Removal of Zn(II) and Ni(II) heavy metal ions by new alginic acid-ester derivatives materials

The present work concerns the preparation of new materials based on alginic acid (AA) and diols in a facile and efficient process by improving the adsorption properties of Zn(II) and Ni(II) metal ions on the modified AA. The materials were analysed by zeta potential, thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), in addition to the Fourier Transform InfraRed spectroscopy (FTIR), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) before and after the adsorption behaviour was conducted. The results show that the esterification of AA with diols of different lengths significantly improves its adsorption efficiency of Zn(II) and Ni(II) with Qmax up to 200 mg/g and 185.185 mg/g respectively. Equilibrium and kinetic studies showed that the Langmuir and Freundlich adsorption isotherm models fit the experimental data well, and followed a pseudo-first order kinetic model and the particle diffusion model with correlation coefficients R2 ≈ 1. [Display omitted] •Ester derivatives of alginic acid were synthesised by Steglich esterification between alginic acid and different diols.•The products were characterized by FTIR, XPS, TGA, DTG, zeta potential and SEM.•The esterification enhances the adsorption of Zn2+ and Ni2+ with poly(AA-g-EG) showing the best adsorption capacity.•Efficient and fast adsorption of the ions Zn2+ and Ni2+ in a short adsorption time.•Poly(AA-g-EG) has an adsorption capacity for Zn2+ and Ni2+ of 200 and 185.185 mg/g respectively.