https://hdl.handle.net/10259/9397 2026-04-17T09:46:39Z 2026-04-17T09:46:39Z Herrero Camargo, Sara https://hdl.handle.net/10259/10884 2025-09-22T08:56:56Z

Estudios de adsorción y desorción de furfural empleando carbón activo y Amberlite XAD-4 Herrero Camargo, Sara The valorisation of solid agricultural waste remains a current challenge. The concept of a biorefinery arises from increasing concerns about environmental issues, as it is an efficient and sustainable way to produce valuable organic compounds from lignocellulosic byproducts, thereby maximizing their value. Corn is the most widely produced cereal globally, and Spain contributes approximately four million tons. Additionally, it is estimated that by 2030, global production of this cereal will increase by 160 million tons, reaching 1.3 billion tonnes. Corn stover has a high content of hemicellulose, cellulose, and lignin, making it a good raw material for the production of furfural. Furfural is a heterocyclic organic compound identified as a platform chemical with various subsequent applications: as an extractant, fungicide, raw material in the synthesis of various chemicals, and as a flavour and fragrance enhancer in the food industry. It is also a precursor to many other compounds of interest, such as succinic acid and furfuryl alcohol. Furfural is produced from the hydrolysis of hemicellulose, generally through acid hydrolysis and dehydration of xylose. This study analysed the selective recovery of furfural from corn stover subcritical water hydrolysates using an adsorption/desorption process, which are more environmentally and economically sustainable hydrolysis and purification methods. Specifically, this work evaluated the effect of the type of adsorbent, the mass/volume ratio, and the presence of impurities (mainly xylose and carboxylic acids) on the furfural adsorption yield, as well as compared batch and fixed bed treatments. After the study, under optimal working conditions (5 g of XAD-4, 75 ml of furfural hydrolysate, adsorption process at 25°C for 60 min, desorption process at 50°C for 30 min, and in a fixed bed), the results showed that the most selective adsorbent for furfural recovery was the Amberlite XAD-4 polymeric resin, with a furfural recovery from the corn waste subcritical water hydrolysate of 66.2% and a purity close to 91.3%.; The valorisation of solid agricultural waste remains a current challenge. The concept of a biorefinery arises from increasing concerns about environmental issues, as it is an efficient and sustainable way to produce valuable organic compounds from lignocellulosic byproducts, thereby maximizing their value. Corn is the most widely produced cereal globally, and Spain contributes approximately four million tons. Additionally, it is estimated that by 2030, global production of this cereal will increase by 160 million tons, reaching 1.3 billion tons. Corn agricultural waste, such as stalks and leaves, have a high content of hemicellulose, cellulose, and lignin, making them a good raw material as biomass for the production of furfural. Furfural is a heterocyclic organic compound identified as a platform chemical with various subsequent applications: as an extractant, fungicide, raw material in the synthesis of various chemicals, and as a flavor and fragrance enhancer in the food industry. It is also a precursor to many other compounds of interest, such as succinic acid and furfuryl alcohol. Furfural is produced from the hydrolysis of hemicellulose, generally through acid hydrolysis and dehydration of xylose.This study analyzed the selective recovery of furfural from corn waste subcritical water hydrolysates using an adsorption/desorption process, which are more environmentally and economically sustainable hydrolysis and purification methods. Specifically, this work evaluated the effect of the type of adsorbent, the mass/volume ratio, and the presence of impurities (mainly xylose and carboxylic acids) on the furfural adsorption yield, as well as compared batch and fixed bed treatments. After the study, under optimal working conditions (5 g of XAD-4, 75 ml of furfural hydrolysate, adsorption process at 25°C for 60 min, desorption process at 50°C for 30 min, and in a fixed bed), the results showed that the most selective adsorbent for furfural recovery was the Amberlite XAD-4 polymeric resin, with a furfural recovery from the corn waste subcritical water hydrolysate of 66.2% and a purity close to 91.3%.

Díez Carretero, Paula https://hdl.handle.net/10259/10870 2025-09-16T00:05:36Z

Recuperación de polifenoles presentes en salvado de trigo y piel de cebolla mediante un proceso combinado de extracción asistida por ultrasonidos y nanofiltración Díez Carretero, Paula Wheat bran and onion skin waste are agri-food by-products generated in large quantities annually. Their valorization represents an important opportunity, linked to sustainability, for obtaining bioactive compounds with beneficial properties. These by-products are notable for their high content of bioactive compounds, specifically phenolic compounds, among which quercetin and ferulic acid stand out for their antioxidant activity. The main aim of this work has been to study the technical feasibility of a combined ultrasound-assisted extraction (UAE) / nanofiltration (NF) process for the recovery of phenolic compounds present in wheat bran and onion skin wastes generated as by-products in local food companies. UAE was firstly performed for the extraction of polyphenols from wheat bran (WB) and onion skin waste (OSW) using an acetate buffer at pH 5 and an aqueous ethanol solution (70 vol. %) as solvents, respectively, under the optimum operating conditions. A final WB extract was obtained with a total polyphenol content (TPC) of 3.56 ± 0.18 mg GAE/g WB and an antioxidant activity (AA) of 7.75 ± 1.20 µmol Fe2+/g WB. An OSW extract was also obtained, with a TPC of 44.47 ± 0.83 mg GAE/g OSW, a total flavonoid concentration (TFC) of 19.22 ± 0.35 mg QE/g OSW, and an AA of 28.38 ± 2.70 mg Trolox/g OSW. Ferulic acid is the main component of wheat bran extract, while quercetin and its glycosylated derivatives are the main components of onion skin extract. Both extracts were then concentrated by nanofiltration (NF) in a high pressure stirred cell, using a NF270 flat polyamide membrane (270 Da cut-off), under optimal operating conditions reaching a volume concentration ratio (VCR) of 5 after 7,5 and 1,8 h for WB and OSW extracts, respectively, with minimal loss of polyphenols in the permeates and recoveries of AA, TPC, and TFC in the concentrates higher than 99% in all cases. The results obtained in this study could contribute to the valorization of agri-food waste using environmentally friendly techniques, demonstrating the potential o

