Sucrose hybridization modification of polycationic gel to realize super-high adsorption of lignins for reusable purification of wastewater

Abstract

Sucrose was first used to modify a polycationic gel to form the novel water treatment material of sucrose-hybridized polycationic gel (SHPCG). The new sucrose hybridization effect allowed the SHPCG to show a super-efficient adsorption ability in the purification of papermaking wastewater. The SHPCG exhibited a super-high adsorption capacity toward lignins, reaching 8279.86 mg/g, i.e., the mass of the lignins adsorbed was 8.28 times higher than the mass of SHPCG adsorbent, which was, furthermore, 2.13–41.20 times higher than those of a series of previously reported polycationic adsorbents without the incorporation of sucrose units. Subsequently, the SHPCG wastes after lignin adsorption could be reused directly to purify dyeing wastewater, and maintained its adsorption capacity, being 278.05 times higher than that of activated carbon. Analysis of the interaction mechanisms showed that the sucrose hybridization effect in the polycationic gel skeleton with a large accommodation space had improved the adsorption associativity and interaction intensity of SHPCG toward lignins, and caused the efficient aggregations of lignins in the SHPCG skeleton. This would be the key factor for the super-high adsorption capacity of SHPCG toward lignins. In addition, there was an electrostatic substitution with coating adsorption effect to help in the efficient reuse of SHPCG wastes.