Influence of pH and ionic strength on removal processes of a sedimentary humic acid in a suspension of vermiculite

Abate, Gilberto; Masini, Jorge C.

doi:10.1016/s0927-7757(03)00418-7

Cited by 80 publications

(56 citation statements)

References 28 publications

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“…8, the increase in the concentration of NaCl from 0.00-0.10 mol/L caused the increase in adsorption amount of PC from 80.0 to 94.3 mg/g. The increase of adsorption amount with the increase in ionic strength can be explained by several mechanisms: (1) the decrease of molecular size of PC, caused by the increase of ionic strength due to minimalization of the electrostatic repulsion between ionized carboxyl groups, facilitated the adsorption (Chen 2004); (2) ionization of NaCl in the aqueous dispersion binds water molecules and the competition between PC molecules and water molecules for adsorption sites occurred at lower level (Seki 2006); (3) the significant increase in adsorption amount of PC at high ionic strength may be due to loss of the colloidal stability, leading to coagulation and precipitation of the PC and further co-sedimentation with the bentonite particles during the intense centrifugation (Abate 2003); (4) in addition, at higher ionic strength the solubility of PC was lower, favoring the mass transfer of PC from the solution phase to the solid phase of bentonite (Zhou 1994). …”

Section: Effect Of Ionic Strength On Adsorptionmentioning

confidence: 99%

Adsorption of Polycarboxylate-based Superplasticizer onto Natural Bentonite

Wang

Zheng

Feng³

et al. 2012

ACT

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The adsorption of polycarboxylate-based superplasticizer onto natural bentonite was investigated in aqueous solution using a batch technique with respect to initial adsorbate concentration, contact time, temperature, pH value and ionic strength. Lower pH value and higher ionic strength were proved to be favorable for the adsorption. The pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to describe the kinetic data and the kinetic constants were also determined. The experimental data fitted the pseudo-second-order model well. The Langmuir, Freundlich and Dubinin-Radushkevich (D-R) equations were applied to describe the equilibrium isotherm and the isotherm constants were also evaluated. The langmuir model agreed with the experimental well. Thermodynamic parameters ( Δ G 0 , Δ H 0 and Δ S 0 ) indicated that the adsorption was endothermic and physical in nature.

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Section: Effect Of Ionic Strength On Adsorptionmentioning

confidence: 99%

Adsorption of Polycarboxylate-based Superplasticizer onto Natural Bentonite

Wang

Zheng

Feng³

et al. 2012

ACT

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“…Further preparation of the K + saturated vermiculite (KVT) is described elsewhere. 4 The cation exchange capacity (CEC) was determined by the method of sodium saturation, 20 resulting the value of 1.17 ± 0.01 mmol g -1 (n = 3).…”

Section: Vermiculitementioning

confidence: 99%

“…[1][2][3] Besides to adsorption onto activated carbon, sorption onto clay minerals is among the main processes that have been studied aiming the removal of NOM from aqueous medium. [4][5][6][7][8][9][10] Humic and Fulvic acid (HA and FA) are the major components of NOM, but HA is more easily removed from waters. This fact has been explained by the intrinsic characteristics of humic substances such as the higher molar volume of humic acids.…”

Section: Introductionmentioning

confidence: 99%

Sequential injection analysis as a tool for on-line monitoring the sorption of fulvic acid onto modified vermiculite

