INSTITUTO DE QUÍMICA

URI Permanente desta comunidade

https://repositorio.ufcat.edu.br/handle/tede/12

O Instituto de Geografia é atualmente composto por 03 (três) cursos de graduação: Química - Bacharelado, Química - Licenciatura e Química Industrial e 2 (dois) Programas de pós-graduação stricto sensu: Mestrado em Química e Doutorado em Química. Este Instituto compõem a estrutura da Universidade Federal de Catalão.

Navegar

Agora exibindo 1 - 7 de 7

Avaliação da adsorção de contaminantes emergentes pela casca de banana e folhas da Typha Angustifolia L.
(Universidade Federal de Goiás, 2015-04-10) Sousa, Priscila Afonso Rodrigues de; Coelho, Luciana Melo; http://lattes.cnpq.br/0074807107314789; Coelho, Luciana Melo; Richter, Eduardo Mathias; Freitas, Sílvia de Sousa
This paper describes the use of analytical methodology for removal of emerging contaminants sulfamethoxazole (SMX), 17α-ethinylestradiol (EE2) and estrone (E1) in water samples. Was used to remove the natural adsorbents Banana and Typha angustifolia L.in raw and treated in acidic medium. The detection and quantification was performed by high performance liquid chromatography (English, HPLC). There was a characterization of bioadsorventes by Infrared Spectroscopy East and X-ray diffraction The point of zero charge of in natura banana peels and treated with HCl was approximately 5.6 and 4.3, respectively, while point of zero charge of Typha angustifolia in natura leaves and treated with HCl was approximately 5.5 and 4.5, respectively. It was determined that the pH only influences the adsorption exerted SMX, and the pH 2 and 8 were most suitable. However, we chose to work with natural pH of the mixtures of the compounds (pH = 5.25). This study used multivariate methods (full 23 factorial design and response surface) to verify the best chemical variables. The optimized and used for construction of isotherms conditions were: cattail in kind (m = 0.38 g; t = 65 min), cattail HCl (m = 0.75 g; t = 64 min), fresh banana (m = 0, 55g, t = 62 min) and banana HCl (m = 0.76g; t = 66 min). There was the determination of LD figures of merit (SMX = 0.02 mg L-1, EE2 = 0.03 mg L-1, E1 = 0.03 mg L-1) QL (SMX = 0.05 mg L-1, EE2 = 0.05 mg L-1, E1 = 0.05 mg L-1), the selectivity was determined by building fortified calibration curves with water samples. The linearity was determined by the correlation coefficient (r = 0.99), recovery values were between 59.9% and 93.6% for the compounds and accuracy of results presented at most 14.7%. The proposed methodology has been applied to real matrix with removal percentages close to 100%.
Avaliação da fibra da bucha vegetal (Luffa cylindrica) e das folhas de taboa (Typha angustifolia L.) como materiais adsorventes para a remoção do agrotóxico tebuconazol de água contaminada
(Universidade Federal de Goiás, 2019-03-18) Silva, Thiago Felipe; Freitas, Silvia de Sousa; http://lattes.cnpq.br/4503172443143993; Freitas, Silvia de Sousa; Alves, Vanessa Nunes; Sarmento, Antover Panazzolo
Agrochemicals are industrialized products made up of a broad junction of chemicals used to combat pest resistance in plantations. The high consumption and the inappropriate disposal of these products can generate great environmental impacts. Adsorption processes employing alternative materials have been evaluated to remove them from the environment, especially from water sources for human consumption. In this work, the adsorption capacity of the materials: bush (Luffa cylindrica) and taboa (Typha angustifolia L.) was evaluated for the removal of the tebuconazole pesticide from aqueous medium. The analytical methodology used to quantify the pesticide in the solution, after the removal, was High Performance Liquid Chromatography with UV-vis detector (HPLC-UV). The values of LD and LQ in the chromatographic method were 0.01 mg L-1 and 0.10 mg L-1 , respectively. The materials were characterized by the FTIR technique, being observed in both materials the presence of functional groups characteristic of lignocellulosic compounds. The micrographs (SEM) indicated the heterogeneity and irregularity of the surface in both materials. The pH at the zero charge point (pHPCZ) was 6.15 for bush (Luffa cylindrica) and 6.62 for taboa (Typha angustifolia L.). The ability to remove tebuconazole from the aqueous medium by the materials was evaluated as a function of the adsorbent dosage, contact time and concentration of the pesticide. The dosages of 20 and 10 g L-1 were used in the adsorption tests with the bush (Luffa cylindrica) and taboa (Typha angustifolia L.), respectively. The kinetic study showed that the adsorption equilibrium was obtained after 40 minutes of contact and the experimental data were better adjusted by the Avrami model, for both materials. Regarding the study of tebuconazole concentration, it was observed