Fenton技术中残余组分对COD测定的干扰和消除研究

Fenton试剂与水样中难降解有机物反应后,残余组分会对后续水样COD测定产生干扰。实验表明,Fenton试剂残余组分中H_2O_2对COD测定产生的干扰较大,其对水样COD测定产生的影响值与H_2O_2浓度成良好的线性关系,而残余组分Fe~(2+)对COD测定产生的干扰与H_2O_2相比,影响值较小,可忽略其影响。通过对比分析掩蔽剂法、催化分解法对H_2O_2干扰消除试验得出,掩蔽剂Na_2SO_3能够迅速的与H_2O_2发生反应,消除H_2O_2的干扰,但掩蔽剂Na_2SO_3也会对水样COD产生一定的干扰,测量结果偏差较大;MnO_2催化分解H_2O_2的效率较高,很好的消除H_2O_2的干扰,但MnO_2分解后水样COD测定值需乘以折减系数0.89,满足试验精度的要求;过氧化氢酶可以将H_2O_2完全分解,分解效率较高,干扰消除效果较好。     

酸性镀锌溶液中硼酸的分析方法

测定酸性镀锌溶液中硼酸的方法有几种,不同方法测定结果的差异较大,问题主要出现在对镀液中锌离子的掩蔽上。为此,研究了亚铁氰化钾掩蔽剂,用亚铁氰化钾沉淀锌离子,消除锌对测定硼酸的干扰,用甘露醇与硼酸反应生成较强的络合酸,以酚酞作指示剂,用氢氧化钠标准溶液滴定。试验表明,本法测定结果的相对平均偏差不大于0.29%,回收率为100.7%。     

原子吸收分光光度法测定钾长石中氧化钾,氧化钠

在钾长石分析中,经典的测定钾、钠的方法是重量法,但分析手续繁复,准确度也较差,而且使用的试剂价格昂贵,因此已很少采用。目前较常用的方法是火焰光度法,但某些共存元素直接干扰其测定,尽管可以通过分离或掩蔽等手段设法消除,但使分析手续变得冗长。此外,滤光片的质量和钾、钠的自吸现象都可使测定结果产生较大偏差。而用原子吸收分光光度法测定钾、钠,干扰因素少,所有在火焰光度法中可能产生的辐射干扰,在原子吸收法中几乎得到全部     

EDTA法测定含磷溶液中硫酸根的测量条件探究

采用EDTA间接配位滴定法测定含磷溶液中的硫酸根含量。重点研究了指示剂选择、钡镁混合液加入方式及用量、pH值的最佳范围、共存离子的影响与消除,以及掩蔽条件的选择作用等。研究结果表明,在不进行萃取分离的条件下,通过加入掩蔽剂消除干扰离子的影响,可以实现对含磷溶液中硫酸根的测定。     

EDTA和EGTA络合滴定法测定粉煤灰溶出液中钙

以除钙工艺前后的粉煤灰溶出液作为分析试液,溶液中的铁、铝、钛、铜、锰等干扰元素不需要分离,在酸性溶液中用三乙醇胺溶液进行掩蔽消除干扰。以酸性铬蓝K-萘酚绿B作指示剂,采用EDTA络合滴定法测定除钙前溶液中钙含量。在测定除钙后溶液中的钙含量时,以钙黄绿素-百里酚酞作为指示剂,采用EGTA络合滴定法测定钙含量。使用这两种方法对除钙前后的钙进行了多次平行测定,两种测定方法测定结果的相对标准偏差在0.95%～2.84%,加标回收率在98.19%～102.66%。     

火焰光度法测定循环水中K+时Ca2+的干扰及消除

通过实验研究了以火焰光度法测定循环水中K~ 时Ca~(2 )对测定结果的干扰及消除干扰的方法。结果表明,随着水中Ca~(2 )浓度的增加,测定结果的误差增大。当水样中的Ca~(2 )浓度大于300mg/L时,需要对其干扰进行消除。采用稀释法、干扰离子等量校正法和干扰离子去除法均能够较好地消除Ca~(2 )对测定结果的影响,但后两种方法操作相对比较复杂。     

一种含硅锰组分较高的钨矿中钙的络合滴定分析

本文主要研究了硅含量较高的钨矿石中钙的含量测定,在强碱性溶液中用EDTA络合滴定钙时,防止钙与硅形成硅酸钙阻碍EDTA与钙的络合,考察使用氟化物掩蔽,浓盐酸分解样品,沉淀分离硅,有效消除硅干扰,达到滴定钙的方法,手续简单,结果准确.     

