Dead-end filtration experiment
Apple juice was filtered at constant pressures commonly found in microfiltration processes, namely 207, 276 and 345 kPa (30, 40 and 50 psi) while the flow-rate was continuously measured by recording the mass change of the permeate with a balance connected to a PC (Scheme 1). The typical behavior of the filtration process with a NFM of 124 μm thickness is shown in Fig. 3. The maximum flow rate (0.67 mL/min at a constant 345 kPa) was achieved during the first part of the experiment. Then, the flow rate slowly decreased. This indicated that the adsorption of organic species and particles caused a progressive fouling, leading to a decrease of the permeate flux through the membrane. After 20 min, the flow rate dropped below 0.15 mL/min and the collected filtrate was 5 g (20 mg/cm2).