http://repositorio.ufc.br/handle/riufc/440 Wed, 10 Jun 2026 21:29:26 GMT 2026-06-10T21:29:26Z http://repositorio.ufc.br/handle/riufc/79247 Título: Correlation between PSD and adsorption of anionic dyes with different molecular weigths on activated carbon Autor(es): Oliveira, José Carlos Alexandre de; Silvino, Pedro Felipe Gadelha; Nogueira Neto, José de Araújo; Silva Junior, Ivanildo José da; Lucena, Sebastião Mardônio Pereira de; Aguiar, José Eurânio Abstract: The correlation between the adsorption capacity of commercial activated carbons and the pore size distributions in the removal of anionic dyes was investigated. We performed experimental adsorption isotherms measurements of the anionic dyes reactive red 120 (RR120), procion red MX-5B (PRMX-5B) and acid blue 25 (AB-25) in the activated carbons WV1050, Norit R1 and Maxsorb. The activated carbons were carefully characterized by N2 adsorption at 77K and molecular simulation methods to obtain the PSDs and retention capacity of selected pores (8.9, 18.5 and 30.9Å). Batch experiments were carried out in order to obtain single component dye isotherms. We found that the proposed selected pores of the PSD directly correlates with adsorption capacity when the size of the dye molecule is compatible with the carbon pore size. Between RR120 and PRMX-5B we noted that dye chemistry strongly affect the retention capacity. Based on our results, the use of N2 derived PSD and molecular simulation of dye retention in selected pores can be a useful tool to guide to the optimization of carbon-based adsorbents for dye removal. Tipo: Artigo de Periódico Fri, 01 Jan 2016 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/79247 2016-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/79187 Título: Optimizing the enzymatic production of biolubricants by the Taguchi method: Esterification of the free fatty acids from castor oil with 2-ethyl-1-hexanol catalyzed by Eversa Transform 2.0 Autor(es): De Luna, Francisco Murilo Tavares; Monteiro, Rodolpho R.C; Rocha, Wesley S.; Vieira, Rodrigo S.; Melo Neta, Maria M.F. de; Soares, Jorge B.; Lafuente, Roberto Fernandez Abstract: The solvent-free esterification of the free fatty acids (FFAs) obtained by the hydrolysis of castor oil (a non-edible vegetable oil) with 2-ethyl-1-hexanol (a branched fatty alcohol) was catalyzed by different free lipases. Eversa Transform 2.0 (ETL) features surpassed most commercial lipases. Some process parameters were optimized by the Taguchi method (L16′). As a result, a conversion over 95% of the FFAs of castor oil into esters with lubricants properties was achieved under optimized reaction conditions (15 wt% of biocatalyst content, 1:4 molar ratio (FFAs/alcohol), 30 ◦C, 180 rpm, 96 h). The substrates molar ratio had the highest influence on the dependent variable (conversion at 24 h). FFAs/2-ethyl-1-hexanol esters were characterized regarding the physicochemical and tribological properties. Interestingly, the modification of the FFAs with 2-ethyl-1-hexanol by ETL increased the oxidative stability of the FFAs feedstock from 0.18 h to 16.83 h. The biolubricants presented a lower friction coefficient than the reference commercial mineral lubricant (0.052 ± 0.07 against 0.078 ± 0.04). Under these conditions, ETL catalyzed the oligomerization of ricinoleic acid (a hydroxyl fatty acid) into estolides, reaching a conversion of 25.15% of the initial FFAs (for the first time). Tipo: Artigo de Periódico Mon, 01 Jan 2024 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/79187 2024-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/79082 Título: Experimental designs for optimizing the purification of immunoglobulin G by mixed-mode chromatography Autor(es): Azevedo, Diana Cristina Silva de; Luna, Francisco Murilo Tavares de; Sousa, Pedro Lucas Rodrigues de; Tavares, Patricia A.; Teixeira, Elvis M.T.S; Lima Dias, Natalia Assumpcao; Lima, Micael de Andrade; Gondim, Diego R.; Silva Júnior, Ivanildo J. Abstract: The main aim of this study was to define the optimal adsorption and elution conditions for the purification of human immunoglobulin G (IgG) by mixed-mode chromatography using the multimodal resin Capto MMC. To this end, Central Composite Experimental Design (ED) was performed for both the adsorption and desorption stages. In the first case, the conditions were systematically studied in batch mode while in the latter case, these were performed in column. For both studies, the experimental design was conducted using high-purity human IgG samples. Buffer pH and concentration as well as the salt concentration were the parameters under study in the ED. Adsorption kinetics and equilibrium experiments were performed under the best conditions defined in the ED (phosphate buffer 60 mmol/L, pH 6.75, no salt). The equilibrium experimental data were fit to the Langmuir equation, with maximum uptake qmax equal to 549.2 mg/g. The qmax value found for IgG in Capto MMC was quite high as compared to other chromatographic techniques that employ single modes of interaction. Regarding elution, the best conditions were obtained with acetate buffer (56.40 mmol/L), pH 5.2 and 0.2 mol/L NaCl. An ultimate recovery of 46.96% for high-purity IgG was achieved. Thus, the effectiveness of Capto MMC for IgG adsorption and recovery could be confirmed. Moreover, electrophoretic runs in the human serum indicated that although co-elution of HSA and IgG proteins occurs, substantial HSA removal and a high IgG recovery were achieved in the elution step. Tipo: Artigo de Periódico Tue, 01 Jan 2019 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/79082 2019-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/79027 Título: ZnxCo(1− x) coatings from choline chloride-ethylene glycol deep eutectic solvent as electrocatalysts for hydrogen evolution reaction Autor(es): Luna, Francisco Murilo Tavares de; Rodriguez Junior, Deomar N.; Sousa, Natália Gomes; Oliveira, Thiago Mielle Brito Ferreira; Abreu, Dieric S.; Schwarzacher, Walther; Neto, Pedro de Lima; Correia, Adriana N. Abstract: Hydrogen has emerged as a clean and renewable energy and its production by water splitting is a promising production route. However, to meet the demand on a commercial scale, research focusing on more efficient electrocatalysts is necessary. In this work, new findings on Zn, Co and Zn-Co coatings produced in deep eutectic solvent based on choline chloride (ChCl) and ethylene glycol (EG) are reported. Varying the concentrations of Zn2+ and Co2+ ions in 1ChCl:2EG, crystalline electrodeposits with fine control of composition and morphology were obtained, and which present different reactivity to electrocatalyze the hydrogen evolution reaction (HER) in alkaline medium. The performance of metallic coatings is influenced by temperature, due to changes in viscosity, ionic diffusion coefficient and charge transport in the electrolyte. The results also revealed that increasing the Co content in the coatings, changes occur in the morphological organization, stability, and electrode area, which positively influence the hydrogen production. Among the different coatings tested (Zn, Co, Zn96-Co4 and Zn3-Co97), Zn3-Co97 was the most promising in terms of Tafel coefficient (108 mV dec–1), exchange current density (8.57 × 10− 6 A cm− 2) and overpotential estimated for HER (333 mV at 10 mA cm− 2) in 1 mol L–1 KOH at 298.15 K, although the other materials also showed electrochemical advantages over the unmodified Cu substrate. The reported data also reiterate the great electrochemical potential of metallic coatings for water splitting and complement the growing energy demand for hydrogen gas. Tipo: Artigo de Periódico Sun, 01 Jan 2023 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/79027 2023-01-01T00:00:00Z