eva‎luating the performance of three-dimensional hybrid hydro‎phobic adsorbents based on nano metal oxide, lignin, an‎d cellulose for oil spill cleanup from water

8/4/2026 12:00:00 AM

The rapid industrialization an‎d population growth in recent decades have led to severe environmental pollution, particularly affecting water resources. One of the novel approaches for removing oil-based pollutants from water involves using three-dimensional (3D) porous hydro‎phobic absorbents. In this study, we investigated polysaccharides, particularly lignin an‎d cellulose as bio-based, hydro‎phobic three-dimensional porous adsorbents. Cellulose-based adsorbents offer intrinsic advantages: renewability an‎d abundance; low density an‎d high specific surface area after conversion to aerogels; rich surface chemistry (abundant hydroxyl groups) enabling tunable hydro‎phobic/oleophilic behavior; environmental compatibility; an‎d efficient, low-cost recyclability. lignin, a byproduct of the pulp an‎d paper industry, was investigated as a high-potential material for producing bio-based absorbents. Initially, the optimization of lignin extraction from black liquor was conducted using the Taguchi method, yielding an efficiency of 82.05%. The extracted lignin was subsequently utilized to fabricate hydro‎phobic aerogels using sodium alginate an‎d various cross-linking agents (such as calcium chloride, iron chloride, an‎d glutaraldehyde), demonstrating a high oil absorption capacity of 26 g/g for organic solvents an‎d oils. To fabricate hydro‎phobic lignin/sodium-alginate aerogels, three crosslinking strategies were employed: CaCl₂ for its accessibility an‎d rapid ionotropic gelation; FeCl₃ to form denser, mechanically stronger ionic networks; an‎d glutaraldehyde (GA), which creates stable covalent bonds that suppress swelling an‎d preserve porosity an‎d performance over repeated adsorption cycles. Given the repeated water/solvent contact inherent to oil removal, GA was selec‎ted as the crosslinker for subsequent cellulose-based systems to ensure aqueous stability an‎d maintain structural integrity under cyclic use. The second section examined the potential application of lignin extracted from black liquor in high-value applications, particularly for removing various organic pollutants using 3D absorbents such as aerogels. Accordingly, a lignin/sodium alginate-based hydro‎phobic aerogel was synthesized through freeze-drying an‎d surface modification via chemical vapor deposition using different cross-linking agents (calcium chloride, iron (III) chloride, an‎d glutaraldehyde). The resulting aerogel exhibited an oil absorption capacity of 26 g/g for various solvents an‎d organic oils. Furthermore, the lignin obtained under optimized conditions was esterified using maleic anhydride to modify its functional groups, enhancing its hydro‎phobicity. The effect of incorporating this esterified lignin in the fabrication of aerogels, along with guar gum, was investigated. The aerogel was synthesized through freeze-drying an‎d cross-linked using glutaraldehyde. The resulting aerogel exhibited high porosity, lightweight properties, an‎d an oil absorption capacity of 32.5 g/g for sunflower oil. In the third section, cellulose was extracted from agricultural waste (date palm fibers) using an alkaline treatment. The in-situ growth of zinc oxide (ZnO) nanoparticles on cellulose fibers was carried out using a hydrothermal method, employing zinc nitrate as a precursor. Subsequently, the cellulose fibers an‎d ZnO nanoparticles were composited with esterified lignin extracted from black liquor under optimized conditions an‎d cross-linked with glutaraldehyde. The effect of this composite material on oil removal was assessed. Furthermore, the performance of composite aerogels synthesized from cellulose fibers, hydrothermally synthesized copper oxide (CuO) nanoparticles, an‎d esterified lignin was eva‎luated for oil absorption. Mean factors influencing the synthesis of lignocellulosic aerogels composited with metal oxide nanostructures were optimized using the response surface methodology (RSM) to enhance oil absorption capacity. For the ZnO-incorporated lignocellulosic aerogel (EL-CF/ZnO), the effects of the ZnO: cellulose mass ratio, ZnO: urea molar ratio, an‎d surfactant weight percentage (wt%) were investigated. Similarly, for the CuO-incorporated lignocellulosic aerogel (EL-CF/CuO), the cellulose: esterified lignin mass ratio, cellulose: CuO mass ratio an‎d surfactant weight percentage were examined. The optimized conditions for EL-CF/ZnO were found to be a ZnO” cellulose mass ratio of 1:5, a ZnO: urea molar ratio of 1:0.32, an‎d a surfactant weight of 0.22 g, resulting in a maximum oil absorption capacity of 18.14 g/g. For EL-CF/CuO, the optimized conditions included a CuO: cellulose mass ratio of 1:5.4, an esterified lignin-to-cellulose mass ratio of 0.3:1, an‎d a surfactant weight percentage of 22% relative to dry cellulose, yielding a maximum oil absorption capacity of 17.56 g/g. These modeled results closely matched the experimental values, with an error margin of less than 10%. Additionally, the synthesized aerogels were characterized using various analytical techniques, including field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), proton nuclear magnetic resonance (¹H-NMR), an‎d nitrogen adsorption-desorption analysis (BET). The oil removal performance of EL-CF/ZnO an‎d EL-CF/CuO was further examined, demonstrating oil absorption capacities ranging from 16.5 to 38 g/g for EL-CF/ZnO an‎d 16.5 to 36.8 g/g for EL-CF/CuO. These findings highlight the potential of the synthesized absorbents for effective an‎d cost-efficient oil pollutant removal.

جاذب سه‌بعدي طبيعي , ايروژل ليگنوسلولزي , ليگنين استري‌شده , نانواكسيد فلز , حذف لكه روغن.

natural 3D sorbent , lignocellulose aerogel , esterified lignin , nano metal oxide , oil sorption

Mahnaz Montazeri

Dr. Noroozbeigi