The removal of phosphate by thermally treated red mud from water: The effect of surface chemistry on phosphate immobilization

Jui Yen Lin, Minsoo Kim, Dan Li, Hyunook Kim, Chin pao Huang

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39 Scopus citations

Abstract

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.

Original languageEnglish
Article number125867
JournalChemosphere
Volume247
DOIs
StatePublished - May 2020

Keywords

  • Bauxite residue
  • Electric double layer
  • Sorption
  • Surface acidity
  • Surface precipitation

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