Application of nanofiltration model for prediction of rejecting typical refractory compounds in coal gasification brine

Nanofiltration has been widely applied in the treatment of industrial effluents, but very few work concerns in the coal gasification brine (CGB), especially in terms of removing the typical refractory compounds (TRCs) with different signs of charge and low molecular weights from it. This study investigated the separation performance of the TRCs using three nanofiltration membranes and assessed the applicability of the DSPM&DE model (Donnan steric pore model and dielectric exclu-sion) in predicting the TRCs rejection ratio. The TRCs rejection ratios of NF270 were greater than 79.15%, and the discrepancies between the experimental values and model data were lower than 5%. The undecane with 156.31 Da, representing the long chain n-alkanes, was exceptionally rejected and its rejection ratio reached to 98.52% at 42.04 L m^–2 h^–1 by NF270. The steric hindrance effect was considered the primary mechanism for separating the uncharged TRCs in the CGB. In general, the DSPM&DE model slightly underestimated the rejection of the positively charged TRCs and predicted accurately for most of the uncharged TRCs. The accuracy of the predicted rejection ratio of the DSPM&DE model for the TRCs with low molecular weight could be improved by incorporating the partition of the TRCs at the interface of solute–membrane.