Roughness measurement of paper using speckle

We present a method of measure of the roughness of the paper based on the analysis of a speckle pattern on the surface. Images of speckle over the surface of paper are captured by means of a simple configuration using a laser, beam expander, and a camera charge-coupled device (CCD). Then we use the normalized covariance function of the fields, leaving the surface to find the roughness. We compare the results obtained with the results obtained with a confocal microscope and the Bendtsen method that is a standard of the paper industry. This method can be considered as a noncontact surface profiling method that can be used online.We present a method of measure of the roughness of the paper based on the analysis of a speckle pattern on the surface. Images of speckle over the surface of paper are captured by means of a simple configuration using a laser, beam expander, and a camera charge-coupled device (CCD). Then we use the normalized covariance function of the fields, leaving the surface to find the roughness. We compare the results obtained with the results obtained with a confocal microscope and the Bendtsen method that is a standard of the paper industry. This method can be considered as a noncontact surface profiling method that can be used online

Paper engineering technology applied on the preservation and conservation of cultural heritage on paper

Programa de doctorat: Doctorat en Enginyeria Tèxtil i PapereraThe different researching lines in the field of Preservation and Conservation of Cultural Heritage on Paper tend to evolve and join other scientific fields in order to comprehend and embrace all the problematics caused by the aging of paper and its nature. Almost every decision made to stabilize the biochemical deterioration of cellulose is strongly conditioned by factors related to the papermaking process of that specific paper. These factors may include the fiber’s origin, the beating, the cooking and bleaching treatments, the technology used in the papermaking, the additives included in the fiber’s solution and posterior surface treatments such as the sizing or the coating among others. The field of Paper Engineering is focused on the development of papermaking technologies through new products and treatments. Those, in addition to the many testing methods used in this field –measurement of paper physical and optical properties, such as tensile strength or brightness ISO-, may be extrapolated to the field of Paper Conservation, adding new criteria and information about how any treatment affects the treated heritage, opening a window for new products and treatments, more bio-compatible with the cellulose nature, allowing to reduce the using of strong chemics and other procedures that are harmful for the environment

Machine-readable pattern for colorimetric sensor interrogation

We present a systematic methodology to generate machine-readable patterns embodying all the elements needed to carry out colorimetric measurements with conventional color cameras in an automated, robust and accurate manner. Our approach relies on the well-stablished machine-readable features of the QR Codes, to detect the pattern, identify the color reference elements and the colorimetric spots, to calibrate the color of the image and to conclude a quantitative measurement. We illustrate our approach with a NH3 colorimetric indicator operating at distinct color temperature ambient lights, demonstrating that with our design, consistent measurements can be achieved, with independence on the illumination conditions

Surface functionalization of cellulosic substrates by using chemical and biotechnological methods

