Water is today the most precious asset for every nation. The possibility of having enough water available and with purity suitable for the type of use that is intended to be done (agriculture or human consumption) is the main objective. In our territory, surface water is mainly contaminated with traces of pesticides and heavy metals.
The work stems from the need to concretely implement a path of environmental sustainability, allowing to reduce waste and to promote water reuse. Our project using the supramolecular chemistry of cyclodextrines proposes a new strategies for catching pollutants in the water.
Our project “Supramolecular Chemistry a solution for the environment”, based on environmental sustainability and in particular the reduction of water waste, uses beta-cyclodextrins (completely natural and starch-derived) absorbed in Liquidambar berries (abundant material in nature) for the removal of heavy metals and polluting molecules from the water.
Synthesis occurs by action of an enzyme called glycosiltransferase cyclodextrine (CGTasis) on starch degraded by thermal hydrolysis or using “ α-amylalsis”. This results in mixtures containing the three types of cyclodextrin.
Supramolecular chemistry studies aggregates stabilized by non- covalent bonds or forms of complexion, it is generally considered a molecule (“host”) that binds, specifically, another molecule (“guest”) to generate a superstructure or complex “host-guest”. The main feature of cyclodextrines is their ability to form include complexes, (host-guest complexes), with a very diverse range of solid, liquid and gaseous compounds, through molecular complexion. In these complexes a guest molecule is placed inside the cavity of the host cyclodextrin. The size of the complex is in relation to the host cavity and the guest molecule. The lipofila cavity of cyclodextrines provides a micro environment in which appropriate sized apolar fractions can fit in to form inclusion complexes. Generally only one host molecule is included in a cyclodextrin molecule; however, in the case of some molecules with low molecular weight, more than one host molecule can fit into the cavity, while in the case of some large molecules more than one cyclodextrin can bind to the guest. The types of molecules that can be encapsulated in cyclodextrines is very varied.
It includes compounds such as ahalatc molecules (linear or branched), aldehydes, ketones, alcohols, organic acids, fatty acids, aromatic molecules, gases and polar compounds such as halogens, i.e. cicides and amines. The formation of an inclusion complex is accompanied by the variation of a specific chemical-physical property that detects its formation (calorimetric variations, and variation of UV-visible spectra).
For our project, both the cyclodextrines and the “cyclodextrines” linked with EDTA were used for the simultaneous capture of copper ions and organic molecules. CD cavities are responsible for capturing dye molecules, forming inclusion complexes, while EDTA groups act not only as cross-linkers but also as chelon sites for metal ions. Phenolphthalein in the basic environment, methylene blue and methylene were used to simulate polluting molecules. In order to completely remove pollutants in the water, the β-cyclodextrines have been absorbed into Liquidambar berries (high contact surface) that were immersed in contaminated water.
So, beta-cyclodextrins can be used for both water and air purification, by reticulating B-CD with cotton fibers, or controlled phytopharmaceutical release. We follow Green Chemistry’s principles to reduce the amount of pesticides which lasts for years.
In conclusion, our idea, in addition to using abundant waste material as berries are not used in other sectors, it is also very practical, because we could use beta-cyclodextrins absorbed in berries, for water purification in the drainage channels of the rice paddies present in our territory. If waters are clean, the aquifers also benefit.
Project videoThis is how I came up with the idea for this project:
Our project aims at environmental sustainability by reducing waste and promoting the reuse of water. The plan was born from the daily observation, on our territory, of berries, which have a particular structure, because of the high contact surface (both external and internal). If water's clean, the aquifers also benefit.