Abstract
Superparamagnetic microparticles modified with an ion exchange system are reported for the recovery of phosphate from waste water by a magnetic separation technique. Layered double hydroxides (LDH), anionic clays, are precipitated from an aqueous solution and deposited by an ultrasonic treatment on superparamagnetic microparticles consisting of Fe3O4 multicores embedded in a SiO2 matrix. Deposition can be conducted in a batch process as well as in a continuous way, using an ultrasonic flow cell. The obtained composite particles show good magnetic separability and have a specific surface area of around 100 m(2) g(-1). Zr doped LDH shows improved phosphate adsorption in waste water. After magnetic separation and regeneration, the composite particles are re-used which is demonstrated for four cycles. Phosphate ions are concentrated in the regeneration solution. Simple, low cost, and a fast continuous synthesis of the composite particles paves the way for application beyond lab scale in real waste water treatment plants.