Adsorption of ethyl acetate onto modified clays and its regeneration with supercritical CO2

Cavalcante, André; Torres, Luis G.; Coelho, G. L. V.

doi:10.1590/s0104-66322005000100008

Cited by 15 publications

(16 citation statements)

References 7 publications

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“…Bentonite is one of the most efficient adsorbing agents for sorption of organic compounds (Cavalcante et al, 2005 andBelarbi andAl-Malack, 2010). Although cement-based S/S is a widely applied and well-established technique for the immobilization of organic hazardous constituents (Karamalidis and Voudrias, 2007) but S/S technology has run into difficulties when trying to solidify organic waste (Vipulanandan, 1995 andOuki andHills, 2002).…”

Section: Introductionmentioning

confidence: 99%

Stabilization and Solidification of a Clay Soil Contaminated with MTBE

2017

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Stabilization and solidification a clay soil contaminated with MTBE Abstract:This paper presents an investigation into stabilization and solidification of a clay soil contaminated with MTBE (Methyl Butyl Ether) using two different agents (cement and mixture of bentonite and cement) through a program of laboratory experiments. The samples were prepared in two stages. In the first stage they were prepared with 20 and 30% cement but in the second stage they were prepared with 20 and 30% mixtures of bentonite and cement (with ratios of bentonite to cement equal to 1:1 and 3:1).Unconfined compression tests (UCT) and leaching tests using GC (Gas Chromatography) apparatus were conducted on the samples that were prepared in the above two stages at different curing times. The results show that by using cement, the strength of the soil is increased. The results of the leaching tests on contaminated soil show a major reduction in the concentration of MTBE. Adding cement to contaminated soil causes reduction in concentration of MTBE but by increasing the curing time the concentration of MTBE is increased. It is also indicted that using combination of bentonite and cement leads to reduction in MTBE concentration and the amount of reduction is decreased by increasing the curing time. The bentonite-cement ratio of 3:1 is more effective than 1:1 in reducing the concentration of MTBE.

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Section: Introductionmentioning

confidence: 99%

Stabilization and Solidification of a Clay Soil Contaminated with MTBE

2017

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“…The presence of the HDTMA + ion inside the intercalated layer increases considerably the d 001 spacing of the original clay. The modified clay containing a small organic ion (TMA + ) behaved almost like the original clay (Cavalcante et al, 2005).…”

Section: Resultsmentioning

confidence: 99%

Desorption Processes: Supercritical Fluid Regeneration of Modified Clays

Mendes

Coelho

2005

Adsorption

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The main objective of this work is the study of the regeneration capacity of modified clays using carbon dioxide. These modified clays are used as organic compounds adsorbents. Modified clays were used to remove ethyl acetate from aqueous solutions. Structural changes on the montmorillonite clay after a treatment with quaternary amines were investigated. The experimental step was also done using a packed column with the clay contaminated by ethyl acetate and toluene. Different pressures and temperatures were employed, leading to different fluid conditions (gas, liquid and supercritical). The results obtained showed the influence of the density of the supercritical CO 2 and of the organic modifier in the desorption process. These data were modeled with a simple model and with models of first and second orders. The better results were reached using the second-order model. This study allows the scale-up of the desorption process for the regeneration of solid matrices using supercritical fluids. The modified clay capacity as a pollutant attenuator remained almost unchanged after a regeneration cycle.

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“…Bentonites are used in various fields of technical applications in civil engineering such as food, chemical and pharmaceutical industry (Kaufhold et al 2002). Modified clays are used as adsorbents in vegetable oil refinery and in the removal of organic compounds in waste water (Caualcante et al 2005). Organoclays have been categorized as the good adsorbents for toxic metals as Cr, Pb, Cd, Hg and Zn (Jahan et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of organoclay modified with cetylpyridinium chloride

Banik

Jahan

Mostofa

et al. 2015

Bangladesh J. Sci. Ind. Res.

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Bentonite has been subjected to modification through ion-exchange reaction by 1-cetylpyridinum chloride. The modified samples were studied by X-ray diffraction (XRD) technique, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The basal spacing of unmodified bentonite, determined by XRD was 14.99 Å and after modification it increased up to 16.97 Å and 16.22 Å at 1CEC and 2CEC. The FT-IR studies revealed structural differences between the modified and unmodified bentonite samples. The IR spectra of the modified bentonite showed the C-C stretching bands (1465 and 1462 cm -1 ) and C-H vibrations (near 2926 and 2852; 2854 cm -1 ). Results of the SEM study revealed a tendency towards lump formation and agglomeration of the organomodified clay particles of bentonite. The possibility of the use of new organoclay to adsorb oils from aqueous solution will be explored. Key words:Organoclay; Adsorption; Surfactant; Cation exchange capacity Available online at www.banglajol.info Bangladesh J. Sci. Ind. Res. 50(1), [65][66][67][68][69][70] 2015 *Corresponding author: E-mail: shanta_samina@yahoo.com Materials and methods MaterialsThe materials used for the synthesis of organoclay are bentonite from local market, 1-cetylpyridinum chloride, hydrochloric acid, acetic acid, sodium bicarbonate, ethanol, sodium chloride, sodium dithionite and hydrogen peroxide (30%) from Merck Germany. The surfactant used in this study is 1-cetylpyridinum chloride (CPC) with a purity of >96%. All the chemicals were used as received without any further purification. Organic solvents for the synthesis and characterization were AR grade and were obtained from Merck Germany. MethodBentonite clay sample was dried, grind and stored in a bottle. Purification of clay was done by the method of Tributh and Lagaly (Tributh and Lagaly, 1986). The cation exchange capacity (CEC) of the clay defined as the total amount of exchangeable cations that the soil can adsorb was estimated by Kjeldahl method (Cuadros and Linares, 1995). The CEC of purified bentonite was 110 meq/100g. Organoclay preparation and characterizationPurification of clay was done respectively by sodium-acetate acetic acid buffer, citrate buffer, sodium dithionite, sodium chloride, hydrochloric acid, sodium chloride and at last distilled water.For synthesis, 5g of purified bentonite was dispersed in 400 mL of water under continuous stirring for 1 h. The amount of surfactant added was calculated with the CEC value (110 meq/100 g clay) of bentonite. Desired amount of 1-cetylpyridinium was added to 200 mL of water in the separate container slowly. The reaction mixture was stirred for 4 hours at 80ºC. The resulting product was separated by filtration and washed with distilled water for 3 times. Then the product was washed with ethanol. Synthesized organoclay was dried in an oven at 80ºC for 48 hours and grind into powder. The concentrations of CPC were 1 CEC and 2 CEC of bentonite, respectively and labeled as OM1 and OM2.In Figure 1, chemical structure ...

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Adsorption of ethyl acetate onto modified clays and its regeneration with supercritical CO2

Cited by 15 publications

References 7 publications

Stabilization and Solidification of a Clay Soil Contaminated with MTBE

Stabilization and Solidification of a Clay Soil Contaminated with MTBE

Desorption Processes: Supercritical Fluid Regeneration of Modified Clays

Synthesis and characterization of organoclay modified with cetylpyridinium chloride

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