Influence of mesoporosity on the sorption of 2,4-dichlorophenoxyacetic acid onto alumina and silica

Sorption of the antibiotic ofloxacin to mesoporous and nonporous alumina and silica

“…As shown in Fig. 1b, the antibiotic is primarily cationic below pK a1 (N 4 in the piperazinyl group), anionic above pK a2 (3-carboxyl , and anionic (ofx − ) ofloxacin in aqueous solution as a function of pH (pK a1 = 6.08 and pK a2 = 8.25) [10,21]. group), and zwitterionic (net neutral) between pK a1 and pK a2 .…”

“…See Goyne et al [21] for detailed methods and data analysis; S BET is the specific surface area ± std. dev.…”

“…However, it should be noted that porosity, in and of itself, is not always the most important governing factor. For instance, 2,4-D did not adsorb to mesoporous or nonporous silica, presumably because of electrostatic repulsion [21].…”

“…Sorption of larger compounds was inhibited due to compound exclusion from the internal mesopore surfaces. Goyne et al [21] documented increased adsorption of the pesticide 2,4-D to alumina sorbents with increased mesoporosity. However, it should be noted that porosity, in and of itself, is not always the most important governing factor.…”

Soil Chemical Insights Provided through Vibrational Spectroscopy

“…Others have used FTIR to investigate the interaction of anionic herbicides and herbicide degradation products with metal oxides to determine the types of complexes and structures formed upon adsorption. Celis et al (1999) and Goyne et al (2004) investigated mechanisms of 2,4-dichlorophenoxyacetic acid (2,4-D) sorption to metal oxide surfaces using transmission FTIR and ATR-FTIR, respectively. Both interpreted the acquired spectra as indication that 2,4-D sorbed to variable charge mineral surfaces via electrostatic interaction between the carboxylate group and ^Metal-OH 2 + surface functional groups on Al and Fe oxides.…”