Adsorption of Hg (II) ions from aqueous solution by diethylenetriaminepentaacetic acid-modified cellulose

Abstract

The diethylenetriaminepentaacetic acid (DTPA)-modified cellulose adsorbent was prepared using N‑[3‑(trimethoxysilyl)propyl]ethylenediamine as a crosslinking reagent and used for the removal of Hg (II) ions from aqueous solution. The resulting adsorbents were comprehensively characterized with FTIR, XRD and SEM. The results showed that DTPA successfully functionalized cellulose, and coordinating DTPA ligand improved the binding properties towards heavy metal ions significantly. Various influencing factors on adsorption performance were investigated, including temperature, initial concentration of Hg (II), solution pH, contact time. Moreover, the reusability of the adsorbent was also assessed. The experimental and modeling results indicated that the adsorption process was better described by Langmuir isotherm model, and the maximum adsorption capacity reached as high as 476.2 mg·g−1, The kinetic date of the adsorption matched well with the pseudo-second-order kinetic model. Furthermore, the cellulose-based adsorbent is reusable, maintaining the adsorption capacity after seven adsorption-desorption cycles. The findings from this work demonstrated that the DTPA-modified cellulose adsorbent can be recognized as an effective adsorbent for Hg (II) removal from aqueous solution.