The study of a novel PS-based degradation system : MIL-88-A as a heterogeneous activator, application on naproxen and comparison with H₂O₂ using a newly developed analytical technique -

Abstract

The thesis work is divided into two parts: In the first section, MIL-88-A, an iron based MOF (Fe³⁺-Fumaric acid), was synthesized in aqueous medium without the use of an organic solvent, then characterized and tested as a heterogeneous persulfate activator for the elimination of naproxen. A solution containing naproxen simulating the waste water effluent of a production facility was placed in continuously stirred reactors and spiked with MIL-88-A-sodium persulfate mix. The system was optimized in terms of MIL-88-A and persulfate dosages where 65-70percent degradation of [Naproxen]₀ = 50 mg L⁻¹ occurred in a period of two hours in conditions of [MIL-88-A]₀ = 25 mg L⁻¹ and [PS]₀ = 5 mM spiked at t = 60 min. MIL-88-A was proved to be recyclable for at least 4 cycles and the introduction of UV-A irradiation to the system enhanced degradation to reach complete removal of naproxen within two hours reaction time . The effect of various factors on the system was studied. Chlorides and phosphates had no effect on the activation-degradation process. On the other hand, bicarbonates exhibited a strong inhibition effect and degradation process was optimal at acidic conditions (pH = 4). The system was also tested against another oxidant, H₂O₂, and the results showed that PS has higher efficiency in naproxen degradation. In the second section, for the sake of comparing MIL-88-A-PS and MIL-88-A-H₂O₂ systems, [H₂O₂] quantification method was developed by simple modifications to an HPLC-DAD setup. The modifications included the use of acidified potassium iodide solution as a mobile phase and a series of capillary columns instead of the reverse phase column usually used. The method’s LDR ranged from 0.01-150 nm with LOD and LOQ 8.29 × 10⁻⁴ mM and 2.76 × 10⁻³ mM respectively. The method was proven to be cost effective where the cost per analysis ranged between 0.8 and 1.8 USD cents depending on the concent