Analytical methodology based on a silicone rod (sr) micro extraction combined with hplc-dad method for the determination of pharmaceuticals and antibacterial products in effluent wastewaters. Characterization of the sorption removal processes by cork
- Autores: Maryam Mallek
- Directores de la Tesis: Victòria Salvadó Martín (dir. tes.), Abdelhamid Ben Salah (codir. tes.)
- Lectura: En la Universitat de Girona ( España ) en 2018
- Idioma: español
- Tribunal Calificador de la Tesis: Josep Galcerán Nogues (presid.), Manuela Hidalgo Muñoz (secret.), Khaled WALHA (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
The control of contamination caused by both regulated and non-regulated micropollutants is of great importance as compounds such as phenol derivatives and pharmaceuticals and personal care products (PPCPs) are detected in influent and effluent wastewater and surface waters at trace levels given that they are not target compounds of industrial and sewage treatment plants. However, it is necessary to control the presence of organic micropollutants in water bodies because of their potential environmental impacts: frequent occurrence, persistence and risk to aquatic life and humans. Many analytical methodologies have been proposed to determine PPCPs, most of them are based on liquid chromatography analysis. The trace levels of PPCPs in environmental waters as well as the complexity of the matrices require the application of sample enrichment and clean-up steps prior their chromatographic analysis even if the most sensitive MS detection is used. The first objective of this thesis was to revise the state of art of sorptive microextraction techniques and their applications for the determination of PPCPs in environmental waters. The principles and innovations of solid-phase microextraction (SPME), stir-bar sorptive extraction (SBSE), stir-rod-sorptive extraction (SRSE), and novel sorptive techniques such as rotating-disk sorptive extraction (RDSE), bar adsorptive micro-extraction (BAµE) and silicone rod(SR) / silicone tube (ST) extraction are described as well as their main strengthens and weakness. Although all these techniques have great potential, there is a clear need for less costly and simpler methods such as the use of bulk materials e.g. silicone rods. The second objective of this thesis was to develop a new analytical method for the determination of naproxen, ketoprofen, carbamazepine, diclofenac and triclosan based on their extraction and preconcentration by polymethylsiloxane (PDMS) rods. This step was followed by liquid desorption and high performance liquid chromatography (HPLC)-DAD analysis. The conditions affecting the extraction (pH, organic modifier, ionic strength, kinetics and sample volume) and desorption (solvent, solvent volume, desorption time, and the application of sonication) of these compounds from the PDMS rod were studied.
The detection limits obtained with the developed method were in the 0.47 to 1.02 µg.L−1 range, except 3.4 µg.L−1 for CBZ, and the RSD% values were in the 0.4–9.7% range. The LODs achieved are relatively as good and near as those of other micro-extraction techniques using the same instrumental system. The developed method was validated by analysing spiked surface water samples at trace levels resulting in recoveries of between 84.8 and 111.2%.The application of the developed method to the analysis of real water samples has demonstrated its feasibility to determine NAP, KET, DCF, CBZ and TCS in river water.
The third objective of this thesis was to evaluate the sorption capacity of granulated cork towards regulate phenolic compounds (phenol (Ph), 2-chlorophenol (2-CP), 2-nitrophenol (2-NP), 2,4-dichlorophenol (2,4-DCP), pentachlorophenol (PCP), and diclofenac (DCF)) and emerging contaminants (triclosan (TCS), naproxen (NAP), ketoprofen (KET), carbamazepine (CBZ), and methyl paraben (MPB). The effect of several parameters, such as pH, compound concentration, and amount of cork on the efficiency of the adsorption process was also studied. Maximum removal percentages of 100% for pentachlorophenol, 75% for 2,4-diclhorophenol, 55% for 2-nitrophenol, 45% for 2-chlorophenol, 20% for phenol were obtained for a 30 mgL-1 solution at pH 6. In the case of PPCPs, the adsorption capacities followed their order of hydrophobicity: TCS and DCF>NAP>KET> CBZ and MPB with removal percentages of 100% for sodium diclofenac, 100 % for triclosan, 82% for naproxen, 57% for ketoprofen, 50% for carbamazepine, and 50% for methyl paraben when small amounts of cork (5-10 mg) and 1 mgL-1 solution were used. In order to characterise the sorption process the experimental data were analysed by the Langmuir and Freundlich isotherm models. Both models fit well with the adsorption isotherms for phenolic compounds whereas in the case of PPCPs, the Freundlich model only fits the experimental data.
Adsorption isotherms provide information for the scaling process allowing the theoretical cork dosage required, to be calculated. The cork dosages needed to reduce the organic micropollutant concentrations from 1 mg.L-1 to 0.1mg.L-1 ranged from 0.91 to 3.13 g.L-1 for NAP, KET, CBZ and MPB showing that cork resulted to be an efficient sorbent for these compounds as well as for DCF and TCS, for which a 100% removal efficiency was obtained by using 5 mg of cork. Moreover, cork is also a useful adsorbent for the removal of all the phenolic compounds studied and especially for the more halogenated phenolic compounds, PCP and 2,4-DCP, which only require 4.9 and 29 g.L-1 of cork, respectively, to reduce their concentrations in aqueous solutions from 1 to 0.1 mg.L-1.
The two great advantages of using granulated and powdered cork as an adsorbent are that, unlike other adsorbents, no pre-treatment is required and, given that it is currently treated as a waste product within the industry, it can be acquired for little or no cost. The cork residue can be used in wastewater treatment plants located near the cork industries resulting in reduced transportation costs.
