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Nutrient‐Substituted Hydroxyapatites: Synthesis and Characterization
Author(s) -
Golden D. C.,
Ming D. W.
Publication year - 1999
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1999.03615995006300030032x
Subject(s) - hydroxyapatites , chemistry , fertilizer , ionic radius , nutrient , carbonate , nuclear chemistry , mineralogy , phosphorus , inorganic chemistry , ion , calcium , organic chemistry
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.