Cross flow microfiltration of oil–water emulsions using kaolin based low cost ceramic membranes

• Inorganic membranes are prepared and used for MF of oily water.
• Membrane fabrication pressures significantly influence flux and fouling index.
• All membranes show significant pore blocking during the first 10 min of run.
• Fouling index reduced from 16.85 to 11.58% for M3 membrane at Re = 3417.
• Membrane prepared at 73 MPa pressure provides optimal MF performance.

Emphasizing upon the need to develop and target applications of low cost ceramic membranes, this work addresses the cross flow microfiltration (MF) of oil–water emulsions. Membranes prepared using uniaxial dry compaction method and possessing higher average pore sizes (3.06–2.16 μm) and porosities (30.1–37.4%) have been used for cross flow MF studies. Cross flow runs were conducted using a feed oil concentration of 400 mg/L of for various combinations of trans membrane pressure differentials (138–207 kPa) and cross flow velocities (Reynolds number = 3417 to 6835). The fitness of various fouling models indicates that combination fouling models could only represent the observed flux decline data which refers to existence of one of the pore blocking phenomena (complete/intermediate/standard pore blocking) during the first 10 min of experimental run followed with cake filtration for the data obtained for later time periods. Experimental investigations inferred that the membrane performance is optimal for maximum combinations of trans membrane pressure (ΔP = 207 kPa), fabrication pressure (73 MPa) and minimal cross flow velocity (Re = 3417) at which conditions, an optimal combination of fouling index, steady state flux and rejection were obtained as 11.58%, 22.14 × 10− 6 m3 m− 2 s and 98.52%, respectively.