Nagy Endre, Hegedüs Imre, Rehman Danyal, Wei Quantum J, Ahdab Yvana D, Lienhard John H
Chemical and Biochemical Procedures Laboratory, Institute of Biomolecular and Chemical Engineering, University of Pannonia, H-8200 Veszprem, Hungary.
Department of Biophysics and Radiation Biology, Semmelweis University, Tüzoltó u. 37-47, H-1094 Budapest, Hungary.
Membranes (Basel). 2021 Feb 14;11(2):128. doi: 10.3390/membranes11020128.
The widely used van 't Hoff linear relation for predicting the osmotic pressure of NaCl solutions may result in errors in the evaluation of key system parameters, which depend on osmotic pressure, in pressure-retarded osmosis and forward osmosis. In this paper, the linear van 't Hoff approach is compared to the solutions using OLI Stream Analyzer, which gives the real osmotic pressure values. Various dilutions of NaCl solutions, including the lower solute concentrations typical of river water, are considered. Our results indicate that the disparity in the predicted osmotic pressure of the two considered methods can reach 30%, depending on the solute concentration, while that in the predicted power density can exceed over 50%. New experimental results are obtained for NanoH2O and Porifera membranes, and theoretical equations are also developed. Results show that discrepancies arise when using the van 't Hoff equation, compared to the OLI method. At higher NaCl concentrations (C > 1.5 M), the deviation between the linear approach and the real values increases gradually, likely indicative of a larger error in van 't Hoff predictions. The difference in structural parameter values predicted by the two evaluation methods is also significant; it can exceed the typical 50-70% range, depending on the operating conditions. We find that the external mass transfer coefficients should be considered in the evaluation of the structural parameter in order to avoid overestimating its value. Consequently, measured water flux and predicted structural parameter values from our own and literature measurements are recalculated with the OLI software to account for external mass transfer coefficients.
广泛用于预测氯化钠溶液渗透压的范特霍夫线性关系，在压力延迟渗透和正向渗透中，可能会在评估依赖于渗透压的关键系统参数时导致误差。本文将范特霍夫线性方法与使用OLI Stream Analyzer得出的实际渗透压值的溶液进行了比较。考虑了氯化钠溶液的各种稀释情况，包括典型的河水较低溶质浓度。我们的结果表明，根据溶质浓度，两种方法预测的渗透压差异可达30%，而预测的功率密度差异可能超过50%。获得了关于纳米水和多孔海绵体膜的新实验结果，并推导了理论方程。结果表明，与OLI方法相比，使用范特霍夫方程时会出现差异。在较高的氯化钠浓度（C>1.5M）下，线性方法与实际值之间的偏差逐渐增大，这可能表明范特霍夫预测中的误差更大。两种评估方法预测的结构参数值差异也很显著；根据操作条件，差异可能超过典型的50-70%范围。我们发现，在评估结构参数时应考虑外部传质系数，以避免高估其值。因此，使用OLI软件重新计算了我们自己的测量以及文献测量中的实测水通量和预测结构参数值，以考虑外部传质系数。
