Síntese e aplicação do compósito geopolímero/Fe3O4 como adsorvente magnético para a remoção de contaminante orgânico em efluente líquido

Abstract

Accompanying population growth, industries, in addition to supplying the needs of the population, have become one of the main sources of environmental contamination, with the textile sector being the main responsible for the increase in concentrations of dyes in water, which in addition to making them inappropriate for consumption lead to health problems, especially when we consider that they can be disseminated through the food chain. In view of these environmental aspects, numerous physical and chemical processes of degradation of these compounds in textile effluents have been studied, as well as the development of new materials for application in already recognized treatment processes, such as adsorption. The adsorption technique is often recommended in the treatment of effluents, including that of the textile industries, due to its low cost, simplicity of operation and no formation of harmful byproducts as in the case of other destructive procedures. In this work, a magnetic geopolymer (MGP) was synthesized and characterized as its adsorbent for acid green dye 16 (VA16). A low temperature (60 ° C) heat treatment procedure was used to synthesize MGP from metakaolin, biogenic rice husk silica and magnetite, having as meso-structuring agents hydrogen peroxide and soybean oil. The obtained material was characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), N2 adsorption-desorption analysis of N2 by Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH), vibrating sample magnetometer (VSM) and scanning electron microscopy (SEM) using energy dispersive X-ray spectroscopy (EDS). The MGP was used as an adsorbent and its activity was investigated for the degradation of a textile organic dye (acid green 16) from aqueous solutions. In the experiments were evaluated different operating variables, such as adsorbent dosage, pH, temperature and initial concentration of dye. The adsorption process was extremely fast, the equilibrium was reached within 30 min and the maximum adsorption capacity in the monolayer was 135.05 mg g-1 and furthermore the MGP had an adsorption capacity of 400 mg g-1 and removal percentage of 98.5%. The adsorbent MGP demonstrated high recyclability and excellent dye removal efficiency after four successive cycles and can removed from the dispersion by applying an external magnetic field. MGP showed to be a good alternative adsorbent, presenting as advantages rapid kinetic, high adsorption capacity and efficiency.