间、对二氯苯在盐水溶液中活度系数的研究

Studies on Activity Coefficients of m-and p-Dichlorobenzene in Aqueous Salt Solutions

本文用紫外可见分光光度法测定了25℃下间位和对位二氯苯在NaF,NaCl,NaBr,KBr,Na_2CO_3,K_2SO_4,Et_4NBr水溶液中的活度系数,logf-c_s关系符合Setschenow盐效应经验公式.盐效应次序为:Na_2CO_3>K_2SO_4>NaF>NaCl>NaBr>KBr>Et_4NBr.通过比较发现:二氯苯的偶极矩对盐效应几乎没有影响.本文选取Debye-McAulay(DMT)和Conway-Desnoyers-Smith(CDST)静电作用理论,定标粒子理论(SPT)及改进前后的内压力理论(IPT和XIPT),计算出理论值,与实验值进行比较,证实改进的内压力理论计算值更接近实际.

The activity coefficients of m-dichlorobenzene and p-dichlorobenzene in aqueous salt solutions have been determined at 298.15K by using spectrophotometric method. The salts used are NaF, NaBr, KBr, Na2CO3, K2SO4, Et4NBr. The relations between log f and cs are in agreement with Setschenow experimental formula. The salting-out order is:Na2CO3 > K2SO4 > NaF > NaCl > NaBr > KBr > Et4NBrIt is found that the salt effect is not affected by the dipole moment of dichlorobenzene. The experimental results are compared respectively with the calculation results of Debye-McAulay (DMT) and Conway-Desnoyers-Smith (CDST) electrostatic theories, scaled particle theory (SPT) and internal pressure theory (IPT). It is shown that the numerical calculation of the modified internal pressure theory gives the best fit with the experimental data.