TITLE:
Remediation Effects of Different Concentration of Nano-Hydroxyapatite Level on Pb-Contaminated Soil
AUTHORS:
Yi Li, Wenqiang Lv
KEYWORDS:
Soil Pb, N-HAP, Remediation of Polluted Soil, In Vitro Digestion Test, Bioaccessibility
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.10 No.9,
September
23,
2022
ABSTRACT: Phosphorus-containing amendments can reduce the mobility of Pb in soil. Hydroxyapatite (HAP) is one of the most commonly
used phosphorus-containing amendments. With the development of nanotechnology,
nano-hydroxyapatie (n-HAP) was gradually applied to remediate soil polluted by
heavy metals. Considering the concentrations of HAP/n-HAP were not more than 5% in most studies, soil polluted by Pb was
artificially prepared and three different concentrations of n-HAP: 5%,
7% and 10% by weight, were added into the Pb-polluted soil separately. The
mixtures of soil and n-HAP were incubated for 180 d and sampled regularly. The
bioaccessibility of Pb in soil was determined using simulated gastric juices of
two in-vitro digestion tests: USPM
(United States Pharmacopeia Methodology) and PBET (Physiologically-Based
Extraction Test). The results showed that the immobilizing efficiency of 5%
n-HAP to Pb in soil was the highest in PBET. The extractable Pb from soil by
USPM was not affected by concentration of n-HAP. So, the least concentration of n-HAP, i.e. 5% n-HAP treatment, was the most cost-effective in
USPM. Soil pH increased with concentration of n-HAP. However concentration of
n-HAP had little effects on content of soil OM. According to regression
analysis, more than 50% differences of the extractable Pb from soil by PBET can
be explained by soil pH, while soil pH, organic matter content and incubation
time together explained nearly 85% differences of extractable Pb from soil by
USPM.