1, University of Cambridge, Cambridge, , United Kingdom
Chlordecone (CLD) was massively used for over two decades (between 1972 and 1993) to control the proliferation of banana weevil [Cosmopolite sordidus] and that has contaminated the agricultural lands on the French West Indies Islands i.e. Guadeloupe and Martinique. After the runoff, this pollutes the surface and groundwater bodies and subsequently contaminates many animals and vegetal foodstuffs. The biomagnification of CLD occurs due to its bioaccumulation in the food chain and reaches a dangerous level in human body. Besides the consumption of contaminated animal or vegetal foodstuff, exposure to CLD could be due to trace amounts of CLD during the consumption of drinking water. Therefore, finding sustainable and effective water filters for CLD adsorption is a subject of great interest.
We have envisioned few techniques in our laboratory on how CLD can easily be removed from the water. Herein, we would like to show only two approaches. In one approach, we obtained a supramolecular host-guest complex between cyclodextrin (CD) and CLD molecules which is inert and completely insoluble in water. Interestingly, the bigger (than CLD alone) size complex starts to sediment in water immediately after the complexation and makes itself easy to be removed from the water by a simple gravitational filtration technique. Several techniques including computational calculation have shown that one cyclodextrin host one CLD molecule in its cavity to form a 1:1 host-guest complex.
The second approach is to obtain highly efficient activated carbon (ACs) filters for the same cause. To this end, we have selected three widely available bio-wastes at those islands i.e. banana peels, coconut husk and sugarcane bagasse. The obtained waste@ACs from these bio-wastes possess very high surface area and prominently high density of acidic surface functional groups. These properties make waste@ACs ideal filters to remove CLD from the water. Notably, after comparing CLD adsorption results between waste@ACs and ACs which is being used at those islands, we have found that waste@ACs are approximately 250% more efficient to that of commercials one for the removal of CLD from the water.
A. Durimel et al. Chem. Eng. J. 229, 2013, 239–249.
V.K. Rana et al. Chem. Eng. J. 293, 2016, 82-89.
V.K. Rana et al. J. Envir. Chem. Eng. 5(2), 2017, 1608-1617.