**1. Introduction**

Water pollution caused by oil spillage related to the rapid development of the petroleum industries have serious effects on the environment and human life [1–3]. To resolve this problem, many methods have been proposed for water purification, such as water/oil separation [4–6], photocatalytic degradation [7,8], and adsorption [9–11]. Among these technologies, the use of porous absorbents with a hydrophobic surface is very promising for the rapid removal of oil from the surface of water. Various types of materials used as absorbents for cleaning oil spills have been fabricated. Oil absorbents can be sorted as inorganic minerals, synthetic organics, and natural organic materials [12]. Inorganic materials, such as fly ash and exfoliated graphite have low oil absorption capacity, whereas synthetic organic materials (i.e., polypropylene and polyurethane) possess high affinity to oil and organic solvents but cause a waste problem after their use due to their very slow degradation. Natural organic materials for oil absorption from plants (cellulose fibers) and animal residues (chitin and chitosan) have attracted increasing attention because of their renewability, low-cost, and biodegradability [13]. In addition, many kinds of natural materials, such as kapok fiber [14,15], cotton fiber [16], wool fiber [17], milkweed [18], and sawdust [19], have been exploited for the simple, effective, and inexpensive treatments of oil spills. However, most of these are hydrophilic, resulting in low oil sorption capacity. Therefore, there is still a need to find new environmental friendly absorbents with high oil absorption capacity, good selectivity, and low-cost.

Aerogels are a highly porous solid that hold up to 99% by volume of air within their pores and are known as the lowest density solid material [20]. These materials have become the most promising absorbents owing to their lightness, high porosity, and large inner surface area. Aerogels can be obtained from both inorganic sources, such as silica [21–23] and metal oxides [24], and organic sources [25–27]. Generally, the mechanism of oil sorption by aerogels is considered to be governed mainly by aerogel surface adsorption, absorption, and diffusion through the voids via interfiber capillary action [28–30], and the amount adsorbed is known to be dependent on surface area and porosity of adsorbents [31].

Concurrently, as an abundant, sustainable, renewable, and biodegradable resource of biopolymer, various cellulose-based aerogels have been investigated [32–37]. However, because the untreated cellulose aerogels have high hydrophilicity, they can absorb both oil and water during the absorption processing [36]. Therefore, the surface modification is needed to improve the hydrophobicity and absorption efficiency. The silanization processing also became one of the best ways for this aim [35,36]. Cellulose can be obtained from plants, such as bamboo. In Vietnam, bamboo is distributed widely in the north and is mainly being used as a raw material for tradition products such as toothsticks, chopsticks, floors, and some furniture. To the best of the authors' knowledge, there are few reports of the fabrication of aerogels from white bamboo and their application as both an absorbent for oil and other toxic chemicals especially at the time when water pollution by oil and chemical spills is becoming a serious problem caused by the huge development of the petrochemical industry.

In this study, bamboo was used as a source of micron-size white bamboo fibrils prior to fabricating the aerogel. The aerogels were prepared in a simple way from the gels of micron-size white bamboo fibrils (MWBFs) in an aqueous alkali hydroxide/urea solution, followed by conventional freeze-drying. The resulting aerogel was rendered hydrophobic and oleophilic after being treated with a silane compound using a common chemical vapor deposition process.

## **2. Experiments**
