TiO2纳滤膜对重金属离子的截留性能

Research on rejection of heavy metal ions with TiO_2 nanofiltration membranes

采用孔径为1.5nm的TiO2纳滤膜,在压力0.4～0.8MPa,pH值3～7的条件下,考察了膜对浓度范围为50～500mg/L的Cu(NO3)2、Ni(NO3)2、ZnCl2和CdCl2四种单组份重金属溶液的截留性能.结果表明:除Cd2+外,膜对重金属离子的截留率随溶液浓度的增大先增大,当浓度达到200mg/L后趋于稳定;升高压力膜的离子截留率会略有增加;当pH=6时,膜对Ni 2+和Cd2+的截留率最低,而对Cu2+和Zn2+的截留率在pH=5～6时达到最高.TiO2膜对Cu2+、Ni 2+、Zn2+和Cd2+的最高截留率分别可以达到96.9%、95.9%、92.5%和83.2%.

Rejection properties of TiO2 nanofiltration membrane （ with mean pore size of 1.5 nm ） with re- spect to the heavy metal salt solutions, namely Cu（NO3）2, Ni（NOa）2, ZnCl2 and CdCl2 were investigated. The effects of processing parameters, such as pH, transmembrane pressure and concentration of heavy metal ions, on membrane jection rate were studied in detail. The results show that heavy metal ions rejec- tion of membrane increases at first with concentration while does not vary too much as the concentration reaches 200 mg/L. But this is not for Cd2＋. Rejection properties of membrane increases slightly as the transmembrane pressure elevated. The membrane exhibits minimal rejection properties towards Ni2＋ and Cd2＋ at a pH value of 6, where the maximal rejection rate towards Cu2＋ and Zn2＋ can be found. Rejection properties of TiO2 nanofiltration membrane towards Cu2＋ , Ni2＋ , Zn2＋ and Cd2＋ can reach maximum values of 96.9%, 95.9%, 92.5% and 83.2%, respectively.