Variation of Used Vegetable Oils’ Composition upon Treatment with Algerian Clays

The treatment of used vegetable oils (UVOs) with clays represents a pivotal step in their industrial recycling process as well as one of the most challenging topics for researchers. In particular, cheap, effective, and sustainable powders need to be explored in order to develop new processes which produce beneficial results in relation to economic and environmental aspects. In this context, five samples within commercial and waste vegetable oils were treated with two sodium- and calcium-based bentonites employing a low oil/bentonite ratio (0.15 wt%). The outcomes of the processes were monitored by FT-IR spectroscopy and compared with the data relative to the parent commercial edible oil. In particular, treatment of FT-IR data by multivariate statistical analysis allowed us to determine a chemical fingerprint characteristic of each sample. Important relationships between the overall chemical composition and the specific clay employed and the treatment time (2 or 4 h) were highlighted. Finally, N2 physisorption, TEM microscopy, and FT-IR analyses of the more efficient Na bentonite allowed us to characterize the material and thus to furnish all the information needed to set-up a general protocol for the partial regeneration of waste vegetable oil destined for further processing.