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|Title: ||Adsorption of selected herbicides from water using activated carbon and polymeric adsorbents|
|Authors: ||Horner, Daniel J.|
|Issue Date: ||1999|
|Publisher: ||© Daniel J. Horner|
|Abstract: ||A range of adsorbents have been evaluated for the adsorption of selected herbicide
compounds from aqueous solution. The adsorption performance of LF -1, a
carbonised polymer produced in the laboratory, Amberlite XAD-4, a commercially
available polymeric adsorbent produced by Rohm and Haas and MN-200, a HypersolMacronet
polymer produced by Purolite, were compared with a commercial activated
carbon, Chemviron F -400.
The pore size distributions of the adsorbents have been investigated using nitrogen
adsorption. F-400, LF-1 and MN-200 were found to contain similar microporous
structures. The carbons also possess a significant degree of mesoporous structure,
which may enhance the diffusion of organic species into the micropores. The pore
size distribution for XAD-4 shows an almost exclusive meso/macroporosity with very
little microporous structure. Spectroscopic analysis and titration of the adsorbents
indicated a number of different oxygen functional groups. XPS and elemental
analysis suggested higher oxygen concentrations than those obtained using direct
titration, which was attributed to bound oxygen within the structure of the adsorbents.
The adsorption capacity of phenol was assessed as a characterisation technique. The
capacity of the carbons was much greater than the polymeric adsorbents.
Analytical techniques were developed and validated for the determination of trace
levels (0.1 parts per billion) of five herbicides; atrazine, benazolin, bentazone,
imazapyr and tric1opyr. Single and multi-component adsorption isotherms are
presented for trace concentrations of the herbicides in aqueous solution. The effect of
pH and fulvic acid upon the adsorption was also investigated. Mini-column
experiments were performed using multi-component mixtures. In all cases, the uptake
of herbicides on F -400 is greater than on the other adsorbents.
Regeneration of F-400 and MN-200 was investigated usmg solvent stripping
techniques. Significant regeneration efficiencies were observed using ethanol at pH
12 and 50°C to make the technique a viable option.|
|Description: ||A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.|
|Appears in Collections:||PhD Theses (Chemical Engineering)|
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