Contact angle system oca15pro

The zeta potentials of the membrane surfaces were determined using a streaming potential technique with an Anton Paar SurPASS 3 device (AntonPaar Gmbh, Graz, Austria) fitted with an adjustable gap cell. During the measurements, two pieces of the membranes (10 mm × 20 mm) were affixed with a double-sided adhesive tape. The measurements were conducted in the pH range of approximately 2–8 (the background electrolyte (KCl) concentration was 0.001 mol·L⁻¹), which was adjusted by adding HCl and KOH solutions. The system was equipped with a pH electrode that continuously monitored the pH.
The wetting capabilities of the unmodified and modified membranes were evaluated by contact angle measurements (Dataphysics Contact Angle System OCA15Pro, Filderstadt, Germany). Ultrapure water (10 μL) was carefully added to the surfaces using a Hamilton pipette, and the contact angles between the membrane and ultrapure water droplets were quickly measured (within 1 s). Three repeated measurements were taken in all cases, and the average values were presented. Photos of underwater oil droplets on membrane surfaces were also captured with the same equipment.

For the description of the hydrophilicity of the investigated membranes, the contact angles – formed between the membrane surfaces and distilled water droplets – were measured using the sessile drop method (DataPhysics Contact Angle System OCA15Pro, Germany) at room temperature. Ten microliters of distilled water were carefully dropped onto the surface, and contact angles were immediately measured, within 3 s. The measurements were repeated five times, and the average values were calculated. In the case of the PES and PVDF membranes, the contact angles were determined to be 55.9 ± 0.8° and 57.2 ± 0.6°, respectively. In the case of nanomaterial (both TiO₂ and TiO₂/CNT)-covered membranes, the dropped water spread immediately on the surface, so the contact angles could not be measured (they can be regarded as zero). The PTFE membrane was hydrophobic in its original form as the contact angle was 105.5 ± 2.5°, but after acetone conditioning, the hydrophilicity cannot be determined as the surface was wet.

Contact angle measurements (Dataphysics Contact Angle System OCA15Pro, Filderstadt, Germany) were carried out to characterize the hydrophilicity of the membrane surfaces. A 10 µL volume of ultrapure water was carefully dropped onto the surfaces, and contact angles formed between the given membrane and the ultrapure water droplet were measured immediately (within 1 s). The measurements were repeated four times, and average values were calculated.
The zeta potential values of some membrane surfaces were also measured using a streaming potential technique in an Anton Paar SurPASS 3 device (AntonPaar Gmbh, Graz, Austria) equipped with an adjustable gap cell. During a measurement, two pieces of the membranes (10 mm × 20 mm) were fixed with double-sided adhesive tapes. The measurements were performed at a pH range of ~2–8 (c_KCl = 0.001 mol/L), which was adjusted by adding HCl and KOH solutions. The system was equipped with a pH electrode, which continuously monitored the pH value.