Dataset to project MINIATURA7 funded by the National Science Centre, Poland (grant number 2023/07/X/ST5/01519)

Abstract

In the project entitled "Decomposition of (nano-)microplastic by photocatalytic method", preliminary research was carried out on the synthesis of a photocatalyst and its use for the decomposition of plastic by photocatalytic method. Photocatalysis is ecological and cheaper due to the reaction conditions. Photocatalysis is carried out at atmospheric pressure, at ambient temperature, and also uses UV radiation or sunlight as an energy source. Plastics are widely used in everyday life mainly due to the low cost of production and use, as well as low weight and durability compared to other materials. It is predicted that by 2050 a total of 26 billion tons of plastic will be produced. This is especially worrying due to the fact that so far only 9% of plastic has been recycled, 12% has been incinerated, and as much as 79% has been thrown away in landfills. As a result, plastics can directly lead to serious pollution of water, atmosphere and soil. Their decomposition under the influence of, among others, mechanical friction/abrasion, exposure to light, temperature, particles smaller than 5 mm are formed, which have been called secondary microplastics. It has been noticed that the toxicity of plastic can be greater when its size decreases to nanometers. Therefore, facing the threats posed by microplastics and perhaps even greater ones from nanoplastics, the aim of the project was to carry out the decomposition of nano- and microplastics using a photocatalytic method in air, water and water with the addition of NaCl, which simulated water in seas and oceans. Initial studies concerned the decomposition of plastic in the form of polystyrene (PS) beads with a size in the nano- and micrometer range on a semiconductor photocatalyst. The hydrothermal synthesis of the photocatalyst was carried out, and then silver nanoparticles were deposited on it. The decomposition of plastic was monitored using microscopic and spectroscopic techniques. It was proven that the synthesized photocatalyst effectively decomposes polystyrene under the influence of UV radiation. Moreover, it shows activity in the water environment in light above 400 nm, although its activity is much lower compared to UV. In UV light, plastic is most effectively decomposed in salt water and water, more slowly in air. Polystyrene decomposition occurs under the influence of reactive oxygen species, which are more easily formed in the water environment. SEM studies allowed precise determination of changes in the size and shape of PS. On the other hand, FTIR studies allowed estimation of PS decomposition, but were not sufficient in the study of intermediate products. These were preliminary studies that should be extended to include studies using techniques such as TG-FTIR, GC, HPLC and others leading to identification of intermediate and final products of plastic decomposition and explanation of the mechanism of polystyrene decomposition.