色釉及色料中钙镁的测定

简单的掩蔽法不能消除色釉及色料中多种金属元素对钙镁测定的影响，需用沉淀分离法除去干扰元素后再测定。本实验采取六次甲基四胺-铜试剂法分离除去色釉及色料中存在的多种金属离子。试验结果表明，此法对色釉及色料中存在的金属离子能分离完全，且沉淀对钙镁离子的吸咐作用极小。分析结果准确可靠。     

分析酸性镀锌溶液中硼酸含量掩蔽剂的选择

目前,测定酸性镀锌溶液中硼酸的方法有几种,不同方法测定结果的差异较大,有些方法的误差是不能允许的。实验表明,不能用柠檬酸钠和EDTA-Na_2掩蔽锌离子。但是,用草酸钠或亚铁氰化钾掩蔽锌离子,能够消除锌离子对测定硼酸的干扰。用甘露醇与硼酸反应生成较强的络合酸,以酚酞作指示剂,用氢氧化钠标准溶液滴定。本法准确度较高,能够满足监控酸性镀锌溶液中硼酸的要求。     

工业硫酸中砷含量测定影响因素探析

采用原子荧光光谱法测定工业H2SO4中的As含量,并对测定过程中可能影响实验准确度的因素进行了考察。实验结果表明,测定过程中体系酸度和金属离子对测定结果有一定影响,砷的荧光强度随着酸度增加而增大,当体系酸度在4%～10%时,测定结果相对稳定。在测量相对误差低于5%时,Cd、Fe、Zn、Pb等金属离子对砷的测定基本不产生干扰作用,而Cu2+和Ca2+则影响较大。     

HCl－NaCl－DMS－OH_2O体系中HCl的活度系数

采用电动势法测定了ＨＣｌ＋ＮａＣｌ＋ＤＭＳＯ＋Ｈ_２Ｏ体系在２９８．１５～３１８．１５Ｋ范围内，总离子强度分别恒定在Ｉ＝０．１，０．２，０．５ｍｏｌ·ｋｇ~（－１）情况下的ＨＣｌ的活度系数。应用最小二乘法拟合，表明ＨＣｌ的活度系数遵守Ｈａｒｎｅｄ规则。从粒子间微观相互作用出发阐明了Ｈａｒｎｅｄ参数α_Ａ的物理意义，并给出了α_Ａ与温度和溶液离子强度之间的关系。     

分析化学实验中Bi3+、Pb2+混合液配制、连测、废液回收与再生

通过对Bi^3 ,Pb^2 混合液配制方法与测定结果的关系实验，确定了硝酸铋溶解时浓HNO3用量及滴定Bi^3 的新方法。络合法连测Bi^2＋后的废液可用硫化钠沉淀，用稀硝酸溶解，再次配成所需酸度和Bi^2 ,Pb^2 浓度的混合液。供学生实验重复使用。     

聚甲氧基二甲醚+水+正己烷三元体系的液液相平衡

聚甲氧基二甲醚（PODE_n）是一种极具应用前景的清洁柴油调和组分。研究了293.15 K、常压下PODE₁+水+正己烷、PODE₂+水+正己烷、PODE₃+水+正己烷、PODE₄+水+正己烷这4组三元体系的液液相平衡。PODE₁-4组分的萃取选择性系数S远大于1,表明正己烷作为萃取剂从水溶液中萃取PODE_1-4是可行的;经Hand结线关联检验,各体系的相平衡数据具有较高的一致性;采用NRTL和UNIQUAC热力学模型对相平衡数据进行拟合,均方根差计算（RMSD）结果和三元相图分析结果表明NRTL和UNIQUAC都能较好地描述三元体系的液液相平衡。     

