Study on Ni(II) adsorption by calcium alginate beads

Nickel is one of the toxic heavy metals, it is widely used in our daily lives, so there is a lot of risk of being released into the water to poison the human, flora, and fauna. In this study, we investigated the adsorption of Ni(II) on calcium alginate beads (CA), a natural polysaccharide with many outstanding advantages. The effects of initial pH, adsorptive times, and initial concentration of Ni(II) on the adsorption process were investigated. The results showed that the pH value of 3-7.5 was favorable for the adsorption of Ni(II) on CA, the equilibrium adsorption started 60 minutes. The pseudo-second order kinetic equation, both Langmuir and Freundlich isothermal models were fit to describe the experimental data. The maximum adsorption capacity reached 6.48 mg/g with wet alginate calcium beads, corresponding to 144 mg