The pristine point of zero charge(p.p.z.c)and zeta potential as a function of pH of boehmite oxide/hydroxide(α-Al_(2)O_(3)·H_(2)O)have been determined for three filter media.The active component in the first two...The pristine point of zero charge(p.p.z.c)and zeta potential as a function of pH of boehmite oxide/hydroxide(α-Al_(2)O_(3)·H_(2)O)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 m^(2)/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 in the pH range of 3–8.The p.p.z.c.value was determined to be 11.38±0.15.The reported values are within accuracy,but they are much higher than the values reported in the literature.X-ray powder diffraction data were supplemented by microscopy,infrared spectroscopy in order to characterize fully synthetic boehmite surfaces.展开更多
Aluminum oxide-hydroxide nanofibers,2 nm in diameter and approximately 250 nm long,are electroadhesively grafted onto glass microfibers,therefore forming a macroscopic assembly of alumina nanofibers on the second soli...Aluminum oxide-hydroxide nanofibers,2 nm in diameter and approximately 250 nm long,are electroadhesively grafted onto glass microfibers,therefore forming a macroscopic assembly of alumina nanofibers on the second solid in highly organized matter.The assembly can be viewed as a straight cylinder with rough surface and charge density of approximately 0.08 C/m^(2).This creates a significant electric field with negligible screening(ka≪1)in the region close to the surface of the assemblies.This field attracts nano-and micron-size particles from as far as 0.3 mm in less than a few seconds,many orders of magnitude greater than the conventional Derjaguin–Landau–Verwey–Overbeek theory that predicts only nanometer-scale effects arising from the presence of the surface.The strong electric field on the surface is then able to retain particles such as micron-size powdered activated carbon as well as much smaller particles such as fumed silica nanoparticles of 10–15 nm in diameter,viruses,atomically thick sheets of graphene oxide,latex spheres,RNA,DNA,proteins,and dyes.展开更多
Aluminum oxide-hydroxide nanolayer with a thickness of approximately 1.2 nm is electroadhesively deposited onto silicious support material with large surface area of about 50 m2/g,forming a highly electropositive comp...Aluminum oxide-hydroxide nanolayer with a thickness of approximately 1.2 nm is electroadhesively deposited onto silicious support material with large surface area of about 50 m2/g,forming a highly electropositive composite of boehmite nanolayer in the form of monocrystalline oxide/hydroxide(α-Al2O3·H2O)on the second electronegative solid.The composite can be viewed as a sphere with a rough surface and charge density of approximately 0.08 C/m2.This creates a significant electric field with negligible screening(ka1)in the region close to the surface of the nanocomposite.This field attracts nano-and micron-sized particles from as far as 200μm in a few seconds,many orders of magnitude greater than conventional Derjaguin–Landau–Verwey–Overbeek(DLVO)theory,which predicts only nanometer-scale effects arising from the presence of the surface.The strong electric field on the surface is then able to retain small particles such as viruses,atomically thin sheets of graphene oxide,RNA,DNA,proteins,dyes as well as heavy metals such as cobalt,arsenic,and lead.Alumina’s nanolayer surface can be further functionalized by adding other submicron or nano-sized particles to target a specific contaminant.An example is shown where alumina nanolayer is coated with nano-sized iron monohydrate to yield an arsenic sorbent that shows high sorption capacity.展开更多
文摘The pristine point of zero charge(p.p.z.c)and zeta potential as a function of pH of boehmite oxide/hydroxide(α-Al_(2)O_(3)·H_(2)O)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 m^(2)/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 in the pH range of 3–8.The p.p.z.c.value was determined to be 11.38±0.15.The reported values are within accuracy,but they are much higher than the values reported in the literature.X-ray powder diffraction data were supplemented by microscopy,infrared spectroscopy in order to characterize fully synthetic boehmite surfaces.
文摘Aluminum oxide-hydroxide nanofibers,2 nm in diameter and approximately 250 nm long,are electroadhesively grafted onto glass microfibers,therefore forming a macroscopic assembly of alumina nanofibers on the second solid in highly organized matter.The assembly can be viewed as a straight cylinder with rough surface and charge density of approximately 0.08 C/m^(2).This creates a significant electric field with negligible screening(ka≪1)in the region close to the surface of the assemblies.This field attracts nano-and micron-size particles from as far as 0.3 mm in less than a few seconds,many orders of magnitude greater than the conventional Derjaguin–Landau–Verwey–Overbeek theory that predicts only nanometer-scale effects arising from the presence of the surface.The strong electric field on the surface is then able to retain particles such as micron-size powdered activated carbon as well as much smaller particles such as fumed silica nanoparticles of 10–15 nm in diameter,viruses,atomically thick sheets of graphene oxide,latex spheres,RNA,DNA,proteins,and dyes.
文摘Aluminum oxide-hydroxide nanolayer with a thickness of approximately 1.2 nm is electroadhesively deposited onto silicious support material with large surface area of about 50 m2/g,forming a highly electropositive composite of boehmite nanolayer in the form of monocrystalline oxide/hydroxide(α-Al2O3·H2O)on the second electronegative solid.The composite can be viewed as a sphere with a rough surface and charge density of approximately 0.08 C/m2.This creates a significant electric field with negligible screening(ka1)in the region close to the surface of the nanocomposite.This field attracts nano-and micron-sized particles from as far as 200μm in a few seconds,many orders of magnitude greater than conventional Derjaguin–Landau–Verwey–Overbeek(DLVO)theory,which predicts only nanometer-scale effects arising from the presence of the surface.The strong electric field on the surface is then able to retain small particles such as viruses,atomically thin sheets of graphene oxide,RNA,DNA,proteins,dyes as well as heavy metals such as cobalt,arsenic,and lead.Alumina’s nanolayer surface can be further functionalized by adding other submicron or nano-sized particles to target a specific contaminant.An example is shown where alumina nanolayer is coated with nano-sized iron monohydrate to yield an arsenic sorbent that shows high sorption capacity.
