Nutrient-substituted hydroxyapatites: synthesis and characterization

Golden, D. C.; Ming, D. W.

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NASA NTRS · 20040088855

Nutrient-substituted hydroxyapatites: synthesis and characterization

Golden, D. C.·Ming, D. W.

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Abstract

Incorporation of Mg, S, and plant-essential micronutrients into the structure of synthetic hydroxyapatite (HA) may be advantageous for closed-loop systems, such as will be required on Lunar and Martian outposts, because these apatites can be used as slow-release fertilizers. Our objective was to synthesize HA with Ca, P, Mg, S, Fe, Cu, Mn, Zn, Mo, B, and Cl incorporated into the structure, i.e., nutrient-substituted apatites. Hydroxyapatite, carbonate hydroxyapatite (CHA), nutrient-substituted hydroxyapatite (NHA), and nutrient-substituted carbonate hydroxyapatite (NCHA) were synthesized by precipitating from solution. Chemical and mineralogical analysis of precipitated samples indicated a considerable fraction of the added cations were incorporated into HA, without mineral impurities. Particle size of the HA was in the 1 to 40 nm range, and decreased with increased substitution of nutrient elements. The particle shape of HA was elongated in the c-direction in unsubstituted HA and NHA but more spherical in CHA and NCHA. The substitution of cations and anions in the HA structure was confirmed by the decrease of the d[002] spacing of HA with substitution of ions with an ionic radius less than that of Ca or P. The DTPA-extractable Cu ranged from 8 to 8429 mg kg-1, Zn ranged from 57 to 1279 mg kg-1, Fe from 211 to 2573 mg kg-1, and Mn from 190 to 1719 mg kg-1, depending on the substitution level of each element in HA. Nutrient-substituted HA has the potential to be used as a slow-release fertilizer to supply micronutrients, S, and Mg in addition to Ca and P.

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NASA Discipline Life Support Systems NASA Center JSC Fertilizers/analysis Hydroxyapatites/analysis/chemical synthesis Carbonates/analysis/chemical synthesis Ecological Systems, Closed Citric Acid/chemistry Minerals/analysis Soil/analysis Life Support Systems Microscopy, Electron Spectroscopy, Fourier Transform Infrared Hydroponics Micronutrients X-Ray Diffraction Solutions

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Golden, D. C., Ming, D. W.. 1999-05-01. Nutrient-substituted hydroxyapatites: synthesis and characterization. https://ntrs.nasa.gov/citations/20040088855

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