Lignocellulosic biomass functionalized with EDTA dianhydride for removing Cu (II) and dye from wastewater: Batch and fixed-bed column adsorption

Abstract

This work aims to introduce new chelating materials based on lignocellulosic biomass from Gundelia Tournefortii (GT). In terms of functionalization, GT has been modified using ethylenediaminetetraacetic dianhydride (EDTAD). Functionalized/modified Gundelia Tournefortii (EGT) and GT were characterized by the Fourier Transform Infra-red (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), and X-ray Diffraction (XRD) analyses. In this regard, adsorption experiments (continuous fixed-bed column, batch) have been conducted using EGT to adsorb contaminants (Cu (II) and dye). The batch tests investigate the optimum condition, factors like: duration of experiment, the value of pH, EGT amount, and the initial concentration of the prepared solution. According to experimental data, sorption followed Langmuir isotherm. Besides, the most suitable kinetics model was pseudo-second-order. The capacity of this adsorbent reached 156.78 mg/g as the maximum amount. In terms of fixed-bed column study, functional items such as flow rate, bed depth, inflow concentration on EGT performance in the continuous adsorption column were assessed. Results confirmed that the enhancement in the inflow concentration and bed length, and flow rate decline, reinforced EGT removal capability. The dynamic capacity of this adsorbent is projected to reach 15.61 mg/g as the maximum amount in certain conditions. Modeling of experimental breakthrough curve demonstrated that the Thomas model is better described rather than Yoon-Nelson and Adams-Bohart models. Also, the results indicated that the Lignocellulosic biomass had dye (Direct Red 23: DR23) removal ability.