The Effect of Light Wavelength on CO2 Capture, Biomass Production and Nutrient Uptake by Green Microalgae: A Step Forward on Process Integration and Optimisation

Microalgae have drawn the attention of several researchers as an alternative to the traditional physicochemical CO2 capture methods, since they can convert CO2 and water into organic matter and release oxygen into the atmosphere. Microalgal growth can be improved by changing light supply, such as light intensity, wavelength, and photoperiod. In this study, the effect of different light wavelengths on CO2 capture, nutrient removal from a synthetic effluent and biomass production of Chlorella vulgaris, Tetradesmus obliquus and Neochloris oleoabundans was studied. The experiments were conducted with light-emitting diodes (LEDs) with different wavelengths: 380-750 nm (white), 620-750 nm (red) and 450-495 nm (blue). The maximum specific growth rate was obtained by N. oleoabundans with white LEDs (0.264 +/- 0.005 d(-1)), whereas the maximum biomass productivity (14 +/- 4 mg(dw) L-1 d(-1)) and CO2 fixation rate (11.4 mg(CO2) L-1 d(-1)) were obtained by C. vulgaris (also with white LEDs). Nitrogen and phosphorus removal efficiencies obtained under white light conditions were also the highest for the three studied microalgae

Performance of Graphene/Polydimethylsiloxane Surfaces against S. aureus and P. aeruginosa Single- and Dual-Species Biofilms

The increasing incidence of implant-associated infections has prompted the development of effective strategies to prevent biofilm formation on these devices. In this work, pristine graphene nanoplatelet/polydimethylsiloxane (GNP/PDMS) surfaces containing different GNP loadings (1, 2, 3, 4, and 5 wt%) were produced and evaluated on their ability to mitigate biofilm development. After GNP loading optimization, the most promising surface was tested against single- and dual-species biofilms of Staphylococcus aureus and Pseudomonas aeruginosa. The antibiofilm activity of GNP/PDMS surfaces was determined by the quantification of total, viable, culturable, and viable but nonculturable (VBNC) cells, as well as by confocal laser scanning microscopy (CLSM). Results showed that 5 wt% GNP loading reduced the number of total (57%), viable (69%), culturable (55%), and VBNC cells (85%) of S. aureus biofilms compared to PDMS. A decrease of 25% in total cells and about 52% in viable, culturable, and VBNC cells was observed for P. aeruginosa biofilms. Dual-species biofilms demonstrated higher resistance to the antimicrobial activity of GNP surfaces, with lower biofilm cell reductions (of up to 29% when compared to single-species biofilms). Still, the effectiveness of these surfaces in suppressing single- and dual-species biofilm formation was confirmed by CLSM analysis, where a decrease in biofilm biovolume (83% for S. aureus biofilms and 42% for P. aeruginosa and dual-species biofilms) and thickness (on average 72%) was obtained. Overall, these results showed that pristine GNPs dispersed into the PDMS matrix were able to inhibit biofilm growth, being a starting point for the fabrication of novel surface coatings based on functionalized GNP/PDMS composites

Fenton-type bimetallic catalysts for degradation of dyes in aqueous solutions

Dye compounds are becoming a problematic class of pollutants for the environment, so it is important to develop stable catalysts for their elimination. First, several studies were performed with different Y zeolites (NaY, (NH4)Y and USY) in order to select the best support for the preparation of the bimetallic catalysts. In particular, NaY zeolite was used as the support for Fe, Cu and Mn metals to prepare mono and bimetallic Fenton-type catalysts by the ion exchange method. The catalysts were characterized by several techniques, such as chemical analysis, nitrogen physisorption, X-ray diffraction (XRD), scanning electron microscopy (SEM) and cyclic voltammetry studies. Characterization results revealed that the metals were successfully ion-exchanged within the NaY zeolite. The prepared catalysts were tested for the aqueous-phase degradation of dye compounds (Procion yellow (PY) and Tartrazine (Tar)) at atmospheric pressure and different temperatures, using H2O2 as the oxidant. All the investigated samples were found to be active in degrading the dyes through the Fenton-type process; however, the oxidation rate was found to be higher in the presence of the bimetallic catalysts. CuFe-NaY displays the best mineralization rate for PY oxidation while MnFe-NaY shows the highest activity for Tar degradation. This work may provide further insight into the design of Fenton-type bimetallic catalysts with improved catalytic properties for environmental remediation.This research work has been developed under the scope of the projects: BioTecNorte (operation NORTE-01-0145-FEDER-000004), supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). This work also has been funded by national funds (Fundação para Ciência e Tecnologia, FCT), through the projects: PTDC/AAGTEC/5269/2014, Centre of Chemistry (UID/QUI/00686/2013 and UID/QUI/0686/2016) and Associate Laboratory LSRE-LCM-UIDB/50020/2020. OSGPS acknowledges FCT funding under the Scientific Employment Stimulus—Institutional Call CEECINST/00049/2018.info:eu-repo/semantics/publishedVersio

