Regeneration and reuse of salt-tolerant zwitterionic polymer fluids by simple salt/water system

Advanced treatment and reuse of dye wastewater using thermo-irreversible on/off switch starch with disruption of dissolution/precipitation dynamic equilibrium

The development of irreversible on/off switching materials is a potential strategy for unidirectional capture and encapsulation of pollutants, preventing the pollutant leakage problem resulting from the reversible dissolution of flocculants. Herein, a thermo-irreversible on/off switch starch (TISS) is prepared through modifying starch by etherification grafting glycidyl phenyl ether and 2,4-bis(dimethylamino)-6-chloro-[1,3,5]-triazine. It breaks the dissolution/precipitation dynamic equilibrium across heating-cooling cycles by thermal-induced irreversible coil-to-globule self-assembly of polymer chains, resulting in a 50-fold decrease in polymer solubility. Particularly, TISS shows a superior double-locking effect on pollutants and flocculants through its unique irreversible conformation memory capability, leading to a high-quality reuse water. 99.9 % of reactive brilliant red dye and 97.9 % of TISS remain fixed within sludge flocs even after prolonged immersion in cold water at 24 °C for 60 days. Furthermore, direct recycling and reuse of dye-bath energy can be realized through the isothermal flocculation and dyeing method, showing a 75 % decrease in energy consumption after three cycles compared to traditional dyeing techniques. This work presents a novel approach to constructing an irreversible pollutant delivery system using thermo-irreversible on/off switch starch, addressing the problems of high energy dissipation and water quality fluctuations during wastewater treatment.

Chaotropic Ions Mediated Polymer Gelation for Thermal Management

Energy and environmental issues have increasingly garnered significant attention for sustainable development. Flexible and shape-stable phase change materials display great potential in regulation of environmental temperature for energy saving and human comfort. Here, inspired by the water absorption behavior of salt-tolerant animals and plants in salinity environment and the Hofmeister theory, highly stable phase change salogels (PCSGs) are fabricated through in situ polymerization of hydrophilic monomers in molten salt hydrates, which can serve multiple functions including thermal management patches, smart windows, and ice blocking coatings. The gelation principles of the polymer in high ion concentration solution are explored through the density functional theory simulation and verified the feasibility of four types of salt hydrates. The high concentration chaotropic ions strongly interacted with polymer chains and promoted the gelation at low polymer concentrations which derive highly-stable and ultra-moisturizing PCSGs with high latent heat (> 200 J g-1). The synergistic adhesion and transparency switching abilities accompanied with phase transition enable their smart thermal management. The study resolves the melting leakage and thermal cycling stability of salt hydrates, and open an avenue to fabricate flexible PCM of low cost, high latent heat, and long-term durability for energy-saving, ice-blocking, and thermal management.