Publications

Export 49 results:
Sort by: Author [ Title  (Asc)] Type Year
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 
K
Lyubchik, S, Lygina E, Lyubchyk A, Lyubchik S, Loureiro JM, Fonseca IM, Ribeiro AB, Pinto MM, Figueiredo AMSá.  2016.  The Kinetic Parameters Evaluation for the Adsorption Processes at ``Liquid–Solid'' Interface. Electrokinetics Across Disciplines and Continents: New Strategies for Sustainable Development. (Ribeiro, Alexandra B., Mateus, Eduardo P., Couto, Nazaré, Eds.).:81–109., Cham: Springer International Publishing Abstract

The kinetic parameters of the adsorption process at ``liquid–solid'' interface have been evaluated through the sets of time-based experiments of the Cr(III) adsorption under varying temperature, initial metal concentration, and carbon loading for two sets of the commercially available activated carbons and their post-oxidized forms with different texture and surface functionality.

M
Surra, E, Bernardo M, Lapa N, Esteves I, Fonseca I, Mota JP.  2018.  Maize cob waste pre-treatments to enhance biogas production through co-anaerobic digestion with OFMSW. Waste Management. 72:193-205. AbstractWebsite

In the present work, the enhancement of biogas and methane yields through anaerobic co-digestion of the pre-hydrolised Organic Fraction of Municipal Solid Wastes (hOFMSW) and Maize Cob Wastes (MCW) in a lab-scale thermophilic anaerobic reactor was tested. In order to increase its biodegradability, MCW were submitted to an initial pre-treatment screening phase as follows: (i) microwave (MW) irradiation catalysed by NaOH, (ii) MW catalysed by glycerol in water and alkaline water solutions, (iii) MW catalysed by H2O2 with pH of 9.8 and (iv) chemical pre-treatment at room temperature catalysed by H2O2 with 4 h reaction time. The pre-treatments cataysed by H2O2 were performed with 2% MCW (wMCW/v alkaline water) at ratios of 0.125, 0.25, 0.5 and 1.0 (wH2O2/wMCW). The pre-treatment that presented the most favourable balance between sugars, lignin, cellulose and hemicellulose solubilisations, as well as low production of phenolic compound and furfural (inhibitors), was the chemical pre-treatment catalysed by H2O2, at room temperature, with a ratio of 0.5 wH2O2/wMCW (Pre1). This Pre1 was then optimised testing reaction times of 1, 2 and 3 days at a different pH (11.5) and MCW percentage (10% w/v). The optimised pre-treatment that presented the best results, considering the same criteria defined above, was the one carried out during 3 days, at pH 9.8 and 10% MCW w/v (Pre2). The anaerobic reactor was initially fed with the hOFMSW obtained from the hydrolysis tank of an industrial AD plant. The hOFMSW was than co-digested with MCW submitted to the pre-treatment Pre1. In another assay, hOFMSW was co-digested with MCW submitted pre-treatment Pre 2. The co-digestion of hOFMSW + Pre1 increased the biogas yield by 38.9% and methane yield by 29.7%, when compared to the results obtained with hOFMSW alone. The co-digestion of hOFMSW + Pre2 increased biogas yield by 46.0% and CH4 yield by 36.3%. In both cases, the methane content obtained in the biogas streams was above 66% v/v. These results show that pre-treatment with H2O2, at room temperature, is a promising low cost way to valorize MCW through co-digestion with hOFMSW.

Ferreira, RC, Dias D, Fonseca I, Bernardo M, Pimenta JLCW, Lapa N, de Barros MASD.  2020.  Multi-component adsorption study by using bone char: modelling and removal mechanisms. Environmental Technology. :1-16.: Taylor & Francis AbstractWebsite
n/a
N
Surra, E, Nogueira MC, Bernardo M, Lapa N, Esteves I, Fonseca I.  2019.  New adsorbents from maize cob wastes and anaerobic digestate for H2S removal from biogas. Waste Management. 94:136-145. AbstractWebsite

