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Comparative molecular characterization of aluminum hydroxy‐gels derived from chloride and sulphate salts
Author(s) -
Leetmaa Karl,
Gomez Mario A.,
Becze Levente,
Guo Fuqiang,
Demopoulos George P.
Publication year - 2014
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.4103
Subject(s) - chloride , aluminium , salt (chemistry) , chemistry , metal , nuclear chemistry , inorganic chemistry , organic chemistry
Background Aluminum ( III ) hydroxy‐gels find important applications in areas such as paint pigments, pharmaceuticals and water treatment or toxic metal sequestration. Since the method of preparation may affect their properties and performance, in this work we prepare aluminum hydroxy‐gels from either chloride or sulphate salts and subject them to comparative characterization.Results Aluminum ( III ) hydroxy‐gels were produced by partial quick neutralization of 2 mol L −1 AlCl 3 or Al( SO 4 ) 1.5 salt solutions with 5 N NaOH at room temperature. The gels were found, following ageing and water washing, to consist of 60–70 wt% Al( OH ) 3 , 5–18 wt% Cl or SO 4 and ∼20 wt% water. Both gel materials upon drying were seen to be highly porous formed from aggregates of very fine particles nucleated during the fast neutralization process. The Al( SO 4 ) 1.5 ‐derived gel was found to differ significantly from the AlCl 3 ‐derived gel both in terms of surface area (38 m 2 g −1 vs. 18 m 2 g −1 ) and chemical features. The aluminum chloride gel material is probably composed of chains of aluminum octahedra (Al n ( OH ) 2. 5 Cl 0 .5n ( H 2 O ) 3n ) while the aluminum sulphate gel of SO 4 ‐stabilized Keggin Al 13 structure: AlO 4 Al 12 ( OH ) 24 ( SO 4 ) 3.5 ( H 2 O ) 12 .Conclusion The distinct molecular structure of the aluminum sulphate‐derived gel may provide an effective matrix for hazardous metal containment. © 2013 Society of Chemical Industry