Catalytic and Photocatalytic Nitrate Reduction Over Pd-Cu Loaded Over Hybrid Materials of Multi-Walled Carbon Nanotubes and TiO2

TiO2 and carbon nanotube-TiO2 hybrid materials synthesized by sol-gel and loaded with 1%Pd−1%Cu (%wt.) were tested in the catalytic and photocatalytic reduction of nitrate in water in the presence of CO2 (buffer) and H2 (reducing agent). Characterization of the catalysts was performed by UV-Vis and fluorescence spectroscopy, X-ray diffraction, temperature programed reduction, N2 adsorption, and electron microscopy. The presence of light produced a positive effect in the kinetics of nitrate removal. Higher selectivity toward nitrogen formation was observed under dark condition, while the photo-activated reactions showed higher selectivity for the production of ammonium. The hybrid catalyst containing 20 %wt. of carbon nanotubes shows the best compromise between activity and selectivity. A mechanism for the photocatalytic abatement of nitrate in water in the presence of the hybrid materials was proposed, based in the action of carbon nanotubes as light harvesters, dispersing media for TiO2 particles and as charge carrier facilitators

Influence of carbon anode properties on performance and microbiome of Microbial Electrolysis Cells operated on urine

"Available online 15 February 2018"Anode performance of Microbial Electrolysis Cells (MECs) fed with urine using different anodes, Keynol (phenolic-based), C-Tex (cellulose-based) and PAN (polyacrylonitrile-based) was compared under cell potential control (1st assay) and anode potential control (2nd assay). In both assays, C-Tex MEC outperformed MECs using Keynol and PAN. C-Tex MEC under anode potential control (0.300V vs. Ag/AgCl) generated the highest current density (904mAm2), which was almost 3-fold higher than the Keynol MEC and 8-fold higher than the PAN MEC. Analysis of anodes textural, chemical and electrochemical characteristics suggest that the higher external surface area of C-Tex enabled higher current density generation compared to Keynol and PAN. Anodes properties did not influence significantly the microbial diversity of the developed biofilm. Nonetheless, C-Tex had higher relative abundance of bacteria belonging to Lactobacillales and Enterobacteriales suggesting its correlation with the higher current generation.This study was supported by the European Union's Seventh Programme for research, technological development and demonstration [Grant number 308535] and by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 [POCI-01- 0145-FEDER-006684], of Project RECI/BBB-EBI/0179/2012 [FCOMP01-0124-FEDER-027462], POCI-01-0145-FEDER-007679 [UID/CTM/ 50011/2013], and by BioTecNorte operation [NORTE-01-0145- FEDER-000004] funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. This work is a result of project “AIProcMat@N2020 - Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020”, with the reference NORTE-01-0145-FEDER-000006, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF) and of Project POCI-01-0145- FEDER-006984 e Associate Laboratory LSRE-LCM funded by ERDF through COMPETE2020 - Programa Operacional Competitividade e Internacionalizaçao (POCI) e and by national funds through FCT. The authors also would like to acknowledge the support of Wetsus, European Centre of Excellence for Sustainable Water Technology.info:eu-repo/semantics/publishedVersio

Optimization of iron-ZIF-8 catalysts for degradation of tartrazine in water by Fenton-like reaction