García Mateo, Alba https://hdl.handle.net/10259/9678 2026-01-16T10:09:43Z

Recuperación de ácido cafeico de disoluciones acuosas mediante extracción de punto de turbidez con tensioactivos no iónicos García Mateo, Alba Food waste has become one of the main problems around the world. More than 85 million tons of food are wasted per year in the European Union, and this waste is generated at different stages throughout the entire food chain. One of the main challenges facing the food industry is being able to minimize or reuse the high amount of waste generated during food processing, which represents a very significant challenge at an environmental, social and economic level. In recent years, different treatments have been proposed for the treatment of these wastes, in order to recover the high added-value compounds present in them for subsequent use, mainly in agri-food, pharmaceutical and cosmetic industries. Among these compounds, the polyphenols present in plants, fruits and vegetables stand out. Polyphenols are bioactive compounds with low solubility in water and are very beneficial for human health due to their antioxidant properties and their ability to prevent chronic diseases such as obesity, cardiovascular diseases and different types of cancer. The most commonly used techniques for the extraction and recovery of polyphenols are not very sustainable and are harmful to the environment, since they use toxic organic solvents. Clean technologies have been investigated as alternatives for the recovery of these compounds in a more economical and environmentally sustainable way. The main objective of this work was to study the technical feasibility of a cloud point extraction process using non-ionic surfactants for the recovery of a model polyphenol (caffeic acid) from aqueous solutions, avoiding the use or organic solvents and allowing the recovery and reuse of these compounds, promoting circular economy and sustainability practices in the food industry. Three non-ionic surfactants were tested, among which Triton X-114 (15% w/v) was selected for subsequent extraction experiments due to its lower cloud point. A design of experiments was performed using response surface methodology (RSM) and central composite design (CCD) for the evaluation of the effect of three factors (temperature, extraction time and salt (NaCl) concentration) on the caffeic acid extraction degree from aqueous solutions (500 mg/L caffeic acid) and the optimization of the operating conditions used in the cloud point extraction process. Caffeic acid content (Folin-Ciocalteu method) and antioxidant capacity (BRS voltammetric method) of the aqueous phases and extracts (surfactant-rich phase), respectively, obtained after cloud point extraction were also determined. The following optimum operating conditions were obtained: temperature of 40 ºC, 40 minutes of extraction time and 10% (w/v) salt concentration (NaCl) added to the feed to lower the cloud point and promote phase separation. For these optimum operating conditions, the model proposed in the design of experiments predicted a caffeic acid extraction degree of 97.22%. Experimentally, a 95.86% of caffeic acid extraction was obtained working under the aforementioned optimum operating conditions. This percentage increased to 97.55% when the extraction was carried out in two stages, obtaining an extract with a high antioxidant capacity (2804.2 ± 91.7 BRS units). The use of the cloud point extraction process proposed in this work would contribute to achieving some of the Sustainable Development Goals (SDGs), such as SDG 9 (Industry, innovation and infrastructure) and SDG 12 (Responsible consumption and production).

Fernández González, Esther https://hdl.handle.net/10259/9143 2024-07-16T11:52:52Z

Estudio de la extracción de compuestos fenólicos de residuos agrarios de mazorca de maíz mediante la metodología de superficie de respuesta Fernández González, Esther Corn is presently one of the most expensively cultivated cereals worldwide, resulting in significant agricultural solid residues. The corncob waste is considered a by-product due to its phenolic fraction rich in phenolic acids and flavonoids that could be substitute synthetic functional additives in various food and pharmaceutical applications. This study has been focused on investigating different extraction processes and operating conditions to recover the phenolic fraction from corncob waste, followed by an identification study to valorise the final extracts. The experiments were conducted using bath extraction with rotary agitation and ultrasound-assisted extraction. The solvent was ethanol, water, and various ethanol-water mixtures. Ultrasonication has been more effective than rotatory agitation, ensuring higher extraction yields in a much shorter contact time. The presence of kaempferol, p-coumaric acid and ethyl-ferulate has been identified in the phenolic profile of all extracts from the treatment of corncob waste with ethanol solvents. The response surface methodology with a Box-Behnken desing (BBD) has been employed to analyse the combined effect of contact time, solid waste amount and ethanol fraction in the solvent on the extraction efficiency. Kinetic experiments were also performed with the optimal solvent selected from the BBD to examine maximising extraction of p-coumaric acid, kempferol and ethyl-ferulate.