Person: Monte Lara, María Concepción
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First Name
María Concepción
Last Name
Monte Lara
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Ingeniería Química y de Materiales
Area
Ingeniería Química
Identifiers
38 results
Search Results
Now showing 1 - 10 of 38
Item Gel Point as Measurement of Dispersion Degree of Nano-Cellulose Suspensions and Its Application in Papermaking(Nanomaterials, 2022) Sánchez Salvador, José Luis; Balea Martín, Ana; Negro Álvarez, Carlos Manuel; Monte Lara, María Concepción; Blanco Suárez, María ÁngelesThe dispersion degree of cellulose micro and nanofibrils (CMFs/CNFs) in water suspensions is key to understand and optimize their effectiveness in several applications. In this study, we proposed a method, based on gel point (Øg), to calculate both aspect ratio and dispersion degree. This methodology was validated through the morphological characterization of CMFs/CNFs by Transmission Electronic Microscopy. The influence of dispersion degree on the reinforcement of recycled cardboard has also been evaluated by stirring CMF/CNF suspensions at different speeds. Results show that as stirring speed increases, Øg decreased to a minimum value, in which the aspect ratio is maximum. Then, Øg increased again. Suspensions with lower Øg, in the intermediate region of agitation present very good dispersion behavior with an open and spongy network structure, in which nanofibril clusters are totally dispersed. Higher stirring speeds shorten the nanofibrils and the networks collapse. Results show that the dispersion of the nanocellulose at the minimum Øg before their addition to the pulp, produces higher mechanical properties, even higher than when CNFs and pulp are agitated together. This method allows for the determination of the CMF/CNF dispersion, to maximize their behavior as strength agents. This knowledge would be crucial to understand why some industrial trials did not give satisfactory results.Item Enzymatic deinking of secondary fibers: cellulases/hemicellulases versus laccase-mediator system(Journal of Industrial Microbiology & Biotechnology, 2012) Ibarra, David; Monte Lara, María Concepción; Blanco Suárez, María Ángeles; Martínez, Ángel ; Martínez, Maria JesúsThe use of enzymes has been suggested as an environmentally-friendly alternative to complement conventional chemical deinking in the recycling of recovered paper. This study compares the use of carbohydrate hydrolases versus laccase-mediator system for deinking printed fibers from newspapers and magazines. For this purpose, two commercial enzyme preparations with endoglucanase and endoxylanase activities (Viscozyme Wheat from Aspergillus oryzae and Ultraflo L from Humicola insolens) and a commercial laccase NS51002 from Trametes villosa), the latter in the presence of synthetic or natural (lignin related) mediators, were evaluated. The enzymatic treatments were studied at laboratory scale, using a standard chemical deinking sequence consisting of pulping, alkaline deinking and peroxide bleaching stages. Then, handsheets were prepared and their brightness, residual ink concentration, and strength properties were measured. Among the different enzymatic treatments assayed, both carbohydrate hydrolases were found to deink the secondary fibers more efficiently. Brightness increased up to 3-4% ISO on newspaper fibers, being Ultraflo 20% more efficient in the ink removal. Up to 2.5% ISO brightness increase was obtained when magazine fibers were used, being Viscozyme 9% more efficient in the ink removal. As regards laccase-mediator system, alone or combined with carbohydrate hydrolases, it was ineffective deinking both newspaper and magazine fibers, resulting in pulps with worse brightness and residual ink concentration values. However, pulp deinking by laccase-mediator system was displayed when secondary fibers rich in lignin, i.e. printed cardboard, were used, obtaining up to 3% ISO brightness increase and lower residual ink concentrations.Item Pitch adsorption on natural and modified talcs(Journal of Pulp and Paper Science, 2009) Tijero Cruz, Antonio; Monte Lara, María Concepción; Blanco Suárez, María Ángeles; Negro Álvarez, Carlos Manuel; Tijero Miquel, Julio FélixTalc is used traditionally for pitch control in papermaking. The effectiveness of talcs as control agent of dissolved and colloidal pitch depends on its structural and surface characteristics of minerals. Talcs are modified by thermal and surface treatments to obtain different properties e.g specific surface, surface energy, surface charge and ratio lypophilic/hydrophilic surface. Five commercial talcs have been tested to determine its capacity to adsorb the lypophilic contaminants by experiments of adsorption isotherms. The talcs correspond to two groups of different mineralogical compositions: one with high concentration of talc and some dolomite; and the other, with medium concentrations of talc and chlorite. Colloidal dispersions of extractives were obtained by extraction of Eucalyptus globulus wood at pilot plant scale with acetone, evaporation of the solvent and reextraction with hexane to increase the selectivity of lypophillic compound extraction. The isotherms of adsorption of the pitch dispersions were carried out at 50ºC on the different talcs. The adsorption took place by a mechanism of colloidal adsorption and the results obtained were adjusted to the Langmuir equation. Results show that talc addition to bleaching waters or process waters can produce high reductions of colloidal pitch concentrations, at comparatively low doses.Item Enhanced Morphological Characterization of Cellulose Nano/Microfibers through Image Skeleton Analysis(Nanomaterials, 2021) Sánchez Salvador, José Luis; Campano Tiedra, Cristina; López Expósito, Patricio; Tarrés, Quim; Mutjé, Pere; Delgado