Prasanna Srinivasa V, Rao R Anantha Padmanabha, Kamath P Vishnu
Department of Chemistry, Central College, Bangalore University, Bangalore 560001, India.
J Colloid Interface Sci. 2006 Dec 15;304(2):292-9. doi: 10.1016/j.jcis.2006.08.064. Epub 2006 Oct 5.
The LDH of Ni with Fe, having the formula Ni(1-x)Fe(x)(OH)2(A(n-))(x/n)yH2O (A = NO3-, Cl-; x = 0.25, 0.33), scavenges CrO4(2-) ions from solution throughout the concentration range examined (0.00625-0.25 N). The CrO4(2-) uptake capacity is independent of the anion in the starting LDH but is higher when x = 0.25 (3.60 meq g(-1)) as compared to x = 0.33 (2.40 meq g(-1)). These values are higher than those observed for control compounds beta-Ni(OH)2 (1.86 meq g(-1)) and FeO(OH) (1.26 meq g(-1)), which do not have any interlayer chemistry, showing that chromate uptake takes place by its incorporation in the interlayer region by a stoichiometric anion-exchange reaction, rather than by adsorption. Nevertheless, the interaction between the LDH and the chromate ions is weak. The weak interaction is due to the mismatch between the symmetry of the chromate ions and the symmetry of the interlayer site, which introduces turbostratic disorder in the chromate-intercalated LDHs. The chromate ions can be completely leached out by soaking the LDH in a sodium carbonate solution.
具有化学式Ni(1-x)Fe(x)(OH)2(A(n-))(x/n)yH2O（A = NO3-、Cl-；x = 0.25、0.33）的镍铁水滑石，在整个研究的浓度范围（0.00625 - 0.25 N）内，可从溶液中清除CrO4(2-)离子。CrO4(2-)的吸附容量与起始水滑石中的阴离子无关，但当x = 0.25（3.60 meq g(-1)）时比x = 0.33（2.40 meq g(-1)）时更高。这些值高于对照化合物β-Ni(OH)2（1.86 meq g(-1)）和FeO(OH)（1.26 meq g(-1)）所观察到的值，后两者没有任何层间化学性质，这表明铬酸盐的摄取是通过化学计量的阴离子交换反应将其掺入层间区域，而不是通过吸附。然而，水滑石与铬酸根离子之间的相互作用较弱。这种弱相互作用是由于铬酸根离子的对称性与层间位点的对称性不匹配，这在铬酸根插层的水滑石中引入了乱层无序。通过将水滑石浸泡在碳酸钠溶液中，铬酸根离子可以被完全浸出。
