溴邻苯三酚红被硒(IV)氧化褪色的程度与存在的硒量成良好的线性关系,据此建立了测定微量硒(IV)的新方法.通过试验确定的最佳反应条件为: λmax=560 nm,在25 mL体积中加入溴邻苯三酚红10.5 mL,室温反应30 min.在选定的条件下,线性范围为0～3 μg/25 mL,ε560=8.05×104L/(mol*cm),用于矿泉水和茶叶中硒含量的测定,结果满意.     

硫酸钡浊度法测定硫代壳聚糖树脂的含硫量

研究硫酸钡浊度法测定硫代壳聚糖树脂含硫量的方法。用w（H2O2）=30%溶液和2.5 mol/L NaOH溶液预处理样品,再用王水消解,样品中硫几乎完全转化为硫酸根。以5%乳化剂OP为稳定剂,0.48 mol/L BaCl2溶液为沉淀剂,在420 nm波长处用浊度法测定含硫量。SO42-浓度在8～190μg/mL范围内与吸光度呈线性关系,检测限为0.6μg/mL,用于硫代壳聚糖树脂含硫量的测定,结果满意。     

复合前驱体溶胶—凝胶法固定木瓜蛋白酶条件的优化

以正硅酸甲酯(TMOS)和甲基三甲氧基硅烷(MTMS)为复合前驱体,以聚乙二醇400(PEG400)为稳定剂,采用溶胶—凝胶法固定木瓜蛋白酶.利用单因素和正交试验设计,得到最佳的固定化条件为:MTMS与TMOS的体积比4∶1,水与硅源的体积比(R值)0.3,用5mL前驱体水解液制备成凝胶,0.1mol/L盐酸溶液的用量210L,PEG400的用量为240L,给酶量150L.在优化条件下制得的固定化酶包封率为84.1%,活力回收率为84.4%.     

催化光度法测定痕量亚硝酸根

通过催化光度法研究了亚硝酸根-溴酸钾-二甲基黄体系痕量亚硝酸根的测定,探讨了试验中影响因素的最佳试验条件.试验结果表明,该方法的线性范围为0.5⁵.0μg/25 mL,NO-2检出限为2.39×10-9g/mL,相对标准偏差为1.02%,试样加标回收率是98.2%.该方法用于测定水样中亚硝酸根含量,取得较为理想的结果.     

电位滴定法测定面粉中溴酸钾的含量

用电位滴定法可以定量检测出面粉中溴酸钾的含量,水溶液中溴酸根最低检出限可达到0.5μg/mL,其回收率可达93.6%;在面粉中其最低检出限为10 mg/kg,在30 mg/kg浓度下其回收率可达81%以上.     

近岸海域表层沉积物中酸可挥发性硫化物的分析方法研究

在GB 17378.5—2007中亚甲基蓝分光光度法测定海洋、河流沉积物中硫化物的原理基础上,优化样品采集、样品处理、吸收液种类、水蒸气流通速度、酸添加时间和添加量、反应时间等影响因素。优化后的方法:称取2.60～3.50g湿样,以乙酸锌-乙酸钠混合溶液为吸收液,添加10mL盐酸溶液(10mol/L),水蒸气流通速度以吸收液中气泡1个/s为宜,反应时间为50min(提取液约100mL)。方法检出限为20μg/L,重复测定硫化物(AVS)含量为59.0×10-6时,重复性相对标准偏差为1.2%。     

溴酸钾氧化邻苯二酚紫催化光度法测定微量亚硝酸根

基于在磷酸溶液中 ,亚硝酸根对溴酸钾氧化邻苯二酚紫的褪色反应具有催化作用 ,建立了催化光度法测定微量亚硝酸根的新方法 .采用正交实验法确定反应的最佳条件为 :磷酸 4 5mL ;溴酸钾 3 5mL ;邻苯二酚紫 2 5mL ;反应时间为 5min ;反应温度为 10 0℃。在选定的条件下 ,方法的灵敏度为 2 54× 10 - 10 g/mL亚硝酸态氮 ,线性范围为 0～ 8μg/2 6mL .用于水样、食品中亚硝酸根的测定 ,结果满意。     

1,3;2,4-二(对甲基苄叉)山梨醇的制备

介绍了聚烯烃成核透明剂1.3;2.4-二(对甲基苄叉)山梨醇(MDBS)的制备工艺过程与结果.以环己烷(2700mL)和甲醇(400mL)为溶荆,以对甲基苯磺酸(7.0g)为催化荆,山梨醇(182.2g,1.0mol)与对甲基苯甲醛(240.2g,2.0mol)回流反应5.5h,然后中和,水洗,蒸馏脱溶,过滤,干燥得MDBS 388.1g[w(MDBS)=98.1%],收率98.5%.     

靛蓝二磺酸钠催化光度法测定水中痕量亚硝酸根

基于亚硝酸根对溴酸钾氧化靛蓝二磺酸钠退色反应的催化作用,建立了一种在室温条件下(25℃)测定水中痕量亚硝酸根的方法.在608nm处,亚硝酸根含量在0.2～1.6 μg/10mL范围内与靛蓝二磺酸钠吸光度的减小值(△A)呈线性关系,检测限为0.02μg/mL.大多数常见离子无干扰.由Arrhenius方程求得表现活化能为39.7 kJ/mol.本方法简便快速,用于环境水样中痕量亚硝酸根的测定,结果满意.     

