Heavy metal-contaminated groundwater treatment by a novel nanofiber membrane

The morphology, interspace and surface properties of a novel nanofiber membrane are characterized by scanning electron microscopy (SEM), pore percent and contact angle. The membrane, named M-1, is prepared from chloridized polyvinyl chloride by high-voltage electrospinning process. The removals of divalent metal cations including Cu2+, Pb2+ and Cd2+ from the simulated groundwater by M-1 have been investigated. To obtain the best heavy metal removal, several experimental methods using M-1 have been presented, including static adsorption, direct filtration, soil-addition filtration, diatomite-addition filtration and micellar enhanced filtration (MEF). Specially, MEF experiments are performed as a function of SDBS concentration and applied membrane layers. From static adsorption experiments, maximum uptakes of Cu2+, Cd2+, Pb2+ and their adsorption equilibrium time have been obtained respectively in the simulated groundwater. Dynamic filtration experiments indicate that the best experimental method for M-1 to remove heavy metal cations is MEF whose optimal experimental conditions are 10-layer filtration and sodium dodecyl benzene sulfonate (SDBS) concentration of 5 mmol/L. The experimental results show that the rejections of copper in the simulated groundwater by MEF using M-1 can reach more than 73%; the rejections of lead more than 82%; and the rejections of cadmium more than 91%. It is indicated that MEF method using M-1 can be used for the treatment of the groundwater containing Cu2+, Pb2+ and Cd2+ with high efficiency.

Due to the 3-dimensional network structure with multilayers, wide ranged pore size distribution and large specific surface area, M-1 prepared by electrospinning are successfully used as the adsorbent and filtration membrane to remove heavy metal from groundwater. The ultimate adsorption capacity of M-1 is over 5 mg of Cu2+, Cd2+ or Pb2+ per gram of M-1.When M-1 is served for filtration membrane, MEF is more effective to remove heavy metal cations from groundwater than direct filtration, soil-addition filtration and diatomite-addition filtration. The optimal experimental conditions of MEF are 10-layer filtration and SDBS concentration of 5 mmol/L. The rejections of copper in the simulated groundwater by MEF using M-1 can reach more than 73%; the rejections of lead, more than 82%; and the rejections of cadmium, more than 91%. In summary, MEF using M-1 can be used for the treatment of the groundwater containing Cu2+, Pb2+ and Cd2+ with high efficiency.