磷酸可待因在安伯来特IRP-69上的离子交换平衡特性研究

采用批式离子交换法研究了磷酸可待因在安伯来特IRP-69上的离子交换平衡特性、动力学及热力学特征.结果表明,在3个温度(298K、308K和318K)及研究的浓度范围内,离子交换吸附等温方程和Freundlich方程都能够对磷酸可待因在安伯来特IRP-69上的离子交换平衡等温线进行很好的拟合,其离子交换动力学特征基本符合二级动力学方程.磷酸可待因在安伯来特IRP-69上的离子交换行为的热力学参数(ΔH、ΔG、ΔS)都小于0.在3个温度(298K、308K和318K)下,同一初始浓度(350mmol/L)的磷酸可待因在安伯来特IRP-69上的平衡交换吸附量分别为1.1295mmol/g、1.1203 mmol/g和1.1129 mmol/g.     

MZn2HPO4PO4 (M=Na+, K+)的合成、表征和标准摩尔生成焓

采用低温固相法和水热法制备MZn2HPO4PO4 (M=Na+, K+) 并用XRD, FT-IR, TG and SEM对其进行表征,用等温量热计测定热化学性质。按照Hess’s定律,设计一新的热化学循环。结果表明,所合成的物质是等结构三斜晶系的目标产物,具有片层结构,分解温度分别为： 415 ℃和430 ℃。从测定的溶解焓和其他的标准热化学数据,计算出MZn2HPO4PO4 (M=Na+, K+) 的标准摩尔生成焓分别为：ΔfHm [NaZn2HPO4PO4, s]=-3042.38±0.31 kJ·mol-1; ΔfHm [KZn2HPO4PO4,s]=-3093.46 ±0.27 kJ·mol-1。     

一种活性磷酸酯的分子内亲核取代反应动力学研究

合成和表征了大环过渡金属配合物NiL(L:高氯酸-5,7,7,12,14,14-六甲基-1,4,8,11-四氮杂环十四烷)。配合物NiL与表面活性剂组成的金属胶束作为模拟水解金属酶用于催化BNPP水解。提出了BNPP催化水解的机理;建立了用于计算动力学常数的动力学模型;计算了相关的动力学和热力学常数。结果表明,这种金属胶束表现出较高的催化活性;BNPP催化水解反应是分子内亲核取代反应;所提出的机理和建立的动力学模型是合理的。     

水相中磷酸氢二铵催化Knoevenagel反应

醛与活泼亚甲基化合物的Knoevenagel反应是有机合成中广泛应用的形成碳碳键的重要方法,该反应一般是弱碱性催化剂存在下完成的,如各类胺、脲[1]等,Lerwis酸[2]、杂多酸[3]、氨基酸[4]等也可用于催化该反应。近年来,无溶剂条件下超声、微波辅射[5-6]也可以促进反应,但大部分是在     

纳米级锂离子电池正极材料LiFePO4

LiFePO₄以其价格便宜,稳定性好,无毒等优点而倍受关注。但是非纳米LiFePO₄的电子导电率低及扩散系数小限制了其在锂离子电池领域的大规模应用。而纳米电极材料以其特有的优点很好的解决了这些问题。本文主要综述了国内外合成纳米级LiFePO₄ 的不同方法及所得材料的对电化学性能和相关机理,以及纳米LiFePO₄作为锂离子正极材料存在的问题。     

A new intumescent flame‐retardant: preparation,surface modification,and its application in polypropylene

Melamine salt of tripentaerythriol phosphate (MTP), as a new intumescent flame‐retardant, was prepared from tripentaerythritol (TPE), polyphosphoric acid, phosphoric pentoxide, and melamine, and then incorporated into polypropylene (PP) to obtain flame‐retarded PP‐MTP. FT‐IR analysis showed that MTP was in the form of cage structure. The flammability, combustion behavior, and thermal degradation and stability of flame‐retarded PP were characterized by using LOI, UL‐94 test, cone calorimetry, and TGA, respectively. By SEM, the char structure of PP‐MTP was analyzed. XRD diffraction tests showed that PP‐matrix of PP‐MTP presented better crystallized phases, when MTP was modified by methyl hydrogen siloxane. The relations of the dispersion of MTP in PP matrix to the compatibility between PP and MTP, and to the flame retardancy were discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Energetics of copper diphosphates – Cu2P2O7 and Cu3(P2O6OH)2

