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dc.contributor.advisorFarrell, Jamesen
dc.contributor.authorChen, Yingying
dc.creatorChen, Yingyingen
dc.date.accessioned2017-06-13T23:39:27Z
dc.date.available2017-06-13T23:39:27Z
dc.date.issued2017
dc.identifier.urihttp://hdl.handle.net/10150/624128
dc.description.abstractPhosphonate antiscalants are commonly used in nanofiltration and reverse osmosis water treatment to prevent membrane fouling by mineral scale. In many circumstances it is desirable to remove these phosphonate compounds before concentrate disposal or further treatment. This research investigated the removal of phosphonate compounds from simulated membrane concentrate solutions using ferric hydroxide adsorbents. Two phosphonate antiscalants were investigated, Permatreat 191® (PT191) and nitrilotrimethylphosphonic acid (NTMP). Batch adsorption isotherms and column breakthrough and regeneration experiments were performed on two commercial adsorbents and a ferric hydroxide loaded polyacrylonitrile fiber adsorbent prepared in our laboratory. The best performing adsorbent was Granular Ferric Hydroxide® (GFH) obtained from GEH Wasserchemie. Adsorption isotherms measured after 24-hour equilibration periods showed initial concentration effects, whereby the isotherms were dependent on the initial adsorbate concentration in solution. Significant differences in adsorption behavior were observed between the PT191 and the NTMP adsorbates. Differences in adsorption behavior between NTMP and PT191 are all consistent with the PT191 containing fewer phosphonate functional groups per molecule than NTMP. Desorption rates were bimodal, with 40-50% of the adsorbed phosphonate being released on a time scale of 10-24 hours, while the remaining fraction was released approximately one order of magnitude more slowly. The slow desorbing fraction primarily resulted from equilibrium effects resulting from significant phosphonate adsorption, even in 1.0 mol/L NaOH solutions. Complete regeneration could not be achieved, even after eluting the adsorbent columns with more than 300 bed volumes of 1.0 mol/L NaOH. However, the incomplete regeneration had only a minor effect on phosphonate uptake in subsequent column breakthrough experiments.
dc.language.isoen_USen
dc.publisherThe University of Arizona.en
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en
dc.subjectgranular ferric hydroxideen
dc.subjectmembrane concentrateen
dc.subjectnitrilotri(methylphosphonic) aciden
dc.subjectNTMPen
dc.subjectphosphonateen
dc.subjectsurface complexationen
dc.titleRemoving Phosphonate Antiscalants from Membrane Concentrate Solutions using Ferric Hydroxide Adsorbentsen_US
dc.typetexten
dc.typeElectronic Thesisen
thesis.degree.grantorUniversity of Arizonaen
thesis.degree.levelmastersen
dc.contributor.committeememberFarrell, Jamesen
dc.contributor.committeememberBaygents, James C.en
dc.contributor.committeememberGervasio, Dominic F.en
thesis.degree.disciplineGraduate Collegeen
thesis.degree.disciplineEnvironmental Engineeringen
thesis.degree.nameM.S.en
refterms.dateFOA2018-06-25T23:48:04Z
html.description.abstractPhosphonate antiscalants are commonly used in nanofiltration and reverse osmosis water treatment to prevent membrane fouling by mineral scale. In many circumstances it is desirable to remove these phosphonate compounds before concentrate disposal or further treatment. This research investigated the removal of phosphonate compounds from simulated membrane concentrate solutions using ferric hydroxide adsorbents. Two phosphonate antiscalants were investigated, Permatreat 191® (PT191) and nitrilotrimethylphosphonic acid (NTMP). Batch adsorption isotherms and column breakthrough and regeneration experiments were performed on two commercial adsorbents and a ferric hydroxide loaded polyacrylonitrile fiber adsorbent prepared in our laboratory. The best performing adsorbent was Granular Ferric Hydroxide® (GFH) obtained from GEH Wasserchemie. Adsorption isotherms measured after 24-hour equilibration periods showed initial concentration effects, whereby the isotherms were dependent on the initial adsorbate concentration in solution. Significant differences in adsorption behavior were observed between the PT191 and the NTMP adsorbates. Differences in adsorption behavior between NTMP and PT191 are all consistent with the PT191 containing fewer phosphonate functional groups per molecule than NTMP. Desorption rates were bimodal, with 40-50% of the adsorbed phosphonate being released on a time scale of 10-24 hours, while the remaining fraction was released approximately one order of magnitude more slowly. The slow desorbing fraction primarily resulted from equilibrium effects resulting from significant phosphonate adsorption, even in 1.0 mol/L NaOH solutions. Complete regeneration could not be achieved, even after eluting the adsorbent columns with more than 300 bed volumes of 1.0 mol/L NaOH. However, the incomplete regeneration had only a minor effect on phosphonate uptake in subsequent column breakthrough experiments.


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