A Novel Preparation and Application of Orange Peel Aerogel for Removal of Oil Contaminants in Soils

Existing soil remediation approaches are lacking in cost-effectiveness, environmental impacts or societal acceptance. Environmental remediation techniques are often characterized by considerable time requirements and may leave residual effects on natural ecosystems, thereby potentially compromising net environmental benefits. This study investigated the oil adsorption capacity of aerogels produced from waste orange peels. Aerogels are highly porous three-dimensional materials made from organic and inorganic materials, with low density and high adjustable specific surface area. Orange peel aerogel was produced from waste orange peels using combined methods of physical, chemical, and thermal modification processes and was dried using the freeze-drying method. Adsorption and reusability tests were conducted after characterization of the aerogel. Surface characterization of the orange peel aerogel indicated it has an ultra-light density of 0.010417 g/cm3, high porosity of 99%, and a measured contact angle of 102°. An adsorption experiment was conducted with sandy and clay soils, and the maximum oil adsorption capacities of the orange peel aerogel were 13.55 mg/g and 9.60 mg/g for sandy and clay soils respectively. High oil adsorption capacity was shown by the produced aerogel and was attributed to its ultra-light density of 0.010417 g/cm3 and high porosity of 99%. In conclusion, the higher oil adsorption capacity of the orange peel aerogel in sandy soil compared with clay soil indicated that soil texture and aerogel properties influenced its oil remediation capacity. The reusability test in three adsorption trials indicated that orange peel aerogel is a sustainable material for the remediation of oil-contaminated soil.