共查询到18条相似文献,搜索用时 953 毫秒
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为了解决湿法磷酸生产中高含量SO3的测定,对硫酸钡浊度测定法的反应条件进行了改进,并自行设计制造了自动化的分析系统。测定时样品由蠕动泵(P)推入酸化盘管(AC)中进行酸化和稀释,由定量环(Sv)取样25μL,注入反应系统。在第一反应盘管(RC1)中,SO3与第一混合试剂中的BaCl2溶液反应生成BaSO4悬浊液,该溶液中的聚乙二醇-4000(PEG-4000)和乙醇通过协同作用避免了BaSO4颗粒的团聚,降低粒子间的相互作用,使BaSO4的生成减少,降低了测定的灵敏度,提高了稳定性。在第二反应盘管(RC2)中,BaSO4与第二混合试剂中的NH3·H2O/乙二胺四乙酸二钠(Na2EDTA)溶液发生络合反应同时被Na2EDTA包裹,进一步降低其灵敏度。最后反应溶液进入流通式光度检测器,在680.0nm波长处测试BaSO4悬浊液的吸光度。经优化试验条件,上述第一混合试剂中3种组分的质量分数或体积分数为:BaCl24%,PEG-4000 3%和乙醇2%;第二混合试剂中Na2EDTA的质量分数为6%,NH3·H2O的体积分数为6%。对实际按本方法及重量法分析进行测定,两种方法所得结果的相对偏差在±2%以内,且不受共存的高含量PO43-和F-的干扰。 相似文献
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通过γ-辐照含有K2S2O8和BaCl2的二(2-乙基己基)琥珀酸酯磺酸钠(AOT)反相微乳液,将S2O82-通过辐射还原实现了SO42-的原位缓释,从而成功制备出BaSO4纳米纤维单晶,并进一步制得多层次的纳米纤维束结构.在此基础上,通过改变水与表面活性剂物质的量之比(ω值)、改变钡盐阴离子和在微乳液连续相添加芳香化合物等手段来调节水化电子(e-aq)产额,控制微乳液水池中S2O82-的还原和SO42-的缓释速率,成功实现了对BaSO4纳米粒子形貌的调控:随着ω值的增加或剂量率的增加,e-aq产额增加,从而加快了SO42-的释放,不利于BaSO4纳米纤维的生成;采用Ba(NO3)2为钡源时,NO3-能有效地降低e-aq产额和S2O82-的还原速率,因而在较高的剂量率和较高ω值下能得到BaSO4纳米纤维;在微乳液油相中加入甲苯来捕获油相中过量电子(e-oil),降低e-aq产额,从而在较高的剂量率下得到BaSO4纳米纤维.研究结果表明:通过e-aq产额调控纳米粒子形貌的机理在BaSO4纳米粒子的制备中得到很好体现. 相似文献
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丙三醇存在下硫酸钡微粒体系的光谱特性研究及其分析应用 总被引:1,自引:0,他引:1
0.10 mol/L HCl-4.0 mol/L丙三醇-0.05 mol/L BaCl2溶液体系的瑞利散射很弱.当有SO4^2-存在时,(BaSO4)n微粒体系在470 nm处产生一较强的瑞利散射峰,SO4^2-浓度在1.0~80μg/mL浓度范围内与I470nm呈线性关系.据此,建立了一个测定水中硫酸根的简便、灵敏的瑞利散射光谱分析新方法.研究结果表明:SO4^2-与Ba^2+由于静电引力可形成BaSO4分子,而BaSO4分子间存在较强疏水作用力和分子间作用力,可聚集形成(BaSO4)n微粒和固液界面,(BaSO4)n微粒和固液界面的形成是导致体系瑞利散射强的根本原因. 相似文献
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六方相WO3纳米带的制备与表征 总被引:1,自引:1,他引:0
以Na2WO4、K2SO4和H2C2O4为原料,采用两步水热合成法制备了六方相WO3纳米带.首先,在探索pH值、K2SO4加入量、反应温度和时间以及表面活性剂等因素对WO3纳米带的前驱物钨酸盐形貌的影响后,给出了前驱物钨酸盐纳米带的合成条件,并讨论了纳米带的形成机理;然后,在180℃的水热条件下对前驱物再处理48 h获得六方相WO3纳米带.测试结果表明,WO3纳米带的形貌保持较好,宽度在100~300 nm间,长度可达数微米,沿纳米带长轴方向为[001]方向. 相似文献
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Nanosized BaSO(4) particles, about 15 nm in size, were synthesized successfully by a membrane reactor at the aids of additives, in which Na(2)SO(4) solutions were added into BaCl(2) solutions gradually through the micropores of ultrafiltration membranes to control the saturation ratio, subsequently the nucleation and growth rates. The effects of additives species, additives concentrations, and membranes molecular weight cut-off (MWCO) on the particle morphology, along with the formation processes of particles, were investigated. CaCO(3) nanoparticles of 30-60 nm in size were also prepared by the reactor. The results revealed that the addition of methyl alcohol, ethanol etc. favor the synthesis of nanoparticles with small size. The particles size decreases with the increase in ethanol concentrations. With the increase in membrane MWCO, the products tend from nanoparticles towards aggregates. 相似文献
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Cu(II)/EDTA adsorption onto TiO2 has been studied with a variation of pH, ionic strength, and type of background electrolytes. Cu(II) adsorption onto TiO2 increased as ionic strength increased when NaClO4 was used as a background electrolyte. This can be explained by the increase of exp(-FPsi/RT) as a part of the electrostatic correction within a surface complexation model. Model predictions described experimental adsorption trends. Types of background anions (ClO4, Cl, NO2, NO3, SO3, and PO4) did not affect adsorption trends and adsorption amounts of Cu(II) onto TiO2. However, different trends were observed with various types of background ions used as ionic strength in EDTA and Cu(II)-EDTA adsorption. EDTA adsorption was decreased by using Na2SO3 and Na3PO4 as background ions, while NaClO4, NaCl, NaNO2, and NaNO3 showed negligible interference on the EDTA adsorption, which matched well with model predictions. The presence Na2SO3 and Na3PO4 also interfered with Cu(II)-EDTA adsorption, to a somewhat greater extent compared to EDTA adsorption, especially at lower pH. This interference was