Comparative study of the adsorption and photo-reduction of hexavalent chromium onto AlPO₄-11 and SAPO-31 substituted Fe₂O₃ from aqueous solutions: Synthesis, characterization, kinetic and thermodynamic studies

ABSTRACT

AlPO₄-11/Fe₂O₃ and SAPO-31/Fe₂O₃ composites were used in the adsorption and reduction of chromium ions in order to compare their catalytic performances. They are characterized by XRD, SEM and EDS. The nature of coordination units of nuclei ²⁷Al, ³¹P and ²⁹Si was determined by MAS-NMR. The best performances on photo-reduction (99%) were obtained on the SAPO-31/Fe₂O₃ due to its acidic surface Fe₂O₃ oxides properties. The estimate of the thermodynamic parameters ΔG°, ΔH° and ΔS° revealed that photo-reduction process was spontaneous, exothermic for AlPO₄-11/Fe₂O₃ and endothermic for SAPO-31/Fe₂O₃. The process follows the first pseudo order kinetic rationalized by the Langmuir-Hinshelwood (HL) model.

KEYWORDS:

• Photo-reduction
• AlPO₄-11/Fe₂O₃
• SAPO-31/Fe₂O₃
• Cr (VI) ions
• kinetic study

Acknowledgements

Our big gratitude to General Direction of Scientific Research and Technological Development (DGRSDT) and Thematic Research Agency in Science and Technology (ATRST) of Ministry of Higher Education and Scientific Research of Democratic Republic of Algeria.

Supplementary material

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