Continuous Cycle of Water Desalination Utilizing Hydrogel as Draw Agent.

Abstract

This document discusses operation of desalination system permanently extracting water from hydrogel draw agent by specially selected wicks. Due to its peculiarity the system combines advantages of both forward and reverse osmosis approaches such as, low power consumption, passive process of a freshwater extraction, continuous duty cycle and scaling possibility. While in modern systems an energy consumption of seawater desalination reaches of about 3 kWh/m 3, including pre-filtering and ancillaries [1], the same parameter for the specific system expected to be as low as for local fresh water supplyi.e., 0.2 kWh/m 3

Perspective Chapter: Hydrogel Draw Agent Desalination Systems – Outlook

“…However, intergranular water initiated by pH-difference is easily extractable with wicks as demonstrated in experimental results of Ref. [20] shortly presented below. pH-dependent swelling of the superabsorbent hydrogel (according to [21]).…”

“…One of the possible ways to provide an energy-efficient process with a continuous duty cycle to overcome the above bottleneck is proposed and experimentally tested in the article [20]. The idea was to provide local stimuli impact on grains of pH-sensitive hydrogel.…”

“…The authors of ref. [20] proposed to use wicks with surface pH different from the pH of hydrogel medium as stimulus for local release of water from hydrogel granules into the intergranular space. This construction proved to be capable of passive extraction of water from swelling hydrogel draw agent in three-stage process:…”