Synthesis of cellulose nanofibers functionalized by dithiooxamide for preconcentration and determination of trace amounts of Cd(II) ions in water samples

A highly efficient natural adsorbent was provided by the synthesis of modified cellulose nanofibers (CNFs) for preconcentration and determination of trace amounts of Cd(II) ions. CNFs were prepared by hydrolysis of wood pulp with strong acid under reflux and sonicating conditions and modified by immobilization of dithiooxamide. Effective factors such as pH of extraction, nanocomposite amount, extraction time, type and concentration of eluent, ionic strength, and sample volume were optimized for the quantitative determination of Cd(II) ions. Results of optimization showed a linear range between 0.1 and 10 ng ml(-1) by a limit of detection of 0.04 ng ml(-1). Statistical analysis showed small relative standard deviations of 2.1%, high preconcentration, and enrichment factors. The nanocomposite also showed high sensitivity and selectivity for detecting very low concentration of Cd(II) ions in real samples at ng ml(-1) level with high accuracy.