Nanocellulose for Paper and Textile Coating: The Importance of Surface Chemistry

Nanocellulose has received enormous scientific interest for its abundance, easy manufacturing, biodegradability, and low cost. Cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs) are ideal candidates to replace plastic coating in the textile and paper industry. Thanks to their capacity to form an interconnected network kept together by hydrogen bonds, nanocelluloses perform an unprecedented strengthening action towards cellulose- and other fiber-based materials. Furthermore, nanocellulose use implies greener application procedures, such as deposition from water. The surface chemistry of nanocellulose plays a pivotal role in influencing the performance of the coating: tailored surface functionalization can introduce several properties, such as gas or grease barrier, hydrophobicity, antibacterial and anti-UV behavior. This review summarizes recent achievements in the use of nanocellulose for paper and textile coating, evidencing critical aspects of coating performances related to deposition technique, nanocellulose morphology, and surface functionalization. Furthermore, beyond focusing on the aspects strictly related to large-scale coating applications for paper and textile industries, this review includes recent achievements in the use of nanocellulose coating for the safeguarding of Cultural Heritage, an extremely noble and interesting emerging application of nanocellulose, focusing on consolidation of historical paper and archaeological textile. Finally, nanocellulose use in electronic devices as an electrode modifier is highlighted

Kumagawa and Soxhlet solvent fractionation of lignin: impact on the chemical structure

We investigated the effects of solvent fractionation on the chemical structures of two commercial technical lignins. We compared the effect of Soxhlet and Kumagawa extraction. The aim of this work was to compare the impact of the methods and of the solvents on lignin characteristics. Our investigation confirmed the potentialities of fractionation techniques in refining lignin properties and narrowing the molecular weight distribution. Furthermore, our study revealed that the Kumagawa process enhances the capacity of oxygenated solvents (ethanol and tetrahydrofuran) to extract lignin that contains oxidized groups and is characterized by higher average molecular weights. Furthermore, the use of tetrahydrofuran after ethanol treatment enabled the isolation of lignin with a higher ratio between carbonyl and other oxidized groups. This result was confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), 13C NMR and two-dimensional (2D) NMR spectroscopies, gel permeation chromatography (GPC), and analytical pyrolysis-gas chromatography–mass spectrometry (Py-GC–MS) analysis. Ultraviolet–visible (UV–vis) spectra evidenced the enrichment in the most conjugated species observed in the extracted fractions. Elemental analyses pointed at the cleavage of C-heteroatom bonds enhanced by the Kumagawa extraction

Plan de manejo ambiental para mitigar los impactos generados por explotacion minera en el municipio de Nechí en el Bajo Cauca - Región de La Mojana

Trabajo de InvestigaciónEsta investigación propone un Plan de Manejo Ambiental enfocado a la explotación minera, especialmente dirigido al municipio de Nechí – Antioquia (Colombia), lo anterior debido a los problemas y fuertes impactos ambientales y sociales, que se han visto con el pasar del tiempo debido al mal manejo de los procesos necesarios para tal fin.INTRODUCCIÓN 1. ANTECEDENTES 2. PLANTEAMIENTO Y FORMULACION DEL PROBLEMA 3. OBJETIVOS 4. MARCO DE REFERECIA TEORICO 5. MARCO DE REFERECIA CONCEPTUAL 6. CARACTERIZACION DEL TERRITORIO 7. ESTUDIO DE IMPACTO AMBIENTAL E IDENTIFICACION DE PROBLEMAS GENERADOS POR LA EXPLOTACION MINERA 8. DISEÑO PLAN DE MANEJO AMBIENTAL 9. CONCLUSIONES Y RECOMENDACIONES 10. BIBLIOGRAFIAPregradoIngeniero Civi

Isolation of Pure Lignin and Highly Digestible Cellulose from Defatted and Steam-Exploded Cynara cardunculus

In this work, a three-step approach to isolate the main components of lignocellulosic cardoon, lignin and cellulose, was investigated. The raw defatted biomass, Cynara cardunculus, after steam explosion was subjected to a mild organosolv treatment to extract soluble lignin (L1). Then, enzymatic hydrolysis was performed to achieve decomposition of the saccharidic portion into monosaccharides and isolate residual lignin (L2). The fractionation conditions were optimized to obtain a lignin as less degraded as possible and to maximize the yield of enzymatic hydrolysis. Furthermore, the effect of the use of aqueous ammonia as an extraction catalyst on both fractions was studied. Each fraction was characterized by advanced techniques, such as elemental analysis and 31P nuclear magnetic resonance (NMR), 13C–1H two-dimensional (2D)-NMR, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and UV–vis spectroscopies for lignin and X-ray diffraction (XRD), Klason compositional analysis, elemental analysis, and ATR-FTIR spectroscopy for cellulose-rich fractions. The impact of the cellulose-rich fraction composition and crystallinity was also correlated to the efficiency of the hydrolysis step, performed using the enzymatic complex Cellic CTec3

Tailoring the Chemical Structure of Cellulose Nanocrystals by Amine Functionalization

