Ultrasound-Induced Intensification of Electrochemical Treatment of Bulk Drug Pharmaceutical Wastewater

Abstract

This study was carried out to intensify the electrochemical treatment of bulk drug pharmaceutical wastewater (BDW) using ultrasound. The effects of the operating parameters on chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiency were studied using a response surface methodology-based central composite design. Under optimum conditions that included an ultrasonic power of 67 W, a current density of 173 A m–2, an initial pH of 4.5, and an interelectrode distance of 0.5 cm, COD and TOC removal efficiencies were found to be 69% and 60%, respectively; the specific energy consumption was 0.69 kWh (g of COD removed)−1, and a synergistic effect of 1.1 was obtained. The morphology and topography analysis of the electrodes after the treatment confirmed continuous in situ cleaning of the electrode because of the use of ultrasound. A possible mineralization pathway based on transformation products formed (identified using liquid chromatography quadrupole time-of-flight mass spectroscopy) was proposed. Phytotoxicity analysis showed that the toxicity of BDW was significantly reduced and the seed germination rate increased to 85% after treatment.

Flow-Through Electrochemical Activation of Persulfate for Efficient Wastewater Treatment using Ti4O7 Reactive Electrochemical Membranes

“…Figure S17 suggested that the oxidation ability in the cathode region mainly resulted from • OH and SO 4 •– , but • OH was the key contributor. Based on these results, a schematic of the REM–persulfate system for contaminant oxidation is shown in Figure S18, mainly including (1) direct contaminant oxidation on the Ti 4 O 7 REM anode surface via DET, (2) indirect oxidation by • OH/SO 4 •– generated by Ti 4 O 7 REM anode and the CAPO process at Ti 4 O 7 REM cathode, and (3) indirect oxidation by active chlorine species in the presence of Cl – . , Considering the results from EPR (Figure S14) and quenching experiments (Figures S16 and S17) as well as the high TOC removal of the RO concentrate samples of pretreated coking wastewater (Figure a), indirect oxidation by • OH may play a key role in oxidizing organics in the REM–persulfate system. See Text S7 for the detailed description of the results of EPR and quenching studies and the proposed mechanism for contaminants oxidation.…”

“…•− generated by Ti 4 O 7 REM anode and the CAPO process at Ti 4 O 7 REM cathode, and (3) indirect oxidation by active chlorine species in the presence of Cl − . 37,38 Considering the results from EPR (Figure S14) and quenching experiments (Figures S16 and S17) as well as the high TOC removal of the RO concentrate samples of pretreated coking wastewater (Figure 4a), indirect oxidation by • OH may play a key role in oxidizing organics in the REM−persulfate system. See Text S7 for the detailed description of the results of EPR and quenching studies and the proposed mechanism for contaminants oxidation.…”

Integrated Hydrogen Peroxide, Sono, and Heterogeneous Photocatalysis Technologies: A Novel Technique for Ammonia and Phosphorus Removal in Real Poultry Slaughterhouse Wastewater

“…The prevalence of the ammonium ion at pH levels below 6 indicates that radical oxidation can be an effective technique for the efficient degradation of ammonia. Consequently, an increase in H 2 O 2 concentration from 0 to 5 mmol/L reduces ammonia removal, possibly due to a scavenging effect caused by the reaction of excess H 2 O 2 with HO (Patidar and Srivastava, 2021). When the pH rises above 6, the primary mechanism for the elimination of free volatile ammonia via ultrasound is revealed.…”

Ultrasound Enhanced Electro-Fenton Mineralization of Benzophenone: Kinetics and Mechanistic Analysis

“…However, incomplete degradation/mineralization, higher chemical requirement, secondary waste generation, pH adjustment before effluent discharge, and high treatment costs limit these methods for scale-up studies and further optimization. Ultrasound-assisted remediation such as sono-electrochemical (US-EC), 11 sono-electro-Fenton-Fe 2 O 3 (SF), 12 sono-photocatalytic, 13 and sono-electro-Fenton (SEF) 14 has been reported to be environment-friendly, in situ generation of ROS chemical-free, use of electron as a green reagent, and easy to operate techniques. These approaches have been reported for the adequate mineralization of the various persistent organic pollutants (POPs), i.e., ofloxacin (OFL), 15 ciprofloxacin, 16 ibuprofen (IBF), 17 and formic acid, 18 without secondary problems such as sludge generation, discharge of effluents, etc.…”