Al nanoclusters in coagulants and granulates: application in arsenic removal from water

The contamination of drinking and irrigation water by arsenic is a severe health risk to millions of people, particularly in developing countries. Arsenic treatment methods therefore need to advance to more durable and cost-effective solutions. In recent years, the unique properties of nanomaterials have received much attention in water treatment research, and their properties (e.g., high number of reactive surface binding sites) may make them suitable for arsenic removal. The aluminum nanoclusters Al₁₃ (AlO₄Al₁₂(OH)₂₄H₂O₁₂ ⁷⁺) and Al₃₀ (Al₂O₈Al₂₈(OH)₅₆(H₂O)₂₆ ¹⁸⁺) have high specific surface charge, deprotonate over a wide pH range and exhibit a high reactivity due to a great number of OH⁻ and H₂O groups. This contribution evaluates these chemical properties of aluminum nanoclusters and their efficiency for water treatment, particularly for arsenic removal. It assesses the advantages and constraints when applied in an industrially produced aluminum coagulant or in Al granulate during water treatment.