Layered Double Hydroxides and the Environment: An Overview - Advanced Materials for Agriculture, Food and Environmental Safety - page 19

1.6.5.6 Removal of Surfactants

Layered double hydroxides have strong surface and interlayer hydrophilic
properties due to their high content of hydroxyl groups and water mol-
ecules. h ese properties limit the adsorption and the intercalation of non-
ionic or hydrophobic contaminants. However, anionic surfactants such as
alkyl carboxylate, alkyl sulphate or alkyl sulphonate are easily adsorbed
and exchanged in LDH structure [151-153]. Dekany et al. [154, 155] com-
pared the adsorption properties of both cationic surfactant/smectites and
anionic surfactant/LDH antitype systems. h e higher charge density of the
anionic clays explains their higher adsorption capacities in terms of ion
exchange capacity percentage. Pavan et al. [156-158] studied the adsorp-
tion of dodecylsulphate, octylsulphate, dodecylbenzenesulphonate and
octylbenzenesulphonate by Mg-Al-LDH.

1.7 Conclusions

In this chapter we have established that LDHs are an important clay mate-
rial. h ey can be easily synthesized in the laboratory by various cheap and
eco-friendly methods. h e LDHs can be synthesized by varying the com-
position of precursor according to their applications in various i elds.
Layered double hydroxides have great potential for wide use in catalysis
in a wide range of applications from rei nery to i ne chemicals and envi-
ronment protection, and especially in the development of multifunctional
catalysts with tailored properties and catalyst supporters. In this chapter we
have examined some cases and discussed recent trends, limits and opportu-
nities of ered by this class of materials for application in the environmental
and pharmaceutical industries. Attention was focused on the use of layered
double hydroxides as an adsorbent for the treatment of water and wastewater
from industrial el uents. Since several reviews have already been published,
our objective was not to make a systematic review of the topic, but instead to
of er a personal view of the more interesting recent direction of research and
at the same time, in areas with an increasing number of publications which
do not parallel the practical relevance of the topic.

Acknowledgements

h e i rst author is extremely grateful to the University Grant Commission,
New Delhi, for the award of Post Doctoral Fellowship for Women (Award
Letter No. F. 15/53/12 (SA-II).