Aguilar, Marc; Monte Lara, María Concepción; Blanco Suárez, María ÁngelesThe present paper proposes a novel approach for the morphological characterization of cellulose nano and microfibers suspensions (CMF/CNFs) based on the analysis of eroded CMF/CNF microscopy images. This approach offers a detailed morphological characterization and quantification of the micro and nanofibers networks present in the product, which allows the mode of fibrillation associated to the different CMF/CNF extraction conditions to be discerned. This information is needed to control CMF/CNF quality during industrial production. Five cellulose raw materials, from wood and non-wood sources, were subjected to mechanical, enzymatic, and (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO)-mediated oxidative pre-treatments followed by different homogenization sequences to obtain products of different morphologies. Skeleton analysis of microscopy images provided in-depth morphological information of CMF/CNFs that, complemented with aspect ratio information, estimated from gel point data, allowed the quantification of: (i) fibers peeling after mechanical pretreatment; (ii) fibers shortening induced by enzymes, and (iii) CMF/CNF entanglement from TEMPO-mediated oxidation. Being mostly based on optical microscopy and image analysis, the present method is easy to implement at industrial scale as a tool to monitor and control CMF/CNF quality and homogeneity.Item Fit-for-use nanofibrillated cellulose from recovered paper(Nanomaterials, 2023) Balea Martín, Ana; Monte Lara, María Concepción; Fuente González, Elena De La; Sánchez Salvador, José Luis; Tarrés, Quim; Mutjé, Pere; Delgado-Aguilar, Marc; Negro Álvarez, Carlos ManuelThe cost-effective implementation of nanofibrillated cellulose (CNF) at industrial scale requires optimizing the quality of the nanofibers according to their final application. Therefore, a portfolio of CNFs with different qualities is necessary, as well as further knowledge about how to obtain each of the main qualities. This paper presents the influence of various production techniques on the morphological characteristics and properties of CNFs produced from a mixture of recycled fibers. Five different pretreatments have been investigated: a mechanical pretreatment (PFI refining), two enzymatic hydrolysis strategies, and TEMPO-mediated oxidation under two different NaClO concentrations. For each pretreatment, five high-pressure homogenization (HPH) conditions have been considered. Our results show that the pretreatment determines the yield and the potential of HPH to enhance fibrillation and, therefore, the final CNF properties. These results enable one to select the most effective production method with the highest yield of produced CNFs from recovered paper for the desired CNF quality in diverse applications.Item Morphological characterization of pulps to control paper properties(Cellulose Chemistry and Technology, 2010) Moral, Ana; Monte Lara, María Concepción; Cabeza, Elena; Blanco Suárez, María ÁngelesProducts at a high and constant level, for meeting the consumer demands. However, since paper recovery is increasing, the quality of recovered paper is decreasing and, what is even worse, it varies along the time. The physical properties of recycled pulp fibres have a strong influence on most of the paper properties and, therefore, they play an important role in the establishment of the optimal papermaking conditions. These properties are directly related to the morphology of fibres and to pulp composition. In recent years, several new fibre and pulp morphological analyzers have been developed and released on the market. The use of online optical fibre analyzers allows papermakers to know the variations in pulp quality, enabling them to adjust the process and to maintain constant the quality of the paper produced. However, most of these devices are optimized for virgin fibres, their application for recovered paper being still limited. The present paper describes the modifications carried out in the programs of a fibre and pulp morphological analyzer (Morfi V7.9.13.E) to optimize its performance for the characterization of recycled pulps. The three programs (VESSELS, FIBRES and SHIVES) that the device includes by default have been considered and validated in a paper mill, producing different grades of newsprint and light-weight coated papers. The results show that, with the modified program, the device appears as a very promising tool to control and improve the final quality of recycled paper.Item Application of cellulose nanofibers to remove water-based flexographic inks from wastewaters(Environmental Science and Pollution Research, 2017) Balea Martín, Ana; Monte Lara, María Concepción; Fuente González, Elena De La; Negro Álvarez, Carlos Manuel; Blanco Suárez, María ÁngelesWater-based or flexographic inks in paper and plastic industries are more environmentally favourable than organic solvent-based inks. However, their use also creates new challenges because they remain dissolved in water and alter the recycling process. Conventional deinking technologies such as flotation processes do not effectively remove them. Adsorption, coagulation/flocculation, biological and membrane processes are either expensive or have negative health impacts, making the development of alternative methods necessary. Cellulose nanofibers (CNF) are biodegradable, and their structural and mechanical properties are useful for wastewater treatment. TEMPO-oxidised CNF have been evaluated for the decolourisation of wastewaters that contained copper phthalocyanine blue, carbon black and diarlyide yellow pigments. CNF in combination with a cationic polyacrylamide (cPAM) has also been tested. Jar-test methodology was used to evaluate the efficiency of the different