Counseling in Israel

Group Contribution Method to Predict the Mass Transfer Coefficients of Organics through Various RO Membranes

“…For example, for all of the BW and SW membrane products, the Δ G solute–membrane intr value of −CH 3 group in a terminal position is larger than that of −CH 2 – group in a medial position, indicating the smaller contribution to the k Organic value and hence causes larger rejection. This is consistent with the previous observation that a hydrophobic CH 2 group raises its energy of interaction and partitions into hydrophobic microphase of polyamide membrane, which is known as the Traube rule for homologous series of surfactants . Furthermore, the presence of halogenated functional groups (i.e., Cl or Br) in a medial position [e.g., 1.699 for −CHCl– for TMG­(D)] has a larger Δ G solute–membrane intr value, indicating the smaller contribution to the k Organic value (i.e., larger rejection), compared to those in a terminal position [e.g., 1.485 for −CH 2 Cl for TMG­(D)].…”

“…For the SW membranes, SW30XHR and TM800M show greater rejection of almost all organics than the BW membranes, and SW30XHR shows slightly larger rejection efficiencies than TM800M. The characterization of RO membrane properties such as mean free volume hole space that represents the tightness of the composite thin active layer and the boron rejection as a surrogate indicator of rejection of organics through various ROs are consistent with the trend observed here. Larger rejection of organics is equivalent to smaller values of k Organic (Figure S1 in the SI), and almost all k Organic values for the SW membranes are smaller than 10 L/(m 2 h).…”