This study investigated the effects of thermal treatment on the solubility and speciation of lead (Pb) adsorbed on synthesized hematite (Pb‐Hm) and in an anthropogenically contaminated soil. The temperature of thermal treatment ranged from 100 to 900 °C, and the speciations of Pb and iron were determined using X‐ray absorption fine structure spectroscopy. In Pb‐Hm samples, the concentration of water‐extractable Pb significantly decreased after being treated at 300 and 600 °C (∼0.50 mg Pb L^–1) compared with the untreated sample (9.83 mg Pb L^–1). Under this temperature range, about 50% of the Pb‐Hm was transformed into massicot (β‐PbO). At 700 °C and above, a slight increase of water‐extractable Pb was probably caused by the formation of minium (Pb₃O₄). In the contaminated soil, water‐extractable Pb increased gradually from 0.30 to 0.40 mg Pb L^–1 with increasing temperature from 25 to 200 °C; then it decreased rapidly to 0.09 mg Pb L^–1 at 300 °C and further decreased to 0.004 mg Pb L^–1 at 900 °C. Cerussite (PbCO₃) and Pb associated with hematite were the major Pb species in the contaminated soil. In the process of thermal treatment, the significant decrease of water‐extractable Pb in the contaminated soil was caused by the transformation of cerussite into hematite‐associated Pb, accompanied by the transformation from ferrihydrite to hematite.

中文翻译：

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热诱导的污染土壤中铅和铁矿物质的溶解度和形态变化

这项研究调查了热处理对合成赤铁矿（Pb-Hm）和人为污染土壤中吸附的铅（Pb）的溶解度和形态的影响。热处理温度范围为100至900°C，并使用X射线吸收精细结构光谱法测定了铅和铁的形态。在Pb-Hm样品中，与未经处理的样品（9.83 mg Pb L ^–1）相比，在300和600°C（〜0.50 mg Pb L ^–1）处理后，水可萃取Pb的浓度显着降低。在此温度范围内，约50％的Pb-Hm转化为块状（β-PbO）。在700°C和更高温度下，水萃取性Pb的轻微增加可能是由于形成了最小（Pb ₃ O₄）。在受污染的土壤中，随着温度从25升高到200°C ，水可萃取的Pb从0.30逐渐增加到0.40 mg Pb L ^–1。然后在300°C时迅速下降至0.09 mg Pb L ^–1，在900°C时进一步下降至0.004 mg Pb L ^–1。赤铁矿（PbCO ₃）和与赤铁矿伴生的Pb是受污染土壤中的主要Pb种类。在热处理过程中，污染的土壤中水可萃取的Pb的显着降低是由于陶粒转变为赤铁矿相关的Pb，同时伴随着铁水铁矿向赤铁矿的转变。