(651b) Novel Nanofiltration Membrane with a Sulfonated Copolymer Selective Layer for the Removal of Heavy Metals

Facing increasing stringent regulations on wastewater discharge containing heavy metal ions, various industries are demanding more efficient and effective treatment methods. Among the various methods available, nanofiltration (NF) has been proven to be a feasible and promising option. However, it should be noted that the development of new membrane materials is constantly required for the advancement of this technology. To this aim, this study reports the first attempt to develop a composite NF membrane comprising of a molecularly designed pentablock copolymer selective layer for the removal of heavy metal ions. The resultant NF membrane has a reasonably high pure water permeability (A) of 2.4 LMH/bar with a mean effective pore diameter of 0.50 nm and molecular weight cut-off of 255 Da. In addition, the newly developed NF membrane can effectively remove heavy metal cations such as Pb²+, Cd²⁺, Zn²⁺ and Ni²⁺ with a rejection greater than 98.0%. Furthermore, the membrane also shows reasonably high rejections towards anions such as HAsO₄^2- (99.9%) and HCrO₄^- (92.3%). This observed performance can be attributed to (1) the incorporation of polyethyleneimine (PEI) as a gutter layer between the selective layer and the substrate and (2) the pentablock copolymer’s unique ability to form a continuous water transport passageway with a defined pore size. The promising preliminary results achieved in the current study provide a useful platform for the development of new NF membranes for the removal of heavy metals.