Layer-by-layer (LbL) assembly technology is a facile method for constructing thin film composite membrane. Herein, a novel nanofiltration (NF) membrane was prepared by LbL assembly of polyethyleneimine (PEI) and sodium lignosulfonate (LS) followed by cross-linking. The surface composition, morphology, and property of PEI/LS bilayer were detailedly investigated by FTIR/ATR, XPS, SEM, AFM, and water contact angle test. The PEI/LS bilayer full of amino and hydroxyl groups presents increased roughness and improved hydrophilicity. Moreover, the NF performance of PEI/LS LbL assembly membranes can be modulated by bilayer number, polyelectrolyte concentration, and salt content. The water flux reduced while the salt rejection greatly improved as increasing the bilayer numbers, PEI concentration, or NaCI content. More than 95% MgSO₄ and MgCI₂, as well as 80% NaCI can be rejected by a NF membrane prepared by 6 PEI/LS bilayers, 1 wt% PEI, 0.5 wt% LS, and 1 mol/L NaCI. Furthermore, this NF membrane can be used to remove more than 95% heavy metal ions (Cd²⁺, Zn²⁺, Mn²⁺, Cr²⁺, Cu²⁺, and Ni²⁺). This work proposed a promising NF membrane by using PEI/LS as low cost polyelectrolytes and facile LbL assembly method, which should receive much attention in water purification.

逐层（LbL）组装技术是一种构造薄膜复合膜的简便方法。本文中，通过聚乙烯亚胺（PEI）和木质素磺酸钠（LS）的LbL组装然后交联来制备新型的纳滤（NF）膜。通过FTIR / ATR，XPS，SEM，AFM和水接触角测试详细研究了PEI / LS双层的表面组成，形态和性能。充满氨基和羟基的PEI / LS双层具有更高的粗糙度和更高的亲水性。而且，PEI / LS LbL组装膜的NF性能可以通过双层数，聚电解质浓度和盐含量来调节。随着双层数，PEI浓度或NaCl含量的增加，水通量减少，而盐分截留率则大大提高。超过95％的MgSO ₄MgCl ₂和80％NaCl可以被由6个PEI / LS双层，1 wt％PEI，0.5 wt％LS和1 mol / L NaCl制成的NF膜拒绝。此外，该NF膜可用于去除超过95％的重金属离子（Cd 2 ⁺，Zn 2 ⁺，Mn 2 ⁺，Cr 2 ⁺，Cu ²⁺和Ni ²⁺）。这项工作通过使用PEI / LS作为低成本的聚电解质和简便的LbL组装方法，提出了一种很有前途的NF膜，这在水净化中应引起广泛的关注。