Commercial Applications of Modular Ion Exchange Membrane Systems for Ion Removal from Drinking Water
Date of Graduation
5-2025
Document Type
Thesis
Degree Name
Bachelor of Science in Chemical Engineering
Degree Level
Undergraduate
Department
Chemical Engineering
Advisor/Mentor
Dr. Jamie Hestekin
Abstract
Iron and other heavy metals are harmful contaminants that can be found in many sources of fresh water, especially well water. Currently, around 43 million Americans use well water as their primary source of potable drinking water [1]. As the commercial desire for portable water treatment systems increases, the scientific advancements for these systems must also increase. Microfiltration membranes allow for portable filtration due to their low-pressure requirements but typically cannot remove metal ions via size exclusion. This work examines the incorporation of ion exchange membranes in series to portable filtration devices to increase the capture of ions without sacrificing the necessary low operating pressures. The ion-exchange membranes used in this work are synthesized via ultraviolet grafting of glycidyl methacrylate intermediate onto microfiltration membranes made of polyethersulfone (PES). These intermediates are modified using sodium sulfite to establish negative fixed charges on the membrane surface. Permeability testing of a variety of ion exchange microfiltration PES membranes with variable grafted weights of the intermediate depict that increased grafted weight on the membrane surface leads to increased operating pressure and decreased flux. When stacked in series, low-grafted-weight filters maintain a practical operating pressure. The stacked series operates below 2 psi whereas the single membrane operates at 4 psi. Operating with these membranes in series increases removal by increasing the charge availability on the membrane surface, as shown by a comparison of a single membrane versus a membrane stack at similar total grafted weights. When a 0.069 mg/cm2 and 0.098 mg/cm2 grafted weight membranes are stacked in series, the capacity increases to 19.3 mg/g compared to the capacity of a single membrane of 0.219 mg/cm2 of grafted weight which has a capacity of 8.25 mg/g. A portable prototype device was designed and created to minimize operating pressure and device footprint. The use of these ion-exchange microfiltration membranes with low grafted weight in portable water treatment systems can allow for increased removal of iron and removal of additional multivalent ionic species from water in a portable device.
Keywords
separations, ion exchange; membranes; chemical engineering; drinking water
Citation
Wilmoth, C. J. (2025). Commercial Applications of Modular Ion Exchange Membrane Systems for Ion Removal from Drinking Water. Chemical Engineering Undergraduate Honors Theses Retrieved from https://scholarworks.uark.edu/cheguht/223
