Low cost porous alumina with tailored gas permeability and mechanical properties prepared using rice husk and sucrose for filter applications

Abstract

The present study demonstrates a cost effective way to produce porous alumina with 39-70 vol% porosity and 64-516 μm avg. pore size (length), using 20-40 wt% rice husk (RH) of <75 μm, 75-180 μm, 180-355 μm, 355-420 μm, and 420-600 μm sizes as pore former and sucrose as binder as well as a pore former. Microstructure of samples revealed interconnected pore microstructure consisting of mixture of coarse elongated pores and fine pores (avg. size 4 μm), created during burnout of RH and sucrose, respectively. Mechanical properties such as three point bending strength (98-14 MPa) and compressive strength (82-6 MPa) of the developed samples were strongly dependent on their porosity and pore size. Also, the Darcian permeability (k1) and non-Darcian permeability (k2) of porous alumina were a strong function of pore microstructure. The Darcian permeability ranges from 0.38 × 10-10 to 9.15 × 10-10 m2 which is in the order of magnitude of gas filters. The non Darcian permeability ranges from 0.33 × 10-5 to 3.92 × 10-5 m. Experimental results agree closely with predictions made based on Forchhemier equation. The developed porous alumina is considered potentially useful in filtration and gas purging applications. © 2015 Published by Elsevier Inc.