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, MgSO4, 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.

Alternative materials for interfacial polymerization: recent approaches for greener membranes

“…2.2.4 Lignin. Zhan et al 84 used lignin alkali (LA) as the aqueous monomer. Lignin is a polymer derived from plant cell walls; it is the second largest natural macromolecule in nature.…”

“…Lignin has many benefits, being renewable, bio-degradable, abundant, cheap, and non-toxic. Zhan et al 84 were the first to perform IP with lignin as the aqueous monomer to produce a NF membrane. The phenol groups in LA reacted under alkaline conditions with acyl groups in TMC forming a dense thin polyester layer.…”

Sustainable membrane technology for water purification—Manufacturing, recycling and environmental impacts

“…In addition to the use of sustainable polymers, non-toxic solvents must be adopted for membrane processing [19][20][21]. Polyesters have been identified as sustainable green materials for membranes [27][28][29]. Polyethylene membranes especially recycled membranes from petroleum products have advantages of antifouling, chemical.…”

A lignin-based membrane fabricated with a deep eutectic solvent

“…The dissolution of lignin to form a homogeneous solution and subsequently a polymeric membrane film has involved the use of harmful chemicals and a complex process that incur high operational costs. 2 For the lignin membranes reported so far, an additional limitation has been its poor mechanical stability, which was in part overcome by blending it with other polymers (lignin/polyvinyl alcohol) 10 during the manufacturing process, interfacial polymerization of alkali lignin as a water-soluble monomer exposed to acyl chloride in the organic phase, 11 and layer by layer assembly of sulfonated lignin sodium salt with poly(diallyl dimethyl ammonium chloride). 12 Therefore, it is highly imperative to develop a simple environmentally friendly method to dissolve lignin and manufacture it into robust membranes for a broad range of separation and purification applications.…”