最大泡压法测表面张力等温线的数据处理方法比较*

对乙酸、丙酸、正丁酸、2-甲基丁酸、3-甲基丁酸、正戊酸、正己酸、乙醇、丙醇、异丙醇、正丁醇、异丁醇、1,2-丙二醇等13种常用试剂在25 ℃下的表面张力数据拟合方法进行了比较,分析了图解法处理数据及多项式、一阶指数函数、幂函数、Shishkovsky经验公式拟合数据的优缺点。指出Shishkovsky经验公式拟合结果准确,受数据样本量影响小,是理想的表面张力数据拟合方法。     

气/液界面上十六烷基三甲基溴化铵水溶液的动态表面性质

用最大泡压法测定了不同温度下浓度低于cmc时十六烷基三甲基溴化铵水溶液的动态表面张力.发现当浓度低于0.10 mol·m-3时动态吸附量ΓT遵s从由Henry吸附等温式导出的动态表面状态方程.在浓度位于0.10至0.80mol·m-3的较大范围内,Tt遵从从Langmuir等温式导出的动态表面状态方程.在吸附的后期十六烷基三甲基溴化铵分子在溶液表面上的吸附遵从混合动力学控制机理.从表观扩散系数计算出吸附为混合动力学控制机理时吸附能垒为6.7～7.1 kJ·     

基于非线性拟合的污泥衍生吸附剂对铅子等温吸附特性研究

利用城市污水厂污泥制取污泥衍生吸附剂，对溶液中铅离子进行吸附实验，研究一定条件下的等温吸附特性。利用线性拟合和非线性拟合两种方法对等温吸附方程进行模拟，得到非线性拟合求得的模型参数比较可靠，同时得到Langmuir模型比Freundlich方程更适合于描述铅离子在污泥衍生吸附剂表面上的吸附行为。     

钙矾石吸附水的模型及等温式

钙矾石３ＣａＯ·Ａｌ２Ｏ３·３ＣａＳＯ４·３２Ｈ２Ｏ是水泥熟料水化的重要产物．它易被空气中的ＣＯ２ 分解,常温下的分解反应为３ＣａＯ·Ａｌ２Ｏ３·３ＣａＳＯ４·３２Ｈ２Ｏ ３ＣＯ２ →３ＣａＣＯ３ Ａｌ２Ｏ３·ｘＨ２Ｏ ３（ＣａＳＯ４·２Ｈ２Ｏ） （２６ -ｘ）Ｈ２Ｏ分解机理［１ ,２］是：Ｈ２Ｏ先吸附在钙矾石表面的活性中心上,吸附态水再吸收ＣＯ２ 成为Ｈ２ＣＯ３ ,然后碳酸与钙矾石反应,实现碳化（即分解）．其分解速率［３］为ｖ＝ｋｐｃｏ２ ｐＨ２ｏ（１）可见水的吸附是钙矾石碳化分解的关键步骤,因此探讨…     

溶液表面张力测定实验的改进

采用最大气泡压力法测定溶液的表面张力。与以往实验的不同之处是使用数字式微压差测量仪代替酒精压力计 ,部分实验仪器也有所改进 ,实验的速度和测得数据的精确度均有明显提高。     

最大泡压法研究C12-2-Ex-C12•2Br在气/液表面的吸附动力学

用最大泡压法考察季铵盐Gemini表面活性剂C₁₂-2-E_x-C₁₂?2Br (x＝1, 2, 3)在气/液表面吸附动力学行为, 研究表明增加表面活性剂体相浓度和温度将加快分子扩散速度, 因此提高了表面吸附的动力学效果. 增加联接链长度x减小了分子预聚集倾向, 溶液中的单分子浓度增加, 有利于初始扩散, 使γ_t降低. 接近饱和吸附时, 由于x较大的单元分子在表面层占据的截面积也较大, 降低了表面层甲基端基的覆盖度, 相对升高了介平衡表面张力. 与对应的同头基同碳原子数的十二烷基三甲基溴化铵(C₁₂TABr)比较, C₁₂-2-E₁-C₁₂?2Br分子更倾向于吸附在表面层上.     

最大泡压法研究C12-2-Ex-C12•2Br在气/液表面的吸附动力学

用最大泡压法考察季铵盐Gemini表面活性剂C₁₂-2-E_x-C₁₂?2Br (x＝1, 2, 3)在气/液表面吸附动力学行为, 研究表明增加表面活性剂体相浓度和温度将加快分子扩散速度, 因此提高了表面吸附的动力学效果. 增加联接链长度x减小了分子预聚集倾向, 溶液中的单分子浓度增加, 有利于初始扩散, 使γ_t降低. 接近饱和吸附时, 由于x较大的单元分子在表面层占据的截面积也较大, 降低了表面层甲基端基的覆盖度, 相对升高了介平衡表面张力. 与对应的同头基同碳原子数的十二烷基三甲基溴化铵(C₁₂TABr)比较, C₁₂-2-E₁-C₁₂?2Br分子更倾向于吸附在表面层上.     

