A novel quaternized chitosan–melamine–glutaraldehyde resin for the removal of nitrate and phosphate anions

Cross‐linked chitosan beads for phosphate removal from aqueous solution

“…By comparison, the adsorption of noncross‐linked beads toward phosphate species is relatively low. At these alkaline conditions (pH 8.5 and 20 ο C), phosphate exists as a dianion ( ) species and the isotherm behavior is well described by the Sips model . The adsorption capacity of the beads decrease as the level of cross‐linking increases, according to the following: EP 2.5 > GA 2.5 > EP 5 > GA 5.…”

“…The prominent band for each bead material occurs in the 3400–3500 cm −1 region corresponding to –OH and –NH 2 stretching. IR bands near 2900 cm −1 correspond to aliphatic C–H stretching, and the signature at 1635 cm −1 corresponds to –NH 2 , while the band at 1380 cm −1 corresponds to –CH symmetric bending vibrations of –CHOH . The band near 1100 cm −1 was attributed to C–O stretching of C–O–H groups.…”

“…Methods for the physicochemical removal of phosphate include ion‐exchange, reverse osmosis, electro‐dialysis, iron‐aided abiotic nitrate reduction, bioremediation, precipitation, and adsorption processes . Adsorption‐based processes are advantageous when compared with other techniques in terms of the infrastructure cost, modular design, simplified technological design, and operation . Diverse types of sorbent materials such as clays, zeolites, and activated carbon materials are commonly used industrial adsorbents for the adsorptive uptake of diverse contaminants in wastewater treatment applications …”

“…The abundant amino and hydroxyl functional groups of chitosan enable modification via cross‐linking to yield materials with variable morphology such as powders or beads with variable acid stability, mechanical strength, pore size distribution, and hydrophile–lipophile balance (HLB) . Cross‐linking of chitosan often results in greater adsorption capacity due to modification of surface area and pore structure properties due to incorporation of new surface functional groups such as quaternary amines and carboxylate groups …”

Adsorption of phosphate from aqueous solution by Zr(IV)‐crosslinked quaternized chitosan/bentonite composite

“…The partial substitution of Al 31 for the tetrahedral Si 41 and Mg 21 makes the layers negatively charged, which is neutralized by exchangeable cations in the interlayer space. Based on these properties of HACC, it has been applied for the preparation of composite films [16], adsorbent material [17], and nanocomposites [18,19]. are in the interlayer of natural MMT.…”