Green lignin‐based polyester nanofiltration membranes with ethanol and chlorine resistance

Abstract As the main water treatment material, polymeric membranes inevitably suffer from membrane fouling. In this work, novel lignin‐based polyester composite nanofiltration membranes (NFM) with ethanol and chlorine resistance were fabricated via interfacial polymerization. Lignin alkali (LA), a green lignin derivative, typically treated as chemical waste in the paper industry, was employed as the aqueous monomer, trimesoyl chloride (TMC) is served as the organic monomer. The structure and separation properties of the lignin‐based NFM were studied, revealing that the dense polyester separation layer may show good performance for dye removal. The rejections of the optimized LA/TMC‐3 membrane with an excellent permeation flux of 13.9 kg m −2 ∙h −1 for rose Bengal sodium salt, brilliant blue, congo red, rhodamine B, MgSO 4 , and NaCl are 97.6%, 97.3%, 97.8%, 71.34%, 51.4%, and 31.8%, respectively. Moreover, the LA/TMC‐3 membrane also shows long‐term tolerance in ethanol and sodium hypochlorite solution; the rejection of LA/TMC‐3 to dye only decreases 8% after 8 days when immersed in alcohol, while the normalized rejection maintains 94% after 4000 ppm‐hours of continuous exposure to chlorine. This lignin‐based polyester membrane may broaden the sustainable utilization sphere of lignin derivatives, at that provide a referable direction for the development of membrane materials.