Fe0去除地下水中六价铬的研究

为了研究零价铁去除水中Cr(Ⅵ)的效果及影响因素。在实验室条件下,通过批试验,考察了铁粉预处理、铁粉用量、初始pH及阳离子对六价铬去除的影响。结果表明:零价铁能够有效、快速的去除污染水体中的六价铬,机理为氧化还原和共沉淀;其去除率受铁粉预处理、铁粉投加量、初始pH及阳离子的影响;在酸性条件下,Fe2+浓度可以作为六价铬是否完全去除的指示剂。     

共沉淀净化污水中重金属的研究

根据化学共沉淀原理对污水中重金属净化的可能性进行了研究。选用FeSO_4和AlCl_3为共沉淀剂,以Cu、Cd、Cr、Hg和Pb为污染重金属。当pH7.0～8.0,共沉淀剂用量浓度为10.0μg/mL,共沉淀时间为24h,共沉淀重金属浓度为:Cu<50μg/mL,Pb<10μg/mL,Cd<5.0μg/mL,Hg相似文献   

Heat-induced structural changes and aggregation of walleye pollack myosin in the light meromyosin region

Heat-induced structural changes and aggregation properties of walleye pollack myosin, light meromyosin (LMM) and heavy meromyosin (HMM) were investigated. According to the circular dichroism (CD) measurement, the α-helix content of the pollack myosin and LMM were estimated to be 72% and 90% at 5°C but decreased to 22% and 21% by increasing the temperature to 60°C with two transitions at 35°C and 50°C, respectively. In contrast, that of HMM decreased gradually from 37% to 33% by increasing the temperature from 5°C to 40°C, and decreased steeply to 20% above 50°C. These results indicate that the decrease in the α-helix content in the myosin molecule upon heating was attributable mainly to the decrease in the α-helix content in the LMM region. In contrast, 1-anilinonaphthalene-8-sulfonate (ANS) fluorescence and light scattering intensity of both myosin and HMM were remarkably increased above 25°C and 35°C, respectively, while those of LMM showed only a slight change even above 60°C. Although LMM alone formed no aggregates detectable by the light scattering measurement, it formed coprecipitates with myosin but not with HMM upon heating at 40°C for 10 min. These facts suggest that LMM bind to the LMM region of the myosin. Further, it was found that myosin gel formed in a test tube by the same heating conditions was significantly weakened by coexistence of LMM. These results suggest that the association of the LMM region of myosin molecules is essential for the heat-induced gelation of myosin.     

铁酸钴纳米粒子的化学共沉淀法制备及表征

采用弱碱 NH4 HCO3作为沉淀剂,CoCl·6H2 O和 FeCl3·6H2 O作为反应物,在一定摩尔比条件下,通过化学共沉淀法制备了铁酸钴纳米粒子,并采用 FT-IR、XRD、TEM和振动样品磁强计对其进行了表征。结果表明,制得的铁酸钴纳米粒子为尖晶石型结构,其粒径为20 nm左右,并且由于反应过程中弱碱 NH4 HCO3分解产生的CO2和 H2 O 气体对产物的阻隔作用,制得的铁酸钴纳米粒子的分散性较好,饱和磁化强度为55.5 Am2·kg-1。     

超声化学共沉淀法制备SO4^2-/ZrO2/Al2O3固体酸及其催化作用

采用超声化学共沉淀法制备SO4^2-/ZrO2/Al2O3固体超强酸催化剂,采用FT-IR、TG-DTG对催化剂进行了表征,并对催化剂的酸性强度及催化乙二胺合成哌嗪的性能进行了研究．结果表明,该催化剂具有桥式双配位结构,该结构在温度超过700℃时被破坏;随浸渍溶液浓度增大,催化剂的酸性强度和含硫量均先增大后减小;随陈化时间增加,催化剂的酸性强度增大,但陈化时间超过9h后,催化剂的酸性强度没有明显变化;焙烧温度不超过550℃时,催化剂的酸性强度随焙烧温度升高而增强,但温度超过550℃后,催化剂的酸性强度随焙烧温度升高反而降低;随催化剂中Al摩尔分数的增大,催化剂的酸性强度先增大后减小．引入Al对于提高乙二胺的转化率、改善哌嗪的收率和选择性具有一定的作用,并且哌嗪的收率和选择性随Al含量的增大而增大．     

