Membranas cerâmicas sintetizadas a partir de cinzas de bagaço de cana-de-açúcar para aplicação em tratamento de efluentes

Abstract

The unbridled consumption of natural resources and the high production of waste has had a negative impact on the environment, creating a growing demand for alternatives to minimize its effects. One of the solutions to this problem is to use waste to manufacture new materials, which is a way of promoting the circular economy and sustainability. Within this context, this study sought to develop a ceramic microfiltration membrane using sugarcane bagasse ash (CBCA) and kaolin as precursors, for application in the pre-treatment of real effluents. This study was divided into two stages, the first corresponding to the development of the ceramic membrane and the second to carrying out filtration tests to assess the efficiency of the microfiltration process. Initially, the ash and kaolin were subjected to physical and chemical characterization tests in order to assess the feasibility of using them in the production of ceramic material. The membranes were then developed using two formulations with different proportions, containing 40% and 60% CBCA of the total mass of the membrane. 0.05% sodium silicate was added as a deflocculating agent and the mixture was wet-mixed under stirring at 250 rpm for 1 hour. To obtain the membrane, the specimens were subjected to uniaxial compaction at 27 MPa in an electric press and then sintered in a muffle furnace at 1200 ºC for 1 hour. The resulting membranes were characterized in terms of linear shrinkage, loss on ignition, water absorption, apparent porosity, XRD, FTIR, BJH. BIT and BET. In order to assess the morphological structure of the samples, scanning electron microscopy (SEM) analysis was carried out, as well as mercury intrusion porosimetry tests to verify the average pore size and actual density of the membranes. The second stage involved collecting real raw effluents from the textile, biodiesel and metallurgical industries, provided by industries located in the Upper Uruguay region of Rio Grande do Sul. The effluents were then characterized before and after filtration to determine the efficiency of the process, with parameters of pH, turbidity, color, total, dissolved and fixed solids, and chemical oxygen demand. The use of CBCA and kaolin precursors made it possible to produce porous ceramic membranes suitable for the microfiltration process. The membrane with the lowest amount of CBCA in its composition showed the best results for removing the physical and chemical parameters evaluated.