Electrical responsiveness of carboxylate multi-walled carbon nanotube cross-linked composite anti-fouling membranes to organic pollutants

Protein has been identified as one of the major membrane foulants in wastewater treatment and reclamation applications. The specific molecular configuration of bovine serum albumin (BSA) impedes electron transfer at the interface, resulting in poor electrochemical signal, and is often used as a blocker for electrochemical biosensors. To improve the precision and speed of fouling detection, the study proposes integrating the electrical properties with the organic fouling process of the membrane to provide the BSA fouling electrical response signal. The unique electrical properties of carboxylate multi-walled carbon nanotubes (O-MWCNTs) were introduced into polyvinylidene fluoride (PVDF) ultrafiltration membranes using a pre-coating method. The conductive coated layer of O-MWCNT facilitates real-time observation of membrane fouling and enables timely cleaning of the membrane to improve fouling resistance. To improve the loading and binding strength of the O-MWCNTs, phenylenediamine (MXAD) was utilized as a cross-linking agent, which improved the composite membrane's overall performance and decreased the membrane's resistance from 1.33 × 106 Ω–37.91 Ω. The electrical signal received from the four-probe resistivity meter showed a response to the fouling level. The combined comparison of the normalized flux and electrical signal trends resulted in a more visual, rapid, sensitive, and accurate indication of membrane BSA fouling, which paves the way for the detection of electrical BSA fouling and subsequent cleaning and reuse of the separation membranes.