Two activated carbons (ACs) were prepared by physical activation of Maize Cob Waste (MCW) with CO2, during 2 and 3 h (MCW(PA)2h and MCW(PA)3h, respectively). Two other ACs were prepared by chemical activation: a) MCW(LD) – MCW was impregnated with anaerobic liquid digestate (LD) and carbonized under N2 atmosphere; and b) CAR-MCW(LD) – previously carbonized MCW was impregnated with LD and carbonized under N2 atmosphere. All ACs were fully characterized for textural and chemical properties, and then used in dynamic H2S removal assays from real biogas samples. Regarding H2S removal, the ACs that were physically activated behaved much better than the impregnated ones: MCW(PA)3h and MCW(PA)2h showed H2S uptake capacities of 15.5 and 0.65 mg g−1, respectively, while MCW(LD) and CAR-MCW(LD) showed values of 0.47 and 0.25 mg g−1, respectively. This may indicate that textural properties (surface area and microporosity) are more important than mineral content in H2S removal. Effectively, both surface area and micropore volume were much higher for the samples of MCW(PA)3h (SBET = 820 m2 g−1 and Vmicro = 0.32 cm3 g−1) and MCW(PA)2h (SBET = 630 m2 g−1 and Vmicro = 0.21 cm3 g−1) than for the ACs that were chemically activated (SBET = 38.0 m2 g−1 and Vmicro = 0.01 cm3 g−1 for MCW(LD); SBET = 8.0 m2 g−1 and Vmicro = 0.01 cm3 g−1 for CAR-MCW(LD)). High oxygen content in MCW(PA)3h favoured the catalytic oxidation reaction of H2S, promoting its removal. The use of MCW as precursor and LD as activating agent of the ACs may contribute for the integrated management of maize wastes and to diversify the applications of anaerobic digestate.

Pérez-Mayoral, E, Matos I, Bernardo M, Fonseca IM.  2019.  New and Advanced Porous Carbon Materials in Fine Chemical Synthesis. Emerging Precursors of Porous Carbons. Catalysts. 9, Number 2 AbstractWebsite

The efficiency of porous carbons in fine chemical synthesis, among other application fields, has been demonstrated since both the porous structure and chemical surface provide the appropriated chemical environment favoring a great variety of relevant chemical transformations. In recent years, metal organic frameworks (MOFs) and covalent organic frameworks (COFs) have emerged as interesting opportunities in the preparation of porous carbons with improved physico-chemical properties. Direct calcination of MOFs or COFs, in the presence or not of others carbon or heteroatom sources, could be considered an easy and practical approach for the synthesis of highly dispersed heteroatom-doped porous carbons but also new porous carbons in which single atoms of metallic species are present, showing a great development of the porosity; both characteristics of supreme importance for catalytic applications. The goal of this review is to provide an overview of the traditional methodologies for the synthesis of new porous carbon structures together with emerging ones that use MOFs or COFs as carbon precursors. As mentioned below, the catalytic application in fine chemical synthesis of these kinds of materials is at present barely explored, but probably will expand in the near future.

Faria, P, Duarte P, Barbosa D, Ferreira I.  2017.  New composite of natural hydraulic lime mortar with graphene oxide. Construction and Building Materials. 156:1150-1157. AbstractWebsite

Recent studies show the incorporation of graphene oxide (GO) in cement composites. But these composites are frequently incompatible with original materials for building rehabilitation. To overcome this limitation, natural hydraulic lime mortars were used as matrix, and the influence of GO percentage and type of mixing was investigated. The influence on the microstructure, mechanical and physical properties was assessed. The best results were obtained with dispersed GO at concentrations of 0.05% and 0.1%. A slight improvement of mechanical and physical characteristics was achieved. This could lead to new mortars with improved properties that can be used for building rehabilitation.

O
Figueira, J, Loureiro J, Marques J, Bianchi C, Duarte P, Ruoho M, Tittonen I, Ferreira I.  2017.  Optimization of Cuprous Oxides Thin Films to be used as Thermoelectric Touch Detectors. ACS Applied Materials & Interfaces. 9:6520-6529., Number 7 AbstractWebsite

The electronic and optical properties of p-type copper oxides (CO) strongly depend on the production technique as it influences the obtained phases: cuprous oxide (Cu2O) or cupric oxide (CuO), the most common ones. Cu films deposited by thermal evaporation have been annealed in air atmosphere, with temperature between 225 and 375 °C and time between 1 and 4 h. The resultant CO films have been studied to understand the influence of processing parameters in the thermoelectric, electrical, optical, morphological, and structural properties. Films with a Cu2O single phase are formed when annealing at 225 °C, while CuO single phase films can be obtained at 375 °C. In between, both phases are obtained in proportions that depend on the film thickness and annealing time. The positive sign of the Seebeck coefficient (S), measured at room temperature (RT), confirms the p-type behavior of both oxides, showing values up to 1.2 mV·°C–1 and conductivity up to 2.9 (Ω·m)−1. A simple detector using Cu2O have been fabricated and tested with fast finger touch events.

