Porosity control of self-supported geopolymeric membrane through hydrogen peroxide and starch additives

Abstract

Geopolymerization is a green innovative technique for the synthesis of self-supporting inorganic membranes using fly ash as a raw material. This paper focuses on the preparation of geopolymeric membranes of different porosities of 5%, 10%, and 15% v/v of hydrogen peroxide (H2O2) and starch (C6H10O5)n which were used as foaming agents. Sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) activated grinded fly ash were used in the preparation of the geopolymeric slurry with and without any additives. No additives in the preparation of geopolymeric membranes resulted in a total porosity of 29% by volume with compressive strength of 18.41 MPa. Geopolymeric membranes prepared with hydrogen peroxide (5%, 10%, and 15% v/v) additives resulted in a total porosity of 36.12%, 41.23%, and 53.21% and compressive strength of 13.05, 9.85, and 5.22 MPa, respectively. Similarly, total porosity of starch additives 31.76%, 37.33%, and 51.09% was obtained with compressive strength of 14.90, 11.53, and 7.37 MPa, respectively. Increase in the pore size after evaporation of hydrogen peroxide was 1.04, 3.4, and 6.6 m, while for starch 1.05, 1.77, and 3.45 m, respectively. The prepared membrane was tested for household wastewater through dead-end filtration.