盐湖卤水协同萃取提锂及基础热力学性质

为了充分利用盐湖卤水中丰富的锂资源,提出了以磷酸三丁酯(TBP)-乙酸丁酯(BA)-FeCl3-260#磺化煤油体系协同萃取提锂的方法。针对该体系,考察了卤水酸度、nFe/nLi比以及温度对协同萃取过程的影响。根据锂离子及其它主要离子萃取率的变化,确定了最优萃取条件为:pH=2,nFe/nLi=3.0,T=20℃。在最优条件下,单级萃取率达到90%左右。同时,研究了萃取过程的热焓、吉布斯自由能及熵变等基础热力学性质。结果表明,在选定的萃取体系和条件下,锂的萃取反应为放热反应,萃取过程为熵减过程。     

Hydrogen storage over alkali metal hydride and alkali metal hydroxide composites

Alkali metal hydroxide and hydride composite systems contain both protic(H bonded with O) and hydridic hydrogen. The interaction of these two types of hydrides produces hydrogen. The enthalpy of dehydrogenation increased with the increase of atomic number of alkali metals,i.e.,-23 kJ/molH2 for LiOH-LiH, 55.34 kJ/molH2 for NaOH-NaH and 222 kJ/molH2 for KOH-KH. These thermodynamic calculation results were consistent with our experimental results. H2 was released from LiOH-LiH system during ball milling. The dehydrogenation temperature of NaOH-NaH system was about 150℃; whereas KOH and KH did not interact with each other during the heating process. Instead, KH decomposed by itself. In these three systems, NaOH-NaH was the only reversible hydrogen storage system, the enthalpy of dehydrogenation was about 55.65 kJ/molH2, and the corresponding entropy was ca. 101.23 J/(molH2 K), so the temperature for releasing 1.0 bar H2 was as high as 518℃, showing unfavorable thermodynamic properties. The activation energy for hydrogen desorption of NaOH-NaH was found to be57.87 kJ/mol, showing good kinetic properties.     

Adsorptive Removal of Thorium(IV) from Aqueous Solutions Using Synthesized Polyamidoxime Chelating Resin: Equilibrium,Kinetic, and Thermodynamic Studies

In this study, an amidoximated chelating ion exchange resin was prepared by poly-acrylonitrile (PAN) grafted potato starch. The adsorbent characterizations such as specific surface area, pore volume, average pore radius, and Fourier transform infrared (FTIR) spectrum of the resin were measured. The effects of pH, adsorbent dosage, contact time, initial concentration of thorium ion, and temperature on adsorption of thorium ion from aqueous solutions were investigated. Four isotherm models including Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin were applied to analyze the equilibrium isotherm data. The results showed that Langmuir and Temkin models had a good agreement with experimental data. The maximum capacity of the adsorbent using the Langmuir isotherm model was 227.27 mg · g^?1. The kinetic models like pseudo-first-order, pseudo-second-order, Elovich, and intraparticle were examined to describe the adsorption process. The kinetics of the adsorption process was found to follow the pseudo-second-order kinetic model. The thermodynamic parameters (ΔG°, ΔH°, ΔS°) were also calculated using equilibrium constant values at various temperatures (25, 35, 45, 55°C) and the positive value for ΔH° showed an endothermic adsorption process. The study suggests that the prepared adsorbent has promising potential for the removal of thorium from wastewaters.      

Theoretical Investigations on the Structure,Density, Thermodynamic and Performance Properties of Bis（2,2-dinitropropyl） formal

Density functional method was used to investigate the IR spectrum,heat of formation and thermal stability of a new energetic material bis(2,2-dinitropropyl) formal(BDNPF).The detonation velocity and pressure were evaluated by using the Kamlet-Jacobs equations based on the theoretical density and heat of formation.The bond dissociation energies for the weakest bonds were analyzed to investigate the thermal stability of the title compound.The results show that the C(1)-N(1) bond is predicted to be the trigger bond during pyrolysis.The crystal structure obtained by molecular mechanics belongs to the P21 space group,with the lattice parameters to be Z = 2,a = 11.5254,b = 6.2168,c = 9.5000  and ρ= 1.66 g/cm3.     

Theoretical studies on the BC2N monolayers with promising photoelectronic characteristics and remarkable environmental stabilities

In this study, density functional theory calculations were performed to investigate the geometric structures, thermodynamic and mechanical stabilities, electronic, and optical properties of two BC₂N monolayers with honeycomb structure. The computational results demonstrate that the BC₂N monolayers have not only visible-light absorption, but also high reducing capacity of photo-induced electrons and excellent carrier mobility. Also, ab initio molecular dynamics simulations with considering the O₂ and H₂O molecule were carried out, which suggest that the crystal structures of both BC₂N monolayers can be well maintained in the moisture-laden air filled with O₂ molecules at 800 K. Accordingly, these BC₂N monolayers with promising photoelectronic characteristics and environmental stability could be utilized as metal-free visible-light-driven photocatalysts in high-temperature environment with moisture and oxygen, which is worthy of being further investigated in experimental and theoretical studies.     