that the removal is little influenced by the increase in tebuconazole concentration in the medium, remaining relatively constant in the concentration range evaluated, for both materials. The experimental data were well adjusted by all models of isotherms evaluated (Langmuir, Freundlich and Sips), with R 2> 0.99. The maximum adsorption capacity (Qmax) of tebuconazole was 8.5651 mg g-1 for bush (Luffa cylindrica) and 13.6419 mg g-1 for taboa (Typha angustifolia L.).The use of the adsorbents to remove the pesticide in natural water sample presented results very similar to those observed when using deionized water, showing that the removal efficiency of these materials is not affected by the type of aqueous matrix. The alternative column adsorption process showed satisfactory removal results (~ 51% removal for bush and ~ 75% removal with taboa), in a significantly shorter time (3-4 min) in relation to the batch process (40 min). Thus, it can be concluded that the adsorbent materials evaluated, bush (Luffa cylindrica) and the taboa (Typha angustifolia L.) can be used for the removal of the tebuconazole pesticide from aqueous medium.
Avaliação do uso de serragem de madeira tratada com ácido como bioadsorvente para a remoção de Diclofenaco de Sódio em meio aquoso
(Universidade Federal de Goiás, 2015-08-13) Silva, Lícia Aparecida; Coelho, Luciana Melo; http://lattes.cnpq.br/0074807107314789; Coelho, Luciana Melo; Rezende, Hélen Cristine de; Freitas, Silvia de Sousa
The present work describes the development of an analytical method for the removal of contaminant emerging Sodium Diclofenac (DCF) present in aqueous solutions. For the removal thereof, it is used as a natural adsorbent sawdust treated in acid medium. The detection and quantification of the analyte were Performed by High-Performance Liquid Chromatography (English, HPLC). The material was characterized according to the techniques of Infrared Spectroscopy and X-Ray Diffraction. The Point of Zero Charge (PZC) was obtained both for the sawdust treated in acid medium, and for the same in kind, obtaining values of 4.8 and 5.5, respectively. We chose to work with the adsorbent treated with acid in natural pH of the solution (6.43), since the adsorption was quite satisfactory (86%). It was determined the LD figures of merit (0.06 mg L-1) and LQ (0.2 mg L-1). The linearity was determined by construction of standard curves prepared in solvent and prepared curves with water samples fortified with the DCF standard. The obtained correlation coefficient was quite satisfactory (r = 0.9999) and the recovery values were between 86% and 117% to the study drug. It used Full Factorial Planning 23 for optimization of chemical variables that can have an effect on the adsorption process. The results obtained by the Pareto chart showed that the only variable that exerted influence on the adsorption was the mass of adsorbent. Therefore, it was determined by univariate optimization, as being 600 mg. To study the adsorption kinetics, it was determined the equilibration time of 180 min, and following the adsorption pseudosegunda-order model. The isotherm obtained was linearized and the result indicated that the adsorption follows the Langmuir model, ie, chemical adsorption occurs monolayer.
Desenvolvimento de método adaptado de extração com ponteiras descartáveis para determinação de íons Pb(II) e Mn(II) utilizando taboa (Typha angustifólia L.) como adsorvente
(Universidade Federal de Goiás, 2020-12-18) Ferreira, Marina Mesquita; Alves, Vanessa Nunes; http://lattes.cnpq.br/7058376443471599; Alves, Vanessa Nunes; Lemos, Valfredo Azevedo; Freitas, Sílvia de Sousa
In this work, the extraction technique with disposable tips (DPX - from English disposable pipette extraction) was used using Typha angustifolia L. (cattail) as an adsorbent. An adapted DPX method was developed for the determination of Pb(II) and Mn(II) ions in aqueous samples, using the Flame Atomic Absorption Spectrometry (FAAS) technique for quantification. The characterization of the cattail was performed through X-Ray Diffraction, Infrared Spectroscopy, X-Ray Fluorescence Spectroscopy, Determination of the pH at the Zero Charge Point and Buoyancy, with results consistent with those observed in the literature. The zero load point of the material was determined at 6.39. The pH of the solution was univariate optimized by selecting the solutions of Pb(II) and Mn(II) ions at a concentration of 1.0 mg L-1 at pH 8. Tests to optimize the parameters that influence the adsorption and desorption of the ions were made in a multivariate manner. Through Doehlert planning, it was possible to obtain optimal values for mass of adsorbent and number of adsorption cycles, being defined in 30 mg and 7 cycles, respectively, for Pb(II) and Mn(II) ions and the concentration of HNO3 and number