Use of the ion polarization theory to interpret certain regularities of changes in characteristics and properties of inorganic compounds

Vlaev, L. T.; Georgieva, Velyana G.; Genieva, Svetlana

doi:10.1007/s10947-006-0396-3

Cited by 5 publications

(3 citation statements)

References 37 publications

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“…To account for different surface areas of the tested adsorbents, surface area normalized Freundlich K F and n parameters were also determined. Ionic (thermochemical) radii of selenite and selenate anions are reported to be 2.39 and 2.49 Å, respectively 56, 57. The diameter of the fully hydrated selenite anion and the diameter of the bare selenite anion were estimated as 6.7 and 3.4 Å, respectively 58.…”

Section: Resultsmentioning

confidence: 99%

Removal of Selenium Species from Waters Using Various Surface‐Modified Natural Particles and Waste Materials

Yiğit

Tozum

2012

CLEAN Soil Air Water

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Waste red mud and natural pumice/volcanic slag particles were surface modified and their selenium adsorption from waters was investigated. Acid activation/heat treatment of original red mud (ORM) particles significantly increased their micropore and external surface area and cumulative volume of pores. Iron oxide coating of pumice/ slags and acid activation of ORM decreased their pH pzc values and increased surface acidity. Selenite/selenate adsorption on iron oxide surfaces and acid activated red mud (AARM) was very fast with approximately first-order adsorption kinetics. Iron oxide coating of pumice/slag and acid activation of ORM particles significantly enhanced their selenite and selenate uptakes. Maximum Se adsorption capacities as high as 6.3 (mg Se/g adsorbent) were obtained by AARM. The extent of selenate uptakes by the surface modified particles was generally lower than those of selenite. Due to competition among Se species and other background water matrix for iron oxide adsorption sites, reduced selenite/selenate uptakes were found in natural water compared to single solute tests. Higher Se uptakes by iron oxide surfaces were found at pH 7.5 compared to pH 8.9, due to increased electrostatic repulsion among iron oxides and Se species at higher pH. The most effective adsorbents among the tested 17 different particles for Se uptake were AARM and iron oxide coated pumice. Se concentrations less than drinking water standards (5-10 mg/L) can be achieved by these particles. These low-cost, natural, or recyclable waste particles appear to be promising adsorbents for Se removal after their surface modification.Abbreviations: AARM, acid activated red mud; BET, Brunauer-Emmett-Teller; DDW, distilled and deionized water; DOC, dissolved organic carbon; IC, iron oxide coated; ICP/MS, inductively coupled plasma/MS; Isp, Isparta pumice; Kula, Kula-Salihli volcanic slag; NOM, natural organic matter; ORM, original red mud; pH pzc , pH of point of zero charge; SEM, scanning electron microscope; SEM-EDX, scanning electron microscope-energy dispersive X-ray spectrometer; SS, steel slag; XRF, X-ray fluorescence Clean -Soil, Air, Water 2012, 40 (7), 735-745 735

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Section: Resultsmentioning

confidence: 99%

Removal of Selenium Species from Waters Using Various Surface‐Modified Natural Particles and Waste Materials

Yiğit

Tozum

2012

CLEAN Soil Air Water

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“…This means that at temperatures higher than T iso , the reactions occurring at higher E would have higher rate (higher rate constants) than these with lower activation energies. It turned out that the following linear dependence exists between lnA and E in these cases (Equation (23)): (23) which is known also as kinetic compensation effect, isokinetic effect, or θ -rule [28,38,[39][40][41]. Besides, linear dependence between E and ΔS ≠ can also be observed [38].…”

Section: Theoretical Approach and Calculationmentioning

confidence: 99%

Non-isothermal degradation kinetics of filled with rise husk ash polypropene composites

Turmanova¹,

Genieva²,

Dimitrova³

et al. 2008

Express Polym. Lett.

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267

132

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“…In addition, size exclusion effects appear to be the other reason that could explain the lower degree of selenate uptake compared to selenite. The ionic radii for selenite and selenate are 2.39 Å and 2.49 Å, respectively [27,28]. The smaller size selenite anions may access some of the internal micropores within the zeolites, while the larger selenate ion may be excluded from some portion of these internal pores [24].…”

Section: Effect Of Bed Composition and Overall Performance Of Columnsmentioning

confidence: 99%

Microbial Enhancement of Selenium Removal in Chemically Modified Zeolite Columns

Kulasekara,

Zhang,

Papelis

2023

Water

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Selenium (Se) is an essential micro-nutrient for living organisms, but elevated concentrations in water can adversely affect health. In this research, we investigate the removal of selenium oxyanions (selenate and selenite) in aqueous systems by integration of adsorption on modified zeolites and microbial reduction. Dynamic sorption-reduction experiments were conducted using two sets of zeolite columns for the removal of selenite and selenate oxyanions, respectively. In each case, one column was fully packed with natural, unmodified zeolites, while the other column was composed of 80% natural and 20% iron-coated zeolites, by mass. The initial selenium concentration, selenite (SeIV) or selenate (SeVI), was 790 μg/L, the pH was 7.5, and the flow rate was 3 mL/min. Initially, as expected, the higher selenate removal (34%) was observed with coated zeolite, twice as high compared to the results with unmodified zeolite. Maximum selenite removal was 89% in the column with modified zeolite. Within approximately 14 days, as the biofilm developed inside the columns, selenium reduction in all four columns reached approximately 99%. Biofilm microbial community composition, assessed by 16S rRNA sequencing, is consistent with the presence of mainly selenium-reducing bacteria (Veillonella, Bacteroides, and Escherichia). Selenium oxyanions were reduced to elemental selenium, visible within the bioreactors as red-color aggregates.

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Use of the ion polarization theory to interpret certain regularities of changes in characteristics and properties of inorganic compounds

Cited by 5 publications

References 37 publications

Removal of Selenium Species from Waters Using Various Surface‐Modified Natural Particles and Waste Materials

Removal of Selenium Species from Waters Using Various Surface‐Modified Natural Particles and Waste Materials

Non-isothermal degradation kinetics of filled with rise husk ash polypropene composites

Microbial Enhancement of Selenium Removal in Chemically Modified Zeolite Columns

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