A sustainable bioprocess to produce bacterial cellulose (BC) using waste streams from wine distilleries and the biodiesel industry: evaluation of BC for adsorption of phenolic compounds, dyes and metals.

BACKGROUND: The main challenge for large-scale production of bacterial cellulose (BC) includes high production costs interlinked with raw materials, and low production rates. The valorization of renewable nutrient sources could improve the economic effectiveness of BC fermentation while their direct bioconversion into sustainable biopolymers addresses environmental pollution and/or resource depletion challenges. Herein a green bioprocess was developed to produce BC in high amounts with the rather unexplored bacterial strain Komagataeibacter rhaeticus, using waste streams such as wine distillery effluents (WDE) and biodiesel-derived glycerol. Also, BC was evaluated as a bio-adsorbent for phenolics, dyes and metals removal to enlarge its market diversification. RESULTS: BC production was significantly affected by the WDE mixing ratio (0-100%), glycerol concentration (20-45 g/L), type of glycerol and media-sterilization method. A maximum BC concentration of 9.0 g/L, with a productivity of 0.90 g/L/day and a water holding capacity of 60.1 g water/g dry BC, was achieved at 100% WDE and ≈30 g/L crude glycerol. BC samples showed typical cellulose vibration bands and average fiber diameters between 37.2 and 89.6 nm. The BC capacity to dephenolize WDE and adsorb phenolics during fermentation reached respectively, up to 50.7% and 26.96 mg gallic acid equivalents/g dry BC (in-situ process). The produced BC was also investigated for dye and metal removal. The highest removal of dye acid yellow 17 (54.3%) was recorded when 5% of BC was applied as the bio-adsorbent. Experiments performed in a multi-metal synthetic wastewater showed that BC could remove up to 96% of Zn and 97% of Cd. CONCLUSIONS: This work demonstrated a low-carbon approach to produce low-cost, green and biodegradable BC-based bio-adsorbents, without any chemical modification. Their potential in wastewater-treatment-applications was highlighted, promoting closed-loop systems within the circular economy era. This study may serve as an orientation for future research towards competitive or targeted adsorption technologies for wastewater treatment or resources recovery.

The Effect of Silica Particle Size on the Mechanical Enhancement of Polymer Nanocomposites.

In the present work, SiO2micro/nanocomposites based on poly-lactic acid (PLA) and an epoxy resin were prepared and experimentally studied. The silica particles were of varying sizes from the nano to micro scale at the same loading. The mechanical and thermomechanical performance, in terms of dynamic mechanical analysis, of the composites prepared was studied in combination with scanning electron microscopy (SEM). Finite element analysis (FEA) has been performed to analyze the Young's modulus of the composites. A comparison with the results of a well-known analytical model, taking into account the filler's size and the presence of interphase, was also performed. The general trend is that the reinforcement is higher for the nanosized particles, but it is important to conduct supplementary studies on the combined effect of the matrix type, the size of the nanoparticles, and the dispersion quality. A significant mechanical enhancement was obtained, particularly in the Resin/based nanocomposites.

Chemical characterisation of artists' spray-paints: A diagnostic tool for urban art conservation.

In this study the chemical characterisation of 24 commercial spray-paints in different colours as used in contemporary public murals, street art, and graffiti is presented. The analyses were focused on the identification of the binding media, pigments, and additives. In addition, four spray-paint samples were analysed in the form of bi-layered paint films to explore the possibility of determining the composition of multi-layered samples. The aim of the study was to provide a useful diagnostic tool for the conservation of spray-paints and the removal of overpaintings from both commissioned murals and any other form of cultural heritage. To achieve this goal, a multi-analytical approach was developed using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) for the identification of the main binder, pigments, and fillers/extenders, while Raman spectroscopy and Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDS) were used as complementary tools for the determination of organic and inorganic pigments, and fillers. Five kinds of binders were detected in this work: (1) acrylic resins combined with nitrocellulose, (2) acrylic resins modified with styrene and combined with nitrocellulose, (3) alkyd resins modified with styrene and combined with nitrocellulose, (4) combined acrylic and alkyd resins modified with styrene and blended with nitrocellulose, and (5) combined polystyrene and acrylic resins. Also, a wide variety of organic pigments and inorganic components were detected.

Development of a Multi-Enzymatic Approach for the Modification of Biopolymers with Ferulic Acid.

A series of polymers, including chitosan (CS), carboxymethylcellulose (CMC) and a chitosan-gelatin (CS-GEL) hybrid polymer, were functionalized with ferulic acid (FA) derived from the enzymatic treatment of arabinoxylan through the synergistic action of two enzymes, namely, xylanase and feruloyl esterase. Subsequently, the ferulic acid served as the substrate for laccase from Agaricus bisporus (AbL) in order to enzymatically functionalize the above-mentioned polymers. The successful grafting of the oxidized ferulic acid products onto the different polymers was confirmed through ultraviolet-visible (UV-Vis) spectroscopy, attenuated total reflectance (ATR) spectroscopy, scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) spectroscopy. Additionally, an enhancement of the antioxidant properties of the functionalized polymers was observed according to the DDPH and ABTS protocols. Finally, the modified polymers exhibited strong antimicrobial activity against bacterial populations of Escherichia coli BL21DE3 strain, suggesting their potential application in pharmaceutical, cosmeceutical and food industries.

Optical and structural properties of nanostructured CuIn0.7Ga0.3(Se(1-x)Te(x))2 chalcopyrite thin films--effect of stoichiometry and annealing.

The aim of this work was to study the dependence of the optical, structural and morphological properties of CuIn0.7Ga0.3(Se(1-x)Te(x))2 (briefly CIGSeTe) thin films for two different stoichiometries (for x = 0.2 and 0.8). The films have been deposited onto soda lime glass (SLG) substrates by the e-beam evaporation technique. The films showed high absorption and revealed optical band gaps ranging from 1.17 eV to 1.06 eV for x = 0 with highest annealing temperatute at 525 degrees C and 1.12 eV to 1.02 eV for x = 0.8 and with highest annealed temperature at 600 degrees C. These results were correlated with the microstructural analysis by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and X-ray diffractometry (XRD). The linear dependence of the lattice parameters as a function of Se and Te contents was examined. X-ray diffraction analyses showed that the films had the single phase chalcopyrite structure. The lattice parameters (a and c) varied linearly with the increase in Te content x from x = 0.2 to x = 0.8. The peak correspondng to the (1 1 2) plane orientation of the films increased with annealing process. Also, SEM images showed that both the grains size and the RMS (root mean square) values increased with annealing and higher Te amount that caused grains aggregation. The relative 600 degrees C elemental composition present in the deposited CIGS films have been measured by using energy dispersive X-ray analysis (EDX).