27-4 Lead Removal from Aqueous Solution Using Calcium Phosphate Minerals

Session: Environmental Geochemistry and Health (Posters)

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Abstract:

Human advancement and industrialization have significantly contributed to societal progress; however, they have also introduced persistent environmental challenges, particularly in the form of toxic heavy metals, such as lead (Pb). Historically valued for its anti-corrosive properties and use in water infrastructure, Pb now poses a growing ecological and public health threat due to its widespread presence and bioavailability. Lead exposure presents serious health challenges, especially to children, as it damages critical systems such as the nervous, renal, and reproductive systems. Beyond humans, lead accumulates in aquatic life, impairing fish through neurotoxicity and reproductive issues, which not only threatens biodiversity but also disrupts entire ecosystems through the food chain. Due to lead’s toxicity and persistence in the environment, there is an urgent need for innovative approaches to immobilize lead and reduce its bioavailability in affected environments. The objective of this project is to determine the potential uptake of lead by apatite [Ca₅ (PO₄) OH] from a wide range of temperatures (near ambient to hydrothermal). The experimental setup consisted of adding ~200 mg of brushite (precursor to apatite) placed at the bottom of the autoclave along with a 0.5 M NaCl solution. To achieve concentrations of 1-15 ppm, aliquots of 1,000ppm Pb standard were added. The autoclaves were then placed into the oven for seven days at six different temperatures (40-250 °C). A total of 24 experiments were conducted.  After the experimental run, the solids and residual fluids were separated. X-ray diffraction (XRD) analysis was conducted to evaluate mineralogy of solids. Inductively coupled plasma–optical emission spectrometry (ICP-OES) was used to quantify lead concentrations in both solids and residual fluids. X-ray diffraction (XRD) analysis confirms that experimental solids are apatite mineralogy. Partition coefficients of Pb between apatite and fluid were calculated as D^Pb = Pb_apatite/Pb_fluid. These D^Pb values vary between 302 to 448 at working temperatures between 80 to 250°C. D values at 40°C resulted greater than that of other working temperatures by a factor of ~7. Overall, results show that lead incorporation into apatite was maximized at 40, 80 and 250 °C. Moreover, the yield of extraction resulted in >92% for all 24 experiments. These findings suggest enhanced lead removal and retention, highlighting the promise of this method for environmental remediation applications.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8027

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