Experiências durante a graduação: Estágio supervisionado na empresa TRIMED Medicina Diagnóstica e desenvolvimento do projeto: “Preparação, caracterização e aplicação de monolitos a partir da mistura de acetato de celulose/acetato butirato de celulose na remoção do agrotóxico atrazina”

Abstract

Monoliths produced from cellulosic derivatives are materials molded as a single piece that typically exhibit a high surface area due to the presence of mesopores, micropores, and a hierarchically interconnected three-dimensional macroporous network. These materials are promising for environmental and industrial applications, such as supports for enzyme immobilization and adsorbents in separation processes. In this work, monoliths were produced from a mixture of cellulose acetate (CA) and cellulose acetate butyrate (CAB) polymers, with the addition of different nonsolvents (NS) for the formation of porous monoliths through the thermally induced solvent phase separation method and by applying the molecular imprinting technique using a template molecule to enhance the monolith’s performance in removing the contaminant atrazine. The appropriate polymeric mixture for monolith formation has a ratio of 3:1 (w/w) of CA to CAB at a concentration of 15% (w/w) for the polymeric solutions. Various monoliths were produced with the polymeric mixture by adding the NS water, butanol, hexanol, and octanol separately, at 70 °C. For molecular imprinting, monoliths were prepared with the addition of atrazine as a solution to the polymeric mixture using the NS octanol, hexanol, and butanol at temperatures of 50 and 70 °C. The characterization techniques employed included infrared absorption spectroscopy, scanning electron microscopy (SEM), specific surface area and porosity analysis (ASAP), thermogravimetric analysis, and differential scanning calorimetry. The bands at 1643, 1459, and 2820 cm⁻¹ confirmed the formation of the polymer blends. The SEM and ASAP results revealed that the monoliths exhibit distinct porous morphologies depending on the type of NS used and the temperature applied. All monoliths, except the one with NS water due to the formation of a dense and compact structure, were subjected to a process for removing the herbicide atrazine. For the other monoliths, the average removal percentage was 50.91%, suggesting that the presence of CAB directly influenced the adsorption of the analyte, as the reference monolith produced with CA achieved a removal of 18.64%. Notably, the results demonstrate the effective formation of the polymer blends, whose hydrophilicity modulation directly influenced the adsorption process's performance.