Person: Balea Martín, Ana
Universidad Complutense de Madrid
Faculty / Institute
Ingeniería Química y de Materiales
Now showing 1 - 10 of 22
- PublicationCelulosa nanofibrilada y su aplicación en la industria papelera para la mejora de productos reciclados(Universidad Complutense de Madrid, 2019-03-01) Balea Martín, Ana; Negro Álvarez, Carlos; Blanco Suárez, ÁngelesLa fabricación de papel es un sector industrial sostenible donde el reciclaje constituye uno de los pilares fundamentales. En Europa, el 54% de la materia prima que utiliza la industria papelera proviene del papel recuperado siendo la tasa de reciclaje del 72% (CEPI 2015). Sin embargo, uno de los principales problemas de las fibras recuperadas es mantener el nivel de calidad de los productos papeleros que aumenta continuamente por las exigencias del mercado. Además, la demanda de papel ha disminuido debido a la recesión económica y al uso de otros soportes de información, lo cual exige una continua reducción de costes dentro del sector para mantener la competitividad de las empresas. Aunque la industria papelera trata de compensar la pérdida de calidad de las fibras secundarias con la aplicación de procesos de refino y el uso de aditivos de resistencia, la baja resistencia mecánica de los productos papeleros sigue siendo la principal fuente de reclamaciones a los fabricantes de papel reciclado. Por este motivo, es necesario la búsqueda de nuevas estrategias que permitan mejorar el enlace entre las fibras, y la celulosa nanofibrilada (CNF) abre nuevos horizontes como agente de resistencia alternativo...
- PublicationGel Point as Measurement of Dispersion Degree of Nano-Cellulose Suspensions and Its Application in Papermaking(MPDI, 2022-02-26) Sánchez Salvador, José Luis; Balea Martín, Ana; Negro Álvarez, Carlos Manuel; Monte Lara, María Concepción; Blanco Suárez, 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.
- PublicationComparison Of Mechanical And Chemical Nanocellulose As Additives To Reinforce Recycled Cardboard(Nature, 2020) Sánchez Salvador, José Luis; Balea Martín, Ana; Monte Lara, M. Concepción; Negro Álvarez, Carlos Manuel; Miller, Meaghan; Olson, James; Blanco Suárez, ÁngelesRecycling cycles cause a decrease in mechanical paper properties due to cellulose fiber degradation. The use of cellulose micro/nanofibers (CMF/CNF) to reinforce paper strength has been well studied, although it has been found to have negative effects on drainage. However, the application of CMF/CNF as paper reinforcement is affected by the nanocellulose type. Thus in this study mechanical and chemical treatments in CNF production were compared. Old corrugated container (OCC) pulp used to produce recycled cartonboard was reinforced with 1) CMF from never-dried northern bleached softwood kraft pulp (NBSK) highly refined in a 16-inch low consistency refiner at 1200 rpm and 25 kW of net power; and 2) CNF from NBSK pulp treated by TEMPO-mediated oxidation and homogenization at 600 bars. CMF/CNF and OCC were pulped at the same time and handsheets formed with cationic starch (CS) as retention system. Mechanical, drainage and flocculation properties were evaluated and compared. Data were also compared with other sources of TEMPO CNF. Results show an improvement in mechanical properties, drainage and flocculation when OCC is reinforced with CMF obtained with LCR. Therefore, high fibrillation was not necessary to improve mechanical paper or cardboard properties.
- PublicationIn Situ Production and Application of Cellulose Nanofibers to Improve Recycled Paper Production(MDPI, 2019-05-09) Balea Martín, Ana; Sánchez Salvador, José Luis; Monte, María de la Concepción; Merayo Cuevas, Noemí; Negro Álvarez, Carlos Manuel; Blanco Suárez, ÁngelesThe recycled paper and board industry needs to improve the quality of their products to meet customer demands. The refining process and strength additives are commonly used to increase mechanical properties. Interfiber bonding can also be improved using cellulose nanofibers (CNF). A circular economy approach in the industrial implementation of CNF can be addressed through the in situ production of CNF using side cellulose streams of the process as raw material, avoiding transportation costs and reducing industrial wastes. Furthermore, CNF fit for use can be produced for specific industrial applications.This study evaluates the feasibility of using two types of recycled fibers, simulating the broke streams of two paper machines producing newsprint and liner for cartonboard, to produce in situ CNF for direct application on the original pulps, old newsprint (ONP), and old corrugated container (OCC), and to reinforce the final products. The CNF were obtained by 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-mediated oxidation and homogenization at 600 bar. Handsheets were prepared with disintegrated recycled pulp and different amounts of CNF using a conventional three-component retention system. Results show that 3 wt.% of CNF produced with 10 mmol of NaClO per gram of dry pulp improve tensile index of ONP ~30%. For OCC, the same treatment and CNF dose increase tensile index above 60%. In both cases, CNF cause a deterioration of drainage, but this effect is effectively counteracted by optimising the retention system.
