One-step crosslinking preparation of tannic acid particles for the adsorption and separation of cationic dyes

Abstract

In this study, a new tannic acid adsorbent (ethylene glycol diglycidyl ether crosslinked tannic acid, TA-EGDE) for adsorptive removal of dyes from water was prepared using EGDE as a cross-linking agent. The resultant TA-EGDE was in particulate form with rough surface morphology and a diameter ranging from 10 to 30 µm. The adsorption performance of the TA-EGDE was evaluated in a flow-through mode using water samples contaminated with methylene blue (MB) and two-component mixed dyes, respectively. The TA-EGDE provided adsorption capacity up to 721.8 mg·g−1 at 65 °C for MB. It showed a high removal efficiency (99%) of MB (50 mg·L–1) from the water sample and could recovery 90% of the adsorbed MB by eluting with acidic ethanol aqueous solution. The excellent adsorption of MB and neutral red on the TA-EGDE may be the result of the synergy of electrostatic interaction and π–π interaction. Furthermore, the TA-EGDE could separate dyes from water samples contaminated with two-component mixed dyes with a separation coefficient ranging from 1.8 to 36.5. The anionic TA-EGDE would be an effective adsorbent to remove and recycle dyes from the contaminated water.