The surface functionalization of cellulose nanocrystals is presently considered a useful and straightforward tool for accessing very reliable biocompatible and biodegradable nanostructures with tailored physical and chemical properties. However, to date the fine characterization of the chemical appendages introduced onto cellulose nanocrystals remains a challenge, due to the low sensitivity displayed by the most common techniques towards surface functionalization. In this paper, we demonstrate the easy functionalization of cellulose nanocrystals with aliphatic and aromatic amines, demonstrating the tunability of their properties in dependence on the selected functionality. Then, we apply to colloidal suspensions of modified nanocrystals 1H-NMR analysis to elucidate their surface structure. To the best of our knowledge, this is the first report where such investigation was performed on cellulose nanocrystals presenting both surface and reducing end modification. These results involve interesting implications for the fields of Cultural Heritage and of Materials Chemistry

Nanocellulose/Fullerene Hybrid Films Assembled at the Air/Water Interface as Promising Functional Materials for Photo-Electrocatalysis

Cellulose nanomaterials have been widely investigated in the last decade, unveiling attractive properties for emerging applications. The ability of sulfated cellulose nanocrystals (CNCs) to guide the supramolecular organization of amphiphilic fullerene derivatives at the air/water interface has been recently highlighted. Here, we further investigated the assembly of Langmuir hybrid films that are based on the electrostatic interaction between cationic fulleropyrrolidines deposited at the air/water interface and anionic CNCs dispersed in the subphase, assessing the influence of additional negatively charged species that are dissolved in the water phase. By means of isotherm acquisition and spectroscopic measurements, we demonstrated that a tetra-sulfonated porphyrin, which was introduced in the subphase as anionic competitor, strongly inhibited the binding of CNCs to the floating fullerene layer. Nevertheless, despite the strong inhibition by anionic molecules, the mutual interaction between fulleropyrrolidines at the interface and the CNCs led to the assembly of robust hybrid films, which could be efficiently transferred onto solid substrates. Interestingly, ITO-electrodes that were modified with five-layer hybrid films exhibited enhanced electrical capacitance and produced anodic photocurrents at 0.4 V vs Ag/AgCl, whose intensity (230 nA/cm2) proved to be four times higher than the one that was observed with the sole fullerene derivative (60 nA/cm2)

Kraft lignin: from pulping waste to bio-based dielectric polymer for organic field-effect transistors

Lignin is an abundant biopolymer deriving from industrial pulping processes of lignocellulosic biomass. Despite the huge amount of yearly produced lignin waste, it finds scarce application as a fine material and is usually destined to be combusted in thermochemical plants to feed, with low efficiency, other industrial processes. So far, the use of lignin in materials science is limited by the scarce knowledge of its molecular structure and properties, depending also on its isolation method. However, lignin represents an intriguing feedstock of organic material. Here, the structural and chemical-physical characteristics of two kraft lignins, L1 and L2, are analyzed. First, several molecular characterization techniques, such as attenuated total reflectance - Fourier transform infrared spectroscopy, elemental analyses, gel permeation chromatography, evolved gas analysis-mass spectrometry, UV–vis, 31P- and 13C- nuclear magnetic resonance spectroscopies are applied to get insights into their different structures and their degree of molecular degradation. Then, their efficient application as gate dielectric materials is demonstrated for organic field-effect transistors, finding the increased capacity of L1 with respect to L2 in triggering functional and efficient devices with both p-type and n-type organic semiconductor molecules

Surface Immobilized His-tagged Azurin as a Model Interface for the Investigation of Vectorial Electron Transfer in Biological Systems

A model system for the electrochemical investigation of vectorial electron transfer in biological systems was designed, assembled and characterized. Gold electrodes, functionalized with a -OCH3 terminated, aromatic self-assembled monolayer, were used as a substrate for the adsorption of variants of copper- containing, redox metalloprotein azurin. The engineered azurin bears a polyhistidine tag at its C-terminus. Thanks to the presence of the solvent exposed tag, which chelates Cu2+ ions in solution, we introduced an exogenous redox centre. The different reduction potentials of the two redox centres and their positioning with respect to the surface are such that electron transfer from the exogenous copper centre and the electrode is mediated by the native azurin active site, closely paralleling electron transfer processes in naturally occurring multicentre metalloprotein

Pinaceae Pine Resins (Black Pine, Shore Pine, Rosin, and Baltic Amber) as Natural Dielectrics for Low Operating Voltage, Hysteresis‐Free, Organic Field Effect Transistors

AbstractFour pinaceae pine resins analyzed in this study: black pine, shore pine, Baltic amber, and rosin demonstrate excellent dielectric properties, outstanding film forming, and ease of processability from ethyl alcohol solutions. Their trap‐free nature allows fabrication of virtually hysteresis‐free organic field effect transistors operating in a low voltage window with excellent stability under bias stress. Such green constituents represent an excellent choice of materials for applications targeting biocompatibility and biodegradability of electronics and sensors, within the overall effort of sustainable electronics development and environmental friendliness

Recent Advances on Renewable and Biodegradable Cellulose Nanopaper Substrates for Transparent Light-Harvesting Devices: Interaction with Humid Environment

Cellulose nanopaper (CNP) has attracted much interest during the last decade as a new fascinating renewable and biodegradable substrate for printed electronics and solar cells. Its outstanding optical and mechanical properties make CNP the ideal substrate for the preparation of photovoltaic devices, since its high transparency and haze favour the absorption of light from the active layer of the solar cell. However, some advances need to be done in the direction of increasing CNP stability in humid environment without compromising its remarkable advantages. This review critically points at these aspects, presenting an overview of state-of-art solutions to enhance nanopaper stability in a humid environment