Abstract

Background: The oil removal from industrial effluents is one of the biggest problems faced in the world. It is a very important environmental issue, and it is necessary to solve this problem. In this sense, ZIFs are increasingly important in the environmental area.

Objective: This work reports a method for the synthesis of ZIF-zni nanocrystals at room temperature in 1 h, and a performance of the ZIF-zni nano adsorbent in the oil removal from the oil-water emulsion.

Methods: ZIF-zni was produced from the solvothermal method, and it was characterized by X-ray diffraction, electron microscopy, contact angle, infrared spectroscopy and thermogravimetry. Oilwater emulsion was produced by lubricant oil and distilled water. Batch-type adsorption at 200 rpm for 2 h was used to evaluate the potential of ZIF-zni for the separation of the oil-water emulsion with initial oil concentration (100, 300 mg/L) and temperature (30, 60°C).

Results: The characterizations showed that the crystalline phase of ZIF-zni was successfully obtained. The ZIF-zni exhibit a very high removal percentage (above 95%) and adsorption capacity. The predictions of multiple linear regression models determined based on the factorial design of experiments are excellent.

Conclusion: The value up to 2879 mg/g of adsorption capacity was reached, thus indicating that the use of the nanoadsorbent ZIF-zni has great potential in the process of separating oil-water emulsion.

Keywords: Metal-organic frameworks, polymorphism, nanotechnology, lubricant oil, emulsion, demulsification.