Investigating the effect of pressure and concentration on permeability ofmethylene blue through a geopolymeric membrane based on phosphorus slag

The effluent from textile factories carries various types of hazardous chemicals through afew stages of manufacturing processes and also known to contain highly coloured species[۱].Notonly colours, the break down products are toxic and harmful to human and living organisms,raising attention to the worldon the importance of removing the dyes from thewastewater.Recently, membrane separation techniques which used polymeric and inorganicmaterials have also been introduced for dye removal[۲].In this article, ۳ pre-prepared membranesp۱, p۲ and p۳ were tested to test the permeability and removal of methylene blue effluent. Eachof the membranes were compacted with distilled water for ۲۵ minutes before starting the effluenttest. In the next step, the membranes were tested at ۳ pressures of ۱, ۲, and ۳ bar andconcentrations of ۲۰, ۳۰, and ۴۰ ppm for ۳۰ minutes. All ۳ membranes are based on phosphorusslag and compounds of mullite and microsilica with sodium hydroxide and sodium silicatealkaline activators. The results showed that all ۳ membranes have a rejection rate of over ۸۵% inall ۳ tested pressures and concentrations. By comparing the results in order to obtain the bestresult, taking into account the optimal permeability of the membrane, p۲ is the selectedmembrane with a separation rate of ۹۷% and a permeability of ۶۹× ۱۰−۷ 𝑚۳ 𝑚۲𝑠 at ۳ barpressures and ۲۰ ppm concentrations. According to the results obtained from the BET analysis,the selected membrane has a pore size of ۱۲.۴۲ nm and a porosity of ۲۰.۸۴%.In the spectrum ofthe sample analyzed by FT-IR, there is a broad and strong main absorption band that appeared inthe range of ۹۷۹𝑐𝑚−۱, which is related to the asymmetric stretching vibrations of Si-O(Al) in thetetrahedronSiO۴ and asymmetric stretching of Al[۳]