氢化物法测定水样中的砷

采用氢化物原子吸收法测定样品中痕量砷,对于样品的前处理及采用氢化物法测定砷含量时,砷的不同价态及共存离子的影响,分别进行了探讨。     

天然沸石吸附电镀废水中重金属离子的实验研究

针对含重金属离子电镀废水,国内外普遍采用化学沉淀法来处理,而化学沉淀法存在运行费用高、二次污染等问题。由于铜离子、锌离子是最常出现在电镀工业中,本文选择铜离子和锌离子为研究对象,本文采用天然沸石处理模拟电镀废水中的铜离子和锌离子,考察了溶液pH值、天然沸石用量、反应时间、共存阳离子等多种物理化学参数的影响。实验结果表明,天然沸石吸附铜离子的最佳参数：当初始浓度为200 mg/L,溶液pH值为7,天然沸石用量为30 g/L,反应时间为20 min时,处理后的水质满足《污水综合排放标准》(GB8978-1996)要求。铜离子分别与锌、镍、铅和六价铬离子共存时,锌和镍离子在低浓度时对铜离子的吸附影响不大;铅和六价铬离子明显抑制铜离子的吸附。天然沸石吸附新离子的最佳参数：初始浓度在200 mg/L,溶液pH值为7,天然沸石用量为30 g/L,反应时间在20 min时,处理后的水质满足《污水综合排放标准》(GB8978-1996)要求。锌离子分别与铜、镍、铅和六价铬离子共存时,铜离子几乎对锌离子无影响;镍离子的影响很小;铅和六价铬离子明显抑制锌离子的吸附,为实际电镀废水的高效处理提供理论依据。     

离子共存问题及解题思路

离子共存是近年来广东高考的必考内容,所谓离子共存,实质上就是看离子间是否发生反应的问题。若在溶液中发生反应,就不能共存。看能否发生反应,不仅是因为有沉淀、气体、水、难电离的物质产生,还涉及到溶液酸碱性、有色、无色,能否进行氧化还原反应等。本文将对离子共存的知识点进行梳理并分析,供参考。     

膨润土吸附水中Cr(Ⅵ)的实验研究

研究了钠化膨润土对Cr6 的吸附行为,考察了溶液中Cr6 的初始质量浓度、吸附剂用量、pH、搅拌时间、温度、粒度等因素对膨润土吸附的影响.结果表明,钠化膨润土对于Cr6 的吸附在1h基本达到吸附平衡,吸附量随溶液pH的增大、温度的升高、膨润土粒度的增加以及溶液中Cr6 的初始质量浓度的增高而降低.在混合体系中,共存离子的存在影响金属离子的吸附效率,共存离子的质量浓度与Cr6 相近时,对Cr6 的吸附效果影响很大,其中,Zn2 的影响大于Pb2 ;共存离子的质量浓度远大于Cr6 时,Zn2 基本没有影响,Pb2 却能提高对Cr6 的吸附效率.     

离子共存的知识点梳理与试题研究

离子共存是近几年的高考热点,在考卷中通常以条件型选择题的形式出现,本文将对离子共存的重要知识点进行梳理,对常见题型进行分析,供读者参考。     

浅谈离子共存题型的总结及解题技巧

离子共存题型是历年高考中的热门考点。在考卷中通常以条件型选择题的形式出现,本文将对离子共存的重要知识点进行梳理,对常见题型进行分析,供读者参考。     

废水中重金属离子吸附影响因素研究

通过对吸附法去除重金属离子的影响因素进行综合评述,在pH、吸附剂用量、初始重金属离子浓度、吸附时间、温度和共存离子等方向对重金属离子去除能力的影响进行分析,为提升吸附能力和节约经济效益提供参考。     

吸附法回收除去钒研究进展

吸附法是一种去除污染水体中重金属的有效经济环保的方法,本文综述了近几年来采用吸附回收去除钒的研究情况,对影响钒离子的各种因素包括吸溶液的pH值、温度、共存离子的影响等因素进行了分析;对吸附热力学和动力学分别进行讨论;对其吸附机理和吸附材料进行了总结,为采用吸附法除去钒离子理论研究和实际应用提供一定的参考。     

