Degradation of Ampicillin with antibiotic activity removal using persulfate and submersible UVC LED: Kinetics, mechanism, electrical energy and cost analysis.

Effective water treatment to remove antibiotics and its activity from contaminated water is urgently needed to prevent antibiotic-resistant bacteria (ARB) emergence. In this study, we investigated degradation of Ampicillin (AMP), an extensively used β-lactam antibiotic, using submersible Ultraviolet C Light Emitting Diode (λ = 276 nm) irradiation source, and Persulfate (UVC LED/PS system). Pseudo first order rate constant (k) for degradation of AMP (1 ppm) by UVC LED/PS system was determined to be 0.5133 min (PS = 0.2 mM). k value at pH 2.5 (0.7259 min) was found to be higher than pH 6.5 (0.5133 min) and pH 12 (0.1745 min). k value for degradation of AMP in deionized water spiked with inorganic anions (Cl=0.5369 min,SO=0.4545 min, NO=0.1526 min, HCO=0.0226 min), in real tap water (0.1182 min) and simulated ground water (0.0372 min) were presented. Radical scavenging experiment reveal involvement of sulfate radical anion and hydroxyl radical in UVC LED/PS system. EPR analysis confirms the generation of sulfate radical anion and hydroxyl radical. Importantly, 74% reduction of total organic carbon (TOC) occurred within 60 min of AMP treatment by UVC LED/PS system. Seven degradation by-products were identified by high resolution mass spectrometry, and degradation pathways were proposed. Antibacterial activity of AMP towards Bacillus subtilis and Staphylococcus aureus was completely removed after UVC LED/PS treatment. ECOSAR model predicted no very toxic degradation by-products generation by UVC LED/PS system. Electrical Energy per order (EEo) and cost of UVC LED/PS system were determined to be 0.9351 kW/m/order and ₹ 7.91/m ($ 0.095/m or € 0.087/m), respectively. Overall, this study highlights, UVC LED/PS system as energy efficient, low-cost, and its potential to emerge as sulfate radical anion based advanced oxidation process (AOP) to treat water with antibiotics.