Treatment Of Waste Streams Containing Ni～(2+) By Micellar Enhanced Ultrafiltration

This paper described the characterization of micellar enhanced ultrafiltration (MEUF) process of waste streams containing Ni²⁺. The study included the rejection of the surfactant and Ni²⁺and the permeate flux with an ultrafiltration membrane that had a MWCO of 40000 Dalton. The interaction between the surfactant and Ni²⁺ was characterized by the fluorescence spectrum and LLS(laser lighter scattering). The effects of interaction on MEUF process were discussed. The enhancement of the MEUF process by Dean vortices was also investigated. The main points were as follows:1. The ultrafiltration membrane that had a MWCO of 40000 Dalton could reject the micelles of SDBS (sodium dodecyl benzene sulfonate) preferably and could be applied in the research of MEUF process. The high rejection of nickel in the waste streams could be obtained when the bulk concentration of SDBS and Ni²⁺ was low. When the SDBS concentration in the bulk was 2.0mmol/L, the rejection of nickel in the waste streams could reach 99.05%, and the permeate nickel concentration was 0.28mg/L which was lower than the concentration of the national discharge standard. This kind of permeate solution could be discharged after some simple treatment. When the pH of bulk was 9.56, the permeate flux could reach 145.8L/m2·h.2. The rejection of nickel remained uncharged and more SDBS monomers came into being the micelles when NPE (nonylphenol ethoxylated) was added to the solution. The surfactant concentration of permeate was reduced effectively and the permeate flux was improved. When the bulk concentration of SDBS was 2.0mmol/L, nickel concentration was 0.5mmol/L and NPE concentration was 0.4mmol/L, the permeate flux was 175.9 L/m²Â·h and the rejection of surfactant increased to 84.4%. The permeate surfactant concentration of 1.152mmol/L was decreased to 0.374mmol/L, 67.5% reduced. As show of the SEM photograph, the shape and size of the substances rejected by the ultrafiltration membrane changed after the NPE was added. The shape of rejected substances was similar to the crystal before NPE was added. With the influence of NPE, the rejected substances transformed into gelatinous substances and the size of particles decreased obviously.3. The research of fluorescence spectrum showed that there was interaction between SDBS and the nickel ion. And direct interaction wasn't present between NPE and the nickel ion. But NPE affected the interaction between the SDBS and nickel ion. When the bulk concentration of NPE exceeded 0.4mmol/L, the increasing of the NPE concentration resulted in the decreasing of the nickel rejection and increasing of the permeate surfactant concentration directly.4. The hydraulics radius of SDBS micelle increased with the increasing of the nickel...