Membrane Characterization And Pilot Study Of The Nanofiltration Membrane

Nanofiltration is a pressure driven membrane process situated between reverse osmosis and ultrafiltration and has attracted increasing attention over the recent years. The advantages of nanofiltration are as follows: Pore diameters of nanofiltration membranes are of nanometers. Low operation pressures can be used to obtain comparable fluxes which is an important energetic advantage. Nanofiltration membranes have high selectivity to different irons because most of them are charged either positively or negatively. Nanofil- tration can be used as new techniques to replace some traditional processes. Now nanofil- tration membrane has been applied to many fields, such as medicine, food industries, biologic engineering, metallurgy, and so on. The main results of this paper were given as follows:1. Experiments showed that both volume fluxes and rejection increase with the increasing pressure, and decrease with the concentration and molecular weight of the organic.2. With the continuous operation mode and batch concentration mode, the concentration of green tea extract solution by nanofiltration was studied. In the continuous operation mode, the permeation flux, elimination of water and the retention coefficient of tea polyphenols were measured at different applied pressures and the characteristics of nanofiltration process were discussed. In the batch operation mode, the retention properties of tea polyphenols for green tea extract solutions with different concentrations were measured. The experiment data were compared with the predictions of the concentration numerical model. The experiment results were fit with the model predictions fairly well. The concentration model can be applied in the description of the concentration process of green tea extraction solution by nanofiltration and can be used for the process design.3. In this series of experiments,membrane separation technology is used to treat the electroplating copper rinse water,to recover the copper and water resources from the wastewater. The results show that the retention rate of NF against copper is more than 99%,the elimination of water 95%,and the conductance of the permeate less than 200μs?cm-1. When the copper concentration in the feed is 140mg/L,it can be concentrated more than 10 times. The experimental results provide basis and references for the design and operation of actual systems.And the application of nanofiltration membrane separation technique in treatment of electroplating wastewater will produce remarkable social and economic benefits.