Optimization of iron zeolitic imidazole framework-8 (FeZIF-8) nanoparticles, as heterogeneous catalysts, were synthesized and evaluated by the Fenton-like reaction for to degrade tartrazine (Tar) in aqueous environment. To achieve this, ZIF-8 nanoparticles were modified with different iron species (Fe2+ or Fe3O4), and subsequently assessed through the Fenton-like oxidation. The effect of different parameters such as the concentration of hydrogen peroxide, the mass of catalyst and the contact time of reaction on the degradation of Tar by Fenton-like oxidation was studied by using the Box-Behnken design (BBD). The BBD model indicated that the optimum catalytic conditions for Fenton-like reaction with an initial pollutant concentration of 30ppm at pH 3.0 were T=40°C and 12mM of H2O2, 2g/L of catalyst and 4h of reaction. The maximum Tar conversion value achieved with the best catalyst, Fe1ZIF-8, was 66.5% with high mineralization (in terms of decrease of total organic carbon TOC), 44.2%. To assess phytotoxicity, the germination success of corn kernels was used as an indicator in the laboratory. The results show that the catalytic oxidation by Fenton-like reaction using heterogeneous iron ZIF-8 catalysts is a viable alternative for treating contaminated effluents with organic pollutants and highlighted the importance of the validation of the optimized experimental conditions by mathematical models.O.A. thanks to ERASMUS + Program for the mobility Ph.D. grant and A.R.B. thanks to Fundação para Ciência e Tecnologia, FCT (Portugal) for her Ph.D. grant (SFRH/BD/141058/2018). This research work has been funded by national funds funded through FCT/MCTES (PIDDAC) over the projects: LA/P/0045/2020 (ALiCE), UIDB/50020/2020 and UIDP/50020/2020 (LSRE-LCM), Centre of Chemistry (UID/QUI/0686/2020), CEB (UIDB/04469/2020) and project BioTecNorte (operation NORTE-01-0145-FEDER-000004), supported by the Northern Portugal Regional Operational Program (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF).info:eu-repo/semantics/publishedVersio

Degradation of pollutants in water by Fenton-like oxidation over LaFe-catalysts: Optimization by experimental design

The effect of different parameters such as temperature, type of catalyst and hydrogen peroxide (H2O2) concentration on the degradation of pollutants in water by Fenton-like oxidation was studied by using the Box-Behnken design (BBD), an effective statistical model to design the experiments. Concerning the heterogeneous catalysts, three bimetallic catalysts with lanthanum (La) and iron (Fe) ion-exchanged into zeolites (NaY and ZSM5) and a natural clay from Morocco were prepared and used for Fenton-like oxidation of organic pollutants in water. Tartrazine (Tar, a food coloring compound known as E102) and caffeine (Caf, a stimulant drug present in popular beverages such as coffee and tea) were selected as pollutants due to their presence in several commercial products for daily consumption. The BBD model indicated that the optimum catalytic conditions for Fenton-like reaction with an initial pollutant concentration of 30ppm at pH 3.0 were T=40°C and 90mM of H2O2. The maximum conversion values achieved with the best catalyst, LaFeZSM5, were 96.6% for Tar after 180min and 51.0% for Caf after 300min of reaction. To increase the conversion of Caf, a modified zeolite electrode was used for electro Fenton-like oxidation without H2O2, at room temperature.O.A. thanks to ERASMUS + Program for the mobility Ph.D. grant and O.B. thanks to Fundação para Ciência e Tecnologia, Portugal (FCT) for his Ph.D. grant (SFRH/BD/140362/2018).This research work has been funded by national funds funded through FCT/MCTES (PIDDAC) over the projects: LA/P/0045/2020 (ALiCE), UIDB/50020/2020 and UIDP/50020/2020 (LSRE-LCM), UIDB/04469/2020 (CEB) and by LA/P/0029/2020 (LABBELS), Centre of Chemistry (UID/QUI/0686/2020) and project BioTecNorte (operation NORTE-01-0145-FEDER-000004), supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF).info:eu-repo/semantics/publishedVersio

