title: Adsorption of Pb, Cd, Cu, Zn, and Ni to titanium dioxide nanoparticles: effect of particle size, solid concentration, and exhaustion.
abstract: OBJECTIVE
  Adsorption of metals (Pb, Cd, Cu, Ni, Zn) to TiO(2) nanoparticles and bulk particles was examined for use as a contaminant removal substrate as a function of particle size, sorbent concentration, and exhaustion.
  
  
  METHODS
  Adsorption experiments were conducted with 0.01, 0.1, and 0.5 g/L nanoparticles in a pH 8 solution and in spiked San Antonio tap water.
  
  
  RESULTS
  When results were normalized by mass, nanoparticles adsorbed more than the bulk particles but when results were surface-area normalized, the opposite was observed. The adsorption data shows the ability of the TiO(2) nanoparticles to remove Pb, Cd, and Ni from solution with similar adsorption at 0.1 and 0.5 g/L. Adsorption kinetics for all metals tested was described by a modified first order rate equation with the nanoparticles having a faster rate of adsorption than the bulk particles. The nanoparticles were able to simultaneously removal multiple metals (Zn, Cd, Pb, Ni, Cu) from both pH 8 solution and spiked San Antonio tap water. Exhaustion experiments showed that both the nanoparticles and bulk particles were exhausted at pH 6 but at pH 8, exhaustion did not occur for the nanoparticles.
  
  
  CONCLUSIONS
  Comparison of K (d), distribution coefficient, with other literature showed that the nanoparticles were better sorbents than other metal oxide nanoparticles and a commercial activated carbon.
authors.affiliation: Department of Civil and Environmental Engineering, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Engates
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Shipley
mesh_terms: D000327:Adsorption; D052918:Environmental Restoration and Remediation / Q000379:methods; D005618:Fresh Water / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000032:analysis / Q000737:chemistry* / Q000648:ultrastructure; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry*; D010316:Particle Size; D014025:Titanium / Q000032:analysis / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium