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Your search keyword '"Gurgel, Leandro Vinícius Alves"' showing total 142 results
Start Over Author "Gurgel, Leandro Vinícius Alves" Publication Type Academic Journals
142 results on '"Gurgel, Leandro Vinícius Alves"'

23. Synthesis and application of sugarcane bagasse cellulose mixed esters. Part II: Removal of Co2+ and Ni2+ from single spiked aqueous solutions in batch and continuous mode

Author

Almeida, Francine Tatiane Rezende de, Elias, Megg Madonyk Cota, Xavier, Amália Luísa Pedrosa, Ferreira, Gabriel Max Dias, Silva, Isabela Almeida, Filgueiras, Jefferson Gonçalves, Azevedo, Eduardo Ribeiro de, Silva, Luis Henrique Mendes da, Gil, Laurent Frédéric, and Gurgel, Leandro Vinícius Alves

Published
2019
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44. Oxidized Renewable Materials for the Removal of Cobalt(II) and Copper(II) from Aqueous Solution Using in Batch and Fixed-Bed Column Adsorption.

Author

Rodrigues, Josilene Aparecida Vieira, Martins, Luide Rodrigo, Furtado, Laís Milagres, Xavier, Amália Luísa Pedrosa, Almeida, Francine Tatiane Rezende de, Moreira, Ana Luísa da Silva Lage, Melo, Tânia Márcia Sacramento, Gil, Laurent Frédéric, and Gurgel, Leandro Vinícius Alves

Subjects
ADSORPTION kinetics, AQUEOUS solutions, ADSORPTION (Chemistry), ADSORPTION capacity, COBALT, COPPER
Abstract

Batch and continuous adsorption of Co2+ and Cu2+ from aqueous solutions by oxidized sugarcane bagasse (SBox) and oxidized cellulose (Cox) were investigated. The oxidation reaction of sugarcane bagasse and cellulose was made with a mixture of H3PO4‒NaNO2 to obtain SBox and Cox, with the introduction of high number of carboxylic acid functions, 4.5 and 4.8 mmol/g, respectively. The adsorption kinetics of Co2+ and Cu2+ on SBox and Cox were modeled using two models (pseudo-first-order and pseudo-second-order) and the rate-limiting step controlling the adsorption was evaluated by Boyd and intraparticle diffusion models. The Sips and Langmuir models better fitted the isotherms with values of maximum adsorption capacity Q max of 0.68 and 0.37 mmol/g for Co2+ and 1.20 and 0.57 mmol/g for Cu2+ adsorption on Cox and SBox, respectively. The reuse of both spent adsorbents was evaluated. Adsorption of Cu2+ and Co2+ on SBox in continuous was evaluated using a 22 factorial design with spatial time and initial metal concentration as independent variables and Q max and effective use of the bed as responses. The breakthrough curves were very well described by the Bohart–Adams original model and the Q max values for Co2+ and Cu2+ were 0.22 and 0.55 mmol/g. SBox confirmed to be a promising biomaterial for application on a large scale. [ABSTRACT FROM AUTHOR]

Published
2020
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45. Ethanol–water organosolv delignification of liquid hot water (LHW) pretreated sugarcane bagasse enhanced by high–pressure carbon dioxide (HP–CO2).

Author

Gurgel, Leandro Vinícius Alves, Pimenta, Maria Teresa Borges, and Curvelo, Antonio Aprigio da Silva

Subjects
*BAGASSE, *ETHANOL, *HOT water, *DELIGNIFICATION, *SUGARCANE, *PHYSIOLOGICAL effects of carbon dioxide
Abstract

