Sludge HAP was prepared from concrete sludge and ortho-phosphorus ions. The sludge HAP is composed of small crystals of hydroxyapatite (HAP) formed on the surface of cement powder of the concrete sludge. The sludge HAP showed the capacity to remove cadmium, copper and fluoride ions from aqueous solutions. The ions captured by the sludge HAP were stable under acid conditions with nitric acid (pH=4). The ion removal capacities of the sludge HAP were comparable to those of HAP prepared from other wastes. The sludge HAP can be applied to heavy metal ions or fluorine ions in water.
- Concrete sludge
- Ion exchange