| Summary: | 碩士 === 嘉南藥理科技大學 === 環境工程與科學系暨研究所 === 94 === Abstract
The purposes of this investigation focus on the preparation of nanofiltration membranes (NF) and their characteristics for wastewater treatment. The nanofiltration membranes were used by considering the asymmetric polysulfone membranes, ion exchanged polysulfone membranes, and photografted poly acrylic acid membranes. it was found that the low rejection rate of asymmetric polysulfone membranes were found in NF process. The permeation rate and salt rejection of asymmetric membrane were 65-20 Kg/m2hr and 10%-15%, respectively. On the other hand, the improvement of separation performance of NF membranes was achieved by applying the sulfonated polysulfone as the membrane material. It was successful prepared by asymmetric sulfonated membrane and enhanced both of permeation rate and salt rejection rate in NF process. It was found that the improvement in NF separation performance was due to the increase in swelling properties and improvement in hydrophilicity of membranes.
The photografting method was used to enhance the NF separation performance of polysulfone membranes. The preparation conditions, characteristics and morphology of photografted membranes were investigated in this study. It was found that the photografted poly acrylic acid enhanced the salt rejection rate and decreased the permeation rate of modified membranes. The permeation rate and salt rejection of photografted membrane were 30-10 Kg/m2hr and 12%-21%, respectively. Those photografted membranes were upgraded the separation performance by ion exchanged method. It was found that the exchanged ions strongly influenced the permeation rate and salt rejection due to the hydrophilic properties. The salt rejection rate of those ion exchanged membranes increased with the exchanged ion in the serial, Na+ < Mg+2< Al+3. The inverse trend was found in the permeation behavior of ion exchanged photografted membranes. In this investigation, the influence of molecular size of ion on the permeation behavior was investigated by using the Al+3 exchanged membranes. The results indicated that over 80% rejection can be achieved by using the secondary ammonia and tertiary ammonia as the permeates in NF process. The NF permeation tests also showed that the operating pressure and temperature showed the significantly affect on the permeation rate and salt rejection.
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