Removal Of Cadmium And Phenol Contaminants In Water By Micelle Enhanced Ultrafiltration

Micellar-enhanced ultrafiltration (MEUF) is a method that could be used for treatingheavy metal and organic wastewater widely in industry with lots of favorable factors, such aseasily operating, low investment and efficacy stabilizes. MEUF is a good promising indealing with low concentrations. The wastewater which commonly contain co-contamiantionand low concentration pollution could be disposed by MEUF. However, amounts of ionicsurfactants has been used in the process to achieve much surfactant micelle, which wouldbring a high surfactant concentration of permeate, and cause recontamination.In this study，treating heavy metal-organic pollution was discussed by MEUF whichaimed at reducing the costs and the dosage of anionic surfactant, optimizing the operation ofcomposite pollution treatment. Surfactant sodium dodecyl sulfate (SDS) and nonionicsurfactant Brij35were systematically studied for cadmium and phenol single and combinedwith MEUF. Polysulfone ultrifiltration membrane was used to ultrifiltriton process andrecycling technology was also studied. The obtained results are as follows:1) With single sodium dodecyl sulfate (SDS) and Brij35/SDS at different molar ratios,the Micelle-enhanced ultrafiltration (MEUF) to remove cadmium ions in aqueous solution hasbeen studied. As a result, with the increase of concentration of SDS, the removal rateincreased and the removal efficiency of Cd(Ⅱ) was up to the maximum99.67%(Cd(Ⅱ)=20mg/L) and93.45%(Cd(Ⅱ)=50mg/L), respectively. With the ratios of Brij35/SDS improved,CMC was reduced, obviously. The removal rate was increased firstly and then decreased.When the concentration of SDS was1,3mM, the Cd(Ⅱ) rejection efficiency reached at72.12%and98.34%, respectively. The effect of feed surfactant concentration on Cd(Ⅱ)rejection was investigated at the optimum composition Brij35/SDS=0.3. The results showedthat the performance of the mixed Brij35/SDS was better than that of pure SDS micellesystem in case of using fewer amounts of surfactant. When the concentration of surfactantwas higher than300mg/L, the rejection was obvious. MEUF using anionic/nonionic mixedsurfactant was able to enhance the rejection rate of contaminants, and reduce the dosage ofSDS.2) The Micelle-enhanced ultrafiltration (MEUF) to remove phenol in aqueous solutionwith single sodium dodecyl sulfate (SDS) and Brij35/SDS at differe nt molar ratios has alsobeen studied. The permeate flux, the concentration of effluent, the removal ratio and rejectioneffect was compared. As a result, with the increase of concentration of SDS and the ratios ofBrij35/SDS, the removal rates were smooth and increased. The results showed that theperformance of the mixed Brij35/SDS was little better than that of pure SDS micelle system in case of using fewer amounts of surfactant, The removal slightly larger, up to42.04%,54.56%,56.26%. The surface of the experimental results, the removal condition of the mixedsurfactant of phenol without optimal multiplexing ratio exists, showing the higher thesurfactant concentration, the removal rate is higher.3) Micellar-enhanced ultrafiltration (MEUF) using single sodium dodecyl sulfate (SDS)was investigated largely in area of compound wastewater treatment. In addition to removeCd(Ⅱ)/phenol efficiently, the following aspects have been stated: the feed mixed surfactantconcentration, the molar ratio of Brij35to SDS，cadmium and phenol concentrations in thepermeate, as well as the retentate, and the permeate flux. With the ratios of Brij35/SDSimproved, the CMC is lower than that of SDS, obviously. The rejections efficiencies ofcadmium and phenol in the MEUF system are enhanced with mixed surfactants concentration.When SDS concentration is fixed at ranges from1mM to3mM, the optimal molar ratio ofBrij35to SDS for the removal of cadmium and phenol is0.5. The phenol rejection is slightlyenhanced in the presence of Cd(Ⅱ). MEUF using anionic/nonionic mixed surfactant is able toenhance the rejection efficiency of contaminants, and reduce the dosage of SDS. When theconcentration of surfactant was higher than1700mg/L, the rejection was obvious. MEUFusing anionic/nonionic mixed surfactant was able to enhance the rejection rate ofcontaminants, and reduce the dosage of SDS.4) The recovery of retentate has been studied. By three times of extracted, the recoveryratio of phenol is higher than85%with achieving optimal results. Precipitation of cadmiumwith NaOH which the ratio of2.5is stable and the precipitate is higher than95%. With theincrease of surfactant concentration, the recovery rate of Brij35is sharply decreased from82.4%to23.1%while surfactant concentration is50~600mg/L, then decreased slowly. At thesame time, the concentration of SDS is increased steady, but the maximum recovery rate isless than20%.