Ocma 500

The composition of the membrane surface was tested using the attenuated total reflection. Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) analyses were performed using a Nicolet 380 FTIR spectrophotometer coupled with Smart Orbit diamond ATR accessory (Thermo Electron Corp., Waltham, MA, USA).
Scanning Electron Microscopy (SEM) (Hitachi SU8000, Tokyo, Japan) and an Atomic Force Microscopy (AFM) (multi-mode 8 AFM, Brucker, Santa Barbara, CA, USA) were used to study the membrane morphology.
The membrane hydrophobicity was determined by water contact angle (WCA). The sessile drop method using the Contact Angle System OCA (Data Physics, Filderstadt, Germany) apparatus was used for the WCA measurements. The measurements were performed for each type of studied membranes, repeated five times across the surface of the sample and the mean value of WCA was determined.
Diameters of membrane pores were measured via a mercury porosimetry technique using Autopore III (Micrometrics GmbH, Aachen, Germany).
Distillate conductivity was measured with a 6P Ultrameter (Myron L Company, Carlsbad, CA, USA).
The oil content in the solutions was examined by infrared method using an oil analyzer OCMA 500 manufactured by Horiba (Kyoto, Japan).

The MD studies were performed using the solutions with salt concentration in the range of 1–100 g/L. Distilled water and pure NaCl (ChemPur, Karlsruhe, Germany) were used for their preparation.
A volume of emulsion concentrate (dosed to the feed) necessary to obtain an assumed oil concentration in the feed was determined based on an analysis performed with an oil content analyzer (OCMA 500, Horiba, Kyoto, Japan). The small quantities of oily contaminants in the seawater originated mainly from bilge water discharged from ships [9 (link)]. For this reason, the oil used in the presented studies was collected from an engine room in a ship. This was heavy machine oil leaked from the piston seals of a marine engine. The oil emulsion concentrate was prepared by adding 5 mL of such oil to 1 L of deionized water. Subsequently, the content was intensively shaken for 5 min, and then the mixture was subjected to ultrasound treatment (620 W, Sonic-6D, POLSONIC, Warszawa, Poland) for 2–3 h. This operation was periodically repeated (every 2–3 days), which allowed one to stabilize the emulsion without adding surfactants. A fresh oil emulsion concentrate was prepared every two weeks.