Metal -surface reactions in mixed aqueous organic solvents

Srour, Rafif K.

doi:10.33915/etd.2131

Cited by 3 publications

(3 citation statements)

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“…For both clay minerals and all cosolvents, pH ranged from 4.5 to 6.9. In this range, pH had minimal effect on Cd 2+ and Zn 2+ sorption to bentonite (44) in aqueous solutions and it is not likely to have affected sorption in cosolvents (37). For illite, this pH range does affect Cd 2+ and Zn 2+ sorption and therefore warrants further investigation in cosolvents.…”

Section: Resultsmentioning

confidence: 83%

“…pH Determination. Equilibrium solution pH was determined spectrophotometrically (22,24) using the conditional dissociation constants, sKMR, of methyl red (MR) in methanoland ethanol-water mixtures at constant ionic strength (37). MR was chosen because its acid (HMR) and base (MR -) forms have strong absorption peaks in the visible portion of the spectrum, its acid dissociation constant is not greatly affected by changes in ionic strength and temperature (24,25), and its color change interval, which covers a pH range of 4.5-6.5, can be conveniently obtained using a simple HOAc-NaOAc buffer system (38).…”

Section: Methodsmentioning

confidence: 99%

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Effect of Alcohols on the Retention Mechanisms of Cd and Zn on Wyoming Bentonite and Illite

Srour¹,

McDonald²

2005

Environ. Sci. Technol.

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The effects of ethanol- and methanol-water mixtures on Zn and Cd sorption onto bentonite and illite were investigated at low initial metal concentration (< or =10(-5) M) and low ionic strength (2.5 mM Ca(NO3)2). For all cosolvent fractions, the percent coverage of Zn and Cd to clay minerals was low (<5%) and independent of the solution dielectric constant, epsilon, except for Zn at 10 microM. Cadmium sorption to bentonite and illite was independent of epsilon. Zinc sorption varied significantly between clay types, cosolvent type, and cosolvent fraction. The partitioning of Zn to bentonite increased from 0 to 10% alcohol-water fraction and decreased after 10%. The same pattern was observed for the partitioning of Zn on illite in methanol-water mixtures. In ethanol-water mixtures, Kf for Zn on illite increased continuouslyfrom 0 to 50% ethanol. The decreased partitioning and hence mobility of Zn to bentonite and illite after 10% alcohol (only in methanol-water mixtures for illite) suggests a potential environmental threat resulting from increased transport of this metal in subsurface environments where these cosolvents are present.

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Section: Resultsmentioning

confidence: 83%

Section: Methodsmentioning

confidence: 99%

Effect of Alcohols on the Retention Mechanisms of Cd and Zn on Wyoming Bentonite and Illite

Srour¹,

McDonald²

2005

Environ. Sci. Technol.

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“…Many people and organizations worldwide promote OF consumption to combat overweight and persistent sickness (Srour, 2019). Hence, educational curricula need to reflect sustainable food policy.…”

Section: Conclusion and Future Research Agendamentioning

confidence: 99%

A longitudinal study on organic food continuance behavior of Generation Y and Generation Z: can health consciousness moderate the decision?