Ti/SnO_2+Sb_2O_3+MnO_2/PbO_2阳极的制备及其性能

用热分解和电沉积联合方法制备了Ｔｉ／ＳｎＯ２＋Ｓｂ２Ｏ３＋ＭｎＯ２／ＰｂＯ２阳极．对该类电极进行了ＥＤＳ、ＳＥＭ、ＸＲＤ研究．测定了电极在１ｍｏｌ／ＬＨ２ＳＯ４溶液中的使用寿命和动力学参数．考察了其作为阳极用于含酚废水处理时的性能．结果表明，所制备电极在硫酸溶液中具有优良的电催化活性和电化学稳定性．     

Color tunable up-conversion emission of ZrO2:Yb3+, Er3+ thin films prepared by chemical solution deposition

The color-tunable up-conversion (UC) emission was observed in ZrO₂:Yb³⁺, Er³⁺ thin films synthesized on fused silica substrates using a chemical solution deposition method. The crystal structure, surface morphology image and optical transmittance of ZrO₂:Yb³⁺, Er³⁺ thin films were detected in the matter of Yb³⁺/Er³⁺ doping content. Under excitation by 980?nm infrared light, intense UC emission can be obtained from ZrO₂:Yb³⁺, Er³⁺ thin films. Photoluminescence study shows that there are two emission bands centered at 548?nm and 660?nm in the UC luminescence spectra, which can be owing to (²H_11/2,⁴S_3/2)→⁴I_15/2 and ⁴F_9/2→⁴I_15/2 transitions of Er³⁺ ions, respectively. In addition, the color coordinate of UC emission between green-red can be tuned by properly adjusting the dopant concentration, because the composition of Yb³⁺/Er³⁺ affect the red/green ratio via the process of cross relaxation and energy back transfer. Our study suggests that ZrO₂:Yb³⁺, Er³⁺ thin films can be considered as promising materials for new photoluminescence devices.     

Thermodynamics of supersaturated solutions: From ternary electrolyte+solute+H2O to binary solute+H2O systems

In our previous paper, a new experimental technique based on the potentiometric method was developed to obtain thermodynamic activity data (in form of activity ratio) particularly for ternary electrolyte+nonelectrolyte+H₂O solutions supersaturated with the nonelectrolyte. In this paper, a rigorous thermodynamic approach is proposed to derive activity data for binary nonelectrolyte+H₂O solutions in the supersaturated region, via cell potentials of an electrolyte tracer and solubility data of the nonelectrolyte. An analysis of thermodynamic consistency is presented to evaluate the reliability and accuracy of the measured data. A systematic experimental investigation of three ternary electrolyte+nonelectrolyte+H₂O and two binary nonelectrolyte+H₂O systems is reported in both under-saturated and supersaturated regions (up to a supersaturation level of approximately 27%). Interesting thermodynamic behaviors are observed and their significance is discussed, with the role of thermodynamics in exploration of crystallization phenomena highlighted.     

2％复硝酚钾水剂的高效液相色谱分析

文章建立了2%复硝酚钾水剂的高效液相色谱分析方法。使用ODS反相柱和可变波长检测器,以甲醇加水(水用0.1%H3PO4调至pH=3)为流动相,外标法对2,4-二硝基酚钾、对硝基酚钾和邻硝基酚钾进行定量分析。结果表明,方法的标准偏差为0.0114(邻硝基酚钾)、0.0158(对硝基酚钾)、0.0011(2,4-二硝基酚钾),变异系数为1.10%(邻硝基酚钾)、1.68%(对硝基酚钾)、0.0011%(2,4-二硝基酚钾),平均回收率为99.19%(邻硝基酚钾)、99.81%(对硝基酚钾)、99.31%(2,4-二硝基酚钾)。     

大孔树脂对食品糖液中Ca2+、Mg2+离子吸附特性的研究

研究了A252大孔树脂对糖液中Ca^2 、Mg^2 的吸附效果。结果表明，该树脂对Ca^2 、Mg^2 的交换能力大，吸附效果好，且该树脂的交换容量与糖液的pH值和流速相关。     

