Hidrogel Selulosa Sabut Kelapa-Kitosan Termodifikasi EDTA Untuk Adsorpsi Ion Cu(II) dan Fe(III)

Cellulose-based hydrogel is a porous material with potential applications as an adsorbent for the treatment of water contaminated with metal ions. This study aimed to evaluate the effect of varying ethylenediaminetetraacetic acid (EDTA) addition on the characteristics of coconut coir cellulose–chitosan-based hydrogel and its adsorption performance toward Cu(II) and Fe(III) ions. Cellulose was extracted from coconut coir through alkaline treatment and bleaching, and subsequently formulated with chitosan by adding EDTA at 0.100, 0.125, and 0.150 g. The hydrogel was prepared through four freeze–thaw cycles. Characterization included cellulose yield, physical properties, swelling ratio, gel fraction, and Fourier transform infrared (FTIR) spectroscopy, while the concentrations of metal ions before and after adsorption were determined using atomic absorption spectrophotometry. The cellulose yield obtained was 33.86%. The gel fractions were 86.00%, 92.00%, and 95.50% for EDTA additions of 0.100, 0.125, and 0.150 g, respectively. The highest swelling ratio was obtained with 0.125 g EDTA at 444.245%, whereas the swelling ratio decreased to 269.775% at 0.150 g EDTA, and the hydrogel exhibited greater brittleness. The FTIR spectra indicated the presence of O–H/N–H, C–H, C–O, and C–N functional groups, along with changes in the absorption bands after contact with metal ions. The highest adsorption efficiencies were obtained at 0.125 g EDTA, reaching 13.8656% for Cu(II) and 16.1172% for Fe(III), with adsorption capacities of 3.410 and 3.793 mg g⁻¹, respectively. These results demonstrate that the amount of EDTA influences the hydrogel network characteristics, swelling capacity, and accessibility of adsorption sites for metal ions.