Differential scanning calorimetry and high temperature oxide melt solution calorimetry are used to study enthalpy of phase transition and enthalpies of formation of Cu₂P₂O₇ and Cu₃(P₂O₆OH)₂. α-Cu₂P₂O₇ is reversibly transformed to β-Cu₂P₂O₇ at 338–363 K with an enthalpy of phase transition of 0.15 ± 0.03 kJ mol⁻¹. Enthalpies of formation from oxides of α-Cu₂P₂O₇ and Cu₃(P₂O₆OH)₂ are −279.0 ± 1.4 kJ mol⁻¹ and −538.8 ± 2.7 kJ mol⁻¹, and their standard enthalpies of formation (enthalpy of formation from elements) are −2096.1 ± 4.3 kJ mol⁻¹ and −4302.7 ± 6.7 kJ mol⁻¹, respectively. The presence of hydrogen in diphosphate groups changes the geometry of Cu(II) and decreases acid–base interaction between oxide components in Cu₃(P₂O₆OH)₂, thus decreasing its thermodynamic stability.     

The Effect of Microwave Sintering on the Microstructure and Properties of Calcium Phosphate Ceramic

Despite good ability to improved biological affinity and activity of calcium phosphate (CP) ceramic to the surrounding host tissue when implanted, CP ceramic is capable to encourage direct bond with bone as their chemical compositions are similar to the mineral phase of bone. However, the low mechanical property of CP ceramic restricts use in load-bearing applications. Therefore, the primary aim of this study was to fabricate dense CP ceramic via used of microwave sintering analyze the microstructure and mechanical properties comparison to conventional ceramic sintering. The sintered specimens were characterized by their surface microstructure, density measurement and hardness test. The result demonstrated that the density and hardness values of sintered CP ceramic specimens by microwave sintering were higher than conventional sintering. The microstructures of CP ceramic microwave sintered specimens show also better microstructures (analyzed by FESEM technique), with fines grain size and the present of apatite layer growth on the surface when examined with SBF solution. It can be concluded that the microwave sintering enhanced better microstructure and mechanical properties of CP ceramic.     

LiZr2(PO4)3包覆对高镍三元正极材料结构及电化学性能的影响

高镍三元正极材料LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811)具有优异的放电能力。但其存在锂镍混排严重、结构稳定性差导致的容量衰减快等问题。为解决这些问题,本论文首先合成NCM811三元正极材料,再利用湿法涂覆的方法将磷酸锆锂LiZr₂(PO₄)₃(LZPO)包覆在NCM811三元正极材料的表面,形成LZPO@NCM811三元正极改性材料,并对改性前后的NCM811三元正极材料结构和电化学性能进行研究。研究结果表明,在NCM811表面包覆1%LZPO得到样品的结构最稳定,材料的电化学性能最好:在0.1 C倍率下,首圈放电容量为210.16 mAh/g,远高于未改性NCM811材料(201.01 mAh/g);在循环200圈后,材料的容量保持率为79.4%,优于未改性的NCM811材料(容量保持率为60.0%)。     

Calcium Phosphate Particles Coated with Humic Substances: A Potential Plant Biostimulant from Circular Economy

Nowadays, the use of biostimulants to reduce agrochemical input is a major trend in agriculture. In this work, we report on calcium phosphate particles (CaP) recovered from the circular economy, combined with natural humic substances (HSs), to produce a plant biostimulant. CaPs were obtained by the thermal treatment of Salmo salar bones and were subsequently functionalized with HSs by soaking in a HS water solution. The obtained materials were characterized, showing that the functionalization with HS did not sort any effect on the bulk physicochemical properties of CaP, with the exception of the surface charge that was found to get more negative. Finally, the effect of the materials on nutrient uptake and translocation in the early stages of development (up to 20 days) of two model species of interest for horticulture, Valerianella locusta and Diplotaxis tenuifolia, was assessed. Both species exhibited a similar tendency to accumulate Ca and P in hypogeal tissues, but showed different reactions to the treatments in terms of translocation to the leaves. CaP and CaP–HS treatments lead to an increase of P accumulation in the leaves of D. tenuifolia, while the treatment with HS was found to increase only the concentration of Ca in V. locusta leaves. A low biostimulating effect on both plants’ growth was observed, and was mainly scribed to the low concentration of HS in the tested materials. In the end, the obtained material showed promising results in virtue of its potential to elicit phosphorous uptake and foliar translocation by plants.