- PublicationOptimization of reagent consumption in TEMPO-mediated oxidation of Eucalyptus cellulose to obtain cellulose nanofibers(Springer Nature, 2022-06-21) Xu, Hongyu; Sánchez Salvador, José Luis; Balea Martín, Ana; Blanco Suárez, Ángeles; Negro Álvarez, Carlos ManuelEucalyptus cellulose is usually pre-treated by oxidation with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), NaBr and NaClO at pH 10.5 and 25 °C before the mechanical process required to obtain cellulose nanofibers (CNFs). In this study, different aspects to improve the effectiveness and sustainability of the TEMPO-mediated oxidation are analyzed. The optimization was carried out at different reaction times by modifying both the concentration of the NaClO and the amount of the catalysts (TEMPO and NaBr). Results show that the carboxyl groups increased up to 1.1 mmol/g with 5 mmol NaClO/g after 50 min, and that the catalyst concentration can be reduced to 0.025 mmol TEMPO/g and 0.5 mmol NaBr/g to minimize costs while maintaining the high fibrillation degree of the CNFs. The kinetic of the reaction can be considered as zero-order with respect to NaClO, and as first order with respect to cellulose. As a result of this work, the catalyst doses are reduced up to 75% compared to the most widely used catalyst doses (0.1 mmol/g TEMPO and 1 mmol/g NaBr), obtaining highly fibrillated CNFs with a lower environmental impact. This reduction of catalyst doses will reduce the costs and facilitate the implementation of CNF production at industrial scale.
- PublicationRecycled Fibers for Sustainable Hybrid Fiber Cement Based Material: A Review(MDPI AG, 2021) Balea Martín, Ana; Fuente González, Elena de la; Monte Lara, M. Concepción; Blanco Suárez, Ángeles; Negro Álvarez, Carlos ManuelReinforcing fibers have been widely used to improve physical and mechanical properties of cement-based materials. Most fiber reinforced composites (FRC) involve the use of a single type of fiber to improve cement properties, such as strength or ductility. To additionally improve other parameters, hybridization is required. Another key challenge, in the construction industry, is the implementation of green and sustainable strategies based on reducing raw materials consumption, designing novel structures with enhanced properties and low weight, and developing low environmental impact processes. Different recycled fibers have been used as raw materials to promote circular economy processes and new business opportunities in the cement-based sector. The valuable use of recycled fibers in hybrid FRC has already been proven and they improve both product quality and sustainability, but the generated knowledge is fragmented. This is the first review analyzing the use of recycled fibers in hybrid FRC and the hybridization effect on mechanical properties and workability of FRC. The paper compiles the best results and the optimal combinations of recycled fibers for hybrid FRC to identify key insights and gaps that may define future research to open new application fields for recycled hybrid FRC.
- PublicationModeling of Hexavalent Chromium Removal with Hydrophobically Modified Cellulose Nanofibers(MDPI, 2022) Ojembarrena Jiménez, Francisco de Borja; Sánchez-Salvador, José Luis; Mateo, Sergio; Balea Martín, Ana; Blanco Suárez, Ángeles; Merayo Cuevas, Noemí; Negro Álvarez, Carlos ManuelCellulose nanofibers (CNF) are sustainable nanomaterials, obtained by the mechanical disintegration of cellulose, whose properties make them an interesting adsorbent material due to their high specific area and active groups. CNF are easily functionalized to optimize the performance for different uses. The hypothesis of this work is that hydrophobization can be used to improve their ability as adsorbents. Therefore, hydrophobic CNF was applied to adsorb hexavalent chromium from wastewater. CNF was synthetized by TEMPO-mediated oxidation, followed by mechanical disintegration. Hydrophobization was performed using methyl trimetoxysilane (MTMS) as a hydrophobic coating agent. The adsorption treatment of hexavalent chromium with hydrophobic CNF was optimized by studying the influence of contact time, MTMS dosage (0–3 mmol·g −1 CNF), initial pH of the wastewater (3–9), initial chromium concentration (0.10–50 mg·L −1 ), and adsorbent dosage (250–1000 mg CNF·L −1 ). Furthermore, the corresponding adsorption mechanism was identified. Complete adsorption of hexavalent chromium was achieved with CNF hydrophobized with 1.5 mmol MTMS·g −1 CNF with the faster adsorption kinetic, which proved the initial hypothesis that hydrophobic CNF improves the adsorption capacity of hydrophilic CNF. The optimal adsorption conditions were pH 3 and the adsorbent dosage was over 500 mg·L −1 . The maximum removal was found for the initial concentrations of hexavalent chromium below 1 mg·L −1 and a maximum adsorption capacity of 70.38 mg·g −1 was achieved. The kinetic study revealed that pseudo-second order kinetics was the best fitting model at a low concentration while the intraparticle diffusion model fit better for higher concentrations, describing a multi-step mechanism of hexavalent chromium onto the adsorbent surface. The Freundlich isotherm was the best adjustment model.