Influence of Ti4+ substitution for Ta5+ on the crystal structure,Raman spectra,and microwave dielectric properties of Ba3Ta4-4xTi4+5xO21 ceramics

This paper systematically investigated the influence of Ti⁴⁺ substitution for Ta⁵⁺ on the phase composition and microwave dielectric properties of Ba₃Ta_4-4xTi_4+5xO₂₁ (x = 0.1, 0.2, and 0.3) ceramics with hexagonal tungsten bronze-like structures. X-ray diffraction and Rietveld refinement results indicated that single-phase Ba₃Ta₄Ti₄O₂₁ could be obtained only with the x values of 0.1 and 0.2, and a secondary phase was detected at an x value of 0.3. The valence state of Ba₃Ta_4-4xTi_4+5xO₂₁ (x = 0.2) ceramics was analyzed through X-ray photoelectron spectroscopy. Increasing Ti⁴⁺/Ta⁵⁺ ratios could reduce sintering temperature and improve the microwave dielectric properties of Ba₃Ta_4-4xTi_4+5xO₂₁ solid solutions. However, the dielectric properties, particularly the quality factor, of Ba₃Ta_4-4xTi_4+5xO₂₁ ceramics deteriorated severely as a result of oxygen vacancy defects caused by the transition of the valence state from Ti⁴⁺ to Ti³⁺ when x = 0.2 and the coexistence of the secondary phase when x = 0.3. Infrared reflectivity spectroscopy was performed to explore the intrinsic dielectric properties of Ba₃Ta_4-4xTi_4+5xO₂₁ (x = 0.1) ceramics. The measured and extrapolated microwave dielectric properties of Ba₃Ta_4-4xTi_4+5xO₂₁ (x = 0.1) ceramics sintered at 1240 °C for 6 h were ε_r ~ 46.5, Q × f = 13,900 GHz, τ_f ~ +49.4 ppm/°C, and ε_r ~ 44, Q × f = 34,850 GHz.     

Achieving highly efficient far-red emission from luminescence-ignorable Ca2MgTeO6:Mn4+ to Ca2-zLnzMgTe1-yWyO6:Mn4+ (Ln = La,Y, Gd) phosphors via solid solution and impurity doping strategies

The Mn⁴⁺-doped Ca2MgTeO6 (CMTO) far-red emitting phosphors with double perovskite-type structure were successfully synthesized. Upon near-ultraviolet (n-UV, 300 nm) light excitation, the as-prepared phosphors showed far-red light at 700 nm attributed to the ²E_g→⁴A_2g transition of Mn⁴⁺ ion. The doping concentration of the CMTO:xMn⁴⁺ samples was optimized to be 0.8 mol%. The relevant mechanism of concentration quenching was demonstrated as the dipole-dipole interaction. Furthermore, solid solution and impurity doping strategies were adopted to improve the far-red emission of the luminescence-ignorable CMTO:Mn⁴⁺ phosphor. Series of Ca₂MgTe_(1−y)W_yO₆:0.8 mol%Mn⁴⁺ (y = 0–100 mol%) solid solution and Ca_2−zLn_zMgTe_0.6W_0.4O₆:Mn⁴⁺ (Ln = La, Y, and Gd, z = 10 mol%) phosphors were synthesized through the above two strategies. The luminescence intensity of the optimal Ca_1.9Gd_0.1MgTe_0.6W_0.4O₆:Mn⁴⁺ phosphor was 13.7 times that of the CMTO:Mn⁴⁺ phosphor and 2.51 times that of red commercial phosphor K₂SiF₆:Mn⁴⁺. Notably, both CMTO:Mn⁴⁺ and Ca_1.9Gd_0.1MgTe_0.6W_0.4O₆:Mn⁴⁺ phosphors exhibited remarkable thermal stability compared with most Mn⁴⁺-doped phosphors. Finally, the highly efficient Ca_1.9Gd_0.1MgTe_0.6W_0.4O₆:Mn⁴⁺ phosphor was successfully applied in fabricating the warm white light diode (w-LED). This working along both lines strategy exhibited great potential for luminescence optimization of Mn⁴⁺-doped oxide phosphors.