This thesis deals with the surface modification of cellulosic substrates by use of chemo-enzymatic methods. Functionalizing cellulose is intended to adjust its properties for various purposes, but particularly for obtaining a chemical feedstock for the production of cellulose derivatives with a variety of uses. At present, cellulosic substrates are chemically or enzymatically modified by treating fibres in aqueous suspensions prior to formation substrates. In this doctoral work, treatments were applied to previously formed cellulosic substrates (FCS), providing advantages in terms of sheet formation, chemical consumption and manufacturing speed. A non-enzymatic and an enzymatic approach to substrate functionalization were examined, with emphasis on the latter. This work is part of the research conducted by the CELBIOTECH Group (UPC-BarcelonaTech) within the framework of Spain's MICINN Projects FUNCICEL (CTQ2009-12904), BIOSURFACEL (CTQ2012-34109) and BIOFIBRECELL (CTQ2010-20238-CO3-01), and the BIORENEW integrated project of the Sixth Framework Program (NMP2-CT-2006-026456). β--cyclodextrins (β--CD) were used to facilitate the chemical modification of three different commercial FCS. Grafting of the substrates was assessed by scanning electron microscopy and FTIR analysis. Drug delivery kinetics were analyzed by UV spectroscopy after loading of the β--CD-grafted substrates with chlorhexidine digluconate (digCHX). Several grafted substrates were found to absorb substantial amounts of active molecules and to release them over a long period (about 20 days). The use of enzyme systems for surface treatments of FCS is still in its infancy. This doctoral work was intended to fill the gap as far as possible. In preliminary tests, the surface hydrophobization was accomplished onto commercial FCS by using laccase in combination with hydrophobic compounds. The efficiency of the method was increased by using lignosulfonates, which improved the surface distribution of hydrophobic compounds, increased hydrophobicity and helped preserve enzyme activity. The influence of processing conditions including LG dose and treatment time was examined, with a view to their optimization for further increased hydrophobicity. Surface enzyme treatments evolved into the preparation of a functionalization solution (FS), consisting of an enzymatic product that was subsequently applied to the surface of FCS. This method was also effective and provided major advantages for industrial implementation; in fact, it is the subject of an international patent application. Surface application of the functionalization solution to FCS was found to confer them hydrophobic and antioxidant properties by effect of physico-chemical interactions between FS and the substrate. Cellulose model surfaces were used to assess FS adsorption, and the WDT, WCA, SEM, AFM and SFE techniques to characterize the treated FCS. Efficient fibre bonding and chemical functionalization were confirmed by thorough washing and Soxhlet extraction of the substrates. As shown here for the first time, surface enzyme treatments have the potential to confer advanced properties to FCS. The performance of the proposed cellulose functionalization technique was assessed by using laccases from various microorganisms. A better understanding of the reaction mechanisms and physico-chemical interactions behind the laccase treatments, and also of FS-substrate interactions, was acquired by using various analytical techniques including DLS, QCM, FTIR, UV-VIS spectroscopy, Z-potential, Turbiscan® and cyclic voltammetry. The chemical structure of the resulting enzyme-oxidized molecules, the sequence for the oxidation reaction, and the potential grafting mechanisms of enzyme-modified compounds to cellulose, were proposed. The effects of the alkyl chain length of the gallates studied and curing treatments used were analysed in terms of the development of hydrophobic and antioxidant properties.La present tesi tracta sobre la modificació superficial de substrats cel·lulòsics utilitzant mètodes químics i enzimàtics. La funcionalització de la cel·lulosa consisteix en ajustar-ne les seves propietats, per a poder-la utilitzar en gran varietat d'aplicacions. Habitualment aquesta modificació s'aconsegueix tractant les fibres en suspensió aquosa i abans de la formació del substrat. No obstant, en la present tesi els tractaments s'apliquen utilitzant substrats cel·lulòsics ja formats (FCS), obtenint una sèrie d'avantatges en termes de formació, consum de químics, i velocitat de fabricació. S’han estudiat dos enfocaments diferents per a la funcionalització: tècniques no-enzimàtiques i enzimàtiques. Els esforços s’han centrat en l'enfoc enzimàtic. Aquest treball es va dur a terme en el grup de recerca CELBIOTECH (UPCBarcelonTech), en el marc dels projectes FUNCICEL (CTQ2009-12904), BIOSURFACEL (CTQ2012-34109) , BIOFIBRECELL (CTQ2010-20238-CO3-01), del MICINN Espanyol i el Projecte integrat BIORENEW (NMP2-CT-2006-026456) del sisè Programa Marc. Pel que fa a la funcionalització no-enzimàtica, s’han utilitzat β-ciclodextrines (β-CD) per a la modificació superficial de tres FCS comercials. L'empelt s’ha avaluat mitjançant microscòpia electrònica de rastreig i anàlisi FTIR. Els substrats empeltats amb β-CDs s’han carregat amb digluconat de clorhexidina (digCHX), i s’ha analitzat l’alliberament d’aquest principi actiu utilitzant espectroscòpia UV. Diversos substrats han estat capaços de retenir quantitats significatives de digCHX, i de mantenir-ne l’alliberament durant períodes de temps de fins a 20 dies. La funcionalització enzimàtica per al desenvolupament de derivats de la cel·lulosa ha guanyat interès en la comunitat científica i industrial darrerament. No obstant, l'ús de sistemes enzimàtics superficials encara es troba en una fase molt prematura; la present tesi fa èmfasi en aquest aspecte. En un primer estudi s’analitza la hidrofobització superficial de FCS comercials, mitjançant una lacasa en combinació amb compostos hidròfobs. L'eficiència s’ha vist augmentada amb l'ús de lignosulfonats (SL), els quals milloren la distribució superficial, augmenten els nivells d’hidrofobicitat, i ajuden a preservar l'activitat enzimàtica. La dosi de LG i el temps de tractament s’han optimitzat resultant en una major hidrofobicitat. Seguidament, els tractaments han evolucionat cap a un nou mètode basat en l’obtenció d'una solució funcionalitzadora (FS), consistent en un producte derivat d’una reacció enzimàtica, el qual és aplicat posteriorment a la superfície dels FCS. Aquest mètode també s’ha mostrat efectiu, i proporciona avantatges importants respecte a la possible aplicació industrial; de fet, el nou mètode ha permès realitzar una sol·licitud internacional de patent. L’aplicació de la FS a la superfície de FCS els confereix propietats hidrofòbica i antioxidant gràcies a les interaccions fisicoquímiques que es produeixen. S’han utilitzat superfícies model de cel·lulosa per tal d’avaluar l'adsorció de la FS, i s’han emprat les tècniques de WDT, WCA, SEM, AFM i SFE per caracteritzar-les. La força de l’enllaç s’avalua mitjançant rentats agressius i extraccions Soxhlet. Es demostra per primer cop el potencial dels tractaments enzimàtics superficials per a conferir propietats avançades als substrats cel·lulòsics. La tècnica també s’ha assajat emprant diverses lacases. S’han utilitzat diverses tècniques d’anàlisi per estudiar els mecanismes de reacció, i les interaccions FS-substrat. Les tècniques han estat: DLS, QCM, FTIR, espectroscopia UVVIS, potencial-Z, Turbiscan® i Voltametria Cíclica. S’ha proposat l’estructura química de les molècules resultants de l’oxidació del LG, els possibles mecanismes d'oxidació, i possibles mecanismes d'empelt entre els compostos modificats i la cel·lulosa. També s’ha analitzat l'efecte de la longitud de la cadena alquílica i dels tractaments tèrmics en les propietats antioxidant i hidrofòbica

