Phosphate-binding protein-loaded iron oxide particles: adsorption performance for phosphorus removal and recovery from water†
Abstract
Adsorbents featuring high-affinity phosphate-binding proteins (PBPs) have demonstrated highly selective and rapid phosphorus removal and recovery. While immobilized PBP is promising for inorganic phosphate (orthophosphate, Pi) removal and recovery, increased adsorption capacity of PBP-based materials is essential to enhance the feasibility of PBP for scaled implementation. Here, magnetic n-hydroxy succinimide (NHS)-activated iron oxide particles (IOPs) were used to immobilize PBP (PBP–IOPs). The PBP–IOPs provided rapid Pi removal, with more than 95% adsorption within 5 min. Slightly acidic pH, room temperature (20 °C), and low ionic strength (0.01 M KCl) demonstrated the best removal efficiency. The Pi adsorption capacity of PBP–IOPs was not affected by anions such as chloride, sulfate, nitrate, bicarbonate, and borate. PBP–IOPs released 99% of total adsorbed Pi using pH adjustment. Conjugation of PBP to higher surface area per mass IOPs increased Pi attachment capacity (0.044 mg g−1) relative to previous studies of PBP immobilized on Sepharose resin (0.0062 mg g−1). Accordingly, PBP–IOPs have the potential to rapidly, spontaneously, selectively, and reversibly capture Pi. Theoretical capacity calculations indicated that parallel improvements in surface area to mass ratio of the base immobilization material together with reducing the size of the Pi-binding amino acid sequence (while retaining Pi specificity) are needed to further advance design and implementation of PBP-based adsorbents.
Please wait while we load your content...