P
Afonso, D, Ribeiro AFG, Araújo P, Vital J, Madeira LM.  2018.  Phenol in Mixed Acid Benzene Nitration Systems. Industrial & Engineering Chemistry Research. 57:15942-15953., Number 46 AbstractWebsite
n/a
Conceição, DS, Graça CAL, Ferreira DP, Ferraria AM, Fonseca IM, do Rego BAM, Teixeira ACSC, Ferreira VLF.  2017.  Photochemical insights of TiO2 decorated mesoporous SBA-15 materials and their influence on the photodegradation of organic contaminants. Microporous and Mesoporous Materials. 253:203-214. AbstractWebsite

Mesoporous silica, SBA-15, decorated with different amounts of TiO2 (anatase) were prepared by a sol-gel method followed by hydrothermal treatment and calcination, in the presence of a soft template, copolymer Pluronic 123. Tetraethyl orthosilicate (TEOS) was used as the SiO2 precursor and commercially available TiO2 anatase nanoparticles as the supported photocatalyst. The materials were characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDS), N2 adsorption-desorption isotherms, raman spectroscopy, ground state diffuse reflectance (GSDR), laser induced luminescence (LIL) and X-ray photoelectron spectroscopy (XPS). The zeta potentials of the pure SBA-15, TiO2/SBA-15 substrate and the commercial anatase sample were monitored through a complete range of pH values. All the nanomaterials developed in this work were studied in terms of their photoactivity in the UV range and in the visible range, separately. In the first case, hydroxyl radicals (OH) were confirmed to be the key active oxidizers in the photodegradation of the pesticide amicarbazone in aqueous medium. On the other hand, in the visible range, and following a dye sensitization process via a fluorescent rhodamine-like dye, two different mechanisms could be identified for the formation of the superoxide radical anion, O2−.

Matos, I, Bernardo M, Fonseca I.  2017.  Porous carbon: A versatile material for catalysis. Catalysis Today. 285:194-203. AbstractWebsite

Heterogeneous catalysis is an exciting field in constant development. New and improved catalysts that can both be effective and economical are always on demand. Activated carbons may well play an important role in this field, as they are a cheaper alternative while more environmentally benign. In this paper, a brief overview of the effort developed in the application of activated carbon as heterogeneous catalysts in various reactions is presented. Functionalised activated carbon has been used as catalyst for fine chemical reactions. Gas-phase reactions for NO, N2O and CO2 conversions were thoroughly studied using activated carbon as catalyst support. In situ characterization techniques proved to be valuable tools to understand carbon gasification mechanism.

Bernardo, M, Correa CR, Ringelspacher Y, Becker GC, Lapa N, Fonseca I, Esteves IAAC, Kruse A.  2020.  Porous carbons derived from hydrothermally treated biogas digestate. Waste Management. 105:170-179. AbstractWebsite

Porous carbons from digestate-derived hydrochar were produced, characterized and their performance to reclaim phosphate from water was evaluated as a preliminary approach to demonstrate their practical application. In a first step, the digestate was converted into hydrochars through hydrothermal carbonization by using two different pH conditions: 8.3 (native conditions) and 3.0 (addition of H2SO4). The resulting hydrochars did not present significant differences. Consecutively, the hydrochars were activated with KOH to produce activated carbons with enhanced textural properties. The resulting porous carbons presented marked differences: the AC native presented a lower ash content (20.3 wt%) and a higher surface area (SBET = 1106 m2/g) when compared with the AC-H2SO4 (ash content = 43.7 wt% SBET = 503 m2/g). Phosphorus, as phosphate, is a resource present in significative amount in wastewater, causing serious problems of eutrophication. Therefore, the performance of the porous carbons samples to recover phosphate – P(PO43−) – from water was evaluated through exploitation assays that included kinetic studies. The lumped model presented a good fitting to the kinetic data and the obtained uptake capacities were the same for both carbons, 12 mg P(PO43−)/g carbon. Despite the poorer textural properties of AC-H2SO4, this carbon was richer in Ca, Al, Fe, K, and Mg cations which promoted the formation of mineral complexes with phosphate anions. The results obtained in this work are promising for the future development of P(PO43−) enriched carbons that can be used thereafter as biofertilizers in soil amendment applications.

