Electrochemical Degradation of Methylene Blue with Seawater and Pb/PbO2 Electrodes from Battery Waste

Electrochemical degradation of methylene blue (MB) dye with seawater electrolyte using lead and lead oxide (Pb/PbO2) electrodes from waste batteries has been successfully conducted. Characterization of battery waste, the effectiveness of dye degradation, sodium hypochlorite (NaOCl) concentration, dissolved oxygen (DO) level, reaction mechanism, the effect of time variation (15, 30, 45, and 60 minutes), and voltage variation (0, 1, 2, 3, 4, and 5 volts) were observed. Characterization showed results by the characteristics of Pb and PbO2 confirmed by X-ray diffractometer (XRD) result-ing in 2θ peaks of Pb at 31.36, 36.38, 52.26, 62.36, 65.38º and 2θ (β-PbO2) at 25.4, 32.0, 36.2, 49.1, 52.2, 59.0, 62.5, 66.9º. The electrode had a hollow granular morphology with lead (Pb) and Oxygen (O) composition that matched the standards of scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDX) and X-ray fluorescence (XRF). Electrode effectiveness on dye degradation measured using UV-Vis spectrophotometer, iodometric titration, and dissolved oxygen (DO) meter showed that dye degradation goes along with increasing NaOCl concentration, DO, elec-trolysis time, and voltage with optimal results obtained at a potential of 5 volts for 60 minutes can degrade MB by 92.68% or about 4.61 mg/L. Atomic absorption analysis confirmed the stability of the electrodes and the release of ions (Pb2+) that were much lower than the safe standard values. Degradation of dyes occurs through demethylation, hydrox-ylation, and ozonation reactions due to electron attack from hypochlorite oxidizer (OCl-), hydroxyl groups (∙OH), and ozone oxygen radicals (O3, ∙O) from the seawater electrolysis process with Pb/PbO2 electrode media against reactive groups and ring binding on MB. These results show the potential of the Pb/PbO2 electrode system from battery waste and seawater as a hypochlorite (OCl-) electrolyte generator to overcome dye waste in water.