Shape Memory Adsorbents for Water Remediation: Recent Progress, Associated Hydrodynamics, and Research Needs

Shape memory materials comprising aerogels, hydrogels, sponges, and ionogels have come on the scene as novel adsorbents for water purification. These materials demonstrate high adsorption capacities, enhanced mechanical strength, and shape resilience at the laboratory scale in unary, binary, and multicomponent adsorbate synthetic solutions. However, their reliable use in real-world water purification applications is significantly limited by hurdles. Based on the available literature, these hurdles are discussed in this review article. The hurdles include the following: (1) the need for extensive testing of the shape memory adsorbents in real and complex wastewaters under the extreme hydrodynamic conditions that can be expected in both pilot-scale column-type studies and real water treatment systems, (2) the redesigning of their synthetic routes to tune their specific physicochemical and mechanical properties so they can withstand harsh environmental conditions over repeated cycles of use, and (3) significant research efforts are required to simulate and optimize large-scale adsorption-based water purification systems for commercial use.