also noted in Cu(II)-EDTA adsorption with a variation of Cu(II)-EDTA concentration at constant ionic strength (3 x 10(-3) M) by using Na2SO3 and Na3PO4, especially at lower ratios of Cu(II)-EDTA to Na2SO3 and Na3PO4. These results suggest that the ratio of Cu(II)-EDTA to Na2SO3 and Na3PO4 is an important factor for the controlling of competition between these background ions and Cu(II)-EDTA onto TiO2. Model prediction generally matched well with experimental adsorption using NaClO4, NaCl, NaNO2, and NaNO3 as backgrounds ions, while a severe deviation was observed in the presence of Na2SO3 and Na3PO4. These results suggest that the mobility of copper ions as Cu(II)-EDTA can be increased from polluted area in the presence of multivalent background ions, especially as the ratio of adsorbates/background ions decreased. 相似文献
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近20年来,随着卤化银微晶合成技术的进步,合成出了诸如T-颗粒、核壳乳剂和外延复合颗粒乳剂等性能优异的微晶体,极大地提高了乳剂的感光性能.但这些乳剂也有一个共同的缺点,即大量消耗贵金属银,且未成影像的银均随定影过程而浪费.为改善此类乳剂的不足,各国科... 相似文献
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In this study, well-dispersed gold nanoparticles were prepared by using intra-molecular reduction of sodium gold sulfite, without using additional reductants and chloride free. The technical parameters including transformation temperature, pH, and concentration were optimized by the single-factor method as 90 C, pH 1, and 0.01 mmol/L [Na3Au(SO3)2], respectively. The resultant colloidal transmission electron microscopy images (TEM) and UV-vis absorption spectrophotometer spectra were acquired to check their properties, and the results show this kind of colloidal gold is controlled to 6 nm in sizes and has good stability in solution. 相似文献
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Fast removal and recovery of Cr(VI) using surface-modified jacobsite (MnFe2O4) nanoparticles 总被引:1,自引:0,他引:1
In this work, the effectiveness of surface-modified jacobsite (MnFe2O4) nanoparticles was investigated for the removal and recovery of Cr(VI) from synthetic wastewater. Ten nanometer modified MnFe2O4 nanoparticles were produced to be a new adsorbent using a co-precipitation method followed by a surface redox reaction. The equilibrium time for Cr(VI) adsorption onto modified MnFe2O4 nanoparticles was as short as 5 min, and the adsorption data fit the Langmuir model well. The maximum uptake of 31.5 mg of Cr(VI)/g of modified MnFe2O4 was obtained at pH 2, which was comparable with other common adsorbents such as activated carbon and sawdust. The effects of ligands (EDTA, SO4(2-), NH4+) and ionic strength were studied in a pH range of 2-10. EDTA and SO4(2-) inhibited the adsorption of Cr(VI) over the entire pH range studied, whereas NH4+ enhanced the uptake of Cr(VI) at pH greater than 6.5. The mechanisms leading to Cr(VI) adsorption by modified MnFe2O4 nanoparticles were determined by X-ray diffraction and X-ray photoelectron spectroscopy to be a combination of electrostatic interaction and ion exchange. Regeneration studies indicated the potential reuse of the modified MnFe2O4 nanoparticles without sacrificing adsorption capacity and the possible recycling of Cr(VI) without changing the valence. 相似文献
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The superfine BaCO3 particles were synthesized by high gravity technology with BaCl2·2H2O and Na2CO3 as the raw materials. The changes of particle size and morphology were studied by adding different amount of EDTA, and rod-like, near-spherical and cylindrical shape BaCO3 were prepared. The BaCO3 particles were analyzed and characterized by TG/SDAT, SEM, XRD and FT-IR. The results indicated that the crystal transformation temperature and decomposition temperature of BaCO3 had increased because of EDTA addition. With the increase of EDTA amount, the shape of BaCO3 changed from irregular rod-like to near-spherical then to cylindrical shape. All different shape BaCO3 adopts orthorhombic crystal systems. 相似文献