溶液表面吸附实验数据的计算机非线性拟合法处理

通过Gibbs公式与Langmuir等温式的结合 ,对溶液表面吸附实验进行数据处理 ,得到两组分稀溶液表面张力σ与溶液浓度c关系式。用计算机进行非线性函数拟合代替传统的作图、作切线、再直线拟合的方法。该方法具有简单快捷、拟合参数能直接反映实验数据质量的特点     

利用Origin双参数拟合表面张力与浓度曲线

在表面张力实验中总结出了一种利用易得易用的Origin软件处理数据的双参数拟合法,不仅更为科学严谨,而且简便易学,适合高校化学实验进行教学改革和计算机辅助教学.     

表面活性剂溶液的动表面张力研究

用振荡射流法分别测定了不同温度下全氟辛酸、十二烷基硫酸钠、二聚氯乙烯正辛醇醚溶液(浓度低于CMC)的动表面张力,讨论了它们的表面吸附动力学,研究结果表明都是扩散控制。     

The Surface Tension of Solids

The surface tension of a solid, unlike that of a liquid, cannot be measured directly. After a discussion of the most important methods used so far, all of which are subject to uncertainty the determination of the surface tension of solids from the wetting equilibrium is described.     

溶液表面吸附实验的再讨论

In the solution adsorption experiment, different adsorption mode has been observed for aqueous ethanol and aqueous n-butanol, respectively. However, it is difficult to make an adjustment by the profiles of σ-c relationship. Choosing the experimental conditions improperly will give wrong results. Since there is no consistency between the Gibbs adsorption isotherm and Langmuir adsorption isotherm, the experimental data should not be fitted by using any algebraic equations or physical models. The data fitting for this experiment should be carried out according to the following steps:fitting the σ-lnc curve manually, making it monotonic and smooth; retrieving more data from this fitting curve, and re-plotting the σ-lnc curve; calculating the first derivatives at these data points (i.e., (∂σ/∂lnc)_T); calculating surface adsorptions by Gibbs adsorption isotherm, Γ=-(∂σ/∂lnc)_T/RT. As for the calculation of the cross-section area for the solute molecule, the effect of concentration of bulk solution (i.e., c) on the surface molecular density should be taken into account.     

液态低沸点气体的表面张力

利用双毛细管法测定了液氮沸点温度下液氮的表面张力。用非线性方程γ=γ0(1-T/TC)n描述了液态N2、O2、Ar、Xe、H2、Ne、He、F2和Kr的表面张力与温度的关系,并采用一元线性回归的方法拟合了上述各流体的参数γ0和n,准确度高于文献值,说明方程能正确表达表面张力与温度的关系。这些数据有利于对上述低沸点气体进行准确的热力学计算。     

十二烷基硫酸钠/聚氧乙烯体系饱和蒸汽压和表面张力

表面活性剂／聚合物体系具有多种工业用途，尤其在提高石油采收率方面具有广泛的应用前景。另外，此类体系中存在复杂而特殊的相互作用．因此，聚合物／表面活性剂体系物理化学性质的研究具有十分重要的理论和实际意义．文献中对此方面的研究已有不少报导[1－6]．1967年，Jones     

Studies on Dynamic Surface Tension of an Outstanding Microemulsifier in Supercritical CO2 and Its Wetting Performance

Dodecyl polyoxyethylene(4) polyoxypropylene(5) ether (LS45) is an outstanding microemulsifier in supercritical CO₂. The dynamic surface tension (DST) of this nonionic surfactant was investigated by using the maximum bubble pressure instrument. The effects of concentration and temperature on DST parameters (n, t_i, t*, t_m, and R_1/2) and its adsorption mechanism were discussed by Rosen's empirical equation and the asymptotic Ward and Tordai equation for the LS45 solution system. Finally, the parameters at 1 s related to Draves's wetting performance, pC_20(1s), C_1s (i)*, and C_1s*, analyzed. The results showed that were with increase of bulk concentration and temperature, dynamic surface activity increased. Parameters at 1 s indicated that LS45 is of high surface activity and a very good wetting agent. One‐second related parameters, C_1s (i)* and C_1s*, are valuable in the treatment of practical applications of surfactants. Optimum wetting can be expected at the concentration of 4.8×10^?4 mol/dm³ for LS45 solution.     

A Corresponding-state Model for Predicting Surface Tension

A generalized corresponding-state model based on two reference fluids was developed for the prediction of surface tensions for non-polar and weakly polar pure fluids and their binary mixtures. Four parameters,po, Tc, Vc and ω, were used in this model, and the acentric factor ω was used as a scaling parameter. This model has been tested for 69 pure substances and 20 binary mixtures; the average absolute deviations are 0. 28 and 0. 20 mN/m, respectively. The results indicate that the predictions by means of this model were in good agreement with experimental data. In addition, the calculated deviation would increase with the excess surface tension rising, and if the excess surface tension is less than 3 mN/m, the prediction will be good and credible.