Fabrication of aerogels from cellulose nanofibril grafted with β-cyclodextrin for capture of water pollutants

Abstract

Interactions at the molecular and surface chemistry are some of the key factors that determine the adsorption capacity of pollutants and emerging contaminants in porous materials. As filtration-based purification of water sources expands, the generation of green materials, such as biopolymers, is the priority. However, to increase the removal capacity, modification of natural polymers appears necessary. Nanomaterials, especially bio-based materials like cellulose nanofibrils, inherently have large surface areas as a consequence of their high aspect ratios. Their capacity to modulate the interactions with contaminants present in water can be modulated by incorporating selective active points, such as hydrophobic cavities, that can further improve their overall adsorption capability. A bio-based material that can fulfil this requirement is β-cyclodextrin, a cyclic oligosaccharide with seven glucose units, which provides an easy grafting strategy onto cellulose due to structural affinity. Another advantage of using cellulose nanofibril is their film formability, aerogels, and hydrogels without the need of harsh chemicals or processes. In this work, an oligosaccharide with a hydrophobic centre -β-cyclodextrin -was immobilized onto bleached softwood cellulose nanofibrils, and then used to generate high surface area aerogels with a density of 175 kg/m 3 and porosities above 88%. Charge density titration, Fourier transform infrared with attenuated total reflectance (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and atomic force microscopy (AFM) characterization techniques were used to assess the successful modification of the fibrils. Inductive coupled plasma mass spectroscopy (ICP-MS) was used to determine the lack of trace chlorine in the material from the grafting process while scanning electron microscopy (SEM) and dynamic vapor sorption (DVS) were used to determine porosity and surface area of the aerogels. The adsorption capacity was tested with two molecules of different natures: a cyanotoxin (microcystin-LR) and a dye (methylene blue), using high-performance liquid chromatography with a UV detector (HPLC-UV) and UV-vis spectroscopy, respectively. The adsorption in equilibrium for CNF-CD aerogels was calculated to be 0.078 mg/g of microcystin-LR and 3.46 mg/g of methylene blue, enlightening its possible use to improve water quality.

Delignified wood aerogels as scaffolds coated with an oriented chitosan–cyclodextrin co-polymer for removal of microcystin-LR

“…The value obtained in equilibrium under this condition (5.4 μg mL −1 ) was higher that the values achieved in our previous work with initial concentrations of 0.8 and 1.5 μg mL −1 , 58 but lower than another work where an adsorption of 96 mg g −1 was achieved utilizing a 3.7 μg mL −1 initial concentration, and using a chitosan, cellulose, and [BMIm + Cl] composite. 45 It is worth pointing out that the grams by which the adsorption capacity was calculated was the total mass of the coating and the nanowood, and the active materials is only a small fraction of the total weight.…”

Modifying soluble NPK release with hydrophobized nanocellulose-based hydrogels for sustainable enhanced efficiency fertilizers

“…Cellulose nanofibrils (CNFs) were prepared as described previously. 43 Briefly, a cellulose pulp suspension was prepared at 2 wt% and washed with consecutive acidic and alkaline steps to eliminate the residual impurities of the pulping process. Thereafter, the pulp was neutralized and processed in a Masuko Super Mass Colloider (MKZA-10-15J) with 20 passes.…”

Assessment of Bio-Based Materials as a Sustainable and Scalable Alternative for Detection of Plasmodium spp. (Haemospororida: Plasmodiidae) Sporozoites in Field Deployable Testing

“…To evaluate the surface character of the bio-based materials, polyelectrolytic titration of the CNCs and chitosan was performed following the method reported before (Gomez-Maldonado et al 2021). Briefly, 15 ml of a 0.04% solution at neutral pH of each polymer was mixed with 25 ml of pDADMAC (positively charged) or PSVK (negatively charged) to complement the expected charge, then centrifuged for 15 min at 3,000 rpm.…”