A New Model Of Electrolyte Solution Theory

Electrolyte solution theory has been widely applied in numerous fields such as chemical engineering,hydrometallurgy,life science,material science, thalassochemistry,enviromnental protection,soil science and the exploitation of salt lake brine.Number of theories and models has been set up and can be classified as follows based on interactions among particles:1)Long range electrostatic forces are only adopted；2)Short range interactions and long range interaction are added together and incorporated in formula.Since the content of the solvents in a solution is much more than that of the solutes,interactions and influences of these solvents should be considered. Thus,it is necessary to exploit a new method to deal with the electrolyte solution systems and propose a new electrolyte solution theory.Based on the statistic thermodynamics grand canonical ensemble and regularity of hydration numbers,a new electrolyte solution model is set up for activity coefficient on the assumption of the total particle number is constant as follows lnr±=-4KAφ/bln(1+bI0.5)[ln(I)+K1/K]-2KAφI0.5/1+bI0.5[ln(I)+K1/K]where Aφ=1/3〔2πNAdw/1000〕1/2〔e2/DKT〕3/ =〔8πNAe2dw/1000DKT〕1/2a, a represents the mean radius of K=aAnAV/NKT,K defines as a coefficient, which reflects volume change of solution with assition of solute; K1=K(ln(2vnw)-ln((v+1)zi2)),K1 refers to influence of solute; interactions of solvents,where value of Ao and b has been shown in Pitzer equation. The primary model is applied to about 40 kinds of binary solutions, results are fairly in agreement with experimental data and the fitting variance is lower than 0.08. The parameters K and K1 relate to the kinds of electrolytes and the valence of electrolyte ions. It proves that primary model is reasonable and deduction is accuracy.And then, the primary model was simplified, an optimized model is extracted as followlnr±=ln(1+b'I0.6)[2ln(I)+c］Where b' represents contribution of interactions resulting from electrolyte ions to total interactions, and c stands for influences of electrolytes and solvents to total interactions.And then, the optimized model is widely applied to the electrolyte solutions and non-electrolyte solutions with variance is lower than 0.01 for single electrolyte solutions, mixed electrolyte solutions and non-electrolyte solutions, the fitting curves are fairy in agreement with experimental data. Meanwhile, applications of optimized model for osmotic coefficient are also tried, and results are also fitted to experimental data.