The extent to which counterions bind to polyelectrolytes influences a variety of polymer-based applications, including polyelectrolyte enhanced ultrafiltration and forward osmosis using polyelectrolytes as draw agents. Potentiometric titrations of poly (2-vinylpyridine) (P2VP), poly (3-vinylpyridine) (P3VP), and poly (4-vinylpydine) (P4VP) were performed using HBr, HCl, HNO 3 , and HClO 4 in both the presence and absence of added NaCl. Because of the systematic differences among the three polyelectrolytes, titration results provide insight into the role of polymer structure in the relative extents to which various counterions bind. Titration data reveal that ionization properties vary as functions of polymer investigated, titrant used, degree of protonation, and added salt concentration. Acid dissociation constants of the pyridinium moieties were found to generally increase with increasing degree of protonation, though appreciable differences were exhibited among the three polymers investigated. For all three polymers, Cl − demonstrated the lowest affinity for the charged pyridinium residues, while the affinities associated with Br − and 3 NO − were nearly identical to each other. The relative extent of binding for 4 CIO − varied across the polymers investigated, and was greatest for P4VP.

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Research experience is becoming an increasingly crucial element of today's undergraduate science curriculum. In recent years, the establishment of the Course-Based Undergraduate Research Experience Network (CUREnet) has provided a framework for the development of courses aiming to cultivate students' proficiency in undergraduate research techniques while fostering scien-

Recent advances in membrane technologies have enhanced the viability of water treatment strategies that employ semipermeable barriers. Forward osmosis (FO), which exploits the natural osmotic pressure gradient between a ''draw'' solution and a ''feed'' solution to produce potable water, offers a low-energy, low-cost alternative to more conventional treatment methods. Surfactants, because of their tendencies to aggregate into micelles and to adsorb at interfaces, provide intriguing osmotic pressures and offer exploitable properties by which draw solutions can be regenerated. The effectiveness of surfactant-based FO using cellulose triacetate membranes has been assessed in terms of water flux and reverse surfactant diffusion using cetylpyridinium chloride, sodium dodecylsulfate, and Triton X-100. The ratios of water flux to surfactant flux exceeded 600 L mol -1 for all surfactants studied. Surfactant recoveries of over 99 % were achieved by ultrafiltration using regenerated cellulose membranes.