treatments and cationic/anionic demand, turbidity and ink concentration in waters were measured. Results show that dual-component system for ink removal has a high potential as an alternative bio-based adsorbent for the removal of water-based inks. In addition, experiments varying CNF and cPAM concentrations were performed to optimise the ink-removal process. Ink concentration reductions of 100%, 87.5% and 83.3% were achieved for copper phthalocyanine blue, carbon black and diarlyide yellow pigments, respectively. Flocculation studies carried out show the decolourisation mechanism during the dual-component treatment of wastewaters containing waterbased inks.Item Extending the limits of paper recycling - improvements along the paper value chain(Forest Systems, 2013) Blanco Suárez, María Ángeles; Miranda Carreño, Rubén; Monte Lara, María ConcepciónAim of study: The purpose of this study is to analyze how paper recycling activities in Europe can be extended through different improvements along the paper value chain. The importance of this study lies in the identification of the present barriers in paper recycling and how they can be overcome. Area of study: Europe. Material and methods: All the main stages along the paper value chain have been analyzed for possible improvements: collection of recovered paper (availability and quality), sorting of recovered paper, paper production, and printing and converting activities. Main results: To increase paper recycling in Europe the following improvements are necessary. First, it is mandatory to increase the availability of recovered paper through more efficient collection systems (avoiding the use of commingled collection systems) and limiting the competition with energy purposes and the exports. Second, it is necessary to extend sorting activities, which can be achieved by reducing sorting costs by the use of automatized sorting systems. Third, there is a need to increase the recyclability of paper products by the commitment of printing and converting industries to use recycling-friendly printing inks and adhesives. Finally, environmental awareness of the citizens is still an important driver for increasing recycling activities, affecting not only recovery but to all the stages along the paper recycling chain. Research highlights: Although the recycling rate in Europe is already very high (68.9%), there is still room to further extend paper recycling activities through different improvements along the paper value chain.Item Characterisation of agricultural residues used as a source of fibres for fibre-cement production(Industrial Crops and Products, 2012) Jarabo, R; Monte Lara, María Concepción; Blanco Suárez, María Ángeles; Negro Álvarez, Carlos Manuel; Tijero Miquel, Julio FélixNowadays, certain components of non-wood annual plants such as corn stalk and industrial hemp core are considered waste materials or used in low value applications; both by-products have a very low cost. On the other hand, given the large quantities of these materials generated worldwide and their renewable character, it is reasonable to explore new routes for their exploitation. The aim of this paper is to study the potential of both corn stalk (Zea Mays L.) and industrial hemp core (Cannabis Sativa L.) fibres as a renewable source of cellulose fibres in the production of fibre-cement. For each source of fibres, a number of chemical cooking treatments were studied. The morphological properties of the fibres were determined using a scanning electron microscope and a fibre and pulp morphological analyser. Pulp refining was carried out in a PFI mill to improve the characteristics of the fibres. In the case of corn fibres, different degrees of refining were applied. The fibre flocculation process was investigated using several polyacrylamides. The process was studied by monitoring the chord size distribution in real time by means of a focused beam reflectance measurement probe. The results indicated both pulps can be used for the production of fibre-cement, having the two types of pulp morphological similarities with the pine fibres currently used. Through the flocculation process it was concluded the floc size depends on the length of the fibres.Item Analysis of the quality of the recovered paper from commingled collection systems(Resources, Conservation and Recycling, 2013) Miranda Carreño, Rubén; Monte Lara, María Concepción; Blanco Suárez, María ÁngelesThe need to increase the recovery rates of recyclables from households, reducing at the same time the collection costs, has favored the spreading of commingled collection systems. This study presents a thorough analysis of the quality of a secondary source of recovered paper of a Spanish newsprint mill, imported from the United Kingdom, where these systems are widely practiced. The results show that the quality of recovered paper from commingled systems is very far from the quality obtained with selective systems: the unusable material content vary from 1% to 29% (11.9% on average) compared to less than 1%. Larger materials recovery facilities (MRF), less oversaturated and with advanced sorting techniques, have demonstrated to be able to render better qualities, the unusable material content varying from 0.3% to 16.6% (8.1% on average). However, the quality is still far from contamination levels typically found with selective systems, especially in terms of non-paper components. This fact limits significantly the use of this recovered paper for graphic paper production where the major potential for an extended use of recovered paper in papermaking lies. Furthermore, there is a discussion on the cost efficiency of these systems and how the legislation and private or public initiatives are affecting the spreading of these systems, especially in the United States and the United Kingdom.