Experimental investigation of pore clogging by microparticles: Evidence for a critical flux density of particle yielding arches and deposits

Prediction of pore fouling by microparticles is still challenging and remains a difficult step to optimize membrane and filtration processes. The scientific issue consists in determining the relevant operation parameters controlling the capture of particles and the clogging of the filter. In this study, we have developed for a dead-end and cross-flow filtration a poly-dimethylsiloxane (PDMS) device which allows direct observation of the clogging dynamics of microchannels (20 mu m wide) by micrometric particles (5 mu m diameter). The experiments highlight the formation of different 3D clogging patterns according to the filtration conditions (particle concentration, flowrate, particle flux density and physical-chemical conditions of suspension). Besides, we have determined under which specific conditions of filtration, the latex microparticles are captured and form arches, clusters or dendrites. For each type of structure, the temporal dynamics of the particle deposition are analyzed by means of the average thickness of deposit. The critical conditions for the formation of arches leading to deposit formation have been identified in term of a combination of operating conditions: the particle concentration and the particle velocity. A critical particle flux density yielding pore clogging is then observed and characterized. Studying these experimental results helps to identify pore clogging mechanisms: deposition, interception and bridging. (c) 2012 Elsevier B.V. All rights reserved.