共查询到19条相似文献,搜索用时 93 毫秒
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通过溶胶?凝胶法制备氨基修饰的磁性纳米粒子。以紫外分光光度法为检测手段,采用静态批次实验研究不同实验参数(吸附时间、溶液 pH 和溶液温度)对铜离子吸附的影响。对铜离子的动力吸附学过程符合准二级动力学模型。准一级动力学模型证明其对铜离子的吸附是一个基于内部粒子扩散的过程。吸附等温线数据既符合Langmuir吸附等温模型又符合Dubinin?Radushkevich吸附等温式。随着溶液pH的增加和温度的升高,水中铜离子的去除效率也增加。另外,铜离子在低 pH 时可以很容易地从吸附材料上面洗脱下来,并且在材料重复使用5次之后,铜离子的回收率仍然保持在90.0%以上。根据吸附活化能和热力学实验结果,可以推断铜离子在吸附剂上的吸附机制是离子交换?表面络合。 相似文献
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氨基磷酸树脂对铅的吸附性能及机理 总被引:12,自引:2,他引:12
研究了Pb2+在氨基膦酸树脂上的吸附行为, 结果表明 树脂的静态饱和吸附容量为822mg/g; 用0.5mol/L的HCl和0.2~0.3mol/L的EDTA洗脱, 洗脱率分别为97%和99%以上. 测得吸附热力学参数分别为 ΔH=9.04kJ/mol, ΔG=-3.99kJ/mol, ΔS=43.7J/(mol*K). 等温吸附服从Freundlich经验式; 表观活化能Ea=13.8kJ/mol; 表观速率常数k298=2.28×10-5s-1; 树脂功能基与Pb2+的配位比为2∶3. 用化学和红外光谱的方法探讨了树脂对Pb2+的吸附机理. 相似文献
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分别采用考马斯亮蓝蛋白测定法和酚.硫酸葡聚糖测定法,比较了不同性状羟基磷灰石粉体(HAP)对唾液蛋白和葡聚糖的吸附能力,研究了纳米HAP吸附唾液蛋白和葡聚糖的动力学和热力学特点。结果表明,对唾液蛋白和葡聚糖的吸附能力纳米HAP明显强于普通HAP,煅烧纳米HAP(nHAPc)又优于未经煅烧的HAP(nHAP);nHAPc对唾液蛋白的吸附属于受颗粒表面ζ电位控制的电性吸附,而nHAPc对葡聚糖的吸附则很可能属于单层特异性吸附。 相似文献
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采用低成本的本地可得的天然锰矿作为吸附剂,研究吸附工艺从水溶液中脱除铅离子和镉离子。利用伪一级、伪二级动力学和颗粒内扩散模型检验动力学吸附数据,计算和比较这些动力学模型的吸附速率常数,发现用伪二级动力学模型能最佳地描述吸附动力学。将 Langmuir 和 Freundlich 等温吸附模型用来拟合不同温度下的平衡数据,发现实验数据与 Langmuir 模型拟合得更好。采用 Langmuir 等温吸附模型计算出锰矿吸附铅离子和镉离子的最大容量分别为 98 和 6.8 mg/g。计算了热力学参数,如吸附吉布斯自由能的变化、焓变与熵变。结果表明,锰矿作为吸附剂对铅和镉的吸附反应是自发的吸热反应。因此,锰矿作为一种天然的矿物吸附剂,可以替代现有的吸附剂来脱除水溶液中的铅离子和镉离子。 相似文献
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选用具有高比表面、强吸附能力的二氧化硅纳米空心微球作吸附剂,对Pb2+、Cu2+及Cr3+的吸附性能进行测试。利用Langmuir线性方程对吸附平衡数据进行拟合。结果表明:二氧化硅纳米空心微球对重金属离子具有较高的饱和吸附量,分别为1.256、0.681、0.563 mmol/g。饱和吸附量与重金属离子的共价指数及电荷密度有很强的相关性,随着共价指数增加或电荷密度的降低,饱和吸附量增大;吸附常数与重金属离子电场强度(有效核电荷数)有关,随着有效核电荷数的增加,吸附常数增大。此吸附过程具有化学吸附特征,再生的吸附剂可以重复使用。 相似文献
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以自制的高纯硫酸镁和由氨水、氢氧化钠组成的复合碱液为原料制备高纯纳米氢氧化镁粉体。考察几种关键因素对镁沉淀率和产物平均粒度的影响。结果表明,随着溶液中Mg2+初始浓度和反应温度的提高,镁沉淀率提高,产物平均粒度先降低后提高;延长反应时间和陈化时间,镁沉淀率和产物平均粒度都提高;提高搅拌速度,镁回收率提高不大,但产物平均粒度减小。当Mg2+初始浓度2.0mol·L-1,反应温度50℃,反应时间60min,搅拌速度900r·min-1,陈化时间90min时,Mg沉淀率为95.4%,得到的氢氧化镁粉体为六方片状颗粒,粒度在50~140nm,且粒度分布均匀,分散性好,纯度很高。 相似文献
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氨基膦酸树脂对铅的吸附性能及机理 总被引:2,自引:0,他引:2
研究了Pb2 在氨基膦酸树脂上的吸附行为 ,结果表明 :树脂的静态饱和吸附容量为 82 2mg/ g ;用 0 .5mol/L的HCl和 0 .2~ 0 .3mol/L的EDTA洗脱 ,洗脱率分别为 97%和 99%以上。测得吸附热力学参数分别为 :ΔH =9.0 4kJ/mol,ΔG =- 3.99kJ/mol,ΔS =43.7J/ (mol·K)。等温吸附服从Freundlich经验式 ;表观活化能Ea=13.8kJ/mol;表观速率常数k2 98=2 .2 8× 10 -5s-1;树脂功能基与Pb2 的配位比为 2∶3。用化学和红外光谱的方法探讨了树脂对Pb2 的吸附机理。 相似文献
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I. V. Nechaev A. V. Vvedenskii 《Protection of Metals and Physical Chemistry of Surfaces》2009,45(4):391-397
Interactions between hydroxide ions and (001), (011), and (111) faces of Cu, Ag, and Au in the gas phase and in an infinitely diluted aqueous solution are nonempirically studied with the density functional method (DFT) with the use of B3LYP functional. Adsorption surfaces are modeled by n-atomic clusters (n = 10–18). The presence of solvent is taken into account in terms of the combined molecular-continuum model, and the effect of polarizable dielectric is estimated with the use of self-consistent solvent reaction field COSMO model. The composition and structure of hydrated hydroxide ion are found