Preparation of nanocellulose-based aerogel by bidirectional freezing method for high performance oil-water separation

Ruizhi, Yang and Yixiang, Zhen and Jialong, Qin and Huimin, Gao and Isabel Lim, Fong and Heng Yen, Khong and Marwa E., El-Sesy and Yadong, Zhao (2025) Preparation of nanocellulose-based aerogel by bidirectional freezing method for high performance oil-water separation. Journal of Environmental Chemical Engineering. pp. 1-42. ISSN 2213-3437

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Abstract

The increase in global trade has significantly burdened marine pollution, particularly regarding oil spills, which adversely affect vulnerable marine ecosystems. Cellulose-based aerogels are considered as highly prospective materials for oil-water separation in environmental remediation due to their highly porous nature, low packing density, cost-effectiveness and functional properties. In this study, 2,2,6,6-tetramethyl-piperidinyl-1-oxyl (TEMPO)-mediated oxidized cellulose (TCN) and sodium carboxymethylcellulose (CMC-Na) were utilized as raw materials to fabricate high strength aerogels for oil-water separation. The results indicated that the freezing method significantly influenced the properties of the aerogels. Specifically, compared to non-directional and unidirectional freezing, aerogels (L-TCN/CMC-Na) prepared via bidirectional freezing exhibited superior mechanical strength, higher porosity, and minimal strength degradation during multiple compression cycles, thereby providing enhanced mechanical properties in oil-water separation applications. To improve the oil absorption efficiency, the aerogels underwent hydrophobic modification using methyltrichlorosilane (MTCS). The L-TCN/CMC-Na aerogels, which have been modified, displayed both hydrophobic and oleophilic properties, achieving contact angles of 133° for water and 0° for chloroform. They showcased remarkable adsorption abilities for a range of oils and organic solvents, such as chloroform, rapeseed oil, pump oil, silicone oil, and hexadecane. Additionally, when used as a separating agent in an oil-water mixture, these aerogels enabled continuous separation of oil and water via a peristaltic pump, reaching separation efficiencies of over 92% for various oils and organic solvents. This study provides new insights into the design and development of high-strength oil-water separation materials and novel cellulose based composite materials.

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