Aplicação de bioadsorventes em sistema combinado adsorção/flotação para tratar água produzida

Abstract

Produced water management is a concern in the oil industry due to the toxicity of the effluent and its immense production volume, so the optimization of contaminant removal techniques, such as adsorption and flotation, is necessary to keep the process sustainable and unexpensive. Therefore, the objective of this work was to develop ecological and cheap bioadsorbent composites to remove contaminants from produced water through the combination of adsorption and flotation techniques. The composite was produced from a mixture of chitosan, biochar and bentonite and characterized by zeta potential, pH at zero charge point, infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Finite bath bioadsorption, dissolved air flotation (DAF) and Sorptive flotation (SF) tests were performed to remove OGC and Cu2+ ions in synthetic effluents and for a real produced water sample. The morphological and surface characterization of the material showed the presence of a rough, heterogeneous and porous surface with organic functional groups (carboxylic acids, amines, OH groups) that can become adsorption sites for heavy metals and organic compounds. The biosorption tests of copper (II) ions by CPAQB showed that the process is favorable and spontaneous, obtaining 62.11 mg/g of maximum adsorption capacity and 93.21% of maximum removal percentage of these metallic species. While for TOG the maximum percentage of removal achieved was 91.59% and 57.0 mg/g of maximum adsorption capacity for CPAQB. The DAF and SF tests for both contaminants showed that the use of the combined adsorption/flotation technique causes an increase in the removal percentage compared to dissolved air flotation with and without surfactant addition. In addition, the treatment of a sample of real produced water via sorptive flotation was successful for the removal of TOG, since its concentration was reduced from 50 mg/L to 12 mg/L, complying with current legislation. Showing that this technique and the CPAQB composite have potential applicability for the treatment of produced water.