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Advanced Phosphate Removal in Dialysis Employing Lanthanum Impregnated Activated Carbon Fixed-Bed Column

Nazarian, Reyhaneh
http://orcid.org/0000-0001-5216-4857
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1515508343971243

Abstract Details

2017, MS, University of Cincinnati, Engineering and Applied Science: Chemical Engineering.
Incorporating a fixed-bed phosphate adsorption column into a kidney dialysis system for enhanced phosphate removal during regular dialysis treatment may be an effective substitute for current medical strategies used to prevent hyperphosphatemia. In this study lanthanum-impregnated activated carbon was evaluated as a non-toxic and biocompatible candidate to serve as a phosphate adsorbent for use in a packed bed column integrated with the dialysis apparatus. Lanthanum-impregnated activated carbon (La-AC) was synthesized using chemical impregnation. The morphology and textural properties of the samples were determined using SEM and nitrogen adsorption-desorption and the amount of lanthanum adsorbed on the surface of activated carbon was determined based on the change in liquid-phase concentration using the Arsenazo chemical assay. Preparation parameters (ratio of lanthanum to activated carbon, calcination temperature, and calcination atmosphere) were investigated and optimized to improve phosphate capacity. It was observed that samples with 28 wt% lanthanum on activated carbon calcined at 650 °C under air had the highest phosphate capacity within the range used in this study. Phosphate loading on La-AC was assessed by determining the batch equilibrium isotherms. Isothermal adsorption studies revealed that phosphate adsorption on the surface of 12 wt% La-AC was well described by the Langmuir model with a maximum phosphate loading of 15.43 mg/g at 37 °C, and 21.14 mg/g at 50 °C. The phosphate adsorption mechanism was further investigated by 1) studying the effects of temperature and solution pH on phosphate adsorption capacity, 2) flow microcalorimetry, and 3) determining the relationship between the phosphate adsorption amount and the change in the pH of the solution. It was concluded that phosphate anions were adsorbed on lanthanum surface active sites mainly via the formation of monodentate and bidentate inner-sphere surface complexes. The enthalpies of formation of the monodenate and bidentate phosphate complexes with lanthanum surface sites were determined to be 21.8 and 44.6 kJ/mol using flow microcalorimetry. Based on the mechanism suggested by the isotherm studies, a kinetic model was developed based on the assumption of two parallel-pathway surface adsorption reactions to form monodentate and bidentate complexes on the surface of the adsorbent. The model was successfully used to describe the observed kinetics of the adsorption. The proposed parallel-pathway kinetic model is more consistent with thermodynamic assumptions of the adsorption mechanism than is the pseudo-second order kinetic model that is often used to describe phosphate adsorption.
Stephen Thiel, Ph.D. (Committee Chair)
Junhang Dong, Ph.D. (Committee Member)
Vadim Guliants, Ph.D. (Committee Member)
123 p.
Chemical Engineering

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Citations

  • Nazarian, R. (2017). Advanced Phosphate Removal in Dialysis Employing Lanthanum Impregnated Activated Carbon Fixed-Bed Column [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1515508343971243

    APA Style (7th edition)

  • Nazarian, Reyhaneh. Advanced Phosphate Removal in Dialysis Employing Lanthanum Impregnated Activated Carbon Fixed-Bed Column. 2017. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1515508343971243.

    MLA Style (8th edition)

  • Nazarian, Reyhaneh. "Advanced Phosphate Removal in Dialysis Employing Lanthanum Impregnated Activated Carbon Fixed-Bed Column." Master's thesis, University of Cincinnati, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1515508343971243

    Chicago Manual of Style (17th edition)

ucin1515508343971243
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This open access ETD is published by University of Cincinnati and OhioLINK.