Hydrogen and Ozone Nanobubbles: Unique Properties and Emerging Applications

Nanobubbles (NBs), defined as gas-filled cavities typically <200 nm in diameter, exhibit unusual stability and interfacial properties compared to conventional bubbles. Their large surface-to-volume ratio, negative zeta potential, and capacity to generate reactive oxygen species (ROS) during collapse make them highly versatile in energy, environmental, and biomedical fields. Among the various gases studied, hydrogen nanobubbles (H₂-NBs) and ozone nanobubbles (O₃-NBs) are drawing significant attention due to their complementary redox characteristics: hydrogen acts as a reducing antioxidant, while ozone is a strong oxidizer.

• Extended Stability: Hydrogen nanobubbles remain dispersed in water for days, overcoming hydrogen’s low solubility.
• Enhanced Mass Transfer: Their nanometric size accelerates gas dissolution, enabling localized high concentrations.
• Redox Modulation: Hydrogen nanobubbles function as gentle reducing agents, scavenging harmful radicals such as hydroxyl (·OH) and peroxynitrite (ONOO⁻).

• Energy-Efficient Aquaculture Systems Stimulate beneficial microbiota in recirculating aquaculture systems (RAS), enhancing nitrification and improving water quality with lower aeration costs.
• Biomedical and Antioxidant Therapy H₂-NBs mitigate oxidative stress, potentially benefiting conditions such as ischemia-reperfusion injury, metabolic disorders, and neurodegenerative diseases.
• Wound Healing and Regenerative Medicine Their antioxidative properties accelerate wound closure and tissue repair, especially in diabetic ulcers.
• Oral Healthcare Hydrogen nanobubble rinses may reduce gum inflammation and periodontal disease by neutralizing ROS in the oral cavity.
• Sports Medicine and Rehabilitation Drinking H₂-NB water reduces muscle fatigue, lowers lactate accumulation, and speeds up post-exercise recovery.
• Anti-Cancer Adjunct Therapy Protects healthy cells from oxidative damage during radiotherapy or chemotherapy, acting as a supportive therapy.
• Food and Agriculture Promotes seed germination, crop growth, and resilience to stress. It also helps maintain the freshness of harvested produce.
• Fuel Cell and Bioenergy Applications Improves electrode performance in microbial fuel cells and serves as a potential hydrogen storage vector.
• Cosmeceuticals and Skincare Incorporated into cosmetics to protect skin cells from UV-induced oxidative damage and aging.
• Food Processing & Preservation Reduces oxidative spoilage in beverages and juices, potentially replacing synthetic preservatives.

• Extended Lifetime: Unlike conventional ozone, nanobubble encapsulation stabilizes ozone in water.
• Localized Radical Production: O₃-NB collapse yields highly reactive ·OH radicals, surpassing ozone’s native oxidation capacity.
• Surface Charge Reactivity: The negative charge attracts organic molecules and microbial membranes, increasing oxidative efficiency.

• Wastewater Treatment and Advanced Oxidation Processes (AOPs) O₃-NBs degrade pharmaceuticals, pesticides, and dyes more effectively than conventional ozone sparging due to extended lifetime and ROS generation.
• Food Safety and Post-Harvest Preservation Washing fruits, vegetables and seafood with nanobubbles helps lower pathogen levels E. coli and Salmonella without chemical residues.
• Medical Disinfection Effective in sterilizing surgical instruments, dental equipment, and hospital wastewater, reducing nosocomial infections.
• Hospital Sanitation & Healthcare Wastewater Inactivates multidrug-resistant organisms (MDROs) in hospital effluents.
• Swimming Pools and Spas Provide a chlorine-free solution for maintaining clean water with fewer harmful byproducts.
• Cold Chain and Seafood Industry Nanobubble treatment slows spoilage of fish and shellfish by minimizing microbial growth, extending shelf life.
• Poultry and Meat Processing Disinfects carcasses and equipment, lowering Salmonella and Listeria contamination without affecting meat quality.
• Dairy Industry Used in cleaning-in-place (CIP) processes to sterilize pipelines and tanks, reducing reliance on hot water and harsh chemicals.
• Pharmaceutical Manufacturing Sterilizes production lines, rinses containers, and removes residual antibiotics in effluents.
• Cooling Tower Water Treatment Prevents biofilm growth and reduces scaling and corrosion, offering an eco- friendly alternative to biocides.
• Textile and Dye Industry Efficiently degrades textile dyes and organic pollutants in wastewater.
• Paper and Pulp Industry Enhances fiber brightness and reduces chemical bleaching requirements.
• Agriculture & Irrigation Improves soil aeration, reduces root pathogens, and promotes healthy plant growth.
• Soil and Groundwater Remediation Oxidizes hydrocarbons and phenolic contaminants, enabling site restoration.
• Algal Bloom Control Suppresses harmful cyanobacteria in lakes and reservoirs.
• Aquaculture Disease Control Improves water clarity and reduces pathogenic bacteria in aquaculture systems.