High-Performance Capacitive Deionization Disinfection of Water with Graphene Oxide-graft-Quaternized Chitosan Nanohybrid Electrode Coating

Water disinfection materials should ideally be broad-spectrum-active, nonleachable, and noncontaminating to the liquid needing sterilization. Herein, we demonstrate a high-performance capacitive deionization disinfection ((DID) electrode made by coating an activated carbon (AC) electrode with cationic nanohybrids of graphene oxide-graft-quaternized chitosan (GO-QC). Our GO-QC/AC (DID electrode can achieve at least 99.9999% killing (i.e., 6 log reduction) of Escherichia coil in water flowing continuously through the (DID cell. Without the GO-QC coating, the AC electrode alone cannot kill the bacteria and adsorbs a much smaller fraction (<82.8 +/- 1.8%) of E. coil from the same biocontaminated water. Our (DID process consists of alternating cycles of water disinfection followed by electrode regeneration, each a few minutes duration, so that this water disinfection process can be continuous and it only needs a small electrode voltage (2 V). With a typical brackish water biocontamination (with 10(4) (FU mL(-1) bacteria), the GO-QC/AC electrodes can kill 99.99% of the E. coil in water for 5 h. The disinfecting GO-QC is securely attached on the AC electrode surface, so that it is noncontaminating to water, unlike many other chemicals used today. The GO-QC nanohybrids have excellent intrinsic antimicrobial properties in suspension form. Further, the GO component contributes toward the needed surface conductivity of the (DID electrode. This (DID process offers an economical method toward ultrafast, contaminant-free, and continuous killing of bacteria in biocontaminated water. The proposed strategy introduces a green in situ disinfectant approach for water purification.