TY - JOUR
T1 - Sorption of the antibiotic ofloxacin to mesoporous and nonporous alumina and silica
AU - Goyne, Keith W.
AU - Chorover, Jon
AU - Kubicki, James D.
AU - Zimmerman, Andrew R.
AU - Brantley, Susan L.
N1 - Funding Information:
The authors thank Mary Kay Amistadi for laboratory assistance, Sridhar Komarneni, Bharat Newalkar, and Stephen Stout for mineral synthesis and preparation, and Chad Trout for assistance with molecular modeling. Financial support was provided by the Penn State Biogeochemical Research Initiative for Education (BRIE) sponsored by NSF (IGERT) Grant DGE-9972759 and by the Penn State Materials Research Science and Engineering Center (MRSEC) sponsored by NSF Grant DMR-0080019. Andrew Zimmerman acknowledges donors to the American Chemical Society Petroleum Research Fund for partial support of this research, and James Kubicki acknowledges the support of Stony Brook-BNL collaboration to establish a Center for Environmental Molecular Sciences (CEMS). Computation was supported, in part, by the Materials Simulation Center, a Penn State MRSEC and MRI facility.
Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2005/3/1
Y1 - 2005/3/1
N2 - Mesoporous and nonporous SiO2 and Al2O3 adsorbents were reacted with the fluoroquinolone carboxylic acid ofloxacin over a range of pH values (2-10) and initial concentrations (0.03-8 mM) to investigate the effects of adsorbent type and intraparticle mesopores on adsorption/desorption. Maximum ofloxacin adsorption to SiO2 surfaces occurs slightly below the pKa2 (pH 8.28) of the antibiotic and sorption diminishes rapidly at pH > pKa2. For Al2O 3, maximum sorption is observed at pH values slightly higher than the adsorbent's point of zero net charge (p.z.n.c.) and less than midway between the pKa values of ofloxacin. The effects of pH on adsorption and ATR-FTIR spectra suggest that the zwitterionic compound adsorbs to SiO 2 solids through the protonated N4 in the piperazinyl group and, possibly, a cation bridge; whereas the antibiotic sorbs to Al 2O3 solids through the ketone and carboxylate functional groups via a ligand exchange mechanism. Sorption edge and isotherm experiments show that ofloxacin exhibits a higher affinity for mesoporous SiO2 and nonporous Al2O3, relative to their counterparts. It is hypothesized that decreased ofloxacin sorption to mesoporous Al 2O3 occurs due to electrostatic repulsion within pore confines. In contrast, it appears that the environment within SiO2 mesopores promotes sorption by inducing formation of ofloxacin-Ca complexes, thus increasing electrostatic attraction to SiO2 surfaces.
AB - Mesoporous and nonporous SiO2 and Al2O3 adsorbents were reacted with the fluoroquinolone carboxylic acid ofloxacin over a range of pH values (2-10) and initial concentrations (0.03-8 mM) to investigate the effects of adsorbent type and intraparticle mesopores on adsorption/desorption. Maximum ofloxacin adsorption to SiO2 surfaces occurs slightly below the pKa2 (pH 8.28) of the antibiotic and sorption diminishes rapidly at pH > pKa2. For Al2O 3, maximum sorption is observed at pH values slightly higher than the adsorbent's point of zero net charge (p.z.n.c.) and less than midway between the pKa values of ofloxacin. The effects of pH on adsorption and ATR-FTIR spectra suggest that the zwitterionic compound adsorbs to SiO 2 solids through the protonated N4 in the piperazinyl group and, possibly, a cation bridge; whereas the antibiotic sorbs to Al 2O3 solids through the ketone and carboxylate functional groups via a ligand exchange mechanism. Sorption edge and isotherm experiments show that ofloxacin exhibits a higher affinity for mesoporous SiO2 and nonporous Al2O3, relative to their counterparts. It is hypothesized that decreased ofloxacin sorption to mesoporous Al 2O3 occurs due to electrostatic repulsion within pore confines. In contrast, it appears that the environment within SiO2 mesopores promotes sorption by inducing formation of ofloxacin-Ca complexes, thus increasing electrostatic attraction to SiO2 surfaces.
UR - http://www.scopus.com/inward/record.url?scp=13844297861&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=13844297861&partnerID=8YFLogxK
U2 - 10.1016/j.jcis.2004.08.150
DO - 10.1016/j.jcis.2004.08.150
M3 - Article
C2 - 15694437
AN - SCOPUS:13844297861
SN - 0021-9797
VL - 283
SP - 160
EP - 170
JO - Journal of Colloid And Interface Science
JF - Journal of Colloid And Interface Science
IS - 1
ER -