Biopolymer-metal composites for selective removal of waterborne orthophosphate Bernd Steiger and Lee Wilson Department of Chemistry, University of Saskatchewan, 110 Science Place, Thorvaldson Building, Saskatoon, SK S7N 5C9 Phosphorous is a vital element for life on earth and is essential for modern agriculture to not only sustain the current level of food production but also to meet the demand of a growing world population. The global phosphate production, however, is tied to phosphate rock mining and therefore hinges on few select countries (i.e., Morocco). With the estimated peak of production around 2030 and declining available resources in the near future, the global food supply is threatened. Recycling efforts for applied phosphorous are currently severely limited. Herein, a modular and facile design strategy through utilization of biopolymer metal complexes was developed to enable a sustainable approach for selective phosphorous capture from aqueous sources in form of orthophosphate. Therefore, the biopolymers alginate (Alg) and chitosan (C) were used to prepare binary (BMC) or ternary metal composites (TMC) with aluminium (Al), copper (Cu) or iron (Fe) as active site and their physico-chemical properties investigated. Systematic adsorption studies in synthetic orthophosphate containing water were performed to screen for orthophosphate selective materials in conjunction with high uptake capacity. Four materials showed desirable adsorption characteristics and isotherm studies at pH 8.5 and pH 6.3 were measured. Investigation in selective orthophosphate recovery from real environmental water from Saskatchewan was simulated through spiking collected well water samples with high salinity (2000 and 6000 mg/L sulfate respectively) with 5 mg/L phosphate. Al-TMC-N shows the least interference from a complex matrix overall, while Fe-TMC-N shows improved removal at very low phosphate concentrations in low salinity environments. This study was able to demonstrate a facile and viable strategy for orthophosphate recovery from real water samples with high salinity for a pathway to sustainable phosphorous capture to address the needs of the agriculture of the future to address a pressing concern for global food security. References 1. A. Kumar, P. Paul, S.K. Nataraj, Bionanomaterial Scaffolds for Effective Removal of Fluoride, Chromium, and Dye, ACS Sustain. Chem. Eng. 5 (2017) 895–903. https://doi.org/10.1021/acssuschemeng.6b02227 2. M.M. Hassan, M.H. Mohamed, I.A. Udoetok, B.G.K. Steiger, L.D. Wilson, Sequestration of Sulfate Anions from Groundwater by Biopolymer-Metal Composite Materials, Polymers (Basel). 12 (2020) 1502. https://doi.org/10.3390/polym12071502 3. I.A. Udoetok, O. Faye, L.D. Wilson, Adsorption of Phosphate Dianions by Hybrid Inorganic–Biopolymer Polyelectrolyte Complexes: Experimental and Computational Studies, ACS Appl. Polym. Mater. 2 (2020) 899–910. https://doi.org/10.1021/ acsapm.9b01123. 4. B.G.K. Steiger, I.A. Udoetok, O. Faye, L.D. Wilson, Counterion Effects in Metal Hybrid Biopolymer Materials for Sulfate Adsorption: An Experimental and Computational Study, ACS Appl. Polym. Mater. (2021) acsapm.1c00706. https://doi. org/10.1021/acsapm.1c00706
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