Kabir

2023

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Purpose This study examines the organic food continuance behavior (OFCB) of young (Generations Y and Z) Bangladeshi consumers as a part of green consumption for sustainable development. Based on the extended “Theory of Planned Behavior” (TPB), this study investigates the reasons for continuing organic food (OF) consumption. This research aims to create a model highlighting the characteristics influencing Bangladeshi consumers to continue eating OFs while considering the moderating role of health consciousness during the COVID-19 health crisis (CHC). Design/methodology/approach This is a longitudinal study, the first phase of which was conducted in 2020, whereas the second phase of data collection is completed on December 31, 2021. Thus, a longitudinal research design (N = 196) was used to investigate whether TPB element have the same impact over the period of time in two data collection phases. It also attempted to reveal if there is any change in the level of influences of Knowledge of organic food health benefit (HAK), and health consciousness on OFCB. A structured questionnaire was used to collect data from the participants of Generations Y and Z. Partial least square structural equation modeling validates the proposed research model. Findings Research results of phase two ensure that out of the five direct hypotheses related to social norm (SNRM), attitude (ATD), perceived behavioral control (PBRC), HAK and CHC, four (ATD, PBRC, HAK and CHC) significantly influence OFCB of Bangladeshi consumers. SNRM has no significant statistical influence on OFCB. On the other hand, all the direct hypotheses, including SNRM, were accepted during the first phase of the study. Hence, when people begin eating OF and recognize the health benefits, their firm behavioral control ensures that what others think has no significant influence on OFCB. Research limitations/implications Most of the data for this study came from those born after 1980, commonly known as Generations Y and Z. Thus, including more data from different age groups may result in different research conclusions. The survey contains a large proportion (62%) of respondents with an income of less than BDT 40,000 per month, a price-sensitive demographic in Bangladesh. The price of OF was not included in this study though price sensitivity may have impacted the study’s findings. Practical implications This research used one moderating and four exogenous variables to determine Bangladeshi consumers’ OFCB. HAK and PBRC are proven to be the strongest determinants. Though health consciousness, Knowledge and self-control are essential, Bangladeshi citizens’ awareness of OF and sustainable consumption is still far below compared to other countries. Consequently, this study urges policymakers to raise health awareness through various social efforts. Social implications The Bangladesh government has various initiatives to encourage sustainable development, including promoting OF consumption. Increased OF consumption will increase demand, resulting in an enormous need for organic production. This phenomenon will benefit society as bio-fertilizers are ecologically benign, resolving soil fertility issues and reducing disease risks while enhancing nutritional content. This study can serve as the foundation for developing a plan to boost the consumption of OFs, which can have a beneficial social impact. Originality/value Since no longitudinal study to explain the continuance of OFs has been observed in Bangladesh, this research uniquely contributes to predicting sustainable consumption behavior.

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Effect of Cosolvents on Ca-Na Exchange onto Wyoming Bentonite

Srour

McDonald

2005

Clays and clay miner.

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Calcium-sodium exchange on Wyoming bentonite in methanol, ethanol and acetone-water systems were investigated at 0.03 N Cl and at room temperature. Calcium-sodium exchange isotherms were plotted at cosolvent concentrations ranging from 0 to 70% wt./wt. using Ca and Na ionic activities before and after correction for CaCl+ formation. In both cases and in all treatments, a greater selectivity of bentonite surfaces for Ca ions was observed. When compared to water, different trends were observed among and within cosolvents. These trends varied depending on whether or not CaCl+ formation was accounted for. Ignoring the formation of CaCl+, the preference of bentonite for Ca increased in methanolwater systems with increased percent methanol at low equivalent Ca fraction (<0.2). At higher Ca fractions, this preference matched that of water. In ethanol-water, no increased preference of the surface for Ca was observed. In acetone-water, increasing cosolvent concentration decreased the preference of the surface for Ca. The magnitude of this decrease was larger at low equivalent Ca fraction (<0.2). After correction for CaCl+, both in solution and on the surface, the preference of bentonite for Ca2+ was larger in methanol- and ethanol-water systems. In acetone-water, increased surface preference for Ca was only apparent at low acetone fractions (<50%). At higher acetone fractions, there was evidence of increased Na loading but no increase in Ca2+ selectivity. Clearly, ion-pair formation and its effects on Ca-Na exchange reactions cannot be ignored in mixtures of aqueous-organic solvents. After accounting for this effect, Ca-Na exchange in the studied solvents appears to be more of a surface- than a solution-controlled phenomenon that involves both electrostatic and specific solvent-surface types of interactions that have not been elucidated.

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Metal -surface reactions in mixed aqueous organic solvents

Cited by 3 publications

References 71 publications

Effect of Alcohols on the Retention Mechanisms of Cd and Zn on Wyoming Bentonite and Illite

Effect of Alcohols on the Retention Mechanisms of Cd and Zn on Wyoming Bentonite and Illite

A longitudinal study on organic food continuance behavior of Generation Y and Generation Z: can health consciousness moderate the decision?

Effect of Cosolvents on Ca-Na Exchange onto Wyoming Bentonite

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