Recovery of different types of hydroxyapatite by precipitation of phosphates of wastewater from anodizing industry

Abstract

Recovery of phosphates from an anodizing industry wastewater was studied by chemical precipitation. Samples of wastewater were selected attending to the highest phosphate concentration observed during 1 year of weekly sampling. Different types of precipitant agents were analyzed in batch systems. Results showed that it is possible to remove 100 % of phosphates when Ca(OH) 2 is used as precipitant agent. The best conditions of precipitation were found following a L 9 orthogonal array design of the Taguchi method. For an initial concentration of phosphates of 4336 mg/L, these best conditions were a Ca/P molar ratio of 5.77, pH 2, stirring time of 15 min and settling time of 1 h. Additionally, it was demonstrated that the factors with more influence in the precipitation of phosphates with Ca(OH) 2 were the pH of the wastewater and the stirring time. When the phosphate removal was performed at pH 6 and 10, hydroxyapatite Ca 5 (PO 4 ) 3 (OH) was found in the

Recovery of Nutrients from Residual Streams Using Ion-Exchange Membranes: Current State, Bottlenecks, Fundamentals and Innovations

“…However, obtaining chemically pure vivianite requires magnetic separation, centrifugation, extraction of organic matters, etc., which significantly increase the cost of the process. In the case of processing industrial wastewater that contains practically no NH 4 + − NH 3 (for example, in phosphoric acid production or in anodizing industry), P V precipitates as hydroxyapatite (Ca 5 (PO 4 ) 3 (OH) or similar substances [ 71 ]), whose value in agriculture and industry is less high.…”

Regeneration Analysis of Bone Char Used in Water Defluoridation: Chemical Desorption Route, Surface Chemistry Analysis and Modeling

“…Te results of FTIR analysis for raw and regenerated (1st, 5 th , and 10th cycles, 0.075 mol/L NaOH) BC samples are reported in Figure 5. Te characteristic absorption bands of BC samples resulting from the stretching and symmetric bending modes of vibration of O-H, stretching vibration of C-H, asymmetric stretching and bending vibrations of C-O from the carbonate group, and symmetric stretching and bending vibrations of P-O from the phosphate group were identifed at ∼3440, 2950-2850, 1620, 1450-1400, 1100-960, and 605-560 cm −1 [31,[41][42][43]. An increase in the absorption band was observed at 2013 cm −1 (which was associated with the presence of PO 3− 4 ) for the BC samples obtained from the 5th and 10th regeneration cycles in comparison with the raw BC, and a gradual decrease in the absorption band at 3444 cm −1 (associated with the presence of hydroxyl groups) of the BC samples from the 1st, 5th, and 10th regeneration cycles.…”

Geochemical cycling in aquifers contributes to the transport, storage and transfer of anthropogenically-derived phosphorus to surface waters

“…Field studies suggest that HAP precipitation is favourable in alkaline aqueous solutions, although recent research suggests that carbonate hydroxyapatite can precipitate at pH 2 (Oubagha et al, 2016;Cichy et al, 2019;Delgadillo-Velasco et al, 2020). Laboratory and modelling studies suggest that HAP is chemically less stable and more soluble compared to FAP and CFA, and that it can dissolve in acidic aqueous solutions (Dorozhkin, 2012;Tõnsuaadu et al, 2012;Aljerf and Choukaife, 2017).…”