Cu(NO3)2(La(NO3)3)-CO(NH2)2-H2O三元体系的等温溶度研究

本文首次报道三元体系Cu(NO₃)₂-CO(NH₂)₂-H₂O(30℃)和La(NO₃)₃-CO(NH₂)₂-H₂O(25℃)的等温溶度及饱和溶液、折光率,绘制相应的溶度图及折光率-组成图。体系中发现有组成为Cu(NO₃)₂·4CO(NH相似文献   

La2O3对Pd/Al2O3催化蒽醌氢化制H2O2性能的影响

 采用湿浸法制备了用于蒽醌氢化制H2O2的La2O3促进的Pd/Al2O3催化剂,并考察了不同La2O3含量对催化性能的影响. 采用XRD,N2物理吸附,CO2-TPD,H2-O2滴定和电子探针等技术对催化剂进行了表征. 结果表明,加入适量的La2O3能够抑制高温焙烧时Al2O3晶粒的长大,增大催化剂的比表面积,提高金属Pd的分散度,增强载体表面碱性,提高催化剂表面的Pd浓度,减小Pd层厚度,从而提高催化剂的氢化活性. 加入La2O3可使催化剂的Pd负载量由0.281%降至0.188%,而催化剂活性提高了44%.     

La（III）催化磷酸二（4－硝基苯酚）酯水解研究

The catalytic hydrolysis of bis（4-nitrophenyl）phosphate （BNPP） by lanthanum（Ⅲ） ion in the presence of amino-alcoholic ligands： diethanolamine （DEA） and triethanolamine （TEA）, was investigated kinetically at 30 ℃. The results indicated that the dinuclear dihydroxo complexes formed by lanthanum（Ⅲ） ion with aminoalcoholic ligands might be the catalytically active species which catalyze the hydrolysis of BNPP to different extents and the catalytic mechanism was believed to involve the synergism of double Lewis acid activation of the substrate and an intramolecular nucleophilic attack of a bridging oxo ligand.     

磺化聚苯乙烯镧离子型聚合物的稀溶液性质

聚电解质行为;比浓粘度;电解质;磺化聚苯乙烯镧离子型聚合物的稀溶液性质     

镧对红壤微生物碳、氮及呼吸强度的影响

室内培养试验表明,La对红壤微生物碳氮及呼吸强度均表现为抑制作用,并随浓度增加,抑制作用增强,在100mg/kg^-1时达到显著水平,随着培养时间的延长,La对微生物碳氮和呼吸强度的有减少的趋势,但短期内抑制作用难以消除,水稻盆栽试验表明,在低浓度时,La对土壤微生物碳氮和呼吸强度有少量刺激作用,但随着浓度的增加,则产生抑制作用并不断增强,在300mg.kg^-1时达到显著水平,土壤微生物量和呼吸强度可以作为评价稀土污染土壤的重要指标。     

La1-xSrxCu0.9Fe0.1O2.5-δ阴极材料的合成与电导率研究

采用低温燃烧合成技术制备了Lal-xSrxCu0.9Fe0.1O2.5-δ(x=0.1-0.4)粉体。利用X-射线衍射(XRD)和差热分析(DTA)技术对粉体的性能进行了表征。XRD结果表明,经800℃焙烧的La0.9Sr0.1Cu0.9Fe0.1O2.5-δ粉体的对称性较低,未形成钙钛矿结构,其余Lal-xSrxCu0.9Fe0.1O2.5-δ(x=0.2-0.4)粉体为四方钙钛矿结构,晶体结构参数之间满足关系式a=b≈2(2c)~(1/2)。DTA结果证明Lal-xSrxCu0.9Fe0.1O2.5-δ在800℃以下是热力学稳定的,不会发生分解反应。采用直流四电极法测试了Lal-xSrxCu0.9Fe0.1O2.5-δ试样在100—800℃之间的电导率。试样的电导率~(ln(σT)与1/T之间呈很好的线性关系,说明Lal-xSrxCu_(0.9)Fe0.1O2.5-δ在测试温度范围内服从小极化子导电机制。Sr掺杂量对试样的电导率和电导活化能有着明显的影响,当Sr掺杂量为0.3时,Lal-xSrxCu0.9Fe0.1O2.5-δ的电导率最高,电导活化能最小。     

Synthesis and application studies of chitosan acryloylthiourea derivative for the separation of rare earth elements

