ABSTRACT
Currently, there is an increased demand for biodegradable materials in society due to growing environmental problems. Special attention is paid to bacterial cellulose, which, due to its unique properties, has great prospects for obtaining functional materials for a wide range of applications, including adsorbents. In this regard, the aim of this study was to obtain a biocomposite material with adsorption properties in relation to fluoride ions based on bacterial cellulose using a highly productive strain of Komagataeibacter sucrofermentans H-110 on molasses medium. Films of bacterial cellulose were obtained. Their structure and properties were investigated by FTIR spectroscopy, NMR, atomic force microscopy, scanning electron microscopy, and X-ray structural analysis. The results show that the fiber thickness of the bacterial cellulose formed by the K. sucrofermentans H-110 strain on molasses medium was 60-90 nm. The degree of crystallinity of bacterial cellulose formed on the medium was higher than on standard Hestrin and Schramm medium and amounted to 83.02%. A new biocomposite material was obtained based on bacterial cellulose chemically immobilized on its surface using atomic-layer deposition of nanosized aluminum oxide films. The composite material has high sorption ability to remove fluoride ions from an aqueous medium. The maximum adsorption capacity of the composite is 80.1 mg/g (F/composite). The obtained composite material has the highest adsorption capacity of fluoride from water in comparison with other sorbents. The results prove the potential of bacterial cellulose-based biocomposites as highly effective sorbents for fluoride.
ABSTRACT
Aerogels have gained significant interest in recent decades because of their unique properties such as high porosity, low density, high surface area, and excellent heat and noise insulation. However, their high cost and low mechanical strength limit their practical application. We developed appropriate conditions to produce aerogels with controlled density, high mechanical strength, and thermal characteristics from bacterial cellulose (BC) synthesized by the strain Komagataeibacter sucrofermentans H-110. Aerogels produced using TEMPO oxidized BC (OBC) exhibited high mechanical strength and lower shrinkage than those from native bacterial cellulose (NBC). Compared to the NBC, the use of TEMPO-oxidized BC with oxidation degrees (OD) of 1.44 and 3.04% led to the reduction of shrinkage of the aerogels from 41.02 to 17.08%. The strength of the aerogel produced from the TEMPO-oxidized BC with an oxidation degree of 1.44% was twice that of the aerogel produced from NBC. The addition of Mg2+ at concentrations of 20 and 40 mM during the preparation of the aerogels increased the strength of the aerogels by 4.9 times. The combined use of TEMPO-oxidized BC and Mg2+ allowed pore size reduction from 1,375 to 197.4 µm on the outer part of the aerogels, thereby decreasing the thermal conductivity coefficient from 0.036 to 0.0176 W/(mâ¢K). Furthermore, novel biocomposites prepared from the aerogels based on NBC and OBC and sodium fusidate, which have high antibiotic activity against Staphylococcus aureus, were obtained. Owing to their antibacterial properties, these aerogels can be used as functional biomaterials in a wide range of applications such as in tissue engineering and fabrication of wound dressing materials.
