Study On Competitive Adsorption Of Heavy Metal Ions To SDS Using Micellar-enhanced Ultrafiltration

Micellar-enhanced ultrafiltration (MEUF) is a new treatment process developed recently to remove heavy metals from wastewater, which combines ultrafiltration with surfactant technology. Compared with the traditional Ultrafiltration technology, this method is of the following advantages:high removal efficiency; low-energy requirements; easy operation; less expensive. In recent times, research activities on sorption of heavy metals have focused on sorption from multi-component systems. This paper have studied the impact factors concerned of removal efficiency and competitive adsorption characteristics of anionic surfactant sodium dodecyl sulfate(SDS) to heavy metals, provided the theoretical basis for enlarging the scope of application of this method to Industrial wastewater treatment. In the study, MEUF was applied to treat zinc、admium and plumbum-containing wastewater and mixed wastewater using SDS and composite regenerated cellulose. The influences of the various factors including initial metal ions concentration、feed SDS concentration and pH on removal efficiency. The data of metal ions adsorption were discribed with the Langmuir isotherm equation and Freundlich isotherm equation. The results of the study are shown as below. The rejection of Pb2+、Zn2+and Cd2+is all above90%before their concentration reach100mg/l and then have fall down when the concentration continues to rise, the rejection of Pb2+is still high. With the increase of SDS concentration, the rejection of metal ions will increase. the rejection of metal ions maintaine above90%when the feed SDS concentration reach0.8CMC(1.8g/l). Variations of pH have strong impacts on the rejection of Zn2+and Cd2+. Their rejection increases sharply when pH<9. With the increase of pH, the rejection of metal ions slowly increase and then keep at98%. While the variations of have a little influence Pb2+, the rejection of Pb2+is still above90%. The permeation flux of Pb2+, Zn2+and Cd2+get best performance when the pressure is0.08Mpa. But improving pressure had no significant effect on their rejection. The Langmuir provided well correlation for Cd2+and Zn2+in single system, the most adsorbable capacity for Cd2+and Zn2+is156.6mg/g、136.6mg/l. The Freundlich have better correlation for Pb2+in single system. The most adsorbable capacity is191mg/g. The Langmuir Model also provided well correlation for Cd2+and Zn2+in the presence of Pb2+. whilst the model showed poor fitting to Pb which was in binary solutions. The effect on absorption of Cd2+and Zn2+in the presence of Pb2was found to be antagonistic. The metal ions sorption followed the order: Pb2+>Cd2+>Zn2+.