Preparação e aplicação de compósitos de carvão ativado e óxido de ferro preparados a partir do defeito PVA do café na remoção de poluentes do meio aquoso

Abstract

The black, green and sour (PVA) coffee defect contribute with ca. 20% of the total coffee production. It should be separate from the normal coffee grains in order to improve the final quality of the beverage. In this way, the present work has the objective to use this reject for the production of adsorbents and materials with catalytic properties for using in the oxidation reactions. Experiments were carried out in two steps: in the first one, activated carbons were prepared from PVA defect using as activating agents zinc chloride and phosphoric acid. The resulting activated carbons were characterized by infrared spectroscopy (FTIR), elementary analysis (CHN), surface area measurements (BET), scanning electronic microscopy (SEM) and thermogravimetric analysis (ATG). The adsorption tests were carried out using as organic models methylene blue (AM), reactive red (VR) and triadimenol (TRD). Chromium (VI) anion in dichromate form was also used. In the second stage, composites CA/iron oxide (goethite, -FeOOH) in the ratio 1:0,005 (w/w) were prepared. The materials were characterized by X-rays diffractometry (XRD), Mössbauer spectroscopy, BET, FTIR and SEM. Catalytic activity of the materials was tested in the oxidation of AM and TRD. The catalytic tests were carried out with and without organic acids [picolinic (PIC) and dipicolinic acid (PDC)]. The produced materials have shown good catalytic activity in the oxidation of organic compounds in aqueous media.