A Novel Gallic Acid-Grafted-Lignin Biosorbent for the Selective Removal of Lead Ions from Aqueous Solutions

Abstract

The low content of phenolic groups limits the application of lignin-based materials as biosorbents for the removal of metal ions. In this work, a novel gallic acid-grafted-lignin (GAL, 4.43 mmol/g hydroxyl group) biosorbent was designed by introducing gallic acid moieties to replace the hydroxyl groups of lignin. These grafted polyphenolic groups provide additional sites for the adsorption of metal ions. The structure of GAL was characterized by FT-IR, 31 P NMR, and 13 C NMR spectroscopy. The adsorption properties of GAL for Pb(II) ions were investigated under batch conditions. Kinetic and isothermal adsorption processes could be welldescribed by the pseudo-second order kinetic model and Langmuir isothermal model, respectively. The grafting of polyphenolic groups onto lignin increased the maximum adsorption capacity of the adsorbent for Pb(II) (119.1 mg/g). The adsorption thermodynamics indicated that the adsorption process was endothermic and spontaneous. In addition, GAL could selectively adsorb Pb(II) with a selectivity coefficient (k) at 1.89 in the presence of coexisting metal ions from aqueous solution. The high adsorption capacity and selectivity for Pb(II) by GAL, together with its environmental compatibility, enable this material to act as a promising biosorbent for removing heavy metal ions from polluted water.

The adsorption of lemon yellow dye using cationic cellulose fibers from rice straw as a sustainable biosorbent in aqueous media

“…Dye is widely used in many fields, but it easily pollutes the environment (Baldikova et al 2015). The characteristics of dye wastewater has a complex composition, deep color, high toxicity, strong acidity, and high COD content, and has always been a problem in terms of environmental protection (Heibati et al 2015;Zhang et al 2017).…”