Quaternized cross-linked peach gum polysaccharide as an adsorbent for fast and selective removal of anionic dyes from aqueous solution

To overcome low adsorption capacity, slow adsorption rate, poor adsorption selectivity, and dissolution of peach gum polysaccharide (PGP), an amino-rich crosslinked PGP (ACPGP) was first synthesized by cross-linking highly soluble PGP. Subsequently, a cation-rich PGP (QCPGP) was prepared from ACPGP through the addition of glycidyltrimethyl ammonium chloride (GTAC) and a secondary quaternization. The step-by-step preparation process was confirmed, and the adsorption properties of PGP, ACPGP, and QCPGP were compared in detail. The adsorption of crude PGP for cationic dyes violet (MV, 135.0 mg/g) and methylene blue (MB, 121.4 mg/g) were spontaneous endothermic, following the pseudo-first-order kinetic model and D-R isotherm. Due to the presence of rich charged groups in their structure, their highly selective adsorption towards new coccine (NC) and tartrazine (TTZ) is spontaneous and endothermic, and can be described by the pseudo-first-order and pseudo-second-order kinetic models, respectively. According to the Langmuir isotherm, the Q m of ACPGP and QCPGP for NC and TTZ was calculated to be 876.2 and 1304.3 mg/g (NC), and 814.5 and 1136.7 mg/g (TTZ), respectively. QCPGP exhibited more advantages in terms of adsorption capacity, adsorption rate (equilibrium time of 10 min), environmental stability, adsorption selectivity, and regeneration efficiency, showing great potential in practical wastewater treatment applications.