- PublicationIdentification of recalcitrant stickies and their sources in newsprint production(American Chemical Society, 2008) Miranda Carreño, Rubén; Balea Martín, Ana; Sánchez de la Blanca, Emilia; Carrillo Ramiro, Isabel; Blanco Suárez, ÁngelesDeposits from different sections of a newsprint paper mill, using 100% recovered paper, were analyzed following an analytical procedure based on scaning electron microscopy-electron dispersive X-ray and consecutive solvent extraction steps with Fourier-transform infrared spectroscopy (FTIR) analyses of the different fractions. Polyvinyl acetate, polyacrylates, styrene butadiene rubber, and derivatives of fatty acids/resin acids are the main stickies-related components identified in the deposits. The removal efficiency of these contaminants along the deinking line was studied by determining the composition of the dichloromethane extractives in the pulp by FTIR analyses. Although the total stickies content is reduced considerably during the process, some compounds, which are found in the deposits, are not removed selectively in the process, indicating their recalcitrant nature. FTIR analyses of unusable materials coming with the raw material (mainly board and mixed office waste) have demonstrated that these materials are one of the main sources of these types of recalcitrant stickies.
- PublicationIndustrial Application of Nanocelluloses in Papermaking: A Review of Challenges, Technical Solutions, and Market Perspectives(MDPI, 2020-01-25) Balea Martín, Ana; Fuente González, Elena de la; Monte Lara, María Concepción; Merayo, Noemi; Campano Tiedra, Cristina; Negro Álvarez, Carlos Manuel; Blanco Suárez, ÁngelesNanocelluloses (NC) increase mechanical and barrier paper properties allowing the use of paper in applications actually covered by other materials. Despite the exponential increase of information, NC have not been fully implemented in papermaking yet, due to the challenges of using NC. This paper provides a review of the main new findings and emerging possibilities in this field by focusing mainly on: (i) Decoupling the effects of NC on wet-end and paper properties by using synergies with retention aids, chemical modification, or filler preflocculation; (ii) challenges and solutions related to the incorporation of NC in the pulp suspension and its effects on barrier properties; and (iii) characterization needs of NC at an industrial scale. The paper also includes the market perspectives. It is concluded that to solve these challenges specific solutions are required for each paper product and process, being the wet-end optimization the key to decouple NC effects on drainage and paper properties. Furthermore, the effect of NC on recyclability must also be taken into account to reach a compromise solution. This review helps readers find upscale options for using NC in papermaking and identify further research needs within this field.
- PublicationInfluence of pretreatment and mechanical nanofibrillation energy on properties of nanofibers from Aspen cellulose(Springer Nature, 2021-07-05) Balea Martín, Ana; Fuente González, Elena de la; Tarrés, Q.; Pèlach, M. Àngels; Mutjé, P.; Delgado-Aguilar, M.; Blanco Suárez, Ángeles; Negro Álvarez, CarlosThe characteristics of cellulose nanofibers (CNFs) depend on many factors such as the raw material, type and intensity of the pre-treatment, and type and severity of the mechanical defibrillation process. The relationship among factors is complex but crucial in determining the final, fit-for-use CNF properties. This study aims to find the relationship between the CNF properties morphology, aspect ratio, nanofibrillation yield, transmittance and cationic demand, and the production process using bleached Aspen thermomechanical pulp as the raw material. Five different types of pretreatments were carried out and five different defibrillation intensities of highpressure homogenization were evaluated. Pretreatments were: PFI refining at 20,000 revolutions, enzymatic hydrolysis with 80 and 240 g of enzyme per ton of dry pulp and TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl)–mediated oxidation with 5 and 15 mmol of NaClO per gram of dry pulp. From the twenty-five different procedures evaluated, results show that both the pretreatment and the severity of the high-pressure homogenization determined both the fibrillation yield and the CNF morphology. Moreover, the main properties of CNFs (cationic demand, yield, transmittance and aspect ratio) can be estimated from the carboxylic content of the pretreated pulp, which would facilitate the control of the CNF production and their tuning according to the production needs.