Degradation of the Nonsteroidal Anti-Inflammatory Drug Piroxicam by Iron Activated Persulfate: The Role of Water Matrix and Ultrasound Synergy

Abstract

This work examined the oxidation of Piroxicam (PIR), a representative nonsteroidal anti-inflammatory drug using iron activated persulfate. The effect of persulfate dosing was vital for the efficiency of the process. The addition of 20 mg/L sodium persulfate (SPS) eliminated 500 μg/L of PIR in less than 20 min at natural pH. PIR decomposition followed pseudo-first-order kinetics, and the observed kinetic constant increased by 2.1 times when the initial concentration of PIR decreased from 2000 to 250 μg/L. Acidic pH favored the PIR destruction, while both sulfate and hydroxyl radicals are involved in PIR destruction at natural pH. The effect of inorganic ions like bicarbonate and chlorides was almost insignificant on PIR removal. The presence of humic acid reduced PIR removal from 100% to 67% after 20 min of treatment with 2 mg/L Fe2+ and 20 mg/L SPS. The experiment that was performed with bottled water showed similar efficiency with ultrapure water, while in the case of secondary effluent, PIR removal decreased by 26% after 30 min of treatment. The Fe2+/SPS/ultrasound hybrid process showed a low degree of synergy (18.3%). The ecotoxicity of aqueous solution using the Vibrio fischeri as an indicator was reduced during the treatment, although with a different trend from the removal of PIR, possibly due to byproducts derived from the oxidation of secondary effluent and PIR.

Coupling Persulfate-Based AOPs: A Novel Approach for Piroxicam Degradation in Aqueous Matrices

“…However, the observed kinetic constant decreased approximately 14 times, i.e., from 0.55 to 0.04 min −1 from ultrapure to secondary effluent. The same behavior was observed in the case of iron-activated persulfate [30], where in the presence of organics the kinetic constant decreased from 0.15 to 0.07 min −1 . Recently, Ioannidi et al [31] demonstrated that even UV-A light could activate persulfate and degrade the endocrine disruptor propyl paraben.…”

“…A similar behavior was observed by Outsiou et al [53], where the addition of more than 50 mg/L chloride increased the removal of bisphenol A using SPS activated by a bimetallic carbon xerogel catalyst. On the contrary, the presence of chloride did not have any particular effect on the destruction of piroxicam using iron-activated persulfate [30]. However, the effect of chloride needs further investigation as several studies have linked its presence to the formation of organochlorine compounds that are potentially carcinogenic [52].…”

“…The separation was achieved on a Kinetex XB-C18 100A column (2.6 µm, 2.1 mm × 150 mm) and a 0.5 µm inline filter (Krudkatcher Ultra) both purchased from Phenomenex (Torrance, CA, USA). The mobile phase, consisting of 75:25 UPW: acetonitrile, eluted isocratically at 0.25 mL/min and 45 • C. Detection was achieved through a photodiode array detector (Waters 2996 PDA) in which the detection wavelength was set at 360 nm, and the analysis of each sample lasted for 10 min [29,30]. The limit of detection was 3.52 µg/L and the limit of quantitation was 11.75 µg/L.…”

“…Recently, Frontistis [30] investigated the degradation of 0.5 mg/L piroxicam using 2 mg/L Fe 2+ and 20 mg/L SPS at inherent pH. The researcher observed only a slight decrease in the presence of 100-250 mg/L bicarbonate.…”

Kinetic Evaluation of Dye Decolorization by Fenton Processes in the Presence of 3-Hydroxyanthranilic Acid

“…Due to such limitations, new alternatives are being sought in order to overcome the inefficiency of conventional techniques for removal or degradation of dyes. Advanced oxidative processes (AOPs) have demonstrated great efficiency in degrading recalcitrant organic pollutants [5,6,7,8,9,10,11,12]. Among AOPs, those based on Fenton reactions are considered promising for dye degradation [13].…”