of desorption cycles, in 0.8 mol L-1 and 7 cycles. The kinetic study indicated that the adsorption of the Pb(II) and Mn(II) ions obey a pseudo-first order and Avrami kinetics, respectively. The maximum adsorption capacity was obtained through the construction of adsorption isotherms, with values of 29.17 and 5.64 mg g-1 being found for the Pb(II) and Mn(II) ions, respectively. Under optimized conditions the extraction method presented detection limits of 17.51 μg L-1 (Pb (II)) and 35.02 μg L-1 (Mn (II)), quantification limits of 58.37 μg L-1 (Pb (II)) and 116.7 μg L-1 (Mn (II)), and a pre-concentration factor of 10 (Pb (II)) and 2 (Mn (II)), being a linear range of 116.7 to 2000 μg L-1 method for Mn (II) and from 58.37 to 2500 μg L-1 for Pb (II). Accuracy was evaluated separately in terms of repeatability and reproducibility, obtaining D.P.R. values of 0.31 and 0.25% for Pb (II), respectively, and 7.00 and 9.88% for Mn (II), respectively. The evaluation was evaluated by means of recovery tests in river water collected near a mining company, recovery values in the range of 80-120% and through the use of certified reference materials, indicating high reliability of the method.
Desenvolvimento de uma metodologia para determinação de Pb2+ em matrizes aquosas utilizando nanopartículas magnéticas
(Universidade Federal de Goiás, 2018-04-20) Silva, Carolina Aparecida de Sousa; Alves, Vanessa Nunes; http://lattes.cnpq.br/7058376443471599; Alves, Vanessa Nunes; http://lattes.cnpq.br/7058376443471599; Coltro, Wendell Karlos Tomazelli; Coelho, Luciana Melo
The iron oxide (Fe3O4) nanoparticles are promising adsorbents and, in this work, they were synthesized, characterized and applied as adsorbents in the adsorption of lead ions (Pb2+) using solid phase magnetic extraction (MSPE). The iron oxide was synthesized by the coprecipitation method and the obtained nanoparticles presented the crystalline phase of the oxide, being proved by the characterization by X-Ray Diffraction, X-ray Dispersive Energy and Absorption Spectroscopy in the Infrared region. In order to obtain information on the surface charge of the synthesized material, the pH at the zero loading point (pHPCZ) was determined indicating that the oxide surface is negatively charged at pH values above 9.4. Once the best pH (9.0) for adsorption was defined, the influence of the variables agitation time and mass of the adsorbent were evaluated, fixing them in 4 min and 3.0 mg respectively, in order to obtain the best conditions of the adsorption. adsorption process. The maximum adsorption capacity was obtained by the construction of adsorption isotherms, and a value of 31.60 mg.g1 was found. Through the kinetic study, it was observed that the adsorption obeys a pseudo-first-order kinetics. After the adsorption was optimized, the best desorption parameters were evaluated, aiming the development of an extraction/preconcentration method. Thus, 500μL of 0.5 mol.L-1 nitric acid was used as the eluent. The analytical performance was evaluated by means of the parameters, limit of detection (L.D.), limit of quantification (L.Q.), precision (D.P.R) and values found were 5.44 μg.L-1 ; 16.48 μg.L-1 and 0.25%, respectively, with the linear range of the method being 16.48 -500 μg.L-1 . Finally, the accuracy of the method was evaluated from recovery tests on samples of mineral water, micellar water and facial makeup with recovery values in the range of 95.94 - 118%. In addition, analyzes of certified water reference material (APS-1071) were also made to verify the accuracy of the proposed method.
Estudo do bagaço de cevada e da palha de milho como materiais adsorventes alternativos para remoção do agrotóxico carbaril de meio aquoso contaminado
(Universidade Federal de Goiás, 2018-08-17) Milhomem, Karoline Pinto; Freitas, Sílvia de Sousa; http://lattes.cnpq.br/4503172443143993; Sarmento, Antover Panazzolo; Coelho, Luciana Melo
In this dissertation, the materials corn straw and barley bagasse were investigated as alternative adsorbents for removal of the carbaryl pesticide from aqueous medium. For this, both materials were ground to obtain uniform particles (granulometry between 20 and 48 mesh) and treated with hydrated ethyl alcohol. The quantification of the carbaryl pesticide was made by High Efficiency Liquid Chromatography with UV-vis detector. The values of LD and LQ for the determination of the carbaryl pesticide by liquid chromatography using the method used were 0.01 mg L-1 and 0.10 mg L-1, respectively. The characterization of the adsorbent materials by FTIR showed the presence of the functional groups: hydroxyl, carbonyl and methyl, very common in lignocellulosic materials. The pH at the zero loading point (pHPCZ) was 7.08 for barley bagasse and 6.44 for corn straw. The adsorption capacity of the investigated materials was