Separation of Ag(I) Ions from Lepidium draba L. Plant and Water and Standard Samples by Carrier Element-Free Coprecipitation Method Prior to their Flame Atomic Absorption Spectrometric Determination

In this work, silver iodide (Ag(I)) ions were separated via the carrier element-free coprecipitation (CEFC) method using an organic coprecipitating agent, 1,6-diamino-4-(4-chlornphenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile [DCODD] prior to its determination by ?ame atomic absorption spectrometry (FAAS). Analytical parameters including pH of aqueous solution, amount of DCODD, standing time, centrifugation rate and time, and sample volume were studied and optimized. Under the best experimental conditions, it was found that extraction can be performed from the sample volume of 500.0 for silver ion (preconcentration factor of 100.0). Linearity was maintained between 0.006 and 1.50 µg.mL^?1 for silver. Detection limit for silver based on 3Sb was 1.60 ng.mL^?1. The relative standard deviation of eight replicate measurements of 0.20 µg.mL^?1of silver was 2.10%. Finally, the developed method was successfully applied to extraction and determination of the silver ions in the Lepidium draba L plant, water and standard samples and satisfactory results were obtained.     

工艺参数对共沉淀法制备TZP纳米粉末的影响

对化学共沉淀法制备了ＴＺＰ纳米粉末进行了系统的研究,探讨了盐溶液浓度,ｐＨ值,煅烧温度对粉末性能的影响,提出了制备ＴＺＰ纳米粉末的适宜工艺参数Ｃ＝１．０ｍｏｌ／Ｌ,ｐＨ＝９．５,Ｔｃ＝７００℃。     

核-壳介孔SiO2的合成

利用不同的三烷氧基硅在胶体介孔SiO2（CMS）的内部和外部表面烷选择性地修饰不同的官能团,这是利用了延迟共沉淀得到双功能化CMS的新方法。此种方法制得的CMS纳米粒子修饰有两种不同的官能团,它们分别位于核和壳上或同时位于核上。我们的合成方法提供了一种新颖的多步共沉淀策略,可将不同的官能团定位修饰在介孔纳米粒子的核或壳上。     

Determination of Trace Lead in Fish Sauces by ID-ICP-MS After Mg(OH)2 Coprecipitation

A method of isotope dilution coupled with inductively coupled plasma mass spectrometry (ID-ICP-MS) after Mg(OH)₂ coprecipitation was employed to determine trace lead (Pb) in fish sauces. The pH values and the amounts of Mg²⁺ in the coprecipitation system and the amounts of isotopically enriched ²⁰⁶Pb reagent added in the measurement were optimized. Results showed that a recovery by adding standard was 92.0% with a relative standard deviation (RSD) of 0.39%. The detection limit estimated with the calculated method used in the study was 7.65 ng g^?1. Through the Mg(OH)₂ coprecipitation, more than 80% of matrix ions such as K⁺, Na⁺, and Ca²⁺ in the samples were effectively removed, and the trace Pb in fish sauces was largely enriched. The concentrations of Pb measured in 12 fish sauces ranged from 0.068 to 0.299 μg g^?1, which was completely within the Pb limit (0.50 μg g^?1), a hygienic standard for aquatic flavorings set in China (GB 10133-2005). It has been well demonstrated that the method of ID-ICP-MS coupled with Mg(OH)₂ coprecipitation is suitable for determining trace Pb in fish sauces containing high levels of salt matrices.