Godino-Ojer, M, Blazquez-García R, Matos I, Bernardo M, Fonseca IM, Mayoral PE.  2019.  Porous carbons-derived from vegetal biomass in the synthesis of quinoxalines. Mechanistic insights. Catalysis Today. AbstractWebsite

We report herein for the first-time acid biomass-derived carbons from vegetal biomass, with high developed porosity, prepared through integrating method comprising pyrolysis and surface phosphonation, able to efficiently catalyze the synthesis of quinoxalines from 1,2-diamines and α-hydroxi ketones, under aerobic conditions. The obtained results indicate that the reaction is mainly driven by a combination of acid function strength and textural properties in terms of conversion and selectivity. Furthermore, our experimental and theoretical observations suggest that the preferred reaction pathway for this transformation, in the presence of the investigated acid carbon catalysts, involves cascade reactions including imination reaction between reactants, successive imine-enamine and keto-enol tautomerisms, heterocyclization followed by dehydration, and aromatization. While the acid sites seem to be a relevant role in each reaction step, the system formed by activated carbon and molecular oxygen could be behind the last oxidative reaction to give the corresponding nitrogen heterocycles.

Godino-Ojer, M, Blazquez-García R, Matos I, Bernardo M, Fonseca IM, Pérez Mayoral E.  2020.  Porous carbons-derived from vegetal biomass in the synthesis of quinoxalines. Mechanistic insights. Catalysis Today. 354:90-99. AbstractWebsite

We report herein for the first-time acid biomass-derived carbons from vegetal biomass, with high developed porosity, prepared through integrating method comprising pyrolysis and surface phosphonation, able to efficiently catalyze the synthesis of quinoxalines from 1,2-diamines and α-hydroxi ketones, under aerobic conditions. The obtained results indicate that the reaction is mainly driven by a combination of acid function strength and textural properties in terms of conversion and selectivity. Furthermore, our experimental and theoretical observations suggest that the preferred reaction pathway for this transformation, in the presence of the investigated acid carbon catalysts, involves cascade reactions including imination reaction between reactants, successive imine-enamine and keto-enol tautomerisms, heterocyclization followed by dehydration, and aromatization. While the acid sites seem to be a relevant role in each reaction step, the system formed by activated carbon and molecular oxygen could be behind the last oxidative reaction to give the corresponding nitrogen heterocycles.

Dias, D, Lapa N, Bernardo M, Godinho D, Fonseca I, Miranda M, Pinto F, Lemos F.  2017.  Properties of chars from the gasification and pyrolysis of rice waste streams towards their valorisation as adsorbent materials. Waste Management. 65:186-194. AbstractWebsite

Rice straw (RS), rice husk (RH) and polyethylene (PE) were blended and submitted to gasification and pyrolysis processes. The chars obtained were submitted to textural, chemical, and ecotoxic characterisations, towards their possible valorisation. Gasification chars were mainly composed of ashes (73.4–89.8wt%), while pyrolysis chars were mainly composed of carbon (53.0–57.6wt%). Silicon (Si) was the major mineral element in all chars followed by alkaline and alkaline-earth metal species (AAEMs). In the pyrolysis chars, titanium (Ti) was also a major element, as the feedstock blends contained high fractions of PE which was the main source of Ti. Gasification chars showed higher surface areas (26.9–62.9m2g−1) and some microporosity, attributed to porous silica. On the contrary, pyrolysis chars did not present a porous matrix, mainly due to their high volatile matter content. The gasification bed char produced with 100% RH, at 850°C, with O2 as gasification agent, was selected for further characterization. This char presented the higher potential to be valorised as adsorbent material (higher surface area, higher content of metal cations with exchangeable capacity, and lowest concentrations of toxic heavy metals). The char was submitted to an aqueous leaching test to assess the mobility of chemical species and the ecotoxic level for V. fischeri. It was observed that metallic elements were significantly retained in the char, which was attributed mainly to its alkaline character. This alkaline condition promoted some ecotoxicity level on the char eluate that was eliminated after the pH correction.