evaluated under different parameters such as material dose (g L-1), contact time between the pesticide solution and the adsorbent material (min) and the concentration of the pesticide in the solution (mg L-1). An alternative adsorption procedure was also proposed with the adsorbents packaged in a column where different doses of the adsorbents were evaluated and finally the adsorption process was evaluated using natural water samples. From the study of the dose of the materials the dose of 20 g L-1, equivalent to 200 mg of the adsorbent material in 10 mL of solution was selected, where 45.1% of the carbaryl was obtained when the barley bagasse was used and 49.2% when corn straw was used. For both adsorbents the kinetic study showed that the adsorption of the carbaryl agrochemical is best represented by the Avrami kinetic model, indicating that the adsorption of the carbaryl is not constant, but follows multiple orders. The maximum adsorption capacity (Qmax) was obtained by the construction of adsorption isotherms, where it was verified that the experimental data of the process of adsorption of the carbaryl by the barley bagasse is better represented by the Langmuir model providing a value of Qmax of 6, 5244 mg g-1. For corn straw, the Sips model was the most adequate with a Qmax value of 1.2625 mg g -1. In the column adsorption procedure the barley bagasse was efficient in all the doses evaluated, obtaining practically the same rate of removal as the procedure performed in batch mode, however in a much shorter time. As for the adsorbent corn straw, the removal through the column procedure was much less effective, suggesting that for this material the batch procedure is more adequate. In the adsorption study using natural water samples as an aqueous matrix, it was verified that the adsorption process of the carbaryl by both adsorbents can be affected by the pH of the medium and also by the presence of other compounds present in the aqueous matrix. In general, the results indicate that the barleybagasse and corn straw materials can be used as adsorbent materials in the treatment of aqueous medium contaminated with the carbaryl pesticide.
Resíduos agroindustriais como adsorventes para remoção de azul de metileno em meio aquoso
(Universidade Federal de Goiás, 2016-06-08) Oliveira, Fabiano Mendonça de; Melo , Edmar Isaias de; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4736951H0; Coelho , Luciana Melo; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4794563A2; Coelho , Luciana Melo; Alves , Vanessa Nunes; Silva , Sidnei Gonçalves da; Melo , Edmar Isaias de
The intensification of human actions, consumption, production and exploitation of raw materials, coupled with rapid population growth and development of industrial activity have caused major environmental impacts, affected the quality of water, soil and human health. The activities of the textile industry generally consume a lot of water, generating a high volume of waste, contributing to the increase in account-level determinants. Some of these contaminants show toxicity even at low concentrations, the dyes. Adsorption has been identified as a promising technique for the removal of dyes from effluents. The organic residues are low cost alternative materials, since considerable quantities thereof are discarded in the environment and have already reported the potential of these materials as adsorbents in removing pollutants. Therefore, this study was to evaluate the use of coconut fiber, bagasse from sugarcane and orange peel as adsorbents in removing the methylene blue dye in an aqueous medium. For both the adsorbent materials were subjected to different treatments using HCl, NaOH and hexane. The raw and processed materials were characterized using the techniques of scanning electron microscopy (SEM), Infrared Spectroscopy in the region and Rays Diffraction X. The parameters evaluated in the adsorption study particle size of the material, pH, agitation time , amount of adsorbent material and adsorption kinetic mechanism of adsorption equilibrium. Optimized kinetic data were fitted to the models of pseudo first order, pseudo second order, intraparticle diffusion and chemisorption, where we found that the most appropriate model was the pseudo second order. The experimental data of the isotherms were drawn to the models of Langmuir and Freundlich. The balance of experimental data fitted to the Freundlich model. The maximum adsorption capacity observed for the coconut fiber raw and treated with HCl, 166.67 and 104.8 mg g-1, respectively. The results show that the organic residues have potential application as adsorbent materials in the remediation of organic pollutants in particular, dyes in wastewater.

Navegar

Navegando INSTITUTO DE QUÍMICA por Assunto "Adsorção"

Resultados por página

Opções de Ordenação