Modular Chitosan-Based Adsorbents for Tunable Uptake of Sulfate from Water

Abstract

The context of this study responds to the need for sorbent technology development to address the controlled removal of inorganic sulfate (SO42−) from saline water and the promising potential of chitosan as a carrier system for organosulfates in pharmaceutical and nutraceutical applications. This study aims to address the controlled removal of sulfate using chitosan as a sustainable biopolymer platform, where a modular synthetic approach was used for chitosan bead preparation that displays tunable sulfate uptake. The beads were prepared via phase-inversion synthesis, followed by cross-linking with glutaraldehyde, and impregnation of Ca2+ ions. The sulfate adsorption properties of the beads were studied at pH 5 and variable sulfate levels (50–1000 ppm), where beads with low cross-linking showed moderate sulfate uptake (35 mg/g), while cross-linked beads imbibed with Ca2+ had greater sulfate adsorption (140 mg/g). Bead stability, adsorption properties, and the point-of-zero charge (PZC) from 6.5 to 6.8 were found to depend on the cross-linking ratio and the presence of Ca2+. The beads were regenerated over multiple adsorption-desorption cycles to demonstrate the favorable uptake properties and bead stability. This study contributes to the development of chitosan-based adsorbent technology via a modular materials design strategy for the controlled removal of sulfate. The results of this study are relevant to diverse pharmaceutical and nutraceutical applications that range from the controlled removal of dextran sulfate from water to the controlled release of chondroitin sulfate.

Binary Pectin-Chitosan Composites for the Uptake of Lanthanum and Yttrium Species in Aqueous Media

“…The smaller particle size of the PC 51 S composite may be due to the formation of the amide linkage between pectin and chitosan polymers [ 13 ]. As the concentration of the chitosan increased, the particle size of composites increased because the swelling behavior of chitosan and water molecules can be absorbed to increase the size of composites [ 30 , 31 ]. The chitosan particle (d = 723 nm) has the smallest diameter when compared to the composites, which concur with estimates from another study [ 24 ].…”

Chitosan Functionalization: Covalent and Non-Covalent Interactions and Their Characterization

“…Besides protective purposes, imine bonds are often reported for the cross-linking of CS chains. Glu is the most common CS cross-linker, leading to the stabilization of CS nanoparticles (NPs) ( Figure 6 , right circle) [ 6 , 51 ]. More specifically, Glu can also be exploited as a simple linker for the conjugation of CS to another polymer containing amino groups, such as polyacrylamide block copolymer [ 78 ].…”

“…Although quite rare, solid state 13 C NMR was also used for the analysis of CS derivatives when liquid state NMR was not appropriate [ 6 , 55 , 88 , 89 ]. This technique is especially useful for the characterization of CS derivatives designed to be insoluble in common aqueous and organic solvents, such as in the case of films, beads, or membranes for water treatments [ 6 , 130 ].…”

“…Due to its biocompatibility, biodegradability, versatility, and low price, CS has gained a lot of attention over the past decades in fields ranging from wound healing and drug delivery [ 3 , 4 , 5 ] to waste water treatment [ 6 , 7 ], textile industry [ 8 ], and food packaging [ 9 ]. The versatility of CS relies on its amino and hydroxyl groups ( Figure 1 ) enabling various types of functionalization that will be described in detail in this review.…”

Novel Maleic Acid, Crosslinked, Nanofibrous Chitosan/Poly (Vinylpyrrolidone) Membranes for Reverse Osmosis Desalination

“…A promising silane base functionalizing agent 3-aminopropyltriethoxysilane (APTES) is added to enhance adhesion or adsorption of the active layer of CA substrate material to control the interfacial morphology. The typical linkage develops between amine (NH 2 ) groups of APTES with hydroxyl (OH) groups of cellulose acetate (CA) units [10][11][12].…”