Dynamic Analysis And Condition Optimization Based On Micellar-enhanced Ultrafiltration With Surfactants For Removing Cu²⁺ From Wastewater

Copper is an essential micronutrient for living creature, but it is great harmful forpeople, plants and animals with high concentration. Chemical industry, printing anddyeing, electroplating, non-ferrous metallurgy, nonferrous metals mining, rinse waterof electronic materials, dye production process often produce waste water containslarge amounts of copper ions. Micellar enhanced ultrafiltration （MEUF） is a newmethod which is based on the surfactant of the unique characteristic of parentalmolecular structure that can remove low concentration heavy metals in the water. It is atechnology that combined the surface active agent with ultrafiltration. Compare withthe traditional ultrafiltration, MEUF has many advantages such as lessen cost, andmore effective removal of cadmium ions. Meanwhile, compared with the methods ofadsorption, distillation and extraction that has low energy consumption and nointersection. The most important is the treated water from MEUF can be directlyrecycled. But it is reported rarely of comparing different types of surfactants to removeheavy metal ions, which is more suitable on influence of the retention rate andmembrane properties comprehensively.In this study, hollow fiber （PES） ultrafiltration membranes, sodium dodecylsulfate（SDS） and sodium dodecyl benzene sulfate（SDBS） which are both cheap andeasy to get selected anionic surfactants have been used to wipe off Cu²⁺. Investigatechanges of properties of surfactant micelles on permeate flux, surfactant and Cu²⁺residue removal and enrichment rates to get more appropriate surfactant and the dose.Further discussing effect of the surfactant concentration, Cu²⁺concentration and pH onremoval of Cu²⁺and permeate flux.Micellar-enhanced ultrafiltration was used to remove Cu²⁺. Experimental resultsshow that the average permeate flux with SDS is always higher than that with SDBS(the average flux with SDS is29.92L·m^-2·h^-1, while that with SDBS is only16.55L·m^-2·h^-1), the permeate concentration of SDS is always lower than that with SDBS.When the permeate concentration of Cu²⁺close to zero,2mM and6mM of SDBS andSDS are respectively required. Cu²⁺rejection and enrichment ratio with SDS arealways higher than those with SDBS (the average Cu²⁺rejection and enrichment ratiowith SDS are respectively85.06%and4.18, while those with SDBS are69.05%and4.05respectively).Besides, the average enrichment ratio of SDS is also higher than that of SDBS （SDS is up to3.89, while SDBS is3.13）.Therefore, SDS is moresuitable than the SDBS for removal of Cu²⁺.In this study, multiple factors are used to research removal of Cu²⁺byultrafiltration experiments with SDS. The results show that:（1） When Cu²⁺=0.6mM,SDS=6mM, it has best consequent, while SDS/Cu²⁺=10.（2） With the SDSconcentration increases, flux has a slight upward trend. Indicating that SDS micelleson the membrane surface are difficult to plug the membrane deposition hole. The roleof concentration polarization and membrane fouling is significantly weakened and donot cause flux decline. Permeate concentration of Cu²⁺reduce and SDS concentration,Cu²⁺and SDS removal rate increase. When the SDS concentration increases from2mM to6mM, Cu²⁺removal rate increases from77.10%to99.03%. When SDSconcentration increases from2mM to16mM, SDS removal rate increases from83.98%to89.99%.（3） Flux increased decreases slightly as the concentration of Cu²⁺increasing, probably because a large number of Cu²⁺plays a role as the electrolyte.Permeate concentration Cu²⁺raises and Cu²⁺removal rate decreased, because SDSmicelles on the adsorption of Cu²⁺is very saturated and can not retain the Cu²⁺withthe discharge of the liquid penetration. Decreases the concentration of SDS, SDSremoval rate increases, Cu²⁺concentration has the effect of strengthening the SDSretention.（4） Effect of pH on the flux is tiny. Permeate concentration of Cu²⁺shortens,Cu²⁺removal rate greatens with the pH value increases. When the pH value increasesfrom2to4, Cu²⁺removal rate increases from90.73%to98.13%. Slight increase inSDS concentration and SDS removal rate decreases slightly. It is due to combinedeffects of two different results of SDS micelles and micelle formation of Cu²⁺adsorption with pH value diversification.Therefore, the MEUF has significantly economic profit and considerablypractical value. The study provides foundation for application and popularization ofheavy metals–containing wastewater treatment by MEUF.