Efficient removal of contaminants from waste lubricant oil by nano-porous bentonite produced via microwave-assisted rapid activation: process identifications and optimization.

The low-cost Ca-bentonite was rapidly converted to a mesoporous adsorbent via microwave-assisted acidification and the obtained materials were employed for the removal of contaminants from waste lubricant oil. In order to understand the role of acid combinations on activation, the agent compositions were prepared according to the mixture design algorithm. The waste oil recovery was carried out in a batch system to determine the appropriate acid composition, optimum microwave power, radiation time, and powder/acid ratio. As power increased, the contaminant removal performance of the adsorbent was effectively raised to achieve appropriate clear base oil. The rise in power behind 600 W negatively affected the performance of the adsorbent in which the color of oil was changed from yellow to brown. The appropriate recovery of waste oil was readily achieved by employment of adsorbents in which the acidification was performed in 15 min. The microwave-assisted technique could shorten the residence time to achieve the maximum efficiency in comparison with the performance of those produced through the conventional method. Although sulfuric acid can be used for acidification of bentonite by microwave heat treatment, the combination of acetic acid, < 50 mol%, with the mentioned acid was identified as an efficient agent to improve the performance of adsorbents which is valuable from an engineering point of view.

Management of adsorbent content in waste motor oil regeneration by spectrophotometrical study and effective acidification in production of nano-porous clay.

In the present work the application of novel technique was highlighted for reduction of adsorbent content in recovery process of waste motor oil by effective acidification. The effects of acidification factors such as acid proportions, adsorbent dose, powder/acid ratio and residence time were analyzed on removal of contaminates from waste oil. Acetic, hydrochloric and sulfuric acids were mixed according to the statistical mixture design algorithm to prepare acidification agents. The dry original clay was submitted into the prepared acidic solutions. The designed instrumental setup allowed the preparation of nano-porous powders where the controlled factors were residence time. The distillation of waste oil was carried out in the industrial scale. The significance of independent variables and their interactions were tested by blending the obtained powders with distillated oil and then the adsorption was evaluated, spectrophotometrically. The experimental results revealed the region in which the optimum regeneration of waste oil is obtainable. In order to well understand the role of nano-structured material on regeneration, the adsorbents were characterized through X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area measurement and scanning electron microscopy. The employment of acetic acid in combination with sulfuric acid plays an effective role in development porous structure and improvement of contaminant adsorption. The powder produced in optimum condition contains nano-pores with diameter about 11 nm. The employment of this technique provides a potential for reduction of adsorbent content, 33.3 wt%. Finally, it was demonstrated that the efficiency of prepared adsorbent supports further development for commercial application purpose.