Animal Biopolymer-Plant Biomass Composites: Synergism and Improved Sorption Efficiency

Abstract

Pelletized biomaterial composites that contain chitosan (C) and torrefied wheat straw (S) at variable weight composition (C:S) were prepared using a facile blending process. The fractional content of the wheat straw was studied to elucidate the role of biomass on the pelletized product and effects of S-content on the physicochemical properties relevant to adsorption phenomena. Chitosan pellets (with and without S) were characterized by spectroscopic (FT-IR and 13C NMR) and thermal (TGA and DSC) techniques to provide support for their respective C:S composition. Confocal microscopy using fluorescein (FL) as a dye probe revealed the presence and an increase in the accessibility of the active sites for the composite pellets according to the S-content (wt %). Equilibrium and kinetic sorption studies using FL and reactive black (RB) dyes revealed an incremental adsorption affinity of the pellets with anionic dyes in variable charge states (FL and RB). The trend for dye adsorption parallels the incremental S-content (wt %) in the composite pellets. This study reports a first-example of a low-cost, facile, and sustainable approach for the valorization of straw and chitosan suitable for sorption-based applications in aqueous media.

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

“…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.…”

“…A review of the literature reveals that studies describing the preparation of adsorbent materials for lead ion removal have emphasized adsorbent systems with a powder-like morphology (Beni and Esmaeili, 2020;Pandey, 2020;Shakoor et al, 2020;Boominathan and Sivaramakrishna, 2021;Shabtai et al, 2021). Despite the practical limitations of powdered adsorbents in column-based systems (Mohamed and Wilson, 2015;Patel, 2019), there are sparse reports that detail other types of adsorbent morphology for chitosan-based materials such as pelletized forms, as described herein (Syauqiah et al, 2015;Mohamed et al, 2017Mohamed et al, , 2020. This study describes a synthetic alternative to conventional covalent modification of biomaterials using a bottom-up preparation method for several types of binary and ternary adsorbent systems.…”

“…The protocol for pellet preparation was adapted from another study (Mohamed et al, 2020). Chitosan pellets (CP) were prepared by mixing chitosan powder (5 g) with 15 mL of aqueous acetic acid (0.2 M), followed by extruding the resulting paste through a syringe.…”

“…The tailoring of biocomposite adsorbents relates to the ability to alter their surface chemistry and textural properties. The variation of the additive composition within a multicomponent system represents a facile approach for meeting this goal, as reported elsewhere (Anisimov et al, 2020;Mohamed et al, 2020;Elanchezhiyana et al, 2021).…”

“…In turn, this study contributes to the science and technology of sustainable biocomposite adsorbents whilst employing a facile bottom-up synthetic method. We anticipate that such types of composite adsorbent materials are amenable as disposable POU water filters, especially for regions with limited access to advanced water treatment, to address the controlled removal of heavy metal cations such as lead and organic dyes (Mohamed et al, 2020).…”