27 documents found, page 1 of 3
Zeolite modification for optimizing Fenton reaction in methylene blue dye degra...
Carvalho, Ana P.; Costa, José; Martins, Angela; Fonseca, António; Neves, Isabel C.; Nunes, NelsonTextile dyes often prove resistant to conventional wastewater treatment processes because of their complex molecular structures. Advanced oxidation methods, such as the Fenton reaction, have thus been recognized as a promising approach for environmental remediation by decomposing these pollutants. This work aimed to study the efficacy of modified zeolites as catalysts in the Fenton reaction for dye degradation,...
Hierarchical zeolites prepared Using a surfactant-mediated strategy: ZSM-5 vs. ...
Martins, Angela; Amaro, Beatriz; Santos, M. Soledade C. S.; Nunes, Nelson; Elvas Leitao, Ruben; Carvalho, Ana P.Hierarchical ZSM5 and Y zeolites were prepared through a surfactant-mediated strategy with NH4OH changing the duration of the treatment and the amount of CTAB surfactant and taking as reference multiples of the critical micellar concentration (CMC). The materials were characterized using powder X-ray diffraction, N2 adsorption isotherms at -196 degrees C, and SEM and TEM microscopy. The catalytic performance wa...
Insights into the thermochemistry of paracetamol in ternary mixtures of eutecti...
Lopes, Andreia; Nunes, Nelson; Elvas Leitao, Ruben; Martins, FilomenaSolution enthalpies of paracetamol, ΔsolH, in choline chloride–ethylene glycol–water mixtures were evaluated at 298.15 K. Solvatochromic UV–vis shifts of fve diferent probes (4-nitroaniline, 4-nitroanisole, 4-nitrophenol, N,N-dimethyl-4-nitroani line and 2,6-diphenyl-4-(2,4,6-triphenylpyridinium-1-yl)phenolate) were also assessed for the same mixtures at the same temperature in order to compute the correspondin...
Study of the ternary mixture of methanol/formamide/acetonitrile via solvatochro...
Nunes, Nelson; Elvas Leitao, Ruben; Martins, FilomenaFollowing previous studies, the ternary mixture of methanol/formamide/acetonitrile (MeOH/Formamide/MeCN) was studied using the UV-Vis absorption spectra at 298.15 K with a set of five probes, 4-nitroaniline, 4-nitroanisole, 4-nitrophenol, N,N-dimethyl-4-nitroaniline and 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenolate (Reichardt betaine dye), for a total of 22 mole ternary fractions. In addition, nine mole...
Low cost modified biochars from peanut shells for the removal of textile dyes
Nunes, Nelson; Santos, Maria Teresa; Martins, AngelaBiochars from peanut shell wastes were produced and further modified with KOH and HNO3 to efficiently remove two industrial dyes, Mordant Orange 1 and Green Malachite oxalate, in aqueous systems. The materials were characterized through elemental analysis, N2 adsorption isotherms, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and the determination of the point of zero charg...
Zeolites and related materials as catalyst supports for hydrocarbon oxidation r...
Martins, Angela; Nunes, Nelson; Carvalho, Ana P.; Martins, LuisaCatalytic oxidation is a key technology for the conversion of petroleum-based feedstocks into useful chemicals (e.g., adipic acid, caprolactam, glycols, acrylates, and vinyl acetate) since this chemical transformation is always involved in synthesis processes. Millions of tons of these compounds are annually produced worldwide and find applications in all areas of chemical industries, ranging from pharmaceutica...
Exploring the effect of hierarchical porosity in BEA zeolite in Friedel-Crafts ...
Nunes, Nelson; Carvalho, Ana P.; Elvas Leitao, Ruben; Martins, Filomena; Fernandes, Auguste; Rocha, João; Martins, AngelaHierarchical BEA zeolite was prepared through desilication or desilication followed by acid treatment. The catalytic performance of BEA zeolite samples was evaluated using Friedel-Crafts acylations with two substrates of different molecular sizes, furan (5.7 Å) and benzofuran (6.9 Å), in the presence of acetic anhydride as acylating agent. The application of the simplified Langmuir Hinshelwood kinetic model sho...
Exploring the Effect of Hierarchical Porosity in BEA Zeolite in Friedel-Crafts ...
Nunes, Nelson; Carvalho, Ana P.; Elvas-Leitão, Ruben; Martins, Filomena; Fernandes, Auguste; Rocha, João; Martins, AngelaHierarchical BEA zeolite was prepared through desilication or desilication followed by acid treatment. The catalytic performance of BEA zeolite samples was evaluated using Friedel-Crafts acylations with two substrates of different molecular sizes, furan (5.7 Å) and benzofuran (6.9 Å), in the presence of acetic anhydride as acylating agent. The application of the simplified Langmuir-Hinshelwood kinetic model sho...
Friedel-crafts acylation reaction over hierarchical Y zeolite modified through ...
Martins, Angela; Neves, Vera; Moutinho, João; Nunes, Nelson; Carvalho, AnaFriedel-Crafts acylation reaction was studied under mild conditions using hierarchical HY zeolite samples prepared through surfactant mediated technology, in the presence of NH4OH, using CTAB or DTAB as surfactants and changing the duration of treatment from 6 to 48 h. The materials were characterized by powder X-ray diffraction, low temperature N2 adsorption isotherms, SEM microscopy and pyridine adsorption fo...
Coal fly ash waste, a low-cost adsorbent for the removal of Mordant Orange dye ...
Rosa, Teresa; Martins, Angela; Santos, Maria Teresa; Trindade, Teodoro; Nunes, NelsonIn this study, a coal fly ash material generated in a Portuguese coal thermal powerplant was tested as a low-cost adsorbent to remove dye molecules. Pre-treatment of the coal fly ash samples was not performed in order to reduce end use cost. Physical and chemical characterization revealed their inert nature and low effects lixiviation in aqueous media. Preliminary adsorption studies include adsorbent quantity, ...