Investigating the effect of mullite on the permeability of distilled waterthrough geopolymeric membrane based on blast furnace slag

geopolymerization technique has been used for membrane synthesis to replace conventionalceramic membrane synthesis. For the past decade, researchers have been working ongeopolymerization reactions by mixing fly ash and minerals as raw materials to replaceexpensive raw materials and high-temperature sintering steps to make mineralmembranes[۱][۲].In this research, ۳ types of geopolymeric membranes (𝑍۱, 𝑍۲, 𝑍۳) have beenused to check the permeability of distilled water at ۳ different pressures of ۱, ۲ and ۳ bar that in𝑍۱ and 𝑍۲ membrane, with constant mullite percentage (۴% W.t) withdifferent ratio of Sodiumsilicate to Sodium hydroxide)۱ and ۲(at ۳ bar pressure, the permeability of distilled waterthrough membrane 𝑍۱ with ratio (W.G)/NaOH=۱ is equal to ۹.۴× ۱۰−۷ 𝑚۳ 𝑚۲𝑠 and membrane 𝑍۲with ratio (W.G)/NaOH=۲ is equal to ۴.۵× ۱۰−۷ 𝑚۳ 𝑚۲𝑠. In the comparison of 𝑍۱ and 𝑍۳membranes, this time by keeping the ratio (W.G)/NaOH = ۱ and increasing the amount ofmullite by (۱۲% W.t) at a pressure of ۳ bar, the permeability increased to ۴۲× ۱۰−۷ 𝑚۳ 𝑚۲𝑠.In themanufacturing of the mentioned membranes, the amount of micro silica in all membranes wasdetermined to be (۳% W.t) . Alkaline activators were used in the construction of𝑍۳ membrane toactivate furnace slag, with ۵.۸۴ (g) of sodium hydroxide, ۵.۸۶ (g) of Sodium silicate(W.G) and۲۸.۵۰ (g) of distilled water.The duration of the experiments for each pressure was ۳۰ minutes,and for testing each membrane, the synthesized membrane was compacted for ۲۵ minutes withpure water under a pressure of ۴ bar. The results of FT-IR analysis show a broad main absorptionband and strong in the range of ۱۰۲۴.۱۳cm−۱, which is the main band related to the asymmetricstretching vibrations of Si-O(Al) in the SiO۴ tetrahedron and the asymmetric stretching of Alalso in the peaks around ۴۵۷.۱۰ cm−۱,[۳]