hrvatski

Effect of water constituents and scavengers on the photocatalytic degradation of anticancer drugs

Relatively newly recognized micropollutants in the environment, whose nano- and micro-scale concentrations could not be detected until recently due to the limited capabilities of instrumentation, are pharmaceuticals. Their increasing production and consumption confirms the fact that many of them are present in various parts of the environment, affecting drinking water supplies and ultimately water quality. While the parent substance is excreted into the environment, the transformation and degradation products newly formed by various biotic and abiotic processes can be more toxic. One such pharmaceutical category that is considered a potential risk to the aquatic environment is anticancer drugs. Due to their physicochemical properties leading to mobility and persistence in the aquatic environment, many of these compounds with their metabolites can cause long-term side effects on terrestrial and aquatic organisms. Classical water treatment methods are not suitable for the removal of micropollutants, so the commonly used advanced oxidation process for this purpose is photocatalysis. The simple mechanism between photocatalyst, TiO2 and light source enables the generation of highly reactive oxygen species that degrade the target compound non-selectively. The photocatalytic efficiency is controlled by various parameters such as the pH, the initial concentration of the pollutant, the light source, the dosage of the photocatalyst, etc. In addition to the above parameters, various organic and inorganic species normally found in natural waters can also greatly affect photocatalysis. Water constituents such as bicarbonate, chloride, nitrate, phosphate ions and humic substances can adsorb on the surface of the photocatalyst, scavenge hydroxyl radicals and produce less active species, absorb photons and reduce the degradation of the pollutant, or ions such as nitrates in a certain environment can promote photocatalysis by .OH production. In this study, the positive or negative influence of the above water constituents on the photocatalytic degradation of crizotinib and imatinib, two anticancer drugs used in patients with lung cancer and leukemia, respectively, was investigated. TiO2 immobilized on a glass fiber mesh was used as the photocatalyst. The mechanism of the photocatalytic reaction was also investigated by adding different radical scavengers.

anticancer drugs, TiO2, water, photocatalytic degradation

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