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Effects of phytic acid sorption on iron polymerization and at the ferrihydrite-water interface
Get PDFPhytic acid is the most predominant organic phosphorus species in soils. Its stability in soils is mainly due to its high affinity for soil colloids, especially Fe (oxyhydr)oxides. They have been acknowledged as mobile/reactive adsorbents for P in soil-water environments. Although several sorption mechanisms were proposed, it is not clear how multi phosphate groups of phytic acid contribute to the surface complexation and/or precipitation processes. In this study, sorption behavior of phytic acid in ferrihydrite was examined using experimental geochemistry, solution 31P nuclear magnetic resonance spectroscopy, X-ray diffraction and scanning electron microscopy. The results indicated inner-sphere surface complexation via P1,3 and P2 functional groups under both pH 5 and 8.5. Under alkaline pH, an additional P5 functional group became active. Coprecipitation experiments showed evidence of the formation of Fe(III)-phytate-like bulk precipitates when the initial phytic acid/Fe(III) molar ratio was high (0.45-0.5). At the low phytic acid/Fe(III) (<0.1), the formation of ferrihydrite was unaffected, but further transformation was still inhibited. The study suggests a new role of phytic acid in the formation of Fe oxyhydroxide minerals.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-05-01The student, Ai Chen, accepted the attached license on 2019-03-22 at 09:27.The student, Ai Chen, submitted this Thesis for approval on 2019-03-22 at 09:39.This Thesis was approved for publication on 2019-03-25 at 10:06.DSpace SAF Submission Ingestion Package generated from Vireo submission #13441 on 2019-08-22 at 16:20:26Made available in DSpace on 2019-08-23T20:44:35Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-03-25Embargo set by: Seth Robbins for item 112265
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Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 112265
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Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 112265
Lift date: 2021-08-23T20:47:38Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 112265
Lift date: 2021-08-23T20:48:32Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 112265 on 2021-08-24T09:15:10Z
Depth sequence distribution and reactivity of phosphorus in intensively managed agricultural soils in East-Central Illinois
Get PDFThis Thesis was approved for publication on 2019-04-08 at 15:57.DSpace SAF Submission Ingestion Package generated from Vireo submission #13519 on 2019-08-22 at 16:20:52Made available in DSpace on 2019-08-23T20:44:40Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-04-08Embargo set by: Seth Robbins for item 112286
Lift date: 2021-08-23T20:44:50Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemSubsurface loss of phosphorus (P) in agricultural soils in the Midwestern U.S. has been receiving attention in the last few decades because of its negative environmental impacts to aquatic ecosystems such as eutrophication and hypoxia. Thus, there is a great interest in understanding the distribution and reactivity of P in the soils influencing the subsurface P loss. In this study, the depth sequence distribution, speciation, reactivity of P, and soil physicochemical properties were investigated in intensively managed agricultural soils in East-Central Illinois using chemical extraction/digestion, batch desorption experiments, infiltrometer measurements, Nuclear Magnetic Resonance spectroscopy, and X-ray diffraction analysis. The results suggested several sources of P contributing to subsurface P loss. During the growing season when the water table is low, calcium P (Ca-P: P adsorbed by calcite/dolomite and/or apatites) in subsoils is likely to be the main source of labile P (>70% of total inorganic phosphorus (IP) in subsoils). Both P desorption from calcite/dolomite and dissolution of Ca-P precipitates contribute to the concentration of labile P in subsoils. Although the amount of other IP species such as Fe-occluded P and non-occluded P was low, P desorption from amorphous Fe oxyhydroxides should not be excluded. During the wet spring season, surface soils becomes an additional source of P. In surface soils, Ca-P was a major IP species (~40-70% of total IP in topsoils) followed by non-occluded P (9-40% of total IP in topsoils) and Fe-occluded P (6-30% of total IP in topsoils). The labile P via dissolution and/or desorption of these IP pools and mineralized organic P in the surface soils can be translocated to tile lines through preferential flow paths. All of these findings should help the Illinois Nutrient Reduction Strategy Plan to develop the strategy to reduce the agricultural nutrient loss to Illinois waters and the Gulf of Mexico.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-05-01The student, Suwei Xu, accepted the attached license on 2019-04-08 at 14:17.The student, Suwei Xu, submitted this Thesis for approval on 2019-04-08 at 14:34.Embargo set by: Seth Robbins for item 112286
