Eduardo Robles

Self-bonded composite films based on cellulose nanofibers and chitin nanocrystals as antifungal materials.

Cellulose nanofibers and chitin nanocrystals, two main components of agricultural and aquacultural by-products, were obtained from blue agave and yellow squat lobster industrial residues. Cellulose nanofibers were obtained using high pressure homogenization, while chitin nanocrystals were obtained by hydrolysis in acid medium. Cellulose nanofibers and chitin nanocrystals were characterized by X-ray diffraction, Atomic Force Microscopy and Infrared spectroscopy. Self-bonded composite films with different composition were fabricated by hot pressing and their properties were evaluated. Antifungal activity of chitin nanocrystals was studied using a Cellometer(®) cell count device, mechanical properties at tension were measured with a universal testing machine, water vapor permeability was evaluated with a thermohygrometer and surface tension with sessile drop contact angle method. The addition of chitin nanocrystals reduced slightly the mechanical properties of the composite. Presence of chitin nanocrystals influenced the growth of Aspergillus sp fungus in the surface of the composites as expected.

Lignin-ester derivatives as novel thermoplastic materials

Spruce and eucalyptus lignins isolated by an organosolv process and lauroyl chloride were used as raw material for the synthesis of lignin-ester derivatives. The obtained products presented new and interesting properties suitable for use as thermoplastic materials. Esterification of the lignins was confirmed by FTIR, GPC, DSC and contact angle measurements. The modification of lignin –OH groups increased the molecular weight properties, changed its thermal behavior (reducing greatly Tg), and improved the hydrophobicity of the material. For composite elaboration, commercial cellulose acetate was used as reinforcement in different percentages (5%, 10%, 25% and 50%) to manufacture composites by press moulding. Thermal and mechanical tests as well as wetting behavior of the composites surface against water analysis were carried out. Surface morphology was analyzed by SEM. The mechanical test revealed tensile strength and Young modulus values of 130–900 kPa and 2–50 MPa respectively, with high elongation at break (5–130%) for eucalyptus lignin composites, while spruce lignin composites showed more a rigid (40–60 MPa) and tough (300–1400 kPa) behavior, but with the ability to deform only up to 6%.

Cellulose Nanocrystal Membranes as Excipients for Drug Delivery Systems

In this work, cellulose nanocrystals (CNCs) were obtained from flax fibers by an acid hydrolysis assisted by sonochemistry in order to reduce reaction times. The cavitation inducted during hydrolysis resulted in CNC with uniform shapes, and thus further pretreatments into the cellulose are not required. The obtained CNC exhibited a homogeneous morphology and high crystallinity, as well as typical values for surface charge. Additionally, CNC membranes were developed from CNC solution to evaluation as a drug delivery system by the incorporation of a model drug. The drug delivery studies were carried out using chlorhexidine (CHX) as a drug and the antimicrobial efficiency of the CNC membrane loaded with CHX was examined against Gram-positive bacteria Staphylococcus aureus (S. Aureus). The release of CHX from the CNC membranes is determined by UV-Vis. The obtaining methodology of the membranes proved to be simple, and these early studies showed a potential use in antibiotic drug delivery systems due to the release kinetics and the satisfactory antimicrobial activity.

Production of cellulose nanoparticles from blue agave waste treated with environmentally friendly processes

Tequila elaboration leaves two main byproducts that are undervalued (bagasse and leaves). Organosolv pulping and Total Chlorine Free bleaching were integrated to obtain cellulose fibers from agricultural waste which consisted of blue agave bagasse and leaf fibers; together they represent a green process which valorizes biomass waste. The obtained celluloses were characterized by FT-IR, colorimetry, and SEM and their extraction yields were evaluated. These celluloses were used to produce cellulose nanocrystals and cellulose nanofibers. First, an acid hydrolysis was performed in a sonication bath to induce cavitation during the reaction to produce cellulose nanocrystals. Then a high-pressure homogenization was selected to produce cellulose nanofibers. These nanocelluloses were characterized by powder XRD, Nanosizer, zeta potential, NMR, and electronic microscopy. Results showed that cellulose from organosolv pulps bleached with TCF bleaching is suitable for nanocellulose production. Moreover, the use of a new step to separate cellulose nanocrystals resulted in yields almost doubling traditional yields, while the rest of the properties remained within the expected.

The Biorefinery Concept for the Industrial Valorization of Grape Processing By-Products

The winemaking industry generates high amounts of underutilized by-products worldwide, which represent a significant economic potential and a great challenge. The main by-product of winemaking is grape marc, consisting of the stalks, skin, pulp (pomace), and seeds that remain after pressing the grapes. Other grape processing by-products include vine shoots (vine prunings), winery sludge (wine lees), effluents, and filtration residues. These residues have an interesting composition to be used as sources of high added-value products generated using environment friendly technologies within the biorefinery frame. Taking into account the problems induced by the disposal of these leftovers in the environment, this chapter describes the sustainable treatment of grape processing by-products within the integral biorefinery approach that promises potential economic benefits from the underutilized sources.

Dataset on cellulose nanoparticles from blue agave bagasse and blue agave leaves

These data and analyses support the research article “Production of cellulose nanoparticles from blue agave waste treated with environmentally friendly processes” Robles et al. [1]. The data and analyses presented here include fitted curves for selected carbons of the 13C CP-MAS NMR analysis; SEM images of the raw and bleached fibers, graphics with chemical composition and visual images of the fibers throughout the process.

Key issues in reinforcement involving nanocellulose

Abstract Nanocellulose, either as cellulose nanocrystals or cellulose nanofibrils, is being used as reinforcement for different types of composites because of its high specific area, low density, biodegradability, and natural origin. But there are still some key aspects that represent an important challenge in the elaboration of composites or other products involving nanocellulose. These are related to the dispersion within the matrix and surface characteristics that can reduce the mechanical properties with the generation of defects in the structure, or the orientation of the nanocellulose elements, as orientation plays an important role in the composite reaction to multidirectional forces. This chapter will present different challenges and summarize composite mechanical theories that the use of nanocellulose particles has represented in the elaboration of composites as well as the different ways in which such challenges have been faced.