Agostinho, DAS, Paninho AI, Cordeiro T, Nunes AVM, Fonseca IM, Pereira C, Matias A, Ventura MG.  2020.  Properties of κ-carrageenan aerogels prepared by using different dissolution media and its application as drug delivery systems. Materials Chemistry and Physics. 253:123290. AbstractWebsite

This work reports the synthesis of kappa-carrageenan aerogels using different dissolution and crosslinking media in order to evaluate its effects on the textural properties of the matrixes and further on the drug loading and release performance. The different aerogel samples were produced through the dissolution of the biopolymer in water with addition of potassium salts as crosslinking agents and, in two different ionic liquids (ILs) derived from imidazolium ion, being further dried with supercritical CO2. The samples were characterized by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), Nitrogen Adsorption-Desorption Analysis, Thermogravimetry (TGA) and Differential Scanning Calorimetry (DSC). The synthesized samples presented surface areas similar to the carrageenan aerogels being their structure constituted mainly by meso and macropores. The absence of ionic liquid in samples was demonstrated by DSC analysis and was corroborated by the cytotoxicity assays which revealed that cellular viability in Caco-2 cells was preserved. Tetracycline was used as a model drug and loaded in two of the prepared aerogels samples. The release experiments were performed with the composites to test in vitro drug release at physiologic pH. With a higher macroporosity, the kappa-carrageenan aerogel prepared by dissolution into ionic liquid showed a higher loading capacity than the one prepared by dissolution into water and a slightly higher release rate. The matrixes were considered to present a good potential to be used as biocompatible carriers on drug controlled delivery.

R
Godinho, D, Nogueira M, Bernardo M, Dias D, Lapa N, Fonseca I, Pinto F.  2019.  Recovery of Cr(III) by using chars from the co-gasification of agriculture and forestry wastes, Aug. Environmental Science and Pollution Research. 26:22723–22735., Number 22 AbstractWebsite

The aim of the present work was to assess the efficiency of biochars obtained from the co-gasification of blends of rice huskþinspace}+þinspace}corn cob (biochar 50CC) and rice huskþinspace}+þinspace}eucalyptus stumps (biochar 50ES), as potential renewable low-cost adsorbents for Cr(III) recovery from wastewaters. The two gasification biochars presented a weak porous structure (ABETþinspace}=þinspace}63–144 m2 g−1), but a strong alkaline character, promoted by a high content of mineral matter (59.8{%} w/w of ashes for 50CC biochar and 81.9{%} w/w for 50ES biochar). The biochars were used for Cr(III) recovery from synthetic solutions by varying the initial pH value (3, 4, and 5), liquid/solid (L/S) ratio (100–500 mL g−1), contact time (1–120 h), and initial Cr(III) concentration (10–150 mg L−1). High Cr(III) removal percentages (around 100{%}) were obtained for both biochars, due to Cr precipitation, at low L/S ratios (100 and 200 mL g−1), for the initial pH 5 and initial Cr concentration of 50 mg L−1. Under the experimental conditions in which other removal mechanisms rather than precipitation occurred, a higher removal percentage (49.9{%}) and the highest uptake capacity (6.87 mg g−1) were registered for 50CC biochar. In the equilibrium, 50ES biochar presented a Cr(III) removal percentage of 27{%} with a maximum uptake capacity of 2.58 mg g−1. The better performance on Cr(III) recovery for the biochar 50CC was attributed to its better textural properties, as well as its higher cation exchange capacity.

Madureira, J, Melo R, Verde SC, Matos I, Bernardo M, Noronha JP, Marga{\c c}a FMA, Fonseca IM.  2018.  Recovery of phenolic compounds from multi-component solution by a synthesized activated carbon using resorcinol and formaldehyde. Water Science and Technology. 77:456–466., Number 2: IWA Publishing AbstractWebsite

The adsorption of four phenolic compounds (gallic acid, protocatechuic acid, vanillic acid and syringic acid) is investigated using a synthesized mesoporous carbon on both single and multi-component synthetic solutions. Some correlation of the adsorption capacity of the carbon and the nature of adsorbate could be made, except for gallic acid whose concentration decrease seems to be not exclusively due to adsorption but also to polymerization reaction. In the multi-component mixture, negative effects in the adsorption capacity are observed probably due to competition for the active centers of the adsorbent surface. In desorption studies, ethanol presents better performance than water and acetonitrile. Vanillic acid is the compound with the higher adsorption and interestingly it is then possible to desorb a relatively high amount of it from the adsorbent, which may represent a possibility for a selective recovery of vanillic acid. These results present a potential way to treat the wastewater from the cork industry.

