Impact of mineral micropores on transport and fate of organic contaminants: A review

Cheng, Hefa; Hu, Erdan; Hu, Yuanan

doi:10.1016/j.jconhyd.2011.09.008

Cited by 76 publications

(40 citation statements)

References 113 publications

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“…2), since it is well known that sorption and entrapment in small-size pores is a major mechanism making organic chemicals unavailable to soil microorganisms and protecting them from biodegradation (Barriuso et al, 1997;Pignatello and Xing, 1996). For example, as the diameters of the smallest bacteria in soils, sediments, and rocks are considered to be larger than 200 nm, they 15 cannot directly access the organic contaminants entrapped or sorbed in these tiny pores (Cheng et al, 2012). In this regard, mercury intrusion porosimetry measurements showed that while only 9-15% of the total porosity of soils 2 and 3 corresponded to pores with a pore radius r p < 100 nm, 50% of the total porosity of soil 1 corresponded to such small pores (Table 1).…”

Section: Accordingly Ef Values Ef= [S]/([s]+[r])mentioning

confidence: 99%

Environmental behavior of the enantiomers of the chiral fungicide metalaxyl in Mediterranean agricultural soils

Celis

Gámiz

Adelino

et al. 2013

Science of The Total Environment

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Improving the existing knowledge on the enantioselectivity of processes affecting chiral pesticide enantiomers in the environment is necessary to maximize the efficacy and minimize the environmental impact caused by the use of pesticides with chiral properties. In this work, the enantioselectivity of the sorption, degradation, and leaching processes of the chiral fungicide metalaxyl in three slightly alkaline, agricultural soils from southern Spain was studied. Batch sorption experiments indicated that the sorption of racemic-metalaxyl on soils, their clay (< 2 µm) fractions, and a number of model sorbents simulating naturally-occurring soil colloidal particles was non-enantioselective; the S-enantiomer was sorbed to the same extent as the R-enantiomer on all soil materials. Soil incubation experiments revealed that the R-enantiomer of metalaxyl was degraded faster than the S-enantiomer in all three soils, but the extent and enantioselectivity of metalaxyl degradation was soil-dependent, occurring more slowly and with less enantioselectivity in the fine-textured soil (soil 1) than in the coarsetextured soils (soils 2 and 3). For soils 2 and 3, S-and R-metalaxyl dissipation data were very well described by single first-order kinetics, whereas for soil 1 dissipation data were better fitted by two coupled first-order equations. It is suggested that sorption and entrapment of metalaxyl enantiomers in the abundant small-size pores of soil 1 (i.e., pore radius < 100 nm) could have resulted in a fraction of the fungicide of reduced bioavailability, and consequently, protected from enantioselective degradation. Metalaxyl leaching through soil columns was also enantioselective; the concentration of S-metalaxyl in all leachates collected was greater than that of R-metalaxyl. Despite being non-enantioselective, sorption influenced the enantioselectivity of metalaxyl leaching, as it determined the residence time of the fungicide within the soil column, and consequently, the extent and enantioselectivity of its degradation during leaching.

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Section: Accordingly Ef Values Ef= [S]/([s]+[r])mentioning

confidence: 99%

Environmental behavior of the enantiomers of the chiral fungicide metalaxyl in Mediterranean agricultural soils

Celis

Gámiz

Adelino

et al. 2013

Science of The Total Environment

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“…Nanoconfined liquids, which are of great interest in biology, geology, tribology and nanotechnology [1][2][3][4][5], exhibit a variety of surprising nanomechanical and viscoelastic properties that are not yet well understood [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Recently, a sharp transition was found as a function of compression rate in several liquids, where the liquid shows liquid-like characteristics at slow compression rate but solid-like peaks in relaxation times when compressed above a critical speed [12,18,20].…”

mentioning

confidence: 99%

Squeeze-out dynamics of nanoconfined water: A detailed nanomechanical study

Khan

Hoffmann

2015

Phys. Rev. E

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In this study, we present a detailed analysis of the squeeze-out dynamics of nanoconfined water confined between two hydrophilic surfaces measured by small-amplitude dynamic atomic force microscopy (AFM). Explicitly considering the instantaneous tip-surface separation during squeezeout, we confirm the existence of an adsorbed molecular water layer on mica and at least two hydration layers. We also confirm the previous observation of a sharp transition in the viscoelastic response of the nanoconfined water as the compression rate is increased beyond a critical value (previously determined to be about 0.8 nm/s). We find that below the critical value, the tip passes smoothly through the molecular layers of the film, while above the critical speed, the tip encounters "pinning" at separations where the film is able to temporarily order. Pre-ordering of the film is accompanied by increased force fluctuations, which lead to increased damping preceding a peak in the film stiffness once ordering is completed. We analyze the data using both Kelvin-Voigt and Maxwell viscoelastic models. This provides a complementary picture of the viscoelastic response of the confined water film.

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“…Adsorption by activated carbon, an efficient and effective method for removal of organic contaminants, has been commonly used for removing atrazine in potable water treatment [12]. Our research has shown that microporous minerals can serve as excellent sorbents for organic contaminants and minerals with more hydrophobic pore spaces exhibit higher sorption capacities [13][14][15]. Dealuminated Y zeolites with high Si/Al ratios have been observed to exhibit high sorption capacities towards atrazine [16,17].…”

Section: Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-striazine]mentioning

confidence: 76%

Rapid extraction and determination of atrazine and its degradation products from microporous mineral sorbents using microwave-assisted solvent extraction followed by ultra-HPLC-MS/MS

Cheng

2013

Microchim Acta

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We have evaluated three methods for the extraction of atrazine and six of its degradation products from microporous mineral sorbents. Soxhlet extraction and ultrasonic extraction, which work well on soils and sediments, recover only <15 % of the atrazine from a dealuminated Y zeolite. Closed-vessel microwave-assisted extraction, in contrast, gives much better recoveries. This is attributed to the accelerated mass transfer at elevated temperatures and the displacement by the solvent forced into the mineral micropores under elevated pressures. Under the optimized conditions, the recovery of atrazine from the hydrophilic Y zeolites (Si/Al ratios <8) is almost quantitative, and ∼77 % for the more hydrophobic ones. The extraction efficiencies for the degradation products of atrazine in the hydrophilic zeolites (74.1-100 %) are also higher than those in the hydrophobic ones (22.3-44.2 %). The extracted compounds were quantified by a combination of ultra-HPLC and tandem MS and resulted in detection limits between 0.04 and 1.41 mg kg −1 on a hydrophilic Y zeolite (Si/Al=2.55), and of 0.09-2.35 mg kg −1 on a hydrophobic zeolite (Si/Al=15).The method was applied to study the degradation of atrazine sorbed on dealuminated Y zeolites.

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Impact of mineral micropores on transport and fate of organic contaminants: A review

Cited by 76 publications

References 113 publications

Environmental behavior of the enantiomers of the chiral fungicide metalaxyl in Mediterranean agricultural soils

Environmental behavior of the enantiomers of the chiral fungicide metalaxyl in Mediterranean agricultural soils

Squeeze-out dynamics of nanoconfined water: A detailed nanomechanical study

Rapid extraction and determination of atrazine and its degradation products from microporous mineral sorbents using microwave-assisted solvent extraction followed by ultra-HPLC-MS/MS

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