Regenerated Cellulose Structured Materials for Coral Reef Restoration

Regenerated cellulose materials using the ionic liquid, 1-ethyl-3-methylimidazolium acetate ([emim][OAc]), were used to produce filaments and 3D-printed meshes <i>via</i> wet spinning and Direct-Ink-Writing (DIW); these structures with highly aligned nanofibrils (wide-angle X-ray scattering) simultaneously displayed extensibility (wet strain as high as 39 %), and tenacities (up to 2.3 cN/dtex). DIW of the respective gels led to meshes with up to 60 % wet stretchability. The IL regenerated structures were demonstrated for reliable performance in marine environments, with prospects of replacing plastic cords and other materials used to restore coral reefs on the coast of Mexico.<br/>Additionally, considering the unique ability of alkali dissolved cellulose to absorb CO₂ at room temperature in a non-catalytic, highly reactive media, here a mineralization process is proposed to produce artificial coral-like supports. The resulting Mineralized Cellulose Material (MCM) exhibits tunable flow properties and a wide range of mechanical properties. The synergistic combination of dissolved cellulose and in-situ mineralized CO₂ into calcium carbonate at different Cellulose: Carbonate ratios allows the production of heterogeneous fluid streams with shear-thinning behavior (viscosities from 10² to 10⁷ mPa.s; and storage modulus G' ranging from 10 to 10⁵ Pa). The CO₂ absorption capacity tracks inversely with cellulose concentration. Two types of MCMs are obtained, the first with low cellulose content, namely MCMl is a dry powder with applications as a flux material for ceramic glazes or cement with porous structures. In contrast, the material with an increased cellulose content, namely MCMh, is a moldable/printable paste that transforms into a tough (stone-like) material after drying. MCMh was tested as an artificial substitute for coral stones in the Gulf of Mexico. LCA results suggest that these technologies bring new opportunities to cellulose and construction industries by removing and utilizing CO₂ emissions for different materials, including the imperative coral reef restoration in the oceans.