pH-Regulated microelectrolysis-kaolinite coupling for Heterosigma akashiwo removal

Mineral-assisted microelectrolysis couples in situ electrochemical oxidation with particle-mediated algal separation for harmful algal bloom control. Here, the process was advanced for Heterosigma akashiwo through comparative mineral evaluation, electrolysis-pH regulation, and interaction analysis. Kaolinite gave the highest removal among four minerals (95.7%) and the largest apparent active chlorine adsorption amount, while time-resolved aggregate and clarification measurements linked this advantage to efficient particle-mediated cell capture and separation. Increasing initial electrolysis pH from 2 to 10 raised removal at 400 μL from 51.8% to >95% together with a larger post-electrolysis active chlorine inventory;92-93% of measured chlorine remained dissolved, and equal-C₀ tests showed comparable apparent adsorption across pH, supporting chlorine availability as the main factor governing apparent adsorption in the contact experiments. Independent dosing identified a super-additive window: 6 mg L^-1 active chlorine plus 0.08 g L^-1 kaolinite yielded 95.2% removal, 18.2 percentage points above Bliss independence. Oxidative and photosystem II responses linked process optimization to algal injury, establishing a parameterized oxidation-separation strategy for bloom control.