K301型高锰酸盐指数在线自动监测仪测定方法的探讨

从反应体系的酸度、反应时间和反应温度3个方面对K301型在线高锰酸盐指数测定方法进行了研究。结果表明：在同一酸度和反应温度下,高锰酸盐指数测定值随反应时间的廷长而逐渐增大和随反应温度的增大而逐渐增大;在相同反应温度和反应时间内,高锰酸盐指数测定值随反应酸度的增大而逐渐增大。综合以上2条件试验得出,加入8mL硫酸,反应时间为10min,反应温度为95℃,测得的高锰酸盐指数与国标方法（GB11892—89）测定结果无显著差异。     

浅谈提高水质监测分析中高锰酸盐指数(酸性法)测定的准确度

高锰酸盐指数的测定与加热时间、水浴温度、高锰酸钾浓度、溶液酸度等影响因素有关,本文总结分析了在实际监测中各因素对CODMn测定的影响,对提高水质监测分析中高锰酸盐指数(酸性法)测定结果的准确度具有指导意义。     

减小高锰酸盐指数测定误差的分析研究

通过对高锰酸盐指数测定原理和方法的探讨,分析在高锰酸盐指数测定过程中产生误差的原因。结果表明,误差的产生与高锰酸钾标准溶液、加热时间、反应体系酸度、滴定速度等因素有关。     

高锰酸盐指数测定的影响因素

高锰酸盐指数值的准确度与高锰酸钾标准溶液浓度、样品加热时间、样品反应温度、酸度、滴定速度有关。在测定标样时,稀释标样的蒸馏水对标样值有很大的影响。     

准确测定高锰酸盐指数的条件因素分析

高锰酸盐指数是一个相对性的条件指标,不同的条件因素都会影响其测定结果。为找出准确测定高锰酸盐指数的方法,从实验用水、加热时间、高锰酸钾标准溶液的浓度、反应体系的酸度以及滴定条件的控制等方面进行分析,提出测定高锰酸盐指数的最佳条件,并指出测定过程中的注意事项,对准确测定高锰酸盐指数具有重要意义。     

浅谈生活饮用水中酸性高锰酸盐指数误差的控制

酸性法测定高锰酸盐指数时,容易存在一定的系统误差,高锰酸盐指数测定过程中产生误差主要与高锰酸盐浓度、加热温度和时间、溶液的酸度等条件有关,因此,在测定时必须严格遵守操作规定及有关细节问题,才能获得相对精确的测量值。     

浅谈影响高锰酸盐指数准确度的若干因素

高锰酸盐指数是一个相对的条件性指标,其测定结果与标准溶液浓度、加热时间与温度、滴定条件、空白值等因素有关.全面总结分析了实际监测中各因素对CODMn测定的影响情况,并指出测定过程中应当注意的关键问题,对高锰酸盐指数的准确测定具有非常重要的意义.     

湖水中高锰酸盐指数测定及其条件探讨

高锰酸盐指数作为较为清洁水样受有机污染物和还原性无机物污染程度的指标,在例行监测中广泛使用。根据酸性高锰酸盐指数法的分析原理和测定过程,高锰酸盐指数的测定结果受到分析过程中多个因素影响,本文从溶液酸度、水浴温度、水浴加热时间、样品稀释倍数等方面,分析和讨论了其对高锰酸盐指数测定结果的影响,从反应机理上分析了以上关键步骤中影响准确测定的原因。在优化的基础上,进行了湖水中高锰酸盐指数的测定。     

浅析加热时间对高锰酸盐指数的影响

高锰酸盐指数常被作为地表水水体受有机污染物和还原性无机物质污染程度的综合指标。在一般酸性介质中测定水质高锰酸盐指数的时候,会受到酸度、水浴温度、加热时间等因素的影响,在此讨论加热时间对高锰酸盐指数的影响,根据GB11892-89的分析步骤实验得出,在30 min的加热时间里数据最符合实际需要。     

水中氯离子对高锰酸盐指数测定的影响

本文采用碱性高锰酸钾氧化法测定不同浓度的氯离子对高锰酸盐指数的干扰情况,并根据标准样品对其进行评价。结果表明,氯离子含量为8000mg/L及以下时不会对CODMn值产生干扰。当氯离子浓度为8000mg/L以上时,对CODMn值产生正干扰,且随着氯离子的增大干扰增强。因此,该方法可以为环境监测中高氯水样的测定提供一定的参考价值。     

探讨影响SERES2000高锰酸盐指数分析仪测定结果的主要因素

高锰酸盐指数是一个条件性的相对指标,本文将讨论加热温度、加热时间等反应条件对SERES2000高锰酸盐指数分析仪测定结果的影响。     

Effect of surface acidity of activated carbons on their characteristics of adsorption from the vapour phase—comparison of retention time for carbons used as adsorbents for gas chromatography

Seventeen kinds of activated carbons of different surface acidity and of known pore-structure were used as adsorbents for gas chromatography. The retention time of various kinds of substrates was determined for each carbon at different temperatures. It was found that surface acidity of carbons has a marked effect on increasing the retention time for polar substances while showing no effect for non-polar substances. Retention times varied with temperature which suggested, when the effect of surface acidity is taken into account, that the pores which were effective for the Chromatographic adsorption have been determined by the temperature. The heat of adsorption calculated on the basis of the retention times observed at different temperatures showed an inverse correlation with dielectric constant of the adsorbates.     

