Sequential Approach for Water Purification Using Seashell-Derived Calcium Oxide through Disinfection and Flocculation with Polyphosphate for Chemical Pollutant Removal

Safe water supply is usually inadequate in areas without water treatment plants and even in a city under emergency conditions due to a disaster, even though safe water is essential for drinking and other various purposes. The purification of surface water from a river, lake, or pond requires disinfection and removal of chemical pollutants. In this study, we report a water purification strategy using seashell-derived calcium oxide (CaO) via disinfection and subsequent flocculation with polyphosphate for chemical pollutant removal. Seashell-derived CaO at a concentration (2 g L–1) higher than its saturation concentration caused the >99.999% inactivation of bacteria, mainly due to the alkalinity of calcium hydroxide (Ca(OH)2) produced by hydration. After the disinfection, the addition of sodium polyphosphate at 2 g L–1 allowed for the flocculation of CaO/Ca(OH)2 particles with adsorbing chemical pollutants, such as Congo red, dichlorodiphenyltrichloroethane, di(2-ethylhexyl)phthalate, and polychlorinated biphenyls, for removing these pollutants; purified water was obtained through filtration. Although this purified water was initially highly alkaline (pH ∼ 12.5), its pH decreased into a weak alkaline region (pH ∼ 9) during exposure to ambient air by absorbing carbon dioxide from the air with the precipitating calcium carbonate. The advantages of this water purification strategy include the fact that the saturation of CaO/Ca(OH)2 potentially serves as a visual indicator of disinfection, that the flocculation by polyphosphate removes excessive CaO/Ca(OH)2 as well as chemical pollutants, and that the high pH and Ca2+ concentrations in the resulting purified water are readily decreased. Our findings suggest the usability of seashell-derived material–polymer assemblies for water purification, especially under emergency conditions due to disasters

Enzyme-Catalyzed Bottom-Up Synthesis of Mechanically and Physicochemically Stable Cellulose Hydrogels for Spatial Immobilization of Functional Colloidal Particles

The dispersion stabilization of colloidal particles and subsequent construction of functional materials are of great interest in areas ranging from colloid chemistry to materials science. A promising strategy is the spatial immobilization of colloidal particles within gel scaffolds. However, conventional gels readily deform and even collapse when changes in environmental conditions occur. Herein, we describe the enzyme-catalyzed bottom-up synthesis of mechanically and physicochemically stable nanoribbon network hydrogels composed of crystalline cellulose oligomers in which cellulose nanocrystals (CNCs) as model colloidal particles are immobilized spatially. The stiffness of the hydrogels increased with the amount of CNCs incorporated. Filling the void space of the hydrogels with hydrophobic polymers resulted in polymer nanocomposites with excellent mechanical properties. The nanoribbon networks will be useful for demonstrating the potential functions of colloidal particles

Enzyme-Catalyzed Bottom-Up Synthesis of Mechanically and Physicochemically Stable Cellulose Hydrogels for Spatial Immobilization of Functional Colloidal Particles

The dispersion stabilization of colloidal particles and subsequent construction of functional materials are of great interest in areas ranging from colloid chemistry to materials science. A promising strategy is the spatial immobilization of colloidal particles within gel scaffolds. However, conventional gels readily deform and even collapse when changes in environmental conditions occur. Herein, we describe the enzyme-catalyzed bottom-up synthesis of mechanically and physicochemically stable nanoribbon network hydrogels composed of crystalline cellulose oligomers in which cellulose nanocrystals (CNCs) as model colloidal particles are immobilized spatially. The stiffness of the hydrogels increased with the amount of CNCs incorporated. Filling the void space of the hydrogels with hydrophobic polymers resulted in polymer nanocomposites with excellent mechanical properties. The nanoribbon networks will be useful for demonstrating the potential functions of colloidal particles

Enzyme-Catalyzed Bottom-Up Synthesis of Mechanically and Physicochemically Stable Cellulose Hydrogels for Spatial Immobilization of Functional Colloidal Particles

The dispersion stabilization of colloidal particles and subsequent construction of functional materials are of great interest in areas ranging from colloid chemistry to materials science. A promising strategy is the spatial immobilization of colloidal particles within gel scaffolds. However, conventional gels readily deform and even collapse when changes in environmental conditions occur. Herein, we describe the enzyme-catalyzed bottom-up synthesis of mechanically and physicochemically stable nanoribbon network hydrogels composed of crystalline cellulose oligomers in which cellulose nanocrystals (CNCs) as model colloidal particles are immobilized spatially. The stiffness of the hydrogels increased with the amount of CNCs incorporated. Filling the void space of the hydrogels with hydrophobic polymers resulted in polymer nanocomposites with excellent mechanical properties. The nanoribbon networks will be useful for demonstrating the potential functions of colloidal particles

Enzymatic Synthesis of Cellulose Oligomer Hydrogels Composed of Crystalline Nanoribbon Networks under Macromolecular Crowding Conditions

Macromolecular crowding, a solution state with high macromolecular concentrations, was used to promote the crystallization-driven self-assembly of enzymatically synthesized cellulose oligomers. Cellulose oligomers were synthesized via cellodextrin phosphorylase-catalyzed enzymatic reactions in the concentrated solutions of water-soluble polymers, such as dextran, poly­(ethylene glycol), and poly­(<i>N</i>-vinylpyrrolidone). The reaction mixtures were transformed into cellulose oligomer hydrogels composed of well-grown crystalline nanoribbon networks irrespective of the polymer species. This method was successfully applied in the one-pot preparation of double network hydrogels composed of the nanoribbons and physically cross-linked gelatin molecules through the simple control of reaction temperatures, demonstrating the superior mechanical properties of the composite hydrogels. Our concept that promotes the growth of self-assembled architectures under macromolecular crowding conditions demonstrates a new avenue into developing novel hydrogel materials