Calcination effect on multi-adsorption abilities of modified montmorillonite

In this study, inorganic-organic modified montmorillonite (IOMMt) was synthesized by modifying montmorillonite (MMt) with Keggin Al₁₃ complex (Al13) and Hexadecyltrimethyl ammonium (HDTMA) simultaneously (AH-coMMt). For comparison, Al₁₃-modified montmorillonite (A-MMt) and HDTMA-modified montmorillonite (H-MMt) were also synthesized. MMt, A-MMt, H-MMt, and AH-coMMt were calcined at 200–800 °C. The changes in structure, physical-chemical property and adsorption ability of IOMMts for nine types of pollutants (methylene blue (MB), methyl orange (MO), bisphenol A (BPA), enrofloxacin (ENR), phosphorus (P), arsenic (As), chromium (Cr), lead (Pb), and cobalt (Co)) were investigated. The XRD, TGA, and FTIR results indicated that the structural changes and the HDTMA's conformational changes in AH-coMMt were similar to H-MMt, but these changes in AH-coMMt were alleviated by the intercalated Al₁₃ in AH-coMMt. The surface areas of H-MMt (106.27 m²/g) and AH-coMMt (180.41 m²/g) increased to the highest values after calcination at 400 and 450 °C, respectively. The adsorption results showed that after calcination at 350–700 °C, the adsorption abilities of AH-coMMt towards particular pollutants (16.8 mg/g for Pb and 3.7 mg/g for Co at 700 °C) were enhanced, and the adsorption abilities of AH-coMMt towards some pollutants (125.8–247.7 mg/g at 400–700 °C for MB, 50.5–55.4 mg/g at 350–700 °C for ENR, and 5.2–7.5 mg/g at 400–700 °C for P) remained better but poor towards MO, BPA, and Cr than singly modified MMts.