Adsorção de metais pesados em serragem de madeira tratada com ácido cítrico

Rodrigues, Rafael Falco; Trevenzoli, Rafael Lopes; Santos, Luciano Rodrigo Gomes; Leão, Versiane Albis; Botaro, Vagner Roberto

doi:10.1590/s1413-41522006000100004

Cited by 29 publications

(29 citation statements)

References 8 publications

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“…An alteration in peak intensity at 1740 cm -1 was observed for the modifi ed material, indicating an increase in the carboxyl group amount. These data corroborate the study performed by Rodrigues [19] in which the appearance of carboxyl groups was demonstrated for the metal adsorption on NaOH-and citric-acid-treated Paraju sawdust. These groups are important because they become negative depending on pH variation, and contribute to greater interactions with the metal ions [26].…”

Section: Adsorption As a Function Of Temperaturesupporting

confidence: 92%

“…After treated with NaOH, the peach palm sheath residue was modifi ed with citric acid (C 6 H 8 O 7 ), according to the procedure recommended by Rodrigues [19]. The peach palm sheath residue was immersed in a 1.2 mol L -1 citric acid solution (proportion: 8.3 mL of solution/1 g of sample), agitated for 30 min, and then the supernatant was discarded.…”

Section: Modifi Cation With Naoh and Citric Acid (C)mentioning

confidence: 99%

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Lead(II) adsorption by peach palm waste

Salvado

Campanholi

Fonseca

et al. 2012

Desalination and Water Treatment

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A B S T R AC TThe aim of the present study was to investigate the effi ciency of chemical treatments for peach palm sheaths, targeting the treatment of Pb(II) contaminated aqueous effl uents. The modification was done with sodium hydroxide and citric acid to introduce carboxyl groups. Pb(II) adsorption was evaluated in function of pH, contact time, metal concentration, desorption ability and thermodynamic factors. An infrared adsorption peak was observed at 1740 cm -1 due to the presence of carboxyl groups. The required time for the system to reach equilibrium was about 150 min, and the Pb(II) adsorption followed a pseudo-second-order kinetic model. The Langmuir model showed the best fi t for the adsorption data. The maximum adsorption capacity and minimum desorption rate values of 65.32 mg g -1 and 74.72%, respectively were obtained for the NaOH-modifi ed peach palm sheath. After using the chemical treatment, the adsorbent properties improved and the system became more spontaneous, as confi rmed by low Gibbs energy values.

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Section: Adsorption As a Function Of Temperaturesupporting

confidence: 92%

Section: Modifi Cation With Naoh and Citric Acid (C)mentioning

confidence: 99%

Lead(II) adsorption by peach palm waste

Salvado

Campanholi

Fonseca

et al. 2012

Desalination and Water Treatment

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“…These modifications increase the water absorption and retention capacity throughout an interaction with modifying agents and active sites generation (Liang et al, 2013;R. F. Rodrigues, Trevenzoli, Santos, Leão & Botaro, 2006)avaliou-se a capacidade da madeira Paraju (Manilkara longifolia.…”

Section: Modifying Methods Of Natural Fibers For Hydrogels Productionmentioning

confidence: 99%

Natural fibers for hydrogels production and their applications in agriculture

Serna-Cock¹,

Guancha-Chalapud²

2017

Acta Agron.