S
Cordeiro, T, Castiñeira C, Mendes D, Florence Danède, Sotomayor J, Fonseca IM, Gomes da Silva M, Paiva A, Barreiros S, Cardoso MM, Viciosa MT, Correia NT, Dionisio M.  2017.  Stabilizing Unstable Amorphous Menthol through Inclusion in Mesoporous Silica Hosts. Molecular Pharmaceutics. 14:3164-3177., Number 9 AbstractWebsite
n/a
Bernardo, MMS, Madeira CAC, dos Santos Nunes NCL, Dias DACM, Godinho DMB, de Jesus Pinto MF, do Nascimento Matos IAM, Carvalho APB, de Figueiredo Ligeiro Fonseca IM.  2017.  Study of the removal mechanism of aquatic emergent pollutants by new bio-based chars, Oct. Environmental Science and Pollution Research. 24:22698–22708., Number 28 AbstractWebsite

This work is dedicated to study the potential application of char byproducts obtained in the gasification of rice husk (RG char) and rice husk blended with corn cob (RCG char) as removal agents of two emergent aquatic contaminants: tetracycline and caffeine. The chars presented high ash contents (59.5–81.5{%}), being their mineral content mainly composed of silicon (as silica) and potassium. The samples presented a strong basic character, which was related to its higher mineral oxides content. RCG char presented better textural properties with a higher apparent surface area (144 m2 g−1) and higher micropore content (V micro = 0.05 cm3 g−1). The alkaline character of both chars promoted high ecotoxicity levels on their aqueous eluates; however, the ecotoxic behaviour was eliminated after pH correction. Adsorption experiments showed that RG char presented higher uptake capacity for both tetracycline (12.9 mg g−1) and caffeine (8.0 mg g−1), indicating that textural properties did not play a major role in the adsorption process. For tetracycline, the underlying adsorption mechanism was complexation or ion exchange reactions with the mineral elements of chars. The higher affinity of RG char to caffeine was associated with the higher alkaline character presented by this char.

T
Sharipova, AA, Aidarova SB, Bekturganova NY, Tleuova A, Kerimkulova M, Yessimova O, Kairaliyeva T, Lygina O, Lyubchik S, Miller R.  2017.  Triclosan adsorption from model system by mineral sorbent diatomite. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 532:97-101. AbstractWebsite

Adsorption of model systems of triclosan by mineral sorbent diatomite is studied. The triclosan equilibrium concentration was measured spectrophotometrically, the morphology of the diatomite characterized using scanning electron microscopy and the amount of the adsorbed triclosan on the diatomite quantified by a mass balance. Adsorption isotherms were analyzed according to the linear/nonlinear form of Langmuir, Freundlich, Sips and Toth isotherm models isotherms, using AMPL software. It is shown that nonlinear Langmuir and Sips isotherm model provided suitable fitting results and no pronounced difference in adsorption efficiency between isotherms measured after 1, 2 and 3days adsorption was observed. Determined maximum adsorption capacity of diatomite towards triclosan qs is 140mg/g. Averaged calculated values of ΔG are −9.9 and −9.6kJ/mol for Langmuir and Sips models respectively. The negative sign of such values indicates spontaneous, physical in nature adsorption.

Sharipova, AA, Aidarova SB, Bekturganova NE, Tleuova A, Schenderlein M, Lygina O, Lyubchik S, Miller R.  2016.  Triclosan as model system for the adsorption on recycled adsorbent materials. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 505:193-196. AbstractWebsite

The adsorption of triclosan as model system was studied to qualify activated carbon sorbents recycled from gas masks (civilian gas mask GP5). The triclosan equilibrium concentration was measured spectrophotometrically, the morphology of the activated carbon characterized by scanning electron microscopy, and the amount of the adsorbed triclosan on the activated carbon quantified by a mass balance method. Experimental isotherms were fitted by Langmuir, Freundlich and Sips adsorption models. It was obtained that the contact time is a crucial sorption parameter that provides information on the optimum adsorption efficiency. It was shown that the maximum efficiency of GP5 (88%) is obtained after 10days of adsorption at a maximal concentration of triclosan and carbon loading 1mg/l. No significant adsorption efficiency differences were measured after 5 and 10days of adsorption. The non-linear Sips isotherm, a combined Freundlich–Langmuir model, provides suitable fitting results. The observed remarkable adsorption capacity of activated carbon (GP5) towards triclosan adsorption (∼85mg/g) makes it a viable solution for wastewater treatment.