Lift date: 2021-08-23T20:46:41Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 112286
Lift date: 2021-08-23T20:47:38Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 112286
Lift date: 2021-08-23T20:48:32Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 112286 on 2021-08-24T09:15:31Z
Reaction condition effects on Re(VII) sorption kinetics at the zerovalent iron-water interface
Get PDFLong lived technetium-99 (99Tc) (t1/2: 2.1 x 105 yr) is one of the major radionuclide risk drivers in low level radioactive waste (LLW) at U.S. Department of Energy sites. Cementitious waste technology (CWT)is presently being used to immobilize LLW. Blast furnace slag is presently being added to the CWT formulation to promote reductive precipitation of the dominant risk driver, pertechnetate, 99Tc(VII)O4- to the sparing soluble 99Tc(IV). Some previous studies show that a variety of hazardous elements immobilized by slag can still remain mobile and leach out of the cement systems. Therefore, use of additional reducing agents should be tested. Because LLW is in caustic brine (high nitrate) solutions, it is a challenging task to reduce 99Tc(VII)O4-. This study evaluated the reducing capacity of zero valent iron (ZVI) as a potential reducing agent in the CWT. Using perrhenate (Re(VII)O4-) as a chemical analogue for 99Tc(VII)O4-, batch Re(VII) sorption experiments were conducted in ZVI as a function of pH (8.2-10.2) and nitrate concentration (0-0.1M). Zero valent iron was effective in reducing Re(VII) to Re(IV), and the initial (< few hrs.) Re sorption was rapid at the ZVI-water interface followed by a slow uptake. Although the extent of Re sorption decreased with increasing pH and nitrate concentration, ZVI immobilized Re(VII) by as much as 10% at pH 10.2. The results suggest that ZVI can be a potential reducing agent to improve the performance of CWT to immobilize 99Tc(VII)O4-.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-05-01The student, Brian Lenell, accepted the attached license on 2016-03-24 at 13:23.The student, Brian Lenell, submitted this Thesis for approval on 2016-03-24 at 13:28.This Thesis was approved for publication on 2016-03-25 at 10:09.DSpace SAF Submission Ingestion Package generated from Vireo submission #9120 on 2016-07-07 at 14:16:19Made available in DSpace on 2016-07-07T21:14:26Z (GMT). No. of bitstreams: 2
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Previous issue date: 2016-03-25Embargo set by: Seth Robbins for item 93229
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Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 93229
Lift date: 2018-07-07T21:18:16Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 93229 on 2018-07-08T09:15:33Z
Effects of phytic acid sorption on iron polymerization and at the ferrihydrite-water interface
No full textPhytic acid is the most predominant organic phosphorus species in soils. Its stability in soils is mainly due to its high affinity for soil colloids, especially Fe (oxyhydr)oxides. They have been acknowledged as mobile/reactive adsorbents for P in soil-water environments. Although several sorption mechanisms were proposed, it is not clear how multi phosphate groups of phytic acid contribute to the surface complexation and/or precipitation processes. In this study, sorption behavior of phytic acid in ferrihydrite was examined using experimental geochemistry, solution 31P nuclear magnetic resonance spectroscopy, X-ray diffraction and scanning electron microscopy. The results indicated inner-sphere surface complexation via P1,3 and P2 functional groups under both pH 5 and 8.5. Under alkaline pH, an additional P5 functional group became active. Coprecipitation experiments showed evidence of the formation of Fe(III)-phytate-like bulk precipitates when the initial phytic acid/Fe(III) molar ratio was high (0.45-0.5). At the low phytic acid/Fe(III) (<0.1), the formation of ferrihydrite was unaffected, but further transformation was still inhibited. The study suggests a new role of phytic acid in the formation of Fe oxyhydroxide minerals.LimitedAuthor requested closed access (OA after 2yrs) in Vireo ETD syste
