Preparation of lignosulfonate‐based nanofiltration membranes with improved water desalination performance

Abstract

Pulping and papermaking generate large amounts of waste in the form of lignosulfonates which have limited valorized applications so far. Herein, we report a novel lignosulfonate‐based nanofiltration membrane, prepared by using polyethylenimine (PEI) and sodium lignosulfonate (SL) via a layer‐by‐layer (LbL) self‐assembly. As a low‐cost and renewable natural polyelectrolyte, SL is selected to replace the synthetic polyelectrolyte commonly used in the conventional LbL fabrication for composite membranes. The prepared LbL (PEI/SL)7 membranes were crosslinked by glutaraldehyde (GA) to obtain (PEI/SL)7‐GA membranes with compact selective layer. We characterized (PEI/SL)7 and (PEI/SL)7‐GA membranes to study the chemical compositions, morphologies, and surface hydrophilicity. To improve the nanofiltration performances of the (PEI/SL)7‐GA membranes for water desalination, we investigated the effects of the crosslinking time, GA concentration and the NaCl supporting electrolyte on membrane structure and performance. The optimized (PEI/SL)7‐GA membrane exhibited a permeating flux up to 39.6 L/(m2·h) and a rejection of 91.7% for the MgSO4 aqueous solution 2.0 g/L concentration, showing its promising potential for water desalination. This study provides a new approach to applying the underdeveloped lignin‐based biomass as green membrane materials for water treatment.

Lignosulfonate-Coated ZIF-8 as an Effective Nanofiller to Prepare High-Performance Thin-Film Nanocomposite Forward Osmosis Membrane for Heavy Metal Ions Removal

“…18,19 For the first time, in the current investigation, we synthesized a novel sodium lignosulfonate (SL)-coated ZIF-8 (ZIF-8@SL) nanoparticle as high-performance nanofillers for modification of TFN-FO membranes to treat the heavy metal ions during the FO process. The SL structure comprises sulfonate functional groups, 20 which improve the dispersibility in m-phenylenediamine (MPD) solution. Furthermore, the SL layer on the ZIF-8 nanoparticles improves the compatibility between the PA structure and enhances the stability of the ZIF-8@SL nanofillers during the FO operation.…”