Kinetic Spectrophotometric Determination of Trace Titanium(Ⅳ) Based on Oxidation Discoloration of Acid Chrome Blue K with Hydrogen Peroxide

A simple and sensitive kinetic spectrophotometric method for the determination of trace amounts of titanium(IV), based upon the catalytic effect of Ti(IV) on the oxidation of acid chrome blue K (ACBK) by hydrogen peroxide in 0.002 mol/L sulfuric acid, is described. The reaction rate is monitored spectrophotometrically by measuring the decrease in absorbance of ACBK at 524 nm. The detection limit of the method is 1.01×10-9 g/mL, and the linear range is 0-0.048 mg/L. The influence of acidity, concentration of reactants, reaction time, reaction temperature and for-eign ions is also discussed. The optimum reaction conditions were established and some kinetic parameters determined. The apparent activation energy of the catalytic reaction is 5.32 kJ/mol. The relative standard deviation for the determi-nation of titanium(IV) at the concentration of 0.048 mg/L is calculated to be 1.31% (n = 11). In combination with sol-vent extraction separation, the method has been successfully applied to the determination of trace titanium(IV) in human hair, plant matter, tea and rock samples. The results are in good agreement with the certified values with the relative standard deviations (RSD) of 1.4%-3.5%.     

A New Reaction for Kinetic Spetrophotometric Determination of Trace Ruthenium——Catalytic Oxidation of Methyl Green by Bromate

A sensitive catalytic spectrophotometric method for the determination of ruthenium （Ⅲ） has been developed, based on its catalytic effect on the oxidation reaction of methyl green with potassium bromate in acid solution medium at 100℃. The above reaction is followed spectrophotometrically by measuring the decrease in the absorbance at 625 nm for the catalytic reaction of methyl green. The calibration curve for the recommended reaction-rate method was linear in the concentration range over 0.00-0.80 μg/L and the detection limit of the method for Ru （III） is 0.006 μg/L. Almost no foreign ions interfered in the determination at less than 25-fold concentration of Ru （Ⅲ）. The method is highly sensitive, more selective and very stable, and has been successfully applied for the determination of trace ruthenium in some ores and metallurgy products.     

Kinetic Spectrophotometric Determination of Trace Titanium（IV） Based on Oxidation Discoloration of Acid Chrome Blue K with Hydrogen Peroxide

A simple and sensitive kinetic spectrophotometric method for the determination of trace amounts of titanium（IV）, based upon the catalytic effect of Ti（IV） on the oxidation of acid chrome blue K （ACBK） by hydrogen peroxide in 0.002 mol/L sulfuric acid, is described. The reaction rate is monitored spectrophotometrically by measuring the decrease in absorbance of ACBK at 524 nm. The detection limit of the method is 1.01×10^-9 g/mL, and the linear range is 0-0.048 mg/L The influence of acidity, concentration of reactants, reaction time, reaction temperature and foreign ions is also discussed. The optimum reaction conditions were established and some kinetic parameters determined. The apparent activation energy of the catalytic reaction is 5.32 kJ/mol. The relative standard deviation for the determination of titanium（IV） at the concentration of 0.048 mg/L is calculated to be 1.31% （n = 11）. In combination with solvent extraction separation, the method has been successfully applied to the determination of trace titanium（IV） in human hair, plant matter, tea and rock samples. The results are in good agreement with the certified values with the relative standard deviations （RSD） of 1.4%-3.5%.     

稻米淀粉接枝丙烯酰胺共聚物的合成及性能分析

以稻米淀粉和丙烯酰胺为原料,过硫酸钾和亚硫酸钠为引发剂,乙二胺四乙酸二钠和尿素为助剂,采用水溶液聚合法制备淀粉接枝丙烯酰胺聚合物絮凝剂。分析了反应温度、引发剂浓度、助剂浓度对产物支链特性黏度的影响,考察了接枝共聚产物不同添加量对赤泥沉降分离效果。结果表明:反应体系中引发剂浓度各为2.22×10-3 mol/L,乙二胺四乙酸二钠浓度为2.68×10-4 mol/L,尿素浓度为0.133 mol/L,40℃下反应得到的接枝共聚物支链特性黏度超过1 100 mL/g,处理赤泥矿浆前5 min的赤泥平均沉降速度为0.021 7 cm/h,上清液的浊度为340NTU。     

甲醇电氧化制备甲醛的研究

介绍了一种用电化学法合成甲醛的新方法,研究了甲醇和盐酸混合体系中各种工艺条件对甲醛收率的影响,得到最佳电解条件如下：电极电流密度为20 mA/cm2,电解温度为40℃,电解时间为6 h,甲醇初始浓度为0.5 mol/L,盐酸初始浓度为1 mol/L。在此条件下电解甲醇,甲醛收率达19.1%,电流效率为28.8%。     

采用酸浸法从废旧锂离子电池中回收金属钴

分别采用盐酸-30%过氧化氢、硫酸-30%过氧化氢和硝酸-30%过氧化氢为浸取液,回收锂离子电池正极材料中的金属钴,研究了浓度、温度、30%过氧化氢的量、反应时间、固-液比等对钴浸取率的影响.经响应面分析实验结果表明,盐酸-30%过氧化氢最适宜做浸取液,最佳工艺条件为:盐酸浓度为4.0 mol/L,盐酸-30%过氧化氢...     

催化荧光法测定痕量亚硝酸根

在稀磷酸介质中，痕量亚硝酸根能催化溴酸钾氧化荧光桃红并使其荧光猝灭，且荧光猝灭程度与亚硝酸根加入量成比例关系，据此建立了催化荧光法测定痕量亚硝酸根的新方法．其激发波长λex=435．8nm，发射波长λem=560nm，测定亚硝酸根的线性范罔为0．0-11ng／mL，检出限为0．37ng／mL．将拟定的方法用于水样、蔬菜、粮食中亚硝酸根含量的测定，结果与Griss法一致．