This study investigated thermal treatment of red mud (RM) and its effect on phase composition, surface property, and sorption capacity exemplified by phosphate. Dehydration (∼600 °C), decomposition of carbonate minerals (700 °C-800 °C), and silicate/aluminate formation (900 °C-1000 °C) occurred upon thermal treatment of RM. Grain growth and vitrification that rendered initial morphology changes and decreased the specific surface area of RM from 26.5 to 4.1 m2/g when treated from 600 to 1000 °C, respectively. Surface acidity, i.e., intrinsic acidity constant and surface acidity density, decreased as well after thermal treatment at 600 °C due to burnouts of organics then increased upon further elevated-temperature treatment because of phase transformation. Thermal activation enhanced phosphate adsorption density (μmol/m2). Multilayer sorption aided by leached metal ions was responsible for phosphate immobilization.

中文翻译：

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通过热处理赤泥从水中去除磷酸盐：表面化学对磷酸盐固定化的影响。

这项研究研究了赤泥（RM）的热处理及其对相组成，表面性质和磷酸盐吸附能力的影响。RM热处理后会发生脱水（〜600°C），碳酸盐矿物分解（700°C-800°C）和硅酸盐/铝酸盐形成（900°C-1000°C）。当从600到1000°C处理时，晶粒的生长和玻璃化分别使初始形态发生变化并使RM的比表面积从26.5降低到4.1 m2 / g。在600°C热处理后，由于有机物的燃尽，表面酸度（即固有酸度常数和表面酸度密度）也下降，然后由于相变而在进一步高温处理时增加。热活化提高了磷酸盐的吸附密度（μmol/ m2）。