Evaluating the potential of ozone in creating functional groups on cellulose

Several eucalyptus pulps (85% of cellulose) with different lignin and HexA content (unbleached, TCF and ECF) as well as cotton linters (97% of cellulose) were treated with ozone (at different pH and ozone doses) in order to modify its fibre-components. Special interest was given in the introduction of functional groups in carbohydrates. The presence of these groups was mainly identified by the chain scissions due to carbonyl groups (CSC=O) produced in cellulose during viscosity measurement. At a dose of 0.5% odp of ozone, the greatest amount of CSC=O (0.5) was created at acidic pH and with the ECF pulp, followed by the TCF (0.3) and by the unbleached (0.2). The same CSC=O (0.2) was obtained in cotton pulp. In this pulp, the ozone concentration had to be increased for the treatment to be effective. A further increase in the accessibility in both pulps was achieved by applying a washing stage between two ozone stages at 0.5% (0.5¿+¿0.5). With this treatment, the CSC=O was increased to 5.3 in the ECF, to 0.8 in the TCF and only to 0.3 in cotton. Brightness reversion and the amount of DNPH consumed were also used to verify the presence of functional groups. At 0.5¿+¿0.5, brightness reversion was increased from 16 to 55% in ECF, from 27 to 46% in TCF and from 7 to 31% in cotton. Therefore, it is shown that functional groups can be introduced by ozone in carbohydrates, but this effect strongly depends on the lignin, HexA and hemicellulose contentThis publication is part of the PID2020-114070RB-I00 (CELLECOPROD) project, funded by MCIN/AEI/10.13039/501100011033. Authors are grateful to Torraspapel S.A. (Zaragoza, Spain), ENCE (Pontevedra, Spain) and CELESA (Tortosa, Spain) for supplying the pulp used. Special thanks are also due to the Serra Hunter Fellow to Oriol CusolaPostprint (published version

