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You searched for subject:(excess adsorption). Showing records 1 – 2 of 2 total matches.

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Virginia Tech

1. Gaddam, Prudhvidhar Reddy. Adsorption in Confined Aqueous Films.

Degree: PhD, Chemical Engineering, 2019, Virginia Tech

This thesis aims to understand the behavior of electrically charged molecules and atoms in thin nanometer scale (< 100 nm) liquid films subject to confinement between two charged interfaces. This situation frequently arises in colloidal suspensions, which consist of tiny sub-microscopic particles (colloid), droplets and large molecules dispersed in a second continuous medium. The stability of these suspensions, i.e. whether the colloidal materials agglomerate and sediment out of the suspension or remain stably suspended, depends on the surface forces between their interfaces during collision events, which frequently arise due to Brownian motion. As the fluid between particles thins as they approach each other during these collision events, the behavior of the dissolved molecules can be significantly different than when they are far apart due to the presence two interacting interfaces. Typically the dissolved molecules are used to tune the surface forces and understanding their behavior in confinement is relevant to a colloid scientist whose aim is to tune the behavior of the suspension. In the first part of this work, a technique is developed that serves as the static analogue to colloidal objects colliding with each other. The equilibrium behavior of a negatively charged fluorescent ion is measured as a function of film thickness and background salt concentration between two negatively charged interfaces. The Poisson-Boltzmann model predicts that with decreased salt concentration, there is a greater magnitude of depletion of the fluorescent ion at large separations and the characteristic length over which there is a change in the magnitude of depletion increases. Good agreement is found between the model and the experiment validating the technique developed and providing the first direct observation of molecular behavior subject to confinement as a function of solution composition. This effect of background salt type and concentration was tested for concentrated electrolytes as well. The experimental results showed an opposite trend to predictions from the Poisson-Boltzmann model. The fluorescent ion was now adsorbed to negatively charged interfaces indicating that the negatively charged interfaces were now positively charged. The magnitude of adsorption at large separations and characteristic length over which the magnitude of adsorption changes was a function of the salt concentration and the ion type. Finally, improvements were made to the original device to overcome limitations with the original device. The limitations were that (1) the maximum film thickness was 50 nm and (2) the interfaces were asymmetric which complicated theoretical calculations of the equilibrium behavior of the ions. In the last part of my thesis, I develop a sample which (1) enables measurements of films up to 1 µm and (2) simplifies the optical modeling necessary in the first two sections of this thesis. Advisors/Committee Members: Huxtable, Scott T. (committeechair), Ducker, William A. (committeechair), Martin, Stephen Michael (committee member), Davis, Richey M. (committee member).

Subjects/Keywords: adsorption; surface excess; colloids; thin films; electrolytes; Debye-length

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Gaddam, P. R. (2019). Adsorption in Confined Aqueous Films. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/91986

Chicago Manual of Style (16th Edition):

Gaddam, Prudhvidhar Reddy. “Adsorption in Confined Aqueous Films.” 2019. Doctoral Dissertation, Virginia Tech. Accessed May 07, 2021. http://hdl.handle.net/10919/91986.

MLA Handbook (7th Edition):

Gaddam, Prudhvidhar Reddy. “Adsorption in Confined Aqueous Films.” 2019. Web. 07 May 2021.

Vancouver:

Gaddam PR. Adsorption in Confined Aqueous Films. [Internet] [Doctoral dissertation]. Virginia Tech; 2019. [cited 2021 May 07]. Available from: http://hdl.handle.net/10919/91986.