离子强度对铬酸盐——重铬酸盐反应速率的影响

<正> 前言铬的几种含氧酸盐可以在水溶液中平衡共存,而它们之间的比例则取决于溶液的酸度。其中铬酸盐—重铬酸盐之间相互转变的反应速率,有人已在一定温度、一定离子强度的条件下用其它多种方法进行过研究,所得结果在数量级上相同。本文则用跳浓弛豫的方法来研究离子强度对此反应的影响。笔者     

离子选择电极法测定牙膏中氟含量的研究与探讨

本文对离子选择电极法测定牙膏中氟化物进行了研究与探讨.讨论了仪器精度、共存离子引入的误差及干扰、测定的pH值范围、电极相关因素的影响、搅拌的影响和测定中应注意的问题等因素对氟离子选择电极法测定牙膏中氟化物的影响。该方法具有选择性好,准确、快速、检测范围宽的特点.     

Dissolved-Air Flotation of Metal Ions

Abstract

Metal ions (copper, nickel, zinc, and ferric ions) were separated from dilute aqueous solutions by dissolved-air flotation. The ions were either precipitated as sulfides or floated (as ions) by xanthates. Copper and nickel were selectively separated; promising results were obtained with single, binary, and ternary mixtures. The effect of several parameters (solution pH, addition of chemical reagents at varying concentrations, and the presence of other ions) on the removal of ions was studied. The collectorless flotation of copper ions was also investigated.     

三维电极法去除配位电镀废水中的镍离子和铜离子

将颗粒状活性炭作为三维电极的粒子,采用三维电极法去除配位电镀废水中的镍离子和铜离子。考察了pH值、电流、极板间距、炭水比(粒子电极活性炭与处理水量的体积比)对镍离子和铜离子去除率的影响。在设定的范围内,镍离子和铜离子的去除率随pH值的升高呈现先升后降的变化趋势,随电流和炭水比的增大而升高,随极板间距的增大而降低。当废水中镍离子和铜离子的初始质量浓度分别为82.309 3mg/L和52.761 5mg/L、活性炭的体积为1 000mL、处理时间为2.0h时,最佳的处理工艺条件为:pH值4、电流0.6A,极板间距20cm,炭水比10∶9。此时,镍离子和铜离子的去除率分别为83.40%和86.20%。出水经过混凝沉淀后,镍离子和铜离子的去除率分别达到99.87%和99.68%,在出水中的质量浓度分别为0.107 2mg/L和0.169 3mg/L,出水水质达到《电镀污染物排放标准》(GB 21900—2008)中表2的排放限值。     

溶剂萃取分离铁锌

氯化物溶液中，铁（Ⅱ）、铁（Ⅲ）、锌（Ⅱ）与氯离子配位，形成不同的络合物，具有可萃性差异。对ＴＢＰ、叔胺、季铵进行分离性能比较后发现，季铵对铁（Ⅱ）、锌表现出优良的分离性能和较大的负载容量。机理研究表明，季铵萃锌是阴离子交换反应。模拟实验证实，经两级萃取能使铁（Ⅱ）、锌几乎完全分离。     

含银玻璃除藻剂的应用研究

本文研究了银离子去除赤潮藻的效果,实验结果表明,当银离子浓度在0.125～0.25mg/L时,能有效抑制和灭杀赤潮生物,但有效期短,为此研制了含银玻璃除藻剂,当这种药剂投加到水体后,随玻璃逐渐溶解缓释出银离子而灭杀赤潮藻,延长了有效期;此外,本文还研究了含银玻璃除藻剂在灭杀赤潮藻后银离子的残留浓度以及对环境的影响。     

Fluoride Ions Behavior in the Presence of Corrosion Products of Iron: Effects of Other Anions

