Flax Biomass Conversion via Controlled Oxidation: Facile Tuning of Physicochemical Properties

Abstract

The role of chemical modification of pristine linen fiber (LF) on its physicochemical and adsorption properties is reported in this contribution. The surface and textural properties of the pristine LF and its peroxyacetic acid- (PAF) and chlorite-treated (CF) fiber forms were characterized by several complementary methods: spectroscopy (SEM, TEM, FT-IR, and XPS), thermal analysis (DSC and TGA), gas/water adsorption isotherms, and zeta potential (ξ). The results obtained reveal that the surface charge and textural properties (surface area and pore structure) of the LF material was modified upon chemical treatment, as indicated by changes in the biomass composition, morphology, ξ-values, and water/dye uptake properties of the fiber samples. Particularly, the pristine LF sample displays preferential removal efficiency (ER) of methylene blue (MB) dye with ER ~3-fold greater (ER~62%) as compared to the modified materials (CF or PAF; ER~21%), due to the role of surface charge of pectins and lignins present in pristine LF. At higher MB concentration, the relative ER values for LF (~19%) relative to CF or PAF (~16%) reveal the greater role of micropore adsorption sites due to the contributing effect of the textural porosity observed for the modified flax biomass at these conditions. Similar trends occur for the adsorption of water in the liquid vs. vapour phases. The chemical treatment of LF alters the polarity/charge of the surface functional groups, and pore structure properties of the chemically treated fibers, according to the variable hydration properties. The surface and textural properties of LF are altered upon chemical modification, according to the variable adsorption properties with liquid water (l) vs. water vapor (g) due to the role of surface- vs. pore-sites. This study contributes to an understanding of the structure-adsorption properties for pristine and oxidized flax fiber biomass. The chemical conversion of such biomass yields biomaterials with tunable surface and textural properties, as evidenced by the unique adsorption properties observed for pristine LF and its modified forms (CF and PAF). This study addresses knowledge gaps in the field by contributing insight on the relationship between structure and adsorption properties of such LF biomass in its pristine and chemically modified forms.

Design of Sustainable Biomaterial Composite Adsorbents for Point-of-Use Removal of Lead Ions From Water

“…The DTG profiles of the biomaterials and kaolinite (Figure 2A) reveal that the agro-waste biomass (O, S) have a slighter broader range of thermal stability vs. the chitosan pellet (CP) material. The former may relate to the presence of (hemi)cellulose and lignins, which impart greater thermal stability to the agro-waste biomass over chitosan alone (Alabi et al, 2020;Dehabadi et al, 2020). By contrast, kaolinite (K) remains stabile over this temperature range, in line with a reported decomposition temperature of 521…”

“…The observed uptake of Pb(II) by CP relates to the metal-ion chelation properties of chitosan (Gao et al, 2018;Wilson and Tewari, 2018) due to its abundant amine and hydroxyl groups (see inset in Figure 4 above). In Figure 5B, the uptake profile likewise follows Langmuir-type behavior for CP and its ternary composites that contain wheat straw (S) (Dehabadi et al, 2020;Mohamed et al, 2020). Based on the various isotherms, the composites that contain 10-30% S show comparable uptake properties to CP.…”

“…Supplementary Figures S1, S2). The IR spectra for CP and the biomass (S, O) share similar features that are characteristic of typical of polysaccharide materials: -OH/-NH groups (3,000-3,700 cm −1 ); -CH groups (∼2,900 cm −1 ); carbonyl or amide (1,650-1,750 cm −1 ); C-C (1,500-1,600 cm −1 ); C-H bending (1,300-1,450 cm −1 ); C-O/C-O-C (1,000-1,200 cm −1 ); and glycosidic (1,075 cm −1 ) bonds (Zawadzki and Kaczmarek, 2010;Alabi et al, 2020;Dehabadi et al, 2020). Kaolinite differs due to its aluminosilicate structure, as follows: -OH groups (3,600-3,700 cm −1 ), Si-O (1,000-1,150 cm −1 ), Al-OH (900-950 cm −1 ), Si-O-Al (750-800 cm −1 ), and Si-O/Si-O-Al (400-550 cm −1 ).…”

“…Due to the water insolubility of the pelletized composite materials, the uptake of Pb 2+ can be determined based on the ability to carry out phase separation of the adsorbent from the aqueous solution after the adsorption process, according to Equation (1). Other studies that employ Equation (1) for the case of dye-based probes is described elsewhere for other types of multi-component biocomposites and their adsorption properties (Sabzevari et al, 2018;Anisimov et al, 2020;Dehabadi et al, 2020). Herein, the Pb(II) uptake of the single component additives (chitosan, kaolinite, and oat hulls) in their powdered form were evaluated at pH 5 and 6.5 in synthetic water in acetate buffer (30 mM), along with tap water at pH 5 (cf.…”

Nanocomposites of Terbium Sulfide Nanoparticles with a Chitosan Capping Agent for Antibacterial Applications

“…The size and crystalline structural features were assessed through XRD, while the structure and interaction of the NPs were analyzed by vibrational spectroscopy (Raman and IR). Thermogravimetry analysis (TGA) profiles of the samples were obtained using a TA Instruments Q50 TGA system (New Castle, DE, USA) with a heating rate of 5 • C min −1 up to 500 • C with nitrogen as the carrier gas, as described by Dehabadi et al [26]. In brief, the particle size distribution (PSD) and zeta potential were measured using a Malvern Zetasizer Nano ZS instrument (Malvern Instruments Ltd., Malvern, Worcestershire, UK).…”