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This paper presents a review on hydrogels applied to agriculture emphasizing on the use of natural fibers. The objectives were to examine, trends in research addressed to identify natural fibers used in hydrogels development and methods for modifying natural fibers, understand factors which determine the water retention capacity of a hydrogel. Consequently, this paper shows some methodologies used to evaluate the hydrogels efficiency and to collect in tables, relevant information in relation to methods of natural fibers modification and hydrogel synthesis. It was found that previous research focused on hydrogels development processed with biodegradable polymers such as starch, chitosan and modified natural fibers, cross-linked with potassium acrylate and acrylamide, respectively. In addition, current researches aimed to obtaining hydrogels with improved properties, which have allowed a resistance to climatic variations and soil physicochemical changes, such as pH, presence of salts, temperature and composition. In fact, natural fibers such as sugarcane, agave fiber and kapok fiber, modified with maleic anhydride, are an alternative to obtain hydrogels due to an increasing of mechanical properties and chemically active sites. However, the use of natural nanofibers in hydrogels, has been a successful proposal to improve hydrogels mechanical and swelling properties, since they give to material an elasticity and rigidity properties. A hydrogel efficiency applied to soil, is measured throughout properties as swellability, mechanical strength, and soil water retention. It was concluded that hydrogels, are an alternative to the current needs for the agricultural sector.Key words: Hydrogels, methods of modifying fiber, nanofibers, superabsorbent, water retention capacity. ResumenEn el presente artículo se presenta una revisión de literatura sobre hidrogeles aplicados a la agricultura, haciéndose mayor énfasis en el uso de fibras vegetales. Los objetivos fueron examinar las tendencias en la investigación, identificar las fibras naturales utilizadas en el desarrollo de hidrogeles, mostrar los métodos de modificación de fibras naturales para la elaboración de hidrogeles, entender los factores que determinan la capacidad de retención de agua de un hidrogel, mostrar algunas metodologías empleadas para evaluar la eficiencia de un hidrogel y recopilar en tablas, información relevante en relación a métodos de modificación de fibras naturales y de síntesis de hidrogeles. Se encontró que las investigaciones se orientan al desarrollo de hidrogeles elaborados a bases de polímeros biodegradables como almidón, quitosano y fibras vegetales modificadas, entrecruzadas con acrilato de potasio y acrilamida. Además, las investigaciones apuntan a la obtención de hidrogeles con propiedades mejoradas, que permitan resistir las variaciones climáticas y los cambios fisicoquímicos del suelo como el pH, la presencia de sales, temperatura y composición. Fibras naturales como caña de azúcar, fibra de agave y fibra de kapoc, modificadas con ...

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“…Inicialmente, foram trituradas e peneiradas (peneira Bertel, 24 mesh) visando obter uma granulometria homogênea. Posteriormente, foram realizados dois tipos de modificação: um apenas com NaOH (E-S, M-S) e o outro com NaOH mais ácido cítrico (E-SAC, M-SAC); as modificações foram realizadas segundo procedimento proposto por Rodrigues et al (2006).…”

Section: Methodsunclassified

Biossorção de cobre utilizando-se o mesocarpo e o endocarpo da macadâmia natural e quimicamente tratados

Boas

Casarin

Caetano

et al. 2012

Rev. bras. eng. agríc. ambient.

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2+). The chemical changes in the biosorbent with sodium hydroxide (NaOH) and with NaOH and citric acid were evidenced by infrared spectroscopy by the appearance of peaks in 1710 and 1420 cm -1 and by scanning electron microscopy, observed an increase of roughness on the surface. The best results of the adsorption were observed in mesocarp modified with NaOH, in pH equal to 5. An equilibrium time adsorbent -adsorbate was 140 min, in addition, the system followed a kinetic model of pseudo-second order and the maximum adsorption capacity was 28.82 mg g -1 . The isotherms for the residues modified with NaOH followed the Langmuir model and the modified with acid were adjusted to the Freundlich model. It was found that the adsorption process was energetically spontaneous due to negative values for the Gibbs energy and the adsorbent has a high capacity of desorption, so this material can be reused. Therefore, this residue is an excellent material to equip future filters for removal of copper II.

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Adsorção de metais pesados em serragem de madeira tratada com ácido cítrico

Cited by 29 publications

References 8 publications

Lead(II) adsorption by peach palm waste

Lead(II) adsorption by peach palm waste

Natural fibers for hydrogels production and their applications in agriculture

Biossorção de cobre utilizando-se o mesocarpo e o endocarpo da macadâmia natural e quimicamente tratados

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