The effect of Sodium Dodecyl Sulfate on Polysulfone membrane for Pb (II) ions removal in an aqueous solution

Abstract

An unsustainable level of contamination increase is driven by industrialization, population growth and growth in developing countries. Contamination of heavy metal ions in wastewater such as Pb (II) are non-biodegradable and poses a serious threat to human health and other living things. One of the major methods for treating heavy metals contamination is by chemical precipitation. However, it produced hazardous sludge that requires further treatment and used a significant quantity of chemicals during the heavy metals treatment process due to its low impact on the environment. As a result, a membrane filtration method as an alternative treatment for treating heavy metals in wastewater has been investigated. In this study, the membranes were fabricated using the wet phase inversion method approach by incorporating polysulfone (PSF) polymer with dimethylacetamide (solvent) and inclusion of different concentrations of sodium dodecyl sulfate (SDS) (M1= 0 wt%, M2= 0.5 wt%, M3= 1.0 wt%, M4= 1.5 wt%, M5= 2.0 wt%). The fabricated membranes were tested to remove 50 mg/L Pb (II) ions in aqueous solution. Scanning electron microscopy (SEM) was used to investigate the morphological structures of membranes. Moreover, the structural characteristics of fabricated membranes were evaluated according to these parameters; contact angle, porosity and mean pores radius. Furthermore, the performance of the membrane was also evaluated for permeation and rejection flux by using dead-end cell filtration. The results indicate that the M4 membrane with 1.5 wt% SDS had the highest rejection rate (90.52%) for Pb (II) ions. This is likely due to the presence of macrovoids and a porous structure, as shown by SEM analyses. Other supporting evidence includes a lower contact angle (63.91^o), higher water uptake (43.58%), higher porosity (85.21%), and a lower mean pore radius (6 nm) for the M4 membrane. The fouling mechanism model suggests that the complete blocking observed in the experimental data indicates that porous blockage occurred on the membrane's surface during the absorption of Pb (II) ions. In conclusion, compared to the pure membrane, it becomes evident that the addition of SDS into the membrane solution enhanced the properties of the membranes. The M4 membrane with a composition of 1.5 wt% concentration SDS demonstrated optimal filtration for removing Pb (II) ions in a water treatment process due to excellent properties mentioned above.