Conditions optimization and kinetics for the cleaning of ceramic membranes fouled by BaSO ₄ crystals in brine purification using a DTPA complex solution

We investigated the cleaning efficiency and kinetics of multichannel ceramic membranes fouled during brine purification. The foulants were first characterized by means of SEM, EDX, and XRD analyses, and we found that mainly BaSO ₄ crystals were deposited on the membrane surface. A cleaning solution composed of diethylenetrinitrilopentaacetic acid (DTPA), oxalic acid, and NaOH was developed to regenerate the fouled ceramic membranes. The membranes could be completely recovered with the cleaning solution. The cleaning rate increased with the concentration of DTPA (CDTPA) and temperature (T) but was not sensitive to the crossflow velocity (CFV) or transmembrane pressure (TMP). The optimized cleaning condition was CDTPA = 1.0×10 ^-3 mol/L, T = 50 °C, CFV = 3.0 m/s, and TMP = 0.10 MPa. A dissolution kinetics model associated with both the concentration factor and temperature factor was developed, which fitted well the experimental results. This model was used to determine the reaction rate constants during the cleaning process at different temperatures. Based on this model, we found that the activation energy of BaSO ₄ dissolution using the cleaning solution consisted of DTPA, oxalic acid, and NaOH was lower than that of using pure DTPA solution. The results support the conclusion that the compound solution provided a better cleaning performance than pure DTPA solution.