The potential for phosphate (PO43-) recovery from synthetic urine matrices using PO43- sorption to nanoscale magnetite was studied. Synthetic fresh and hydrolyzed urine were used to closely resemble the behavior of real urine. Nanoscale magnetite was synthesized by the co-precipitation of Fe (II) and Fe (III) salts. The BET (Brunauer-Emmett-Teller) surface area of as prepared 8-10 nm sized magnetite was measured as 192.5 m2/g. Adsorption isotherm experiments were conducted at pH 4, 6 and 8.5 using 0.5 to 2.5 g L-1 magnetite dosage with 50 mg L-1 initial PO43- concentration in hydrolyzed urine. The adsorption data from the hydrolyzed urine matrices were fitted using both Langmuir and Freundlich isotherms. Maximum adsorption capacity using the Langmuir isotherm model was calculated as 35.1 mg PO43- as P/g magnetite at pH 4, 21.5 mg PO43- as P/g magnetite at pH 6 and 10.9 mg PO43- as P/g magnetite at pH 8.5. These results suggest that higher sorption capacity of the magnetite toward PO43- at lower pH can be attributed to the favorable electrostatic attractions between positively charged magnetite and the negatively charged PO43- species in solution. In experiments with fresh urine, using a 2 g L-1 magnetite dosage with 50 mg L-1 initial PO43- concentration, up to 51% PO43- as P removal was observed at pH 6 after 48h equilibrium. The results from this study contribute to an improved understanding of P and Fe chemistry in synthetic urine matrices, which is essential for developing efficient use of nanoscale iron oxide-based adsorbents towards P recovery.

Phosphate removal from synthetic urine matrices using nanoscale magnetite

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.