Council of Science Editors:

Gaddam PR. Adsorption in Confined Aqueous Films. [Doctoral Dissertation]. Virginia Tech; 2019. Available from: http://hdl.handle.net/10919/91986


University of Akron

2. Spade, Michael P. Evaluation of the Beneficial Reuse of Baked-Alum Water Treatment Residual to Adsorb Phosphorous.

Degree: MSin Engineering, Civil Engineering, 2020, University of Akron

Excess phosphorous in water ways is known to be a cause of harmful algal blooms. These blooms have caused problems with water aesthetics and recreational use. Water Treatment Residual (WTR) has been shown to have an affinity for phosphorous. Since WTR is a bi-product of the drinking water treatment process it has the potential of being a low-cost alternative to remove excess phosphorous from water ways, potentially preventing harmful algal blooms. A previous study proved there was a beneficial reuse for WTR produced at the Akron Water Treatment plant for binding excess phosphorous. This research thesis looked further into Akron Water Treatment Plants WTR, to see if baking could increase its phosphorous adsorption capacity.Initial 24-hour sorption studies determined optimal baking temperatures of 175°C for Al-WTR (ce = 0.31 mg/L, qe = 117.21) and 150°C for PAC-WTR (ce = 0.20 mg/L, qe = 120.00). Isotherm studies for baked Al-WTR (175°C) and PAC-WTR (150°C) found that there was a net desorption of phosphorous when in distilled background solution. A statistical analysis across all experimental conditions determined that baked PAC-WTR (mean qe 11.00 mg/kg) performed significantly (ρ < 0.05) better than baked Al-WTR (mean qe 8.18 mg/kg). When the specific condition of the isotherm experiments were considered, baked PAC-WTR sorbed more PO4 (mean qe 36.64 mg/kg) (ρ < 0.05) when subjected to raw water at 20°C and static in conditions. Baked Al-WTR was the next best (mean qe 21.42 mg/kg) significantly (ρ < 0.05) in 5°C Static in raw water.Continuous flow column tests were also conducted to find the sorption maximum of the baked WTR, and to compare the adsorption capacity of As-Is WTR versus baked WTR conducted. Baked WTR was found to have an affinity for phosphorous with a sorption capacity of 7.91 mg-P/g-WTR for baked Al-WTR and 16.21 mg-P/kg-WTR. When compared to As-Is WTR, baked PAC WTR was the only material found to have a higher adsorption capacity by 83% compared to As-Is PAC-WTR at the same run time.After analysis of all experiments it was concluded that As-Is WTR performed significantly (ρ < 0.05), better than baked WTR and would be the recommended reuse of Akron Water Treatment Plant’s WTR for the adsorption of phosphorous. There were not many papers on the reuse of baked WTR. This paper evaluated the economics and the effect of baking on phosphorous adsorption. While it was not found to be beneficial for phosphorous adsorption at selected temperatures, the analytical methods used could be employed for further analysis on the effects of baked WTR. Advisors/Committee Members: Cutright, Teresa (Advisor).

Subjects/Keywords: Engineering; Civil Engineering; Environmental Engineering; Environmental Science; Water Treatment Residual, Alum, PAC, Baked Water Treatment Residual, Aluminum Leaching, Adsorption, Excess Phosphorous, Phosphorous adsorption, pH, Passive Treatment, Eutrophication, Cyanobacteria

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Spade, M. P. (2020). Evaluation of the Beneficial Reuse of Baked-Alum Water Treatment Residual to Adsorb Phosphorous. (Masters Thesis). University of Akron. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=akron1588850478064345

Chicago Manual of Style (16th Edition):

Spade, Michael P. “Evaluation of the Beneficial Reuse of Baked-Alum Water Treatment Residual to Adsorb Phosphorous.” 2020. Masters Thesis, University of Akron. Accessed May 07, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1588850478064345.

MLA Handbook (7th Edition):

Spade, Michael P. “Evaluation of the Beneficial Reuse of Baked-Alum Water Treatment Residual to Adsorb Phosphorous.” 2020. Web. 07 May 2021.

Vancouver:

Spade MP. Evaluation of the Beneficial Reuse of Baked-Alum Water Treatment Residual to Adsorb Phosphorous. [Internet] [Masters thesis]. University of Akron; 2020. [cited 2021 May 07]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=akron1588850478064345.

Council of Science Editors:

Spade MP. Evaluation of the Beneficial Reuse of Baked-Alum Water Treatment Residual to Adsorb Phosphorous. [Masters Thesis]. University of Akron; 2020. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=akron1588850478064345

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