2.7.1. Water Flux of the Membranes

The volume of water that flowed through the PMO-MGs/PES composited ultra-filtration membranes per unit of time and area under a certain test pressure was known as the pure water flux [44,45]. Utilizing a cross-flow membrane filtration apparatus with a constant trans-membrane pressure of 0.2 MPa, the filtration tests were conducted. The contact area of PMO-MGs/PES composited ultrafiltration membrane was a circle that had a diameter of 30 mm.

The membranes were pre-pressurized using ultrapure water under 0.25 MPa for 1 h before measurement in order to achieve steady flux. The membrane’s temperature-sensitive water flow was tested at 0.2 MPa in the 20–45 °C range with a 5 °C step increase. For each measured temperature, the water was passed through the membrane for 1 h to ensure that the membrane reached the corresponding temperature. Afterward, the water flux of the membrane was tested for 5 min. Three measurements were made, and the average value was taken and presented.

The water flux (J_w) was calculated via Equation (3):

where Q, A and t were the permeate volume (L) of the water solution, the effective contact area of the membrane (m²) and the permeation time (h), respectively.