Organosolv delignification assisted by high–pressure carbon dioxide (HP–CO 2 ), a low cost, non–corrosive and recoverable compound was evaluated as a potential green pretreatment technology for lignin extraction from liquid hot water (LHW) pretreated sugarcane bagasse to produce fermentable sugars in a lignocellulosic biorefinery concept. In this study, LHW pretreated bagasse (180 °C for 20 min with a liquid–to–solid ratio ( LSR ) of 9 (v/w)) was delignified with an ethanol–water mixture (1:1, v/v) and HP–CO 2 as a co–solvent at milder temperatures (111.7–168.3 °C) and times (23.8–66.2 min) at a LSR of 5 (v/w). To evaluate the effects of varying operational conditions on the lignin content and delignification extent, while preserving the glucan fraction, a 2 2 central composite design was used as a factorial planning. Solid fractions with low lignin contents (7.35% and 10.78%) and high delignification extents (82.5% and 72.2%) with good glucan preservations (84.6% and 85.3%) were obtained at 140 °C for 45 min and 111.7 °C for 45 min, respectively. These solid fractions were subjected to enzymatic hydrolysis, yielding enzymatic conversions of 60.8% and 63.7%, respectively. [ABSTRACT FROM AUTHOR]

Published
2016
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46. Activated carbons from agricultural byproducts (pine tree and coconut shell), coal, and carbon nanotubes as adsorbents for removal of sulfamethoxazole from spiked aqueous solutions: Kinetic and thermodynamic studies.

Author

Tonucci, Marina Caldeira, Gurgel, Leandro Vinícius Alves, and Aquino, Sérgio Francisco de

Subjects
*ACTIVATED carbon, *ANTIBACTERIAL agents, *CARBON nanofibers, *AQUEOUS solutions, *NANOTUBES
Abstract

In this study, four different adsorbent materials: commercial powdered activated carbon (PAC) from pine tree (PAC-I) and coconut shell (PAC-III) agricultural crop wastes, coal (PAC-II), and carbon nanotubes (CNT) were tested and compared for the removal of sulfamethoxazole (SMX) from spiked aqueous solutions. The kinetic, extrathermodynamic, and thermodynamic parameters for the adsorption of SMX on PACs and CNT were also determined. The results indicate that PAC-I was the best adsorbent for SMX adsorption. SMX adsorption was only favorable with PAC-I and CNT, leading to Gibbs free energies in the range of −39 to −44 kJ mol −1 and showing that the adsorption process was spontaneous in all temperature ranges (15–45 °C) tested. Langmuir model best described SMX adsorption on PAC-I and led to maximum adsorption capacity of ∼131 mg g −1 (at 25 °C), which was ∼4.6 times higher than that observed for CNT. The mechanism of SMX adsorption on PAC-I and CNT was suggested with basis on thermodynamic and extrathermodynamic parameters. The kinetic studies showed the pseudo-second-order model best described SMX adsorption, yielding k 2 values of 0.0035 and 0.0016 g mg −1 min −1 for PAC-I and CNT, respectively. [ABSTRACT FROM AUTHOR]

Published
2015
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47. Enhancing liquid hot water (LHW) pretreatment of sugarcane bagasse by high pressure carbon dioxide (HP-CO2).

Author

Gurgel, Leandro Vinícius Alves, Pimenta, Maria Teresa Borges, and Curvelo, Antonio Aprigio da Silva

Subjects
*HOT water, *WATER treatment plants, *SUGARCANE, *BAGASSE, *CARBON dioxide, *GREEN technology, *HEMICELLULOSE
Abstract

Highlights: [•] LHW-HP-CO2 evaluated as a potential green technology for hemicelluloses extraction. [•] At 100°C for 30min and 115°C for 60min xylan equivalent ranged 10–12g/L. [•] At 115°C for 60min, the cellulose preservation achieved 97.2%. [•] Enzymatic hydrolysis yielded 30.43g/L glucose and 41.17% cellulose conversion. [ABSTRACT FROM AUTHOR]

Published
2014
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48. Application of Raw and Chemically Modified Biomasses for Heterogeneous Cu-Catalysed Conversion of Aryl boronic Acids to Phenols Derivatives.

