Possibilities for exploitation of invasive species, Arundo donax L., as a source of phenol compounds

Recycling and reuse are a fundamental pillar for reducing global pollution. In this context, the use of waste generated by invasive species control actions, as a natural raw material for the exploitation of their bioactive compounds, provides a great interest for a more sustainable industry. In this study, phenolic compounds were determined from the different parts that compose the invasive species Arundo donax L. The experiments were carried out using response surface methodology (RSM) by the Box-Behnken method, allowing us to evaluate the factors (temperature, time and type of solvent) and the values that optimized the extraction. The highest concentration of total phenolic compounds equivalent in gallic acid (GAE) was obtained from extracts with distilled water, with the fraction of leaves (7.43 mg GAE /g) in first place, followed by inflorescences (5.15 mg GAE /g) and finally stems (2.73 mg GAE /g).These optimum values were obtained using conditions of 6 h and 45 °C for leaves and stems and 4 h and 35 °C for inflorescences.. Identification and quantification of phenolic acids and flavonoids were carried out by HPLC–MS/MS analytical technique. In general, stem extracts were the most abundant in phenolic acids with potential pharmacological properties. These studies provided promising results for the Arundo donax L. species as a source of polyphenols, making full use of its residue and aiming to boost the circular economy in important industry sectors.Financiado para publicación en acceso aberto: Universidade de Vigo/CISU

Anthocyanins and total phenolic compounds from pigment extractions of non-native species from the Umia river basin: Eucalyptus globulus, Tradescantia fluminensis, and Arundo donax

Alien invasive species (AIS) and non-native species are a prominent and extended problem in a wide range of areas in Europe and around the world. Centered in the Umia’s riparian forest, in Galicia, we found at least three main AIS needing to be controlled and harvested to preserve the biodiversity of the area. Previous studies probed that leaves and bark of selected species—Tradescantia fluminensis, Arundo donax, and Eucalyptus globulus—have important antioxidant properties, suitable for use in pharmaceutical and industrial contexts. A comparison of four solid-liquid extraction methods—Soxhlet extraction, ultrasound assisted extraction, thermal agitator, and infusion—was conducted in order to define the most efficient method in correlation within antioxidant (anthocyanins and total phenols) extraction. Water was selected as solvent, providing a sustainable research background without implying any chemical additives. The best extraction yields were obtained with Soxhlet extraction for all raw matter, with best results for Tradescantia fluminensis (41.89%) and Eucalyptus globulus leaves (39.35%); followed by the ultrasonic assisted extraction method, with better yield performed with Eucalyptus leaves (27.07%). On the contrary, Tradescantia fluminensis showed better efficiency with thermal agitator (35.07% compared to 23.19% from ultrasound extraction). After extractions, identification and quantification of total phenolic compounds and anthocyanins were carried out using spectrophotometric determination and acid hydrolysis in butanol method. In general, the best extraction yield in correlation with higher antioxidant content was performed by thermal agitator method, and Eucalyptus globulus leaves were demonstrated to be the better anthocyanins (6.18 ± 0.82 mg CC/g) and total phenols containers (172.40 ± 44.53 mg GAE/g). Studies provided promising possibilities for the residues of the three non-native species analyzed, as a source of antioxidants, favoring circular economy systems, as well as taking care of biodiversity in affected environments.Xunta de Galicia | Ref. Becas predoctorales 29

Thalassiosira pseudonana and Skeletonema costatum biomass optimization: cultivation, harvesting, extraction of oils and biodiesel and pelletization of the residue

