One of the most intriguing properties of aerogels is their high surface area. Besides, it can also be easily separated from aqueous solutions and has a low processing cost, making it an ideal adsorbent solution widely used for removing organic and inorganic pollutants from contaminated water. Aerogels are versatile materials, where several factors such as precursor materials and their proportion, processing techniques, drying methods, additives, and crosslinkers, among others, can change their intrinsic characteristics, highlighting the pore size, surface area, and consequently, its final properties such as density, shrinkage rate, mechanical performance, and removal of potential toxic elements (PTEs). Thus, nanocellulose-based aerogels are promising adsorbent materials due to their high mechanical properties and the high removal capacity of pollutants in water. Therefore, mechanical performance and cadmium removal were evaluated from a nanocellulose-based aerogel, obtained with nanocellulose isolated through microwave assisted pre-treatments and combinatory mechanical processing methods from wood waste lignocellulosic fibers. The synthesis of nanocellulose aerogels consisted in homogenization of nanocellulose in 40 mL of an alkaline solution of NaOH and urea, which was pre-cooled at -12 °C using a water ice bath. The solution was maintained at low temperatures (between 0 and -12 °C) until complete homogenization of the nanocellulose, which then received volumes of 1 mL of pure epichlorohydrin, being homogenized again. The mixtures were ultrasonicated using a high-intensity ultrasound (Sonics 750 W, Vibracell, Sonics) for 10 and 20 min, at a power of 100 kJ, with an amplitude of 40%, and then subjected to mechanical stirring for 1 h. The homogenized dispersion rested for 3 h. The resulting dispersions were neutralized with an acid HCl solution (10 mol.L-1), adjusting the pH of the samples. The resulting colloidal solutions were frozen in molds at -6 °C for 24 h and taken to freeze-drying at -98 °C for 48 h, using a lyophilizer to obtain nanocellulose aerogels. After freeze-drying the nanocellulose hydrogels, the samples were immersed in distilled water three times to remove the excess crosslinking agent and other synthesis compounds. Firstly, the obtained aerogels were structurally stable, with a shrinking rate of 19.2 ± 2.2%, density of 0.1 ± 0.0 g.cm-3, and 95 ± 2% porosity. The material reached a compressive modulus of 26.2 ± 7.4 kPa, compressive strength at a break of 1012.5 ± 12.0 kPa, and 85.5 ± 2.3% compressive strain. A 100% Cd(II) adsorption rate was achieved for higher adsorbent dosages (5 g.L-1) and concentrations of contaminants (100 ppm). A possible adsorption mechanism may be linked to the high density of available hydroxyl groups, thus nanocellulose-based aerogels are a possible robust green alternative adsorbent for Cd(II) contaminated waters with sustainable appeal due to the lignocellulosic waste raw material used to isolate nanocellulose.
Bem-vindo(a) aos Anais do VII NanoMat, evento organizado pela Pós-graduação em Nanociências e Materiais Avançados da Universidade Federal do ABC (UFABC) com o intuito de reunir e debater trabalhos desenvolvidos por alunos e pós-doutorandos em Materiais e áreas afins.
Comissão Organizadora
Pedro Alves da Silva Autreto
Andre Luiz Martins de Freitas
Aryane Tofanello
Comissão Científica
Ferramenta completa de submissão, avaliação e publicação de anais para eventos científicos.