Acceleration of methane production by carbon nanotubes

Book of Abstracts of CEB Annual Meeting 2017[Excerpt] Carbon nanotubes and other conductive materials have been found to influence the rates of several anaerobic reactions. A range of different conductive carbon materials (CM) were reported to enhance methane production by anaerobic microbial communities. In most studies, the improvement of the overall process is attributed to the ability of these compounds to promote direct interspecies electron transfer (DIET) between bacteria, degrading more complex substrates, and methanogens, producing methane. The occurrence of DIET in the majority of these systems is not, however, proved and the effect of such conductive compounds on the activity of individual members, inside complex microbial communities, was never investigated. Thus, we herein present the results obtained when incubating pure cultures of methanogens, without any other microbial partner, in the presence of increasing concentrations of carbon nanotubes (CNT). Methane production from acetate, by the acetoclastic methanogens Methanosaeta concilii and Methanosarcina mazei, and from hydrogen plus carbon dioxide, by the hydrogenotrophic methanogens Methanospirillum hungatei and Methanobacterium formicicum, was accelerated, up to 17 times, in the presence of CNT [1]. Physical/chemical properties of the growth media changed in the presence of CNT, with redox potential decreasing with increasing CNT concentrations, and thus favouring methanogenesis. These findings show that CNT influences the microbial activity of methanogens in pure cultures and most likely this effect is extended to methanogens in complex communities as well, occurring in anaerobic bioreactors and in the environment. [...]info:eu-repo/semantics/publishedVersio

Genome of Herbaspirillum seropedicae Strain SmR1, a Specialized Diazotrophic Endophyte of Tropical Grasses

The molecular mechanisms of plant recognition, colonization, and nutrient exchange between diazotrophic endophytes and plants are scarcely known. Herbaspirillum seropedicae is an endophytic bacterium capable of colonizing intercellular spaces of grasses such as rice and sugar cane. The genome of H. seropedicae strain SmR1 was sequenced and annotated by The Paraná State Genome Programme—GENOPAR. The genome is composed of a circular chromosome of 5,513,887 bp and contains a total of 4,804 genes. The genome sequence revealed that H. seropedicae is a highly versatile microorganism with capacity to metabolize a wide range of carbon and nitrogen sources and with possession of four distinct terminal oxidases. The genome contains a multitude of protein secretion systems, including type I, type II, type III, type V, and type VI secretion systems, and type IV pili, suggesting a high potential to interact with host plants. H. seropedicae is able to synthesize indole acetic acid as reflected by the four IAA biosynthetic pathways present. A gene coding for ACC deaminase, which may be involved in modulating the associated plant ethylene-signaling pathway, is also present. Genes for hemagglutinins/hemolysins/adhesins were found and may play a role in plant cell surface adhesion. These features may endow H. seropedicae with the ability to establish an endophytic life-style in a large number of plant species

Fragrance carriers obtained by encapsulation of volatile aromas into zeolite structures

Supplementary data associated with this article can be found in the online version at doi: 10.1016/j.indcrop.2022.115397Encapsulation of fragrances into porous materials is a technique to preserve or mask the odor of aroma compounds as well as to enhance their thermal and oxidative stability. There is great interest in studying the potential of essential oil-derived fragrance carriers using low-cost materials such as zeolitic structures for healthcare, food, textiles or agricultural applications. Two zeolite structures, faujasite (FAU) and mordonite (MOR) were used as carriers for encapsulation of different fragrances present in essential oils, in order to prepare stable fragrance carriers. To this purpose, commercial vanillin (Van) was encapsulated in NaMOR, commercial D-limonene (Lim) and cinnamaldehyde (Cinn), extracted from cinnamon stick, were encapsulated into NaY and NaX, respectively, and methyl anthranilate (MA), a synthetized fragrance with a fruity grape scent, was encapsulated in NaY. The retention of fragrances in zeolite structures increased in the order NaX < NaY < MOR for cinnamaldehyde, limonene, methyl anthranilate or vanillin. The most promising fragrance carriers prepared, MAThe authors are grateful for funding through FCT (Foundation for Science and Technology, Portugal) under Project POCI-01-0145-FEDER-006958 for financial support to the Research Centres, CQ/UM (UID/ QUI/0686/2020), CBMA/UM (UIDB/04050/2020), LA/P/0045/2020 (ALiCE), UIDB/50020/2020 and UIDP/50020/2020 (LSRE-LCM), fun ded by national funds through FCT/MCTES (PIDDAC), and through project BioTecNorte (operation NORTE-01-0145-FEDER-000004), sup ported by the Northern Portugal Regional Operational Programme (NORTE 2020) under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund. The NMR spec trometer Bruker Avance III 400 is part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project No 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC). OSGPS acknowledges FCT funding CEECINST/00049/2018. We also thank the master students from the academic year 2017–18 of Master’s in Chemical Analysis and Charac terization Techniques (Universidade do Minho) for their contribution preparing the fragrance carriers samples.info:eu-repo/semantics/publishedVersio