High efficient removal of phosphate in aqueous solution by eco-friendly materials

Abstract

The efficiency of phosphate removal in aqueous solution by CaO, Ca(OH)2 and CaCO3 has been studied in this work. Batch of experiments conducted with the initial phosphate concentrations from 5 to 1000 ppm have shown that CaCO3 could be applied for phosphate removal at low concentration with the maximum phosphate removal capacity at 4.0 mg/g. In contrast, the highest phosphate removal capacity of CaO and Ca(OH)2 was 287.36 mg/g and 235.21 mg/g at initial concentration of 500 ppm, and phosphate removal rate was 85% and 97% at initial concentration of 5 ppm. Crystalline hydroxylapatite was detected in the precipitate by XRD analysis. The molar ratio of P in the precipitate and Ca in the materials (CaO and Ca(OH)2) was 0.52 and 0.56 at initial concentration of 500 ppm, compared to P/Ca molar ratio of 0.6 in hydroxylapatite. Moreover, hydroxylapatite is the main component of fertilizer that can be applied for agriculture.

Enhanced removal of phosphate from wastewater by precipitation coupled with flocculation

“…In previous work, the phosphate removal by using CaO and Ca(OH)2 was tested at initial phosphate concentrations from 5 to 1000 ppm [17]. The results showed that the phosphate removal efficiency reached 85% and 95% at the initial phosphate concentration of 5 ppm by using CaO and Ca(OH)2, respectively.…”

“…This value made up at 287.36 mg/g and 235.21 mg/g, respectively. Moreover, the product after phosphate treatment can be used as phosphate fertilizer for plants in acid crops [17]. Nevertheless, separation of the precipitate by filtration method (2.7 μm filter paper) seems not to be effective in the sample of initial phosphate concentration at 50 and 1000 ppm.…”