Effects of extraction time and phosphorus speciation on soil test phosphorus (STP) in Illinois agricultural soils
Get PDFThe student, Anthony Miller, submitted this Thesis for approval on 2017-03-27 at 11:16.This Thesis was approved for publication on 2017-03-28 at 10:29.DSpace SAF Submission Ingestion Package generated from Vireo submission #10621 on 2017-08-10 at 13:38:23Made available in DSpace on 2017-08-10T19:14:38Z (GMT). No. of bitstreams: 3
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Previous issue date: 2017-03-28Phosphorus (P) loss from agricultural soils is the leading cause of accelerated eutrophication of surface waters. As an essential plant nutrient, however, adequate soil P is required for plant growth. Soil test phosphorus (STP) methods have been developed to correlate P levels in soil to crop growth, so that producers may better estimate the supply of P. There are numerous limitations in STP procedures, however, including: inaccurate estimation of plant available P, (i.e., dissolved reactive P (DRP)), unknown speciation in STP extracts, and the unknown relationship between STP and temporal-scale P release. Assessing these limitations, the appropriate colorimetric methods to distinguish orthophosphate from organic phosphate (Po) in Bray P-1, and Mehlich III extracting solutions were first evaluated, including the effects of acid hydrolysis reactions on Po (phytic acid) and polyphosphate (tripolyphosphate and pyrophosphate) in the STP extracting solutions. Based on the assessment, the effects of extraction time and P speciation on the STP procedures were studied in P rich fertilizer-amended and manure-amended Central Illinois agricultural soils. Although the extent of P release is proportional to the total P extracted by STP methods, the results are highly influenced by longer extraction times and P species. A longer extraction time increases STP values, lowering fertilizer recommendations. Manure-amended soils released more inorganic P (Pi), Po, and colloidal P than did fertilizer-amended soils. The fraction of Po was substantial (10-50% of total P) in STP soil extracts. Overall, the results of this study suggest the complexity of interpreting current STP procedures for fertilizer recommendations.Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2017-08-10 without embargo termsThe student, Anthony Miller, accepted the attached license on 2017-03-27 at 11:11
Effects of pCO2 on hydroxyapatite formation and its stability: Implications for understanding phosphorus availability in calcareous soil
Get PDFSubmission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2025-12-01The student, Shravani Kalita, accepted the attached license on 2023-11-05 at 12:43.The student, Shravani Kalita, submitted this Thesis for approval on 2023-11-05 at 17:17.This Thesis was approved for publication on 2023-11-16 at 16:49.DSpace SAF Submission Ingestion Package generated from Vireo submission #19367 on 2024-03-01 at 13:29:08Hydroxyapatite is an important phosphorus (P) sink in calcareous soils. The activity of carbonate in soil pore water, however, is often underestimated because soil respiration and solution-calcite equilibria could elevate pCO2 much greater than 415 ppmv. Thus far, the role of pCO2 in hydroxyapatite formation in calcareous soils has not been extensively investigated. Accordingly, the effects of pCO2 (415 ppmv to 20,000 ppmv) and aging time (7 days to 1 month) on hydroxyapatite formation were investigated using experimental geochemistry and X-ray diffraction (XRD) analysis. X-ray diffraction (XRD) analyses showed a decrease in the quantity of hydroxyapatite with increasing pCO2. This is attributed to decreased calcium (Ca) activity and an increase in calcium carbonate formation. Scanning Electron microscopy (SEM) showed rounded particles of hydroxyapatite and zeta potential values of these particles remained positive (2-112 mV) at pH 8 in all samples regardless of pCO2 and aging times. Dissolution experiments showed that higher pCO2 values facilitated the release of P from hydroxyapatite, suggesting the carbonate ligand-promoted dissolution mechanism. Hydroxyapatite was stable at pH 6, but dissolution was enhanced by decreasing pH from 6 to 4. Hydroxyapatite prepared under higher pCO2 released more phosphate than that prepared under pCO2 = 415 ppmv, indirectly suggesting higher solubility in carbonate-substituted hydroxyapatite. The variability of pCO2(g) should be considered to better understand the P cycle in calcareous soils
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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