Author

Torres, Fernanda Guimarães, Teodoro, Filipe Simões, Gurgel, Leandro Vinícius Alves, Bourdreux, Flavien, Zayene, Olfa, Gaucher, Anne, Gil, Laurent Frédéric, and Prim, Damien

Subjects
BORONIC acid derivatives, PHENOL derivatives, BORONIC acids, CELLULOSE
Abstract

This work describes the application of raw and chemically modified cellulose and sugarcane bagasse for ipso-hydroxylation of aryl boronic acids in environmentally friendly reaction conditions. The catalytic efficiency of five support-[Cu] materials was compared in forming phenols from aryl boronic acids. Our investigation highlights that the CEDA-[Cu] material (6-deoxy-6-aminoethyleneamino cellulose loaded with Cu) leads to the best results under very mild reaction conditions. The optimized catalytic sequence, allowing a facile transformation of boronic acids to phenols, required the mandatory and joint presence of the support, Cu2O, and KOH at room temperature. CEDA-[Cu] was characterized using 13C solid-state NMR, ICP, and FTIR. The use of CEDA-[Cu] accounts for the efficacious synthesis of variously substituted phenol derivatives and presents very good recyclability after five catalytic cycles. [ABSTRACT FROM AUTHOR]

Published
2022
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49. Characterization of depolymerized residues from extremely low acid hydrolysis (ELA) of sugarcane bagasse cellulose: Effects of degree of polymerization, crystallinity and crystallite size on thermal decomposition

Author

Gurgel, Leandro Vinícius Alves, Marabezi, Karen, Ramos, Luiz Antonio, and Curvelo, Antonio Aprigio da Silva

Subjects
*POLYMERIZATION, *HYDROLYSIS, *THERMAL analysis, *CHEMICAL decomposition, *SUGARCANE, *AGRICULTURAL wastes, *CELLULOSE, *BAGASSE
Abstract

Abstract: Sugarcane bagasse cellulose was subjected to the extremely low acid (ELA) hydrolysis in 0.07% H2SO4 at 190, 210 and 225°C for various times. The cellulose residues from this process were characterized by TGA, XRD, GPC, FTIR and SEM. A kinetic study of thermal decomposition of the residues was also carried out, using the ASTM and Kissinger methods. The thermal studies revealed that residues of cellulose hydrolyzed at 190, 210 and 225°C for 80, 40 and 8min have initial decomposition temperature and activation energy for the main decomposition step similar to those of Avicel PH-101. XRD studies confirmed this finding by showing that these cellulose residues are similar to Avicel in crystallinity index and crystallite size in relation to the 110 and 200 planes. FTIR spectra revealed no significant changes in the cellulose chemical structure and analysis of SEM micrographs demonstrated that the particle size of the cellulose residues hydrolyzed at 190 and 210°C were similar to that of Avicel. [Copyright &y& Elsevier]

Published
2012
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50. Delignification of sugarcane bagasse using glycerol–water mixtures to produce pulps for saccharification

Author

Novo, Lísias Pereira, Gurgel, Leandro Vinícius Alves, Marabezi, Karen, and Curvelo, Antonio Aprigio da Silva

Subjects
*SUGARCANE, *BAGASSE, *GLYCERIN, *WATER, *MIXTURES, *PULPING, *EXPERIMENTAL design, *TEMPERATURE effect
Abstract

Abstract: This paper describes the organosolv delignification of depithed bagasse using glycerol–water mixtures without a catalyst. The experiments were performed using two separate experimental designs. In the first experiment, two temperatures (150 and 190°C), two time periods (60 and 240min) and two glycerol contents (20% and 80%, v/v) were used. In the second experiment, which was a central composite design, the glycerol content was maintained at 80%, and a range of temperatures (141.7–198.3°C) and time (23–277min) was used. The best result, obtained with a glycerol content of 80%, a reaction time of 150min and a temperature of 198.3°C, produced pulps with 54.4% pulp yield, 7.75% residual lignin, 81.4% delignification and 13.7% polyose content. The results showed that high contents of glycerol tend to produce pulps with higher delignification and higher polyoses content in relation to the pulps obtained from low glycerol content reactions. In addition, the proposed method shows potential as a pretreatment for cellulose saccharification. [Copyright &y& Elsevier]

Published
2011
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