Optimizing bacterial cellulose production towards materials for water remediation

Cellulose is a renewable alternative to mass consumption plastics, but its manufacture by the classical methods is not sustainable due to the use of large amounts of strong acids, bases and/or organic species (e.g. ionic liquids) in its production, generating many residues. Bacterial cellulose (BC) has a simpler processing because it is much more cleanly generated. In this work, BC aerogels and xerogels are compared in order to ascertain how the bacterial culture conditions (pH, carbon and nitrogen sources) and the raw hydrogels processing determine their thermal stability, crystallinity index, swelling ratio and flammability. The most notable results are the influence of the drying method on the swelling ratio and the carbon source on the thermal stability. Finally, a feasible application of BC aerogels is presented by treating contaminated water and by capturing water within a non-polar solvent, taking advantage of the dry BC sorption capacity.Financial support was obtained from the Spanish Ministry of Economy, Industry and Competitiveness (MINEICO), through project IJCI-2016-27789, the Spanish Research Agency (AEI) through GRAPEROS project (ref ENE2016-79282-C5-1-R1 and associated EU Regional Development Funds), and from Gobierno de Aragón (Grupo Reconocido DGA T03_17R, A02_17R and associated EU Regional Development Funds). Dr. J.M.G.-D. greatfully acknowledges MINEICO for his ‘Juan de la Cierva – Incorporación’ research contract.Peer reviewe

Facile synthesis of titania/hyperbranched polyglycidol nanohybrids with tunable morphologies: from solid spheres, capsules to tubes

Titania/Hyperbranched polyglycidol (HBP) nanohybrids with tunable morphologies have been synthesized via a sol-gel process at ambient temperature. One-shot addition of varied amounts of titanium precursor tetraisopropoxide (TTIP) yields spherical titania/HBP solid particles with tunable size, while a controlled addition of TTIP results in spherical titania/HBP capsules. The average outer and inner diameters of the resultant capsules are also controllable according to the amount of TTIP via an Oswald ripening process. In addition, the modality of additional water supplied in the reaction systems can tune the morphologies of the resulting titania/HBP particles from nanocapsules to nanotubes owing to the accelerated hydrolysis rate of TTIP. The tunability in morphologies of the titania/HBP nanostructures ranging from solid spheres, capsules to tubes could be attributed to the self-assembly of a large amount of titania/HBP aggregates in a rapid, controlled and anisotropic manner, respectively. Surprisingly, by means of HBP contained in the resulting titania/ HBP nanostructures, the gold nanoparticles are in situ generated and encapsulated into titania/HBP matrix in the absence of additional reducing agent. The as- prepared gold nanoparticles functionalized titania/HBP hybrids exhibit excellent catalytic function toward the reduction of 4-nitrophenol. This strategy demonstrates a typical example for functionalizing the titania/HBP hybrids targeted to specific applications