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Study of nanochitosan polymer co-transport in the presence of the insecticide difenoconazole in porous media under static and dynamic conditions

Kardamaki Eleni

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Summary

In recent decades, a variety of problems have been created around the world that the environment and the ecosystem have to deal with. One of the main problems that dominates today is the pollution of surface and groundwater. The needs for clean and potable water is constantly increasing as it grows in tandem with the rapid increase of the Earth's population, where water is essential. But at the same time with this need, water pollution from various internal and external factors is also increasing. Therefore, the supplies of clean water that exist now on Earth are constantly decreasing due to this pollution. Thus, it is important to constantly develop new technologies to assist in the purification of these waters. However, most of the technologies that have been developed are insufficient to remove pesticides and other substances from arable land, and these substances are then carried underground through the water. It is therefore important to use a multi-functional formulation to alleviate and reduce the concentration of pesticides in the environment and water resources and thus their pollution. For the reduction of pesticides, a great deal of interest has been given to polymers. Chitosan belongs to the class of polymers and its action is of particular importance as it can be used in various fields of science. Its special properties, pHysicochemical, biological, ecological and high absorption properties can justify the widespread use of chitosan in many processes. This polymer belongs to the class of hydropHobic insecticides belonging to the pyrethroids and is frequently used in the agricultural sector as it has quite high effectiveness. However, its use may cause slight toxicity to other nuisances occurring in the environment. The use of pesticides in the environment is constantly increasing, but so is the impact on soil and water. Therefore, research is still ongoing in the development of mechanisms to reduce these problems and, above all, to reduce pollution. One key technology is adsorption, which removes pollutants and pesticides. Adsorption is the result of attractive forces exerted either between the pollutants and the surface of the solids or the adsorbent. It is a process which is likely to produce little or no toxic pollutants. Thus, compared to other pHysical, chemical and biological methods, it is the most widespread and most widely used. The experiment carried out examined the possibility of adsorption of Chitosan to Difenoconazole through a porous medium. This process is an innovative alternative in terms of environmental remediation, as it also explains the transfer of the contaminant in the subsurface. In order to carry out the correct procedure of the experiment and to extract the data used, three series of experiments were carried out. Initially, the first experiments that took place were the Intermittent Batch experiments, which were applied under both static and dynamic conditions to study the interaction of Chitosan with Difenoconazole. Subsequently, using the same procedure followed for the experiments conducted above, the second set of experiments was performed with the addition of quartz sand. These second series experiments using quartz sand were designed to simulate the soil in the experiment. To conduct these two sets of experiments, several parameter changes were made to simulate a range of combinations found in nature. In particular, four concentrations of Difenoconzole were used in dosing experiments (15μL, 30μL, 60μL, 120μL), where in all four experiments the concentration of Chitosan was 0.015g and its pH was adjusted to 6.5. Two experiments were then performed in which the pH was varied (4, 8). Also 15μL of Difenoconazole and 0.015g of Chitosan were added. Therefore, there were three experiments performed at different pH as the same experiment was performed at pH 6.5. Finally, changes in ionic strength (1mM, 50mM, 100mM) were also performed and 15μL Difenoconazole and 0.015g Chitosan were used while the pH was kept constant at 6.5. Then the same static and dynamic experiments were performed with the addition of quartz sand, a material that simulates large part of the soil layer. From these experiments, data on absorption were found using spectropHotometer in order to compare the parameters. Finally, four full column experiments in saturation conditions were also carried out. These experiments were aimed to perform a study on the effect of quartz sand and pore water velocity on the transport of Difenoconazole and Chitosan. An experiment was conducted separately for each material as well as one containing both materials together. The experiment consisting of both materials had a better result. A result that shows how important the role of the Chitosan polymer as an adsorbent of the insecticide is. Finally, the experimental data were placed in ColloidFit software to simulate the pseudo-second order adsorption kinetic model and then placed in Igor Pro to construct the diagrams.

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