Produção de matrizes lignocelulósicas via acetilação com propriedades adsortivas de poluentes ambientais

Abstract

Cellulose is a structural polymer that gives plants rigidity, is biodegradable, renewable, and readily available. Cellulose as a matrix for pollutant remediation has been employed after bleaching steps, purification, and/or chemical modifications. The purification/bleaching process makes the product more expensive and difficult to use. Based on this premise, studies were conducted to develop simple and low-cost technologies for the development of an innovative product for the sorption of heavy metals and/or pesticides in lignocellulosic matrices. The study sought to evaluate the environmental impact on the waters and soil of the Ivinhema river basin (B.H.I). The study was carried out with mapping of critical points, sample collection and physical-chemical analysis of river water (AF) from the B.H.I (Ivinhema River Watershed) for evaluation of the pollutant potential and analysis of parameters for product (bio)design and potential application. In the HF and soil samples the determination of metals by atomic absorption spectroscopy (AA) and chromatographic analysis of organochlorines were performed. From a total of 5 sampling points, distributed over 38,212 km2, at least 4 elements with concentrations above the specification level expressed in the environmental legislations could be detected in the B.H.I and organochlorine products in the samples collected. The product design considered the synthesis of cellulose acetate (CA) using fresh corn stover biomass (Zea mays), which was partially delignified with 0.5% NaOH at 80°C for 15 minutes under stirring. This partially delignified biomass was functionalized by acetylation with anhydride/acetic acid/H2SO4. The dry product obtained after this step was the material used in the remediation of pollutants in water samples for the metals Pb and Cd. The sorption is due to the interaction of these pollutants inside and on the surface of the fibrous particles. It can be considered that there is a complementary interaction between the adsorbent product and the sorption processes of the soil for the retention of metal ions and pesticide molecules, reducing the availability of these pollutants in the wet environment, and thus preventing the mobility of these species in soil and water.