Fotodegradação de hidrogel de poliacrilamidana presença de íons para o uso na agricultura

Abstract

Hydrogels are defined as tridimensional polymer networks with waterholding capacity within its structure that have theability to swell without the occurrence of its dissolution. This type of producthas been widely used in agriculture as a soil conditioner, because the polyacrylamide, basic constituent of the hydrogel, has the characteristic of absorbing water by physical process, and stock for the plants according to their water requirements. However, the hydrogel has endured its chain degradation because of to UV radiation, high temperatures and salts present in the soil, causing the release of residues and toxic substances, such as acrylamide which is a synthetic and non-biodegradable substance. This study aimed to evaluate the photodegradation of polyacrylamide and the effect of some metallic ions present in the soil in the degradation of this polymer. For the evaluation of photodegradation of polyacrylamide was built a photodegradation chamber with artificial lighting, in which the hydrogel samples were stored, receiving the addition of ions solutions: aluminum, calcium, iron, phosphorus, nitrogen and potassium. After the photodegradation of different samples of hydrogel were made material characterization tests to determine the impact of different ions in the photodegradation process of the material. The chemical analysis of the polyacrylamide was performed by Fourier transform infrared spectrometry (FTIR) and the physical analysis was performed by Scanning Electron Microscopy (SEM) in which together to demonstrate the degree of polymer degradation. Was also assessed the water retention in soil with of the gel and the degradation kinetics of polymer in different times of exposure to light and salt solutions. The results showed that after degraded polyacrylamide lost its water retention characteristics, with the modification of its polymer chains and gel appearance. Furthermore with the FTIR was observed a decrease in the amide grouping being indicative of the polyacrylamide chain scission in acrylamide.