Abate¹,

Santos

Colombo

et al. 2006

J. Braz. Chem. Soc.

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Este trabalho apresenta um sistema de injeção seqüencial associado a uma unidade de filtração tangencial e um detector na região do ultravioleta, para monitorização em linha da sorção de ácido fúlvico em duas vermiculitas modificadas. Com o sistema proposto foi possível melhorar a resolução temporal, na investigação do tempo de equilíbrio necessário para o sistema sorventesoluto atingir o equilíbrio químico. A sorção em uma suspensão 10 g L -1 de vermiculita, modificada por intercalação com poliidroxicátions de Fe(III) foi rápida, atingindo o equilíbrio após 4 min de tempo de contato, resultando em sorção de 97,9 % do ácido fúlvico inicialmente presente em uma solução 10 mg L -1 . A sorção na suspensão 10 g L -1 de vermiculita organofílica, obtida por troca iônica com brometo de hexadeciltrimetilamônio apresentou uma rápida taxa inicial de sorção, seguida por processos de dessorção e readsorção, atingindo o equilíbrio após 30 min de tempo de contato, com sorção de 98% do ácido fúlvico inicialmente presente em uma solução 10 mg L -1 . This paper presents a sequential injection system associated with a tangential filtration unit and an ultraviolet detector for on-line monitoring of fulvic acid sorption onto two modified vermiculites. With the proposed approach it was possible to improve the temporal resolution in the investigation of the equilibrium time needed for the system sorbent-sorbate to reach the chemical equilibrium. Sorption onto a 10 g L -1 suspension of vermiculite material modified by intercalation of polyhydroxycations of Fe(III) was fast, reaching the equilibrium after 4 min of contact time, and resulting in sorption of 97.9 % of the initial 10 mg L -1 fulvic acid concentration. Sorption onto a 10 g L -1 suspension of an organic vermiculite which was modified by ion exchange with hexadecyltrimethylammonium bromide exhibited a fast initial rate of sorption, followed by desorption and re-adsorption processes, reaching the equilibrium after 30 min of contact time, with sorption of 98% of the initial 10 mg L -1 fulvic acid concentration.

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“…The material was ground, and the fraction between 0.27 and 56 μm was separated by decantation according to described elsewhere. 31 Approximately five grams of this vermiculite were treated with 0.050 mol L -1 HCl solution under agitation in an orbital shaker for 30 min. The solids were centrifuged and washed once with 40 mL of deionized water.…”

Section: Sample Preparationmentioning

confidence: 99%

Sorption of atrazine, propazine, deethylatrazine, deisopropylatrazine and hydroxyatrazine onto organovermiculite

Abate

Masini

2005

J. Braz. Chem. Soc.

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hexadeciltrimetil-amônio (HDTMA-VT) no espaço interlamelar. A VTK bruta teve interação desprezível com AT, PROP e DEA, interação moderada com DIA e forte interação com HAT. No caso do material HDTMA-VT as porcentagens de remoção em meio aquoso (concentrações iniciais entre 0,05 a 1,00 mg L -1 ) foram: 56 -63% para AT, 43 -45% para DEA, 30 -24% para DIA, 12 -19% para HAT e 77 -78% para PROP. As taxas de sorção de AT, DEA e PROP em HDTMA-VT foram significativamente aumentadas com relação a VTK. Força iônica e pH tiveram pouca influência na sorção. A dessorção dos compostos previamente sorvidos sobre os minerais HDTMA-VT variou de 20 a 30% após um tempo de contacto de 24 h.The interaction of atrazine (AT), propazine (PROP), deethylatrazine (DEA), deisopropylatrazine (DIA) and hydroxyatrazine (HAT) was studied with the clay mineral vermiculite saturated with K + (VTK), and with the mineral modified by insertion of hexadecyltrimethyl-ammonium (HDTMA-VT) in the interlayer of VTK. The crude VTK exhibited negligible interaction with AT, PROP and DEA, moderate interaction with DIA and strong interaction with HAT. For the HDTMA-VT materials, removal percentages from aqueous medium for initial concentrations between 0.05 and 1.00 mg L -1 were 56 to 63% for AT, 43 to 45% for DEA, 12 to 19% for HAT and 77 to 78% for PROP. Sorption of AT, DEA and PROP onto HDTMA-VT was significantly enhanced in comparison to VTK. Ionic strength and pH had no significant influence on the sorption process. Desorption of all compounds from HDTMA-VT after 24 h of contact time was between 20 and 30% of the amount initially adsorbed.

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Influence of pH and ionic strength on removal processes of a sedimentary humic acid in a suspension of vermiculite

Cited by 80 publications

References 28 publications

Adsorption of Polycarboxylate-based Superplasticizer onto Natural Bentonite

Adsorption of Polycarboxylate-based Superplasticizer onto Natural Bentonite

Sequential injection analysis as a tool for on-line monitoring the sorption of fulvic acid onto modified vermiculite

Sorption of atrazine, propazine, deethylatrazine, deisopropylatrazine and hydroxyatrazine onto organovermiculite

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