Novel PVC-melamine mixed matrix membranes for the Sirius Red removal from aqueous solutions: Experimental study and RSM modeling

In this paper, ultrafiltration polyvinyl chloride (PVC) mixed matrix membranes (MMMs) containing melamine were synthesized via the phase separation procedure in order to remove Sirius Red (SR) dye from the aqueous solution. The amount of melamine loading in the membrane structure was 1, 3, and 5 wt%. The fabricated MMMs were characterized by Fourier transform infrared (FTIR), Field emission scanning electron microscopy (FESEM), water contact angle, and mechanical resistance tests. Other specifications such as porosity, mean pore size and pure water flux of MMMs were also investigated. The obtained pure water flux data showed an increase up to 180 L/m(2)h for the PVC membrane containing 3 wt% of melamine (PVC-G-Mel3) and then decreased due to the agglomeration of melamine particles. Next, the rate of dye removal by MMMs at different pH values and feed concentrations was evaluated during the filtration time of 24 h. The ultrafiltration results were modeled by Design Expert 12 software to study the interaction of these parameters on SR removal as well as the effect of each independent factor. The dye removal efficiency gradually decreased with an increase in the feed concentration, while exhibiting a peak as pH increased from 2 to 8. The outcomes revealed that the highest dye removal efficiency of 95.65% was obtained at pH 5 and the color concentration of 30 ppm. Furthermore, the PVC-G-Mel3 MMM was regenerated by washing with 0.01 M hydrochloric acid solution for a few minutes and then cleaning with deionized water for 2 h before the next cycle. The flux recovery at 30 ppm feed concentration after three regeneration cycles was 95.44%, which showed that the synthesized MMMs can be a good candidate for removing SR dye from aqueous solution.