Complex Aerogels Generated from Nano-Polysaccharides and Its Derivatives for Oil–Water Separation

Abstract

The complex aerogel generated from nano-polysaccharides, chitin nanocrystals (ChiNC) and TEMPO-oxidized cellulose nanofibers (TCNF), and its derivative cationic guar gum (CGG) is successfully prepared via a facile freeze-drying method with glutaraldehyde (GA) as cross-linkers. The complexation of ChiNC, TCNF, and CGG is shown to be helpful in creating a porous structure in the three-dimensional aerogel, which creates within the aerogel with large pore volume and excellent compressive properties. The ChiNC/TCNF/CGG aerogel is then modified with methyltrichlorosilane (MTCS) to obtain superhydrophobicity/superoleophilicity and used for oil–water separation. The successful modification is demonstrated through FTIR, XPS, and surface wettability studies. A water contact angle of 155° on the aerogel surface and 150° on the surface of the inside part of aerogel are obtained for the MTCS-modified ChiNC/TCNF/CGG aerogel, resulting in its effective absorption of corn oil and organic solvents (toluene, n-hexane, and trichloromethane) from both beneath and at the surface of water with excellent absorption capacity (i.e., 21.9 g/g for trichloromethane). More importantly, the modified aerogel can be used to continuously separate oil from water with the assistance of a vacuum setup and maintains a high absorption capacity after being used for 10 cycles. The as-prepared superhydrophobic/superoleophilic ChiNC/TCNF/CGG aerogel can be used as a promising absorbent material for the removal of oil from aqueous media.

Structurally Integrated Properties of Random, Uni-Directional, and Bi-Directional Freeze-Dried Cellulose/Chitosan Aerogels

“…However, in composite aerogels, the new peak at 1470cm − 1 formed after cross-linking reaction, corresponding to the amide bond formation between formaldehyde and chitosan. In composite aerogels, the sharp peak at ~ 1690cm − 1 is evidence of cross-linked aerogels corresponding to aldehyde group formation (Yagoub et al 2019). Formaldehyde addition to aerogels develops structural stability and enhances the mechanical strength of nal aerogels by providing strengthening units within the micro-orientation of aerogels.…”

Biorefinery Approach for Aerogels

“…Silane based modifiers, such as trimethylchlorosilane (TMCS) [195], hexamethyldisilazane (HMDS) [195], methyltrimethoxysilane (MTMS) [196,197], hexadecyltrimethoxylan (HDTMS) [198] and methyltrichlorosilane (MTCS) [199] have been known as popular cellulose modifiers for various applications. For example, HDTMS-modified cellulose foams absorbed up to 79 g/g of motor oil, 162 of sunflower oil and retained good performance after 20 sorption cycles.…”

Robust Silica-Cellulose Composite Aerogels with a Nanoscale Interpenetrating Network Structure Prepared Using a Streamlined Process

“…Aerogels are synthetic materials characterized by fine internal void spaces, open-pore geometry, and useful properties including low density, high porosity, high specific surface, and low thermal conductivity [1][2][3]. These materials have broad application potential in thermal insulation [4,5], oil absorption [6], catalysis [7], electrode materials [8], CO 2 remove [9], tissue engineering [10], energy storage [11], adsorption of heavy metal ions [12], and as drug carriers [13]. The unique microstructure of aerogels is associated with low solids content and a fragile gel skeleton that cannot withstand external impact, and typical inorganic oxide aerogels with a pearl-necklace-like gel skeleton are particularly vulnerable [14,15].…”