Lignin particles for multifunctional membranes, antioxidative microfiltration, patterning and 3D structuring

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Materials & Interfaces, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsami.9b16931We introduce a new type of particle-based membrane based on the combination of lignin particles (LPs) and cellulose nanofibrils (CNF), the latter of which are introduced in small volume fractions to act as networking and adhesive agents. The synergies that are inherent to lignin and cellulose in plants are re-engineered to render materials with low surface energy (contact angle measurements) and can be rendered water-resistant with the aid of wet-strength agents (WSAs). Importantly, they are most suitable for antioxidative separation (ABTS•+ radical inhibition): membranes with uniform porous structures (air permeability and capillary flow porosimetry) allow effluent oxidation at 95 mL/cm2, demonstrating, for the first time, the use of unmodified lignin particles in flexible membranes for active microfiltration. Moreover, the membranes are found to be nonfouling (protein adhesion and activity rate). The inherent properties of lignin, including UV radiation blocking capacity (UV transmittance analysis) and reduced surface energy, are further exploited in the development of tailorable and self-standing architectures that are almost entirely comprised of nonbonding LP (solids content as high as 92 w/w%). Despite such composition, the materials develop high toughness (oscillatory dynamic mechanical analysis), owing to the addition of minor amounts of CNF. Multifunctional materials based on thin films (casting), 3D structures (molding), and patterned geometries (extrusion deposition) are developed as a demonstration of the potential use of lignin particles as precursors of new material generation. Remarkably, our observations hold for spherical LPs since a much poorer performance was observed after using amorphous powder, indicating the role of size and shape in related applicationsPostprint (author's final draft

Natural additives to enhance the barrier properties of nanocellulose films

Finding alternatives to fossil-based materials is one of the most important challenges of our time. Since cellulose is the most abundant natural polymer on the planet, its use to solve this challenge would be ideal. In the present work, cellulose nanocrystals (CNC) were mixed with different plasticizers to obtain films with improved properties. To this aim, a first study was conducted in order to find the optimal amounts of plasticizer which maximize the compatibility with nanocellulose. The studied additives were Sorbitol (Sor), Glycerol (Gly), Maltitol (Mal), Xylitol (Xyl), Mannitol (Man), Gellan gum (Gg), and Ethylene glycol (Eg). The addition of these plasticizers to the CNC matrix was expected to improve the film flexibility and workability, which is one of the major limitations of this polymer. The selected plasticizers show similar structure to nanocellulose, with free hydroxyl groups which allow compatibility with nanocellulose, resulting in homogeneous films. The films with different amounts of additives were characterized in terms of barrier properties, crystallinity, SFE (surface free energy), and biodegradability. The barrier properties of the films were analyzed in terms of air, oil, water, water vapor and oxygen permeabilities. Results show that all additives decreased air and water permeance, to a greater or lesser extent. CNC films with Mal, Sor, and Xyl had a better oxygen barrier than the control, showing a total oxygen resistance at RH below 60%. About WVTR at moderate (50%) and drastic (90%) humidity, Mal and Gg showed values below the control. Films containing Mal provided the best barrier properties to oxygen and water vapor transmission. The interaction of the films with other compounds (liquids or adhesives) was observed through SFE. In relation to biodegradability, all the additives increased the biodegradability of CNC-based films when subjected to a biodegradability test under controlled composting conditions. These biodegradability results are relevant in terms of the environmental impact of the films, especially if the films are intended to provide a sustainable alternative to traditional food packaging materialsPostprint (published version

