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

Abstract

The activated persulfate degradation of piroxicam, a non-steroidal anti-inflammatory drug (NSAID) belonging to oxicams, was investigated. Persulfate was activated with thermal energy or (UV-A and simulated solar) irradiation. Using 250 mg/L sodium persulfate at 40 °C degraded almost completely 0.5 mg/L of piroxicam in 30 min. Increasing piroxicam concentration from 0.5 to 4.5 mg/L decreased its removal. The observed kinetic constant was increased almost ten times from 0.077 to 0.755 min−1, when the temperature was increased from 40 to 60 °C, respectively. Process efficiency was enhanced at pH 5–7. At ambient conditions and 30 min of irradiation, 94.1% and 89.8% of 0.5 mg/L piroxicam was removed using UV-A LED or simulated solar radiation, respectively. Interestingly, the use of simulated sunlight was advantageous over UV-A light for both secondary effluent, and 20 mg/L of humic acid solution. Unlike other advanced oxidation processes, the presence of bicarbonate or chloride in the range 50–250 mg/L enhanced the degradation rate, while the presence of humic acid delayed the removal of piroxicam. The use of 0.5 and 10 g/L of methanol or tert-butanol as radical scavengers inhibited the reaction. The coupling of thermal and light activation methods in different aqueous matrices showed a high level of synergy. The synergy factor was calculated as 68.4% and 58.4% for thermal activation (40 °C) coupled with either solar light in 20 mg/L of humic acid or UV-A LED light in secondary effluent, respectively.

Advanced Oxidation Processes Based on Sulfate Radicals for Wastewater Treatment: Research Trends

“…Another important factor influencing the efficiency of the process is the temperature of the solution. The activation of PS by means of thermal energy was studied by several researchers, demonstrating that pollutant degradation is favored under higher activation temperatures [56]. As a matter of fact, Cheken et al [50] evaluated the removal of 10 pharmaceuticals at room temperature (20 • C) and found a degradation percentage lower than 8% in 5 h of reaction.…”

“…In order to overcome the limitations linked to the operating costs related to the implementation of SR-AOPs, a large amount of research has been focused on increasing AOPs sustainability, based on aspects such as the reduction in energy requirements, the minimization of waste and, consequently, the achievement of the so-called circular economy [10]. Among these works, the ones focused on the efficiency of solar energy-based AOPs stand out, since they allow the production of radicals in a more sustainable way [50,56]. Indeed, Chekem et al [50] carried out a study based on the PS/solar energy process for the elimination of piroxicam, caffeine, bezafibrate, atenolol, diclofenac, ibuprofen, niflumic acid, tramadol, carbamazepine, trimethoprim and sulfamethoxazole in WW [50].…”

Preparing a dual-function BiVO4/NiFe-LDH composite photoanode for enhanced photoelectrocatalytic wastewater treatment and simultaneous hydrogen evolution

“…Therefore, the PC technology presents a promising application potential for wastewater treatment. [8][9][10][11][12][13][14][15][16][17] Recently, many high-performance photocatalysts have been designed and synthesized with good applications in PC degradation and removal of antibiotic wastewater. [18][19][20] However, most photocatalysts have some common defects, such as a high recombination rate of e À -h + pairs, low separation and migration efficiency of photogenerated carriers, and they are difficult to separate and recover from wastewater.…”

UV and Zero-Valent Iron (ZVI) Activated Continuous Flow Persulfate Oxidation of Municipal Wastewater

“…Advanced oxidation processes (AOPs) have become a topic of leading interest nowadays due to the promising perspectives they demonstrate [22]. Processes with various combinations of oxidants, catalysts, and conditions are implemented to find the most appropriate method in terms of increased efficiency, low cost, and feasibility [23,24]. In wastewater treatment, photo-Fenton and photo-Fenton-like oxidation processes are increasingly investigated because of their high efficiency in eliminating target compounds in wastewater and leachate [25].…”