Mathematical modeling of enrichment of estrogens in water samples using reverse osmosis device

Estrogens that constitute some of the potent endocrine disruptors are present in the water environment in very low concentrations (below ng/L) requiring sample enrichment to increase its concentration prior to an analytical determination. Currently, solid-phase extraction is the most commonly used enrichment method, but reverse osmosis (RO) may provide a promising alternative with the advantage of maintaining whole water sample including hydrophilic constituents such as humic substances. Subsequent in vitro assessment of such complex samples can provide more realistic information on their estrogenicity. Therefore, a novel experimental enrichment device employing the RO process using a flat-sheet membrane was developed for sample enrichment. In the current study, we aim to develop a mathematical model describing the RO enrichment process using the novel device. The mathematical model was created in MATLAB-Simulink software and validated with experimental results. NaCl at 0.2 and 2 g/L and tap water spiked with 17α-ethynylestradiol (EE2) at concentrations of 10 and 50 ng/L were used as model compounds. A mean relative error between the model and experimental results were 1.5 and 0.9 % for NaCl samples, and 17.3 and 14.4 % for E2, respectively. These results suggest the usefulness of the model for describing the RO system and suitability of the RO device for the enrichment of estrogens prior to instrumental or in vitro analysis. [Display omitted] •Model of dissolved solids enrichment in semi-batch RO system was optimized.•Percent deviation between the modeled and experimental data improved significantly.•Block for estrogens enrichment-time profile was added to the optimized model.•Experimental enrichment of 17α-ethynylestradiol validated the developed model.