Recovery of lignin from water and methanol using low-cost kaolin based tubular ceramic membrane

This study investigated the performance of low-cost tubular ceramic membranes fabricated using kaolin, quartz and calcium carbonate as inexpensive raw materials following the extrusion method for lignin recovery from water and methanol. The effect of different concentrations of carboxymethyl cellulose (CMC) as a binder along with the raw materials on the membrane properties such as porosity, pure water permeability, flexural strength and chemical stability was first studied. The increase in CMC concentration resulted in enhancement of chemical stability, flexural strength and pure water permeability alongside a decrease in porosity of the membrane. Based on the characterization results, membrane prepared using 3 wt% CMC was found suitable for microfiltration applications, which showed porosity of 36 %, flexural strength of 38 MPa and average pore size of 0.18 μm. The prepared membrane was further tested for the recovery of lignin - a key value-added component in biorefinery operation - from water and methanol. Cross-flow microfiltration experiments performed using the membrane at five different applied pressures (34−172 kPa) showed maximum lignin rejection values of 82.5 % and 80 % with lignin-water and lignin-methanol solutions, respectively, at an applied pressure of 34 kPa.