Improved Desalination by Polymer Grafting

TL;DR

This paper demonstrates that grafting specially designed polyampholytic block copolymers onto electrodes significantly enhances capacitive deionisation desalination performance through improved ion adsorption and charge utilization.

Contribution

It introduces interfacial block copolymer grafting as a novel method to boost CDI efficiency without changing pore structures.

Findings

Polymer grafting improves desalination performance via dipolar and steric effects.

Block copolymer architecture offers additional performance gains.

Neutral polymers can also enhance CDI, but less effectively.

Abstract

Freshwater scarcity demands desalination technologies that are efficient, scalable, and sustainable. Capacitive deionisation (CDI) is promising but remains limited by inefficient ion adsorption and poor charge utilisation. Here, we show that suitably chosen polyampholytic block copolymer grafting can substantially enhance CDI performance, via a combination of dipolar response and steric effects. Using mean-field classical density functional theory and grand-canonical Monte Carlo simulations, we demonstrate that such polymer grafted electrodes enable strongly improved desalination performance, without altering the pore architecture. Even an electrode grafting by simple neutral polymers can generate an improvement, although a suitably designed block polymer architecture offers an additional performance gain. These results establish interfacial block copolymer grafting as a powerful route toward high-performance, membrane-free desalination.