Castanheiro, JE, Fonseca IM, Ramos AM, Vital J.  2017.  Tungstophosphoric acid immobilised in SBA-15 as an efficient heterogeneous acid catalyst for the conversion of terpenes and free fatty acids. Microporous and Mesoporous Materials. 249:16-24. AbstractWebsite

Alkoxylation of α−pinene, β−pinene and limonene was performed in the presence of SBA-15-occluded tungstophosphoric acid (HPW). The HPW was immobilised in SBA-15 using the sol-gel method. The catalysts were characterised by N2 adsorption, FT-IR, Raman spectroscopy, X-Ray diffraction, ICP-AES and TEM. A series of catalysts with different heteropolyacid loadings ranging from 1.8 to 19.3 wt. % were prepared. PW4-SBA-15 (with 10.8 wt. %) exhibited the highest catalytic activity for the alkoxylation of α-pinene with ethanol. An approximately 53% selectivity to α-terpinyl ethyl ether was observed over the PW-SBA-15 catalysts. PW4-SBA-15 was also used as a catalyst for the alkoxylation of other terpenes, including β-pinene and limonene. The PW4-SBA-15 catalyst exhibited high catalytic stability for the alkoxylation of α-pinene with ethanol. PW4-SBA-15 was also used as a catalyst for the esterification of free fatty acids (i.e., palmitic, stearic and oleic acids) with ethanol. Good catalytic activity was observed for the PW4-SBA-15 catalyst with the different substrates used in the esterifications.

U
Lourenço, SC, Torres CAV, Nunes D, Duarte P, Freitas F, Reis MAM, Fortunato E, Moldão-Martins M, da Costa LB, Alves VD.  2017.  Using a bacterial fucose-rich polysaccharide as encapsulation material of bioactive compounds. International Journal of Biological Macromolecules. 104:1099-1106. AbstractWebsite

The potential of a bacterial exopolysaccharide named FucoPol, produced by the bacterium Enterobacter A47, as encapsulation matrix was explored. Spherical capsules with a smooth surface were produced by spray drying. The obtained microcapsules had average diameters ranging from 0.5 to 26.7μm and presented thin walls (thickness from 222 to 1094nm). The capsules were loaded with two bioactive compounds: gallic acid (GA) and oregano essential oil (OEO). Both bioactive materials were encapsulated in FucoPol particles, retaining their antioxidant activity after the drying process. Release studies showed that GA release in simulated gastric and intestinal fluids was faster than that of OEO, envisaging that the latter had established stronger interactions with the polymer matrix. These results suggest that FucoPol has a good potential for use as encapsulating material of bioactive compounds for application in several areas, including food, cosmetic or pharmaceutical products.

V
Bianchi, C, Ferreira LM, Loureiro J, Rodrigues A, Duarte P, Baptista AC, Ferreira IM.  2016.  Vanadium Pentoxide Alloyed with Graphite for Thin-Film Thermal Sensors, Mar. Journal of Electronic Materials. 45:1987–1991., Number 3 AbstractWebsite

The thermoelectric (TE) properties of vanadium pentoxide (V2O5) alloyed with graphite (G) were studied as a function of its incorporation percentage. Variable weight percentages of graphite powder (0–50{%}) were added to V2O5 powder and their mixtures were evaporated by a thermal evaporation technique to form thin films with a thickness in the range of 30–80 nm. In the infrared wavelength region, the transmittance of the obtained films increased as the G percentage was increased, while in the visible range, it decreased with G up to 10{%}. The TE properties were improved when G was in the range of 10–30{%}, while it decreased for the other percentages: Seebeck coefficient (S) changed from 0.6 mV/K to 0.9 mV/K and was zero with a G of 50{%}; the electrical conductivity varied slightly from 5 ($Ømega$m)−1 to 0.7 ($Ømega$m)−1 while the mobility improved from 0.07 cm2/V s to 1.5 cm2/V s and the respective carrier concentration was reduced, from 1 × 1018 cm−3 to 4 × 1016 cm−3. These films were applied as temperature sensors evaluating the thermovoltage as a function of thermal gradient between two electrodes, in which one was maintained at room temperature.