Flotation separation of strontium via phosphate precipitation

• Published in: Water science and technology 2017-06, Vol.75 (11-12), p.2520-2526
• Main Authors: Thanh, Luong H V, Liu, J C
• Format: Article
• Language: English
• Subjects: Adsorption; Agglomeration; Aggregation; Ammonium; Ammonium compounds; Anions; Calcium; Cetrimonium Compounds - chemistry; Chemical Precipitation; Colloids; Cytotoxicity; Desalination; Electrostatic properties; Environmental Restoration and Remediation - methods; Flotation; Geology; Nuclear power plants; pH effects; Phosphates; Phosphates - chemistry; Precipitates; Precipitation; Separation; Sodium; Sodium dodecyl sulfate; Sodium Dodecyl Sulfate - chemistry; Sodium lauryl sulfate; Strontium; Strontium - chemistry; Studies; Surface chemistry; Surfactants; Wastewater; Water Pollutants, Chemical - chemistry
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2017.129

Flotation separation of strontium (Sr) from wastewater via phosphate precipitation was investigated. While 37.33% of Sr precipitated at highly alkaline pH in the absence of PO , it completely precipitated as Sr (PO ) at a molar ratio ([PO ]:[Sr ]) of 0.62 at a lower pH value. The presence of Ca hindered Sr precipitation, yet it could be overcome by increasing the PO dose. Sodium dodecyl sulfate (SDS) was a better collector for dispersed air flotation of Sr (PO ) than cetyl trimethyl ammonium bromide, or mixed collector systems of SDS and saponin. The highest separation efficiency of 97.5% was achieved at an SDS dose of 40 mg/L. The main mechanism in the precipitate flotation is adsorption of anionic SDS on the positively charged surface of colloidal Sr (PO ) via electrostatic interaction. SDS enhanced the aggregation of Sr (PO ) precipitates as the size increased from 1.65 to 28.0 μm, which was beneficial to separation as well.