- Title
- Sorptive and microbial properties of low-cost adsorbents used in the extraction of ciprofloxacin and isoniazid from aqueous solution
- Creator
- Dube, Cyril Simbarashe
- Date Issued
- 2017
- Date
- 2017
- Type
- text
- Type
- Thesis
- Type
- Masters
- Type
- MSC
- Identifier
- http://hdl.handle.net/10962/59178
- Identifier
- vital:27450
- Description
- This work describes how coal fly ash (FA), kaolinite, perlite, talc and vermiculite were used to remove ciprofloxacin and isoniazid from aqueous solutions. The adsorptive features of the adsorbents were evaluated for ciprofloxacin and isoniazid with regards to the effects of contact time, pH, solid/liquid ratio and antibiotic concentration. All adsorbents were sterilised by dry heat before use to avoid the proliferation of antimicrobial resistance by the bacteria present on the adsorbents during experiments. The regression correlation coefficients indicate that the linearised form of the Langmuir isotherm gives the best fit for the sorption of both antibiotics onto FA and talc, ciprofloxacin onto kaolinite, and isoniazid onto perlite and vermiculite with R2 values ranging from 0.908 - 0.999. The linearised form of the Freundlich isotherm best describes the sorption of ciprofloxacin onto vermiculite and isoniazid onto kaolinite with R2 values of 0.999 for both. The linearised form of the Temkin isotherm best describes the sorption of ciprofloxacin onto perlite with an R2 = 0.997. The values of the Freundlich exponent, 1/n, range from 0.221 - 0.998, indicating a favourable adsorption of ciprofloxacin and isoniazid onto the adsorbents. The heat of sorption, B, calculated from the Temkin plots has values ranging from 0.018 - 10.460 J/mol, indicating a physical adsorption process (physisorption). Adsorption equilibrium on all adsorbents was achieved after 30 min for both antibiotics and the kinetic data obtained conforms best to the pseudo-second order equation with R2 values ranging from 0.998 - 0.999. The removal of ciprofloxacin and isoniazid by all adsorbents except FA was strongly influenced by the pH suggesting that electrostatic interactions play a major role in the adsorption processes. All adsorbents except FA removed showed excellent adsorption of ciprofloxacin from aqueous solutions with all of them achieving removals ranging from 80 - 99%. The adsorbents were less efficient in removing isoniazid and kaolinite gave the highest removal of 55 %. Furthermore, the microbial quality of the adsorbents was investigated and the results revealed that kaolinite, talc, perlite and vermiculite were heavily contaminated with microorganisms. FA was sterile. The fungi isolated from the mineral adsorbents were in concentrations ranging from 2.13 x 106 to 1.25 x 107 CFU/g and were mostly moulds; Penicillium spp., Aspergillus niger, Aspergillus fumigatus, Aspergillus flavus, Cladosporium spp. and Rhizopus oryzae. One yeast was isolated and was identified as Candida albicans. The bacteria identified were in concentrations ranging from 4.96 x 106 - 1.19 x 109 CFU/g. E. coli, Enterobacter cloacae, Exiguobacterium spp., Pseudomonas aeruginosa, Bacillus spp. and Serratia liquefaciens. The leachability index (LI) values obtained for adsorbents indicated that it is highly unlikely that microorganisms could be leached out of the adsorbents by rain. Heat inactivation of the microorganisms at a 105 °C was totally unsuccessful. However, it was established that a dry heat dose of 160 °C for at least 15 min was sufficient to eradicate all microorganisms present in the adsorbents. The D-values for coliform bacteria from all samples were very similar ranging from 1.7-2.2 min indicating homogeneity in heat resistance by the microorganisms. The Pseudomonas aureginosa isolated had a D-value of 2.2 min. The fungi isolated from the samples had D-values ranging from 2.1-3.2 min.
- Format
- 162 Leaves
- Format
- Publisher
- Rhodes University
- Publisher
- Faculty of Pharmacy, Pharmacy
- Language
- English
- Rights
- Dube, Cyril Simbarashe
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