and the hydration energy is estimated in satisfactory agreement with the experimental data. Relative effects of the metal nature, crystal face orientation, and adsorption site on the adsorption characteristics are determined, and the geometrical parameters of the chemisorption bond and the degree of the partial charge transfer are estimated. A comparative analysis of the results obtained shows that the adsorption on-top position, which is energetically unfavorable in the gas phase, becomes prevailing in an aqueous solution, which can be explained by the increased stability of the on-top adsorption complex. 相似文献
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非均相沉淀法制备高热稳定性铝镁复合阻燃剂 总被引:2,自引:0,他引:2
根据晶体成核与生长理论,使新生成的氢氧化镁以非均相成核方式均匀地沉积在氢氧化铝核材表面,形成氢氧化镁包覆氢氧化铝的核-壳结构,制备出兼有氢氧化铝和氢氧化镁优点的复合阻燃剂.研究温度、复合阻燃剂中氢氧化铝与氢氧化镁质量比、加料方式等对复合阻燃剂性能的影响,通过研究不同因素对铝镁复合阻燃剂热稳定性的影响效果,得到优化的工艺条件.结果表明:制备的铝镁复合阻燃剂初始热分解温度可提高到260 ℃,阻燃性能得到进一步提高,填充有机高聚物后其氧指数达到33,主要力学性能指标均优于国家标准要求值. 相似文献
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Maryam Agheli Ali Habibolahzadeh 《Protection of Metals and Physical Chemistry of Surfaces》2016,52(6):972-974
The present study evaluates adsorption of hexavalent chromium ion (Cr(VI)) from contaminated solution on nano-porous anodic aluminum oxide (AAO). The AAO sorbent was characterized by field emission scanning electron microscope (FE-SEM) and Fourier transform infrared (FTIR) spectroscope. Effects of the solution pH, contact time, and AAO quantity on Cr(VI) adsorption were investigated. It was shown that Cr(VI) adsorption on AAO was strongly pH dependent and Cr(VI) removal increased by decreasing of the pH, Cr(VI) displays anion-type sorption behavior on the AAO sorbent. Chromium ion removal of 82% was obtained at presence of 0.05 g/L AAO, pH of 1, and contact time of 40 min in the solution. 相似文献
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D.J. Spedding 《Corrosion Science》1976,16(12):903-908
The adsorption of very low concentrations of H2 35S from air on to thin foil samples of lead was investigated using a continuous flow technique. The H2S uptake rate was constant at r.t. over the r.h. range 40–80% but increased markedly from 80–100% r.h. Autoradiography revealed a non-uniform adsorption in the low relative humidity range changing to a uniform uptake from 80–100% r.h. The possible nature of the adsorption sites, and the role of water vapour in the adsorption process is discussed. 相似文献
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Mg(OH)2 nano-particles with fiber-like morphology were prepared by chemical precipitation process, with the bittern from Qinghai Salt Lakes used as Mg^2+ raw material and ammonia water as precipitator. The influence of aging procedure on the Mg(OH)2 crystal was investigated by TEM and crystalline size calculation. The Mg(OH)2 nano-particles were characterized by XRD, SEM, TEM and TG-DTA methods. The results indicate that the Mg(OH)2 nano-particles with perfect crystal are obtained after aging procedure above 50 ℃, and the grain size increases with increasing aging temperature and prolonging aging time. Mg(OH)2 particles with fiber-like morphology, 20-60 nm in diameter and 300-500 nm in length are observed, Mg(OH)2 will decompose into MgO at temperature range 347-623℃. 相似文献