Composites of cellulose nanocrystals in combination with either cellulose nanofibril or carboxymethylcellulose as functional packaging films

Cellulose nanocrystals (CNC) were mixed with either cellulose nanofibril (CNF) or carboxymethylcellulose (CMC) in variable proportions (0/100, 20/80, 40/60, 50/50, 60/40, 80/20 and 100/0) to obtain cast films with acceptable barrier and mechanical properties as replacements for food packaging plastics. Both CNF and CMC improved tensile strength, elongation, UV opacity, air resistance, hydrophobicity (WCA-water contact angle), water vapor transmission rate (WVTR) and oxygen impermeability in pure CNC. WVTR and oxygen permeability were strongly dependent on relative humidity (RH). Interestingly, the greatest effect on WVTR was observed at RH¿=¿90% in films containing CMC in proportions above 60%. CMC- and CNF-containing films had oxygen impermeability up to an RH level of 80% and 60%, respectively. The previous effects were confirmed by food packaging simulation tests, where CMC-containing films proved the best performers. The composite films studied were biodegradable—which constitutes a major environmental related advantage—to an extent proportional to their content in CMC or CNFThis publication is part of the PID2020-114070RB-I00 (CELLECO- PROD) project, funded by MCIN/AEI/10.13039/501100011033. The authors would also like to thank the consolidated research group AGAUR 2017 SGR 30 with Universitat de Barcelona (UB) and to the Serra Húnter Fellowship awarded to O. Cusola. With the support from the Secretariat for Universities and Research of the Ministry of Business and Knowledge of the Government of Catalonia and the European Social FundPostprint (published version

Improving filmogenic and barrier properties of nanocellulose films by addition of biodegradable plasticizers

Cellulose nanocrystals (CNCs) were mixed with various additives to obtain films with good barrier and mechanical properties as replacements for petroleum-based plastics. The influence of different doses of additives including sorbitol (Sor), glycerol (Gly), maltitol (Mal), xylitol (Xyl), mannitol (Man), gellan gum (Gg), and ethylene glycol (Eg) on the resulting films was examined. Both the type of additive and its amount were found to affect film morphology, barrier, optical and mechanical properties. Most of the additives showed good results at low doses. All additives, except Eg and Man, improved film elongation; also, they increased tensile strength and decreased air and water permeance. The films containing Sor, Xyl, and Mal exhibited the highest barrier properties, providing films with totally resistance to oxygen under 60% of relative humidity conditions. Interestingly, those films containing additives were more easily biodegraded than the control filmPostprint (author's final draft

A straightforward bioprocess for a cleaner paper decolorization

A new biotechnological sequence for decolorizing red and black colored paper was developed to reduce the environmental impact of the chemicals used in paper recycling processes. Commercially available low-redox potential laccase from Myceliophthora thermophila, which operates optimally under alkaline conditions, was used in combination with natural mediators to make the process even greener. Based on the optical properties of the resulting decolorized paper, red and black dyes were efficiently removed by all laccase–mediator systems. The best results were provided by the laccase–methyl syringate combination, followed by the laccase–acetosyringone system and the laccase–syringaldehyde system. The decolorization rate for red paper achieved with the laccase–methyl syringate treatment exceeded that obtained with ozone. Red was removed by about 98% by combining two enzymatic stages and hydrogen peroxide stage, and black by 65%, without altering the physical properties of the colored paper in either case. A sequence combining oxidative and reductive (formamidine sulfinic acid) chemical treatments led to comparable optical and physical properties for the two types of paper. The effects of Myceliophthora thermophila laccase and methyl syringate were similar to those of high-redox potential laccase from Trametes villosa combined with either methyl syringate or the synthetic mediator violuric acidPostprint (author's final draft