Thermochemistry of N‐heterocyclic carbenes with 5‐, 4‐, 3‐, and 2‐membered rings

N‐heterocyclic carbenes (NHCs) based on imidazole‐2‐ylidene ( 1 ) or the saturated imidazolidine‐2‐ylidene ( 2 ) scaffolds are long‐lived singlet carbenes. Both benefit from inductive stabilization of the sigma lone pair on carbon by neighboring N atoms and delocalization of the N pi lone pairs into the nominally vacant p‐pi atomic orbital at the carbene carbon. With thermochemical schemes G4 and CBS‐QB3, we estimate the relative thermodynamic stabilization of smaller ring carbenes and acyclic species which may share the keys to NHC stability. These include four‐membered ring systems incorporating the carbene center, two trivalent N centers, and either a boron or a phosphorus atom to complete the ring. Amino‐substituted cyclopropenylidenes have been reported but three‐membered rings containing the carbene center and two N atoms are not known. Our calculations suggest that amino‐substituted cyclopropenylidenes are comparable in stability to the four‐membered NHCs but that diazacyclopropanylidenes would be substantially less effectively stabilized. Concluding the series are acyclic carbenes with and without neighboring N atoms and a series of “two‐membered ring” azapropadienenylidene cations of form :C?N?W with W = an electron‐withdrawing agent. We have studied W = NO₂, CH₂(+), CF₂(+), and (CN)₂C(+). Although these systems display a degree of stabilization and carbene‐like electronic structure, the stability of the NHCs is unsurpassed. © 2014 Wiley Periodicals, Inc.     

Thermodynamic and kinetic study of ibuprofen with hydroxyl radical: A density functional theory approach

Ibuprofen, a frequently detected pharmaceutical in natural and engineered waters, was studied in both neutral and anionic forms using density functional theory at the B3LYP/6‐311++G**//B3LYP/6‐31G* level of theory in its reaction with hydroxyl radical ( ? OH). The reaction pathways included ? OH addition to aromatic ring, abstraction of a H‐atom, and nucleophilic attack on the carbonyl group. The results showed that H‐atom abstraction pathways are the most favorable. The free energy change for H‐atom abstraction reaction ranges from ?37.8 to ?15.9 kcal/mol; for ? OH addition ranges from ?3.85 to ?1.23 kcal/mol; and for nucleophilic attack on the carbonyl group is 13.9 kcal/mol. The calculated rate constant between neutral ibuprofen and ? OH, 6.72 × 10⁹ M^?1s^?1, is consistent with the experimental value, 6.5 ± 0.2 × 10⁹ M^?1s^?1. Our results provide direct evidence for byproduct formation and identification on the molecular level. © 2013 Wiley Periodicals, Inc.     

Grüneisen γ通用函数及完全物态方程

在分析Grüneisen γ近似函数的适用范围和热力学γ高压演化特性的基础上, 根据Grüneisen γ系数的物理性质和变化特点, 利用数学分析的方法建立了Grüneisen γ通用函数γ_n(v). 将γ_n(v)代入热力学函数γ(v, T), γ(v, T)即成为全压力区连续可导的函数, 并由γ(v, T)直接导出了等熵温度函数T_S(v); 再根据等熵温度与Hügoniot 温度的函数关系获得了Hügoniot温度方程的解析函数T_H(v), 从而使Hügoniot方程成为完全物态方程. 对几种金属做了检验, 由等温方程推算Hügoniot方程, 或者由Hügoniot方程推算等温方程, 其结果都与实验符合得很好.     

Study of the Inhibition Efficiency for Some Novel Surfactants on the Carbon Steel (Type H-11) Pipelines in 0.5 M HCl Solution by Potentiodynamic Technique

In this article, three deferent surfactants as corrosion inhibitor were prepared in two steps. In the first step, maleic anhydride was amidated with dodecylamine to produce 2-ene-4-dodecanamide butanoic acid. In the second step, the resulting product was further esterified with different molecular weights of polyethylene glycol (m.wt. = 200, 400, and 600), namely, polyoxy ethylenyl-x-ene-4-dodecanamide butanoic acid, where x = 2, 4, or 6 according to molecular weights of polyethylene glycol used). The chemical structures of these inhibitors were confirmed by FTIR and ¹H NMR. The corrosion inhibition effect of the synthesized inhibitors has been investigated on the carbon steel (type H-11) pipelines in 0.5 M HCl solution by the potentiodynamic polarization method. From the obtained results, it was found that the maximum inhibition efficiency (90.44%) was exhibited by polyoxy ethylenyl-6-ene-4-dodecanamide butanoic acid, while the minimum inhibition efficiency (79.84%) was obtained by polyoxy ethylenyl-2-ene-4-dodecanamide butanoic acid at 200 ppm and 35°C. Also, the values of activation energy and thermodynamic parameters were calculated and discussed. Adsorption of the synthesized inhibitors was found to follow the Langmuir's adsorption isotherm. Mixed physical and chemical adsorption mechanism is proposed.     

羧酸盐双子表面活性剂的合成及性能

为筛选环境友好的新型双子表面活性剂,以水杨酸为原料设计合成了5个羧酸盐型双子表面活性剂EODPN1-EODPN5[2,2'-(1,2-CH₂CH₂-二-O-)-二-(4-C_nH_2n+1COPhCOONa),n=5,7,9,11和13],并通过核磁共振波谱仪(NMR)和傅里叶变换红外光谱仪(FT-IR)等对目标产物进行了结构表征。 探究了EODPN作为表面活性剂的性能,并利用Gibbs表面吸附方程,通过理论计算得到相关热力学参数,结果表明,目标分子具有优异的表面活性,临界胶束浓度(CMC)值低(最低达0.4 mmol/L),表面张力性能优良(最低达29.74 mN/m),单位面积表面吸附量(Γ)高(最高达3.37×10^-6 mol/m²)。 通过改变疏水基烷基碳链的长度,优化了EODPN的表面活性和自组装能力,筛选出EODPN4为最佳的表面活性剂。 借助EODPN4能与铜离子稳定结合,实现了表面活性剂含量的检测。