Application Of The Electrolyte Molecular Interaction Volume Model (eMIVM) In Polyelectrolyte Systems

Polyelectrolytes are widely used in water treatment,food processing and pigment production.Various surfactants,ion exchange resins and sols are closely related to polyelectrolytes.All kinds of functional membranes used in reverse osmosis,ultrafiltration and other membrane separation processes are also polyelectrolytes.Therefore,the theoretical study of polyelectrolyte solution has important significance and application background.Thermodynamic models of polyelectrolyte solutions are critical for these industrial applications.At present,many thermodynamic models have been successful in engineering practice,such as Manning Limiting Laws.But there are also some problems,such as weak theoretical basis,strong empirical capability and relatively weak predictive ability.Therefore,it is very important to introduce a thermodynamic model with good theoretical basis,few model parameters and certain predictive ability.In this paper,electrolyte molecular interaction volume model(e MIVM)was applied to the calculation of polyelectrolyte systems,and the activity coefficients and osmotic coefficients of polyacrylic acid,polymethacrylic acid systems were calculated respectively.The osmotic coefficients and activity coefficients of the ionic surfactant systems containing sodium or chloride were calculated.The activity coefficients and osmotic coefficients of the biochemical polymer systems such as sodium glutamate were calculated.Several important polyelectrolyte systems were predicted.At the same time,the calculated results were compared with the electrolyte NRTL equation(e NRTL),and corresponding analysis was made.(1)In polyacrylic acid,polymethacrylic acid systems,the total average deviations and relative errors of e MIVM fitting are 0.0718,12.26%,0.0602,6.59%,0.0669,5.32%,0.0411,3.69%,0.2392,61.29%,0825,7.65% respectively.The total average deviations and relative errors of electrolyte NRTL fitting were 0.0748,12.59%,0.0707,7.28%,0.0681,5.69%,0.0497,4.39%,0.2394,65.82%,0.0967,9.09%respectively.Through calculation,it can be found that in polyacrylic acid,polymethacrylic acid systems,e MIVM's calculated results are better than e NRTL,and the calculated results are closer to the experimental values.(2)In the ionic surfactant systems containing sodium or chlorine,the total average deviations and relative errors of e MIVM fitting were 0.0275,3.27%,0.0594,13.19%,respectively.The total average deviations and relative errors of e NRTL fitting were 0.0447,5.13%,0.0606,13.95%,respectively.Through calculation,it is not difficult to find that e MIVM still has advantages over e NRTL in the calculation of two-component ionic surfactant,and the calculated results are more accurate.(3)In the biochemical polymer systems such as sodium glutamate,the total average deviations and relative errors of e MIVM and e NRTL equation fitting are0.0813,6.89%,0.0831,7.05%,respectively.From the calculation deviations and relative errors,the result of e MIVM is better than that of e NRTL,and the results is more accurate.(4)The activity coefficients and osmotic coefficients of ternary systems are predicted by fitting parameters of binary systems and compared with Manning limiting laws.The total average deviations and relative errors of e MIVM,e NRTL and Manning limiting laws are 0.6472,68.98%,1.3602,4.425e+03,0.2877,39.18%respectively.By comparison,it is found that the prediction results of e MIVM and Manning limiting laws are in the same order of magnitude,but the deviations and relative errors are about twice as large as Manning limiting laws.However,compared with e MIVM and e NRTL,the prediction errors of e NRTL is twice as large as that of e MIVM,and the relative errors is nearly two orders of magnitude larger.Therefore,e MIVM has the ability to predict the ternary systems.However,compared with Manning limiting laws,the local composition models such as e MIVM and e NRTL may need to be further improved according to the characteristics of polymers.The above results are the preliminary application of e MIVM in polyelectrolyte systems,and will provide valuable thermodynamic datas for the practical application of polyelectrolyte systems.