Production of renewable fuels by blending bio-oil with alcohols and upgrading under supercritical conditions

The work studied a non-catalytic upgrading of fast pyrolysis bio-oil by blending under supercritical conditions using methanol, ethanol and isopropanol as solvent and hydrogen donor. Characterisation of the bio-oil and the upgraded bio-oils was carried out including moisture content, elemental content, pH, heating value, gas chromatography-mass spectrometry (GCMS), Fourier transform infrared radiation, ¹³C nuclear magnetic resonance spectroscopy, and thermogravimetric analysis to evaluate the effects of blending and supercritical reactions. The GCMS analysis indicated that the supercritical methanol reaction removed the acids in the bio-oil consequently the pH increased from 2.39 in the crude bio-oil to 4.04 after the supercritical methanol reaction. The ester contents increased by 87.49% after the supercritical methanol reaction indicating ester formation could be the major deacidification mechanism for reducing the acidity of the bio-oil and improving its pH value. Simply blending crude bio-oil with isopropanol was effective in increasing the C and H content, reducing the O content and increasing the heating value to 27.55 from 17.51 MJ·kg^‒1 in the crude bio-oil. After the supercritical isopropanol reaction, the heating value of the liquid product slightly further increased to 28.85 MJ·kg^‒1.     

活性炭UF膜分离污水中COD的实验研究

试验考察了粉末活性炭的投加对超滤膜运行性能的影响,结果表明:随粉末活性炭投量的增加膜稳定运行时间延长,通量下降率降低。粉末活性炭的投加对膜过滤阻力影响不大。在此基础上又对PAC-UF组合系统去除有机物的效果进行了进一步研究,主要是对比研究了不同PAC投加量对5种不同配置水样中有机物的去除效果。得出如下结论:在相同PAC投加量下,CODMn值大的水样的CODMn平均去除率高,且出水CODMn值相近。说明了PAC-UF组合系统出水稳定,受水质差异的影响不大。     

片钠铝石的水热合成研究

用水热法合成了片钠铝石[NaAl(OH)2CO3]粉体，粉体颗粒长径比很大，呈针状。研究了几种反应条件对NaAl(OH)2CO3合成的影响。实验结果表明：水热反应体系的酸碱度、温度、起始反应物的组成以及反应时间等都会影响反应产物的相组成及其颗粒形貌和大小。随着反应体系的pH值的升高，粉体粒径增大，团聚减轻，但以pH值为9.5的体系中的得到的粉体综合性能最好。适当增加反应体系的NaHCO3的用量，NaAl(OH)2CO3粒径明显减小。适当降低反应温度，缩短反应时间均有助于提高产物的均匀性，并且可以减小颗粒尺寸。     

芬顿-絮凝联合处理高浓度有机物海水的试验研究

为了使盐场晒盐池海水能用于海水淡化,针对有机物浓度较高的盐池海水进行了芬顿-絮凝联合预处理试验。选取聚丙烯酰胺(PAM)作为絮凝剂,考察Fe SO4·7H2O和H2O2用量、芬顿反应条件和絮凝剂用量等参数对CODMn和浊度去除效果的影响。结果表明,在氧化阶段p H值为4,Fe SO4·7H2O投加量为125 mg/L,H2O2投加量为50 mg/L,反应时间为60 min,PAM投加量为1 mg/L,海水CODMn和浊度去除率分别为59.6%和96.2%,均较单独采用传统絮凝技术有较大提高。     

钾长石作为助熔剂熔融还原磷矿的可行性研究

研究了钾长石对磷矿熔融还原反应的工艺及动力学,考察了反应温度、反应时间、酸度值及焦炭过剩系数对磷还原率的影响.结果表明磷的还原率均随反应温度、反应时间、酸度值、焦炭过剩系数的增大而增大,最佳工艺条件为反应温度1300℃,反应时间40min,酸度值0.85,焦炭过剩系数1.05,磷的还原率达到99.61％.针对不同温度下还原率与时间的变化进行拟合,得到不同温度下的反应速率,再由反应速率对浓度的对数值作图,得到反应级数.结果表明磷矿熔融还原的反应级数不是定值而是随反应温度变化的.利用Arrhenius公式计算得到反应的活化能Ea为100.71kJ/mol.     

Rheometers with square root of time-temperature programming for the cure of rubbers

Because of the drawbacks resulting from using a constant temperature, calorimetry has been developed with scanning mode and temperature programming with a constant heating rate. Following this way, a theoretical approach was made with moving die rheometers, showing some advantages over the method done under isothermal conditions. However, if it usual to vary the temperature linearly with time, it is shown that a better way consists in increasing the temperature of the dies with the square root of time. The theoretical study of this new method is made enabling the evaluation of the torque-temperature curves. Some advantages are obtained with respect to the linear programming, coming from the principle of this new method. Thus, the rate of heating is faster at the beginning of the process when the rubber sample is heated up to a temperature where the reaction starts, and becomes lower within the temperature range where the reaction develops. A method has been elaborated for evaluating the kinetic parameters from these torque-temperature curves. The effect of the parameters of interest, with the value of the rate of heating and the thickness of the rubber sample, is determined. Thus the value of the heating rate should be between 10 and 50 K/min^0.5. A slight change in the thickness of the sample over the average value of 0.2 cm is of little effect. The profiles of temperature developed through the thickness of the sample are flatter than those obtained with the isothermal rheometer, leading subsequently to more uniform profiles of the state of cure, as they are obtained by calculation. Moreover, shorter times of experiment are obtained over the method based on the linear programming temperature system. The kinetic parameters such as the activation energy and the pre-exponential factor, as well as the overall order of the reaction, are thus obtained from only one experiment.