The behavior of fluoride ions in the presence of corrosion products of iron in drinking and water solutions was analyzed and the adsorption capacities of the iron oxides (corrosion products of iron) for fluoride ions were determined. Drinking water containing naturally 2.45 mg of fluoride ions per liter was characterized and the concentrations of other anions were determined. The effect of contact time, the initial concentration of fluoride ions, and the effect of other anions naturally present in the drinking water were considered. The kinetic results could be adjusted to the pseudo-second order model, which indicated that the sorption mechanism was chemisorption and the equilibrium was reached in 24 hours. The presence of bicarbonate and chloride ions diminishes the removal efficiency of the fluoride ions, whereas other anions (sulfate, phosphate, and nitrate) did not show any significant effect. The results reflect that the iron oxides products from the corrosion of a hydraulic infrastructure allow the removal of fluoride ions from water.     

Electrodissolution of iron in sodium sulfate and sodium bicarbonate solutions at pH8

The effect of sulfate ions on the electrochemical behaviour of iron electrodes in the presence of bicarbonate ions has been investigated. In solutions containing sulfate ions only, iron electrodes experience uniform corrosion and sulfate ions are aggressive. In the presence of bicarbonate ions, the sulfate ions become less aggressive and a pitting–repassivation process is observed. The differences in electrochemical behaviour have been compared and explained by examining the formation of probable products and their physicochemical properties during electrochemical polarization.     

Electrodissolution of iron in sodium sulfate and sodium bicarbonate solutions at pH8

The effect of sulfate ions on the electrochemical behaviour of iron electrodes in the presence of bicarbonate ions has been investigated. In solutions containing sulfate ions only, iron electrodes experience uniform corrosion and sulfate ions are aggressive. In the presence of bicarbonate ions, the sulfate ions become less aggressive and a pitting–repassivation process is observed. The differences in electrochemical behaviour have been compared and explained by examining the formation of probable products and their physicochemical properties during electrochemical polarization.     

真空制盐两碱净化过程成垢离子的脱除及控制

通过研究卤水两碱法净化过程成垢离子(Ca2+,Mg2+和CO32-)的行为,揭示卤水净化成垢离子脱除与控制的基本规律.研究了"NaOH-Na2CO3"两碱用量对卤水中钙镁离子净化效果及精卤中残留碳酸根离子浓度的影响.研究结果表明,通过优化两碱用量,调控卤水pH值,可以在脱除钙镁离子的同时,实现碳酸根离子的高效利用,控制...     

Hydrothermal modification of natural zeolites to improve uptake of ammonium ions

The modification of natural zeolites was carried out under hydrothermal conditions to improve the effectiveness of the uptake of ammonium ions. Natural zeolites originating in Japan, such as mordenite and clinoptilolite with quartz, feldspar and a trace of layered silicate, were treated with 0.1, 0.3, 1.0 and 3.0 M NaOH solutions at temperatures from 25 to 150 °C under autogenous pressure for 7 days. After the hydrothermal treatment, the transformation of the zeolites to phillipsite, hydroxyl‐sodalite and analcime was observed, depending on the temperature and NaOH concentration. The amounts of ammonium ions taken up into the hydrothermally‐treated zeolites were compared with those of the starting materials. The treated products, containing mainly phillipsite, took up twice the amount of ammonium ions as the starting materials. The maximum uptake of ammonium ions was 1.92 mmol g^?1. The number of ammonium ions taken up into phillipsite was equal to the number of Na⁺ ions released from phillipsite. These results indicate that the uptake of ammonium ions proceeds by an ion‐exchange mechanism with Na⁺ ions. Copyright © 2005 Society of Chemical Industry     

影响化学镀镍液活性的研究

通过实验研究了在中温碱性化学镀镍溶液体系中,影响碱性化学镀液活性与寿命的最主要因素不是亚磷酸根的累积,而是镀液中铵盐的累积.通过采用不合铵盐的碱替代氨水来调节镀液pH值的方式,能有效地控制镀液中铵盐的累积,有效地延长了镀液的使用寿命.