Pristine point of zero charge (p.p.z.c.) and zeta potentials of boehmite’s nanolayer and nanofiber surfaces

摘要

ABSTRACTThe pristine point of zero charge (p.p.z.c) and zeta potential as a function of pH of boehmite oxide/hydroxide (α-Al2O3·H2O) have been determined for three filter media. The active component in the first two filter media is boehmite nanofibers, only 2?nm in diameter and about 300?nm long. Boehmite nanofibers create high zeta potential (ζtrue≥46 mV) in aqueous solutions in the pH range of 3–8. The p.p.z.c. values were determined to be 11.60?±?0.15 for nanofibers grafted onto microglass fibers and 11.40?±?0.15 for agglomerated nanofibers. In the third filter media, a boehmite nanolayer in the form of monocrystalline oxide/hydroxide with a thickness of approximately 1.2?nm is electroadhesively deposited onto siliceous support material with large surface area of about 50?m2/g, therefore forming a highly electropositive composite of boehmite nanolayer on the second highly electronegative solid. Boehmite’s oxide-hydroxide nanolayer surface creates high zeta potential (ζtrue≥50 mV) in aqueous solutions i...