Methyl orange uptake from aqueous solutions using chitosan-modified with epichlorohydrin and copper (II) Schiff base

In this work, we prepared a chitosan-modified with epichlorohydrin and copper (II) Schiff base ECH@Cu-CSSB by simple one-pot reaction of chitosan, 2-hydroxy-3-methoxybenzaldehyde, epichlorohydrin and Cu(CH₃COO)₂. The composite ECH@Cu-CSSB was characterized using Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and scanning electron microscope (SEM). In addition, it was subsequently utilized for the methyl orange (MO) dye removal from aqueous solutions using a batch technique. The effect of various parameters such as pH solution, adsorbent dose, shaking time, temperature, and initial dye solution was studied. The adsorption initial pH, initial MO concentration, and temperature show a negative impact on MO removal percentage. At the same time, the adsorption contacts time and adsorbent doses have a positive effect. The maximum MO removal efficiency of the ECH@Cu-CSSB was found to be 99.4 % at initial pH of 2, adsorbent dose of 0.02 g, initial concentration of 40 mg/L, contact time of 90 min, and temperature of 25 °C. The kinetic and isotherm models were applied using experimental data and the result confirmed that the results fitted well with the pseudo-second-order and Temkin isotherm models. Therefore, different electrostatic attractions, H-bonding, Yoshida H-bonding, π-π, and n-π stacking are the main reasons for the adsorption of MO dye onto ECH@Cu-CSSB. The results of this work revealed that the as-prepared composite ECH@Cu-CSSB showed great potential as a good efficient adsorbent for MO uptake dye and can be used for other organic dyes.