Síntese de zinc imidazolate framework-8 para adsorção de óleo lubrificante automotivo de emulsão óleo em água.

Abstract

Oil, as a common pollutant in wastewater, has many effects on the biosphere. Automotive lubricating oil in liquid effluents also has potential for pollution. Oil-in-water (O/W) emulsions can have potentially polluting characteristics similar to the oils that gave rise to them, but with lower concentrations and must be treated to meet the discharge pattern in receiving bodies. Although the batch-type adsorption has been widely used for automotive lubricating oil demulsification, many adsorbents have low adsorption capacity. Zinc Imidazolate Framework-8 (ZIF-8) is a promising adsorbent in the oil separation from water and in the vegetable oil demulsification from synthetic O/W emulsions. In this context, the objective was to apply ZIF-8 in the mineral-based automotive lubricating oil adsorption from synthetic O/W emulsions, by batch systems. ZIF-8 was synthesized by the solvothermal method according to a methodology reported in the literature. The structure of the ZIF-8 was characterized by X-ray diffraction (XRD), infrared region spectroscopy (IR) and assays of water contact angle. ZIF-8 stability test was performed in distilled water. As a way of representing effluents with lubricating oil, synthetic O/W macro emulsions were used. The influence of the dosage of ZIF-8 on demulsification was verified. The recyclability of ZIF-8 with use and reuse was evaluated, without regeneration and with chemical regeneration with solvent. Based on the results of XRD and IR, ZIF-8 has been successfully synthesized at the laboratory level. The ZIF-8 showed hydrophilic and hydrophobic characteristics, stability in aqueous solution, and oil adsorption capacity around 2811.1 mg/g at a adsorbent dosage 0.1 g/L. ZIF-8 was easily regenerated with ethanol and it was able to reuse up to 4 cycles with a dosage of 10 g/L with efficiency up than 95 %.