High-performance hydrophobic aerogel based on nanocellulose, graphene oxide, polyvinyl alcohol, and hexadecyltrimethoxysilane: Structure, properties, and applicability

The most prevalent kinds of contaminants found in water sources are oil and organic substances, which are often present in either spilled or emulsified states. Due to the vast surface area and porous structure, nanocellulose aerogel is an environmentally benign material widely employed for its efficacy in adsorbing oils and organic pollutants. In this study, an aerogel composed of nanocellulose (CNF), graphene oxide (GO), and polyvinyl alcohol (PVA), subsequently modified with hexadecyltrimethoxysilane (HDTMS), exhibited a well-defined structure and demonstrated proficient removal of waste oil and certain organic solvents from water at high speed. By a simple and cheap preparation method from solution mixing and freeze-drying, the resultant aerogel has a high porosity of 97.26%, a light density of 0.0036 g/cm3, a mesoporous structure with a mean pore diameter of 3.5 nm, and a surface area of 15.717 m2/g. Aerogel exhibits pronounced superhydrophobic behavior, achieving a contact angle of up to 152o, thereby substantially impeding water permeation through its structure in experimental assessments of selectivity and efficacy in separating oil-water mixtures. According to Langmuir isotherm model, DO adsorption occurred in a monolayer. CNF/GO/PVA/HDTMS aerogel exhibited a maximum adsorption capacity of 322.58 mg/g, with the pseudo-second-order model effectively representing this adsorption process. Furthermore, the CNF/GO/PVA/HDTMS aerogel displays a strong adsorption capability towards oils and organic solvents, with a range of 10 to 25 times the original volume of the aerogel. Another feature of the resultant aerogel is its good deemulsion ability on both water-in-oil and oil-in-water emulsions. The pump extraction method is more effective than the extraction method in oil recovery and reuse of the aerogel. The results obtained in the study show a potential environmentally friendly material for the treatment of oily and organic solvent wastewater from industries.