Ultrafiltration technology with a ceramic membrane for reactive dye removal: Optimization of membrane performance

Abstract

An ultrafiltration (UF) ceramic membrane was used to decolorize Reactive Black 5 (RB5) solutions at different dye concentrations (50 and 500mg/L). Transmembrane pressure (TMP) and cross-flow velocity (CFV) were modified to study their influence on initial and steady-state permeate flux (Jp) and dye rejection (R). Generally, Jp increased with higher TMP and CFV and lower feed concentration, up to a maximum steady-state Jp of 266.81L/(m2h), obtained at 3bar, 3m/s and 50mg/L. However, there was a TMP value (which changed depending on operating CFV and concentration) beyond which slight or no further increase in steady-state Jp was observed. Similarly, the higher the CFV was, the more slightly the steady-state Jp increased. Furthermore, the effectiveness of ultrafiltration treatment was evaluated through dye rejection coefficient. The results showed significant dye removals, regardless of the tested conditions, with steady-state R higher than 79.8% for the 50mg/L runs and around 73.2% for the 500mg/L runs.Finally response surface methodology (RSM) was used to optimize membrane performance. At 50mg/L, a TMP of 4bar and a CFV of 2.53m/s were found to be the conditions giving the highest steady-state Jp, 255.86L/(m2h), and the highest R, 95.2% simultaneously.