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGMicroalgae are one of the most promising feedstocks for biofuel production that can solve the energy crisis, climate change, and the depletion of fossil fuels. Biorefineries have production capacity bottlenecks that prevent them from being economically profitable, without leaving aside the environmental safety of by-products. This research aims to analyze critical stages such as harvesting or lipid extraction from two microalgae species currently unknown, such as Thalassiosira pseudonana and Skeletonema costatum. Inorganic flocculation with a low concentration of iron or aluminum salts (FeCl3 and Al2(SO4)3) was achieved to recover >60% biomass in just 20 min in both cases. Lipids extractions through chloroform: methanol (solvent ratio 2:1) obtained low performance due to the ionic strength medium. The fatty acid composition of the algae extracts showed that stearic acid (C18:0) and palmitoleic acid (C16:1) were predominant in both species. In addition, residues from the lipid extraction process were used for the manufacture of pellets. The data collected showed that these solid biofuels should be combined with other biomass typologies if the end-use are biomass boilers. The development of these studies provides new information on different microalgae species and their potential to use their biomass through an integrated utilization

Characterization of cellulose derived from invasive alien species plant waste for application in the papermaking industry: physic-mechanical, optical, and chemical property analysis

This study examines the potential of four invasive plant species, both arboreal and herbaceous, within the riparian forest of the Umia River in Galicia, a common ecosystem in northern Spain. These invasive species (Arundo donax, Phytolacca americana, Eucalyptus globulus, and Tradescantia fluminensis) were collected and assessed for their suitability as an alternative source of pulp and paper materials for the paper industry to mitigate the environmental impacts associated with conventional cellulose fiber production from harmful monocultures. Cellulosic material from leaves, bark, and/or stems of each of the selected species was isolated from lignin and hemicelluloses through kraft pulping processes. Resulted fibers and pulps were analyzed visually, morphologically, chemically, and mechanically to evaluate their papermaking properties. To compare these properties with those of commercially available pulp, test sheets were concurrently produced using commercial bleached Eucalyptus cellulose. The findings reveal that the employed fibers exhibit promising characteristics for artistic paper production. Regarding the pulp, two refining times were tested in a PFI machine, and the Schopper–Riegler degree was measured. Paper sheets underwent various tests to determine thickness, basis weight, apparent volume, apparent density, permeability, and chemical composition, as well as microscopic optical and morphological properties. The fibers obtained from the waste derived from the removal of invasive exotic species and biodiversity control present a viable and intriguing alternative for decentralized paper production, yielding noteworthy results for the creative sector. This research highlights the potential of harnessing invasive species for sustainable and innovative paper manufacturing practices.Universidade de Vig

Influence of Microcystis sp. and freshwater algae on pH: changes in their growth associated with sediment

Samples from two reservoirs with eutrophication problems, located in Pontevedra and Ourense (Northwestern Spain), were cultured, along with a third crop from a reservoir with no problems detected in Ourense (Northwestern Spain). The samples were grown under the same conditions (with an average temperature of 21 ± 2 °C, and a 3000 lux light intensity) in triplicate, and their growth, absorbance and pH were studied. High correlation values were obtained for pH and cellular growth (R2 ≥ 95%). The water from Salas showed the greatest microalgal growth (0.15 × 106 cells/ml to 31.70 × 106 cells/ml of "Microcystis sp." for the last day of culturing) and the greatest increase in pH (5.72–9.02). In all the cultures studied here, the main species that reproduced was "Microcystis sp.", which can produce neurotoxins and hepatotoxins. In addition, water samples were cultured with sediments of their own reservoir and with others to observe their evolution. The sediments studied in this case were rich in biotites, which can lead phosphate to be a limiting factor for phytoplankton due to the formation and sedimentation of insoluble salts of ferric phosphate. In crops grown with sediments from the Salas reservoir, actinobacteria developed which can inhibit microalgal growth. The study of the growth of cyanobacteria and possible methods of inhibiting them directly concerns the quality of water and its ecosystems, avoiding pollution and impact on ecosystems

Microalgal biomass quantification from the non-invasive technique of image processing through red-green-blue (RGB) analysis