The adsorption behaviors of lanthanum (III) from an aqueous chloride medium, using Chitosan acryloylthiourea (CATU) derivative, were studied using an equilibrium batch technique. Here, the chemical modification of chitosan is of interest because the modification would not change the fundamental skeleton of chitosan, would keep the original physicochemical and biochemical properties, and finally would bring new or improved properties. The optimum pH value was defined to be 5.0 at a temperature of 298?K. Kinetic and isotherm experiments were carried out at the optimum pH. It was enough to reach the adsorption equilibrium at 4 hours and the maximum uptake capacity was 2.1?mmol?g^?1 at 25°C. Complexion, ion exchange, and electrostatic interaction were all believed to play a role in lanthanum adsorption on CATU derivative. The equilibrium adsorption data were fitted to a second-order kinetic equation. The Langmuir adsorption isotherm models were used to describe the adsorption process. The proposed method was validated and successfully applied for the determination of lanthanum in certified reference samples and ore sample with satisfactory results. The elution experiment was carried out by 0.05?mol/L CaCl₂ as an eluent.     

粉煤灰磁性吸附剂的制备及磷吸附机理

通过化学沉淀法制备了CMS@La_2O_3磁性磷吸附剂。结构及磁性表征显示,氧化镧较均匀的包覆在粉煤灰磁珠表面;样品的比磁化强度达20.35 emu·g~(-1),可实现高效磁分离。利用钼酸铵分光光度法对所得磁性吸附剂的磷吸附性能进行了试验研究。研究表明,其最高磷比饱和吸附量可达19.50 mg·g~(-1),吸附时间、pH值、共存阴离子等因素对磷吸附效果均具有显著影响。吸附动力学拟合表明,CMS@La_2O_3对含磷离子的吸附符合准二级动力学方程,以化学吸附为主,磁性吸附剂对含磷离子的吸附反应过程可由La_2O_3表面羟基化-离子交换模型解释。吸附磷后的CMS@La_2O_3吸附剂经处理后可多次循环使用。     

Isomorphous rare‐earth tris[bis(2,6‐diisopropylphenyl) phosphate] complexes and their catalytic properties in 1,3‐diene polymerization and in the inhibited oxidation of polydimethylsiloxane

Crystals of mononuclear tris[bis(2,6‐diisopropylphenyl) phosphato‐κO]pentakis(methanol‐κO)lanthanide methanol monosolvates of lanthanum, [La(C₂₄H₃₄O₄P)₃(CH₃OH)₅]·CH₃OH, ( 1 ), cerium, [Ce(C₂₄H₃₄O₄P)₃(CH₃OH)₅]·CH₃OH, ( 2 ), and neodymium, [Nd(C₂₄H₃₄O₄P)₃(CH₃OH)₅]·CH₃OH, ( 3 ), have been obtained by reactions between LnCl₃(H₂O)_n (n = 6 or 7) and lithium bis(2,6‐diisopropylphenyl) phosphate in a 1:3 molar ratio in methanol media. Compounds ( 1 )–( 3 ) crystallize in the monoclinic P2₁/c space group and have isomorphous crystal structures. All three bis(2,6‐diisopropylphenyl) phosphate ligands display a κO‐monodentate coordination mode. The coordination number of the metal atom is 8. Each [Ln{O₂P(O‐2,6‐ⁱPr₂C₆H₃)₂}₃(CH₃OH)₅] molecular unit exhibits four intramolecular O—H…O hydrogen bonds, forming six‐membered rings. The unit forms two intermolecular O—H…O hydrogen bonds with one noncoordinating methanol molecule. All six hydroxy H atoms are involved in hydrogen bonding within the [Ln{O₂P(O‐2,6‐ⁱPr₂C₆H₃)₂}₃(CH₃OH)₅]·CH₃OH unit. This, along with the high steric hindrance induced by the three bulky diaryl phosphate ligands, prevents the formation of a hydrogen‐bond network. Complexes ( 1 )–( 3 ) exhibit disorder of two of the isopropyl groups of the phosphate ligands. The cerium compound ( 2 ) demonstrates an essential catalytic inhibition in the thermal decomposition of polydimethylsiloxane in air at 573 K. Catalytic systems based on the neodymium complex tris[bis(2,6‐diisopropylphenyl) phosphato‐κO]neodymium, ( 3′ ), which was obtained as a dry powder of ( 3 ) upon removal of methanol, display a high catalytic activity in isoprene and butadiene polymerization.