Synthesis and characterization of ecosorbents and their application in waste cooking oil

Abstract

Globally, millions of tons of waste cooking oils (WCO) are generated yearly, and the recovery rate for manufacturing chemicals such as biodiesel is still low. Unfortunately, part of the WCO has been directly discharged into natural environments, underscoring the industrial significance of developing novel technologies for its utilization. As a possible solution to its recovery, this research proposes a new approach for Agave Americana fiber (AF) as a filler in castor oil-based polyurethane, obtaining ecosorbents and evaluating the sorption capacity of WCO. The pristine PU and PU/AFX% ecosorbents (X stands for AF content between 5 and 20 wt%.) were characterized by SEM, OM, density, FTIR, XRD, contact angle (CA), TGA, and water absorption. The inclusion of AF fillers impacted density and influenced morphological, physical–chemical, and thermal properties. Sorption capacity and efficiency were evaluated by varying the contact time and concentration in the oil/water system, and a direct influence of fiber content on sorption capacity was observed. PU/AF20% presented the highest CA and the best sorption capacity and efficiency. Response surface methodology (RSM) evaluated the optimization behavior of sorption capacity (for water and oil), emphasizing a strong dependency on sorption capacity as a function of fiber content variation. Langmuir and Freundlich isotherm models well defined the sorption mechanisms, and the Langmuir model demonstrated the best fit for PU/AF20%, exhibiting a maximum adsorption capacity of 163.93 g g-1. PU/AF20% reusability was evaluated for 21 cycles with a maximum efficiency of 74.2% for oil systems. Thus, AF is an innovative filler in castor oil-based polyurethane for discarded waste cooking oil sorption.