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGContinuous monitoring of biomass concentration in microalgae cultures is essential and one of the most important parameters to measure in this field. This study aims at digital image processing in RGB and greyscale models, being a simple and low-cost method for cell estimation. Images obtained from different photobioreactors with wastewater and at different conditions for the cultivation of Chlorella vulgaris were analyzed. The results suggested that this technique is very effective under controlled lighting conditions, in contrast to photobioreactors placed outdoors and of different design, presenting a lower linearity. The accuracy of the method could be improved with a high-quality charge-coupled device (CCD) camera. The development of efficient methods to assess biomass concentration is an important and necessary step towards large-scale microalgae cultivation. The colour analysis technique has a great potential to meet the needs of monitoring cultures in a cost-effective and automated way using simple and cheap instruments

Water toxicity in reservoirs after freshwater algae harvest

Blooms of microalgae and cyanobacteria increase every year, presenting great problems for the environment. Finding a way of harvesting these microalgae could be useful for water governance. Furthermore, the method should not cause cell lysis and should thus avoiding discharging toxins into the water. Three reservoirs were studied, two of them with eutrophication problems (As Conchas and A Baxe) and another (Salas) with no such problems. Three different harvesting methods were studied; electroflocculation (EF) with the application time being varied; centrifugation, with application times and speeds being varied; and finally, natural sedimentation. The highest efficiency was obtained in the culture from A Baxe, which had a higher initial absorbance value (1.664), using EF (90.64% for an application time of 2 min and 30 s) and centrifugation at 4000 rpm (92.25% for2 minutes, 92.73% for 5 min). Electrofloculation can obtain up to 84% more biomass than natural sedimentation alone. Sample toxicity was studied before and after harvesting using Microcystest and found to be higher after harvesting. It was observed that for the same sample, the higher the yield was the greater the toxicity was. For the A Baxe culture with an application time of 2 min, a speed of 2000 rpm and a yield of 87.02%, a toxicity figure of 0.94 μg/L was obtained, while for a speed of 4000 rpm the yield was 92.25% and the toxicity was 1.05 μg/L. The toxicity limit set by the World Health Organization (WHO) is 1 μg/L, and this small difference seems to be key. With these results, this study concludes that chlorophyll levels may interfere with the test used. Future tests or analyses should be developed so as to avoid such interference, which may alter the toxin values. Electroflocculation seems to be a promising method since it does not cause the lysis of "Microcystis aeruginosa", whereas the centrifugation method could give problems. Finally, it is worth highlighting the importance of performing toxin measurements after harvesting the microalgae to check that the method is viable in natural ecosystems

Multiple phase and dielectric transitions on a novel multi-sensitive [TPrA][M(dca)3] (M: Fe2+, Co2+ and Ni2+) hybrid inorganic–organic perovskite family

The hybrid inorganic–organic [TPrA][M(dca)3] (M: Fe2+, Co2+ and Ni2+) compounds, where TPrA is the tetrapropylammonium cation and dca is the dicyanamide anion, are unique multi-sensitive compounds that display multiple phases and dielectric transitions. These materials exhibit up to three first-order structural transitions (between the polymorphs I, Ia, Ib and II) associated with the same number of dielectric transitions in the temperature range of 210–360 K. The mechanisms responsible for these dielectric responses are found to be novel within the hybrid perovskites, involving ionic displacements of the A-site cations (TPrA) and order/disorder processes of the X anions (dca). In addition, the phase transitions and dielectric transition temperatures can be tuned by applying external hydrostatic pressure or by inducing internal pressure by modifying the tolerance factor through ionic substitution in the B-sites. This multi-sensitive response towards temperature, external and internal pressure opens up promising technological applications for this family of materials, such as dielectric transductors or multistimuli-sensors, whose response can be modulated in a wide range of temperatures and pressuresThe authors are grateful for the financial support from Ministerio de Economía y Competitividad MINECO (MINECO) ENE2014-56237-C4-4-R and Xunta de Galicia under the project GRC2014/042. J. M. B.-G. also wants to thank Barrié Foundation for a predoctoral fellowship and S. Y.-V. to the Xunta de Galicia for a postdoctoral grant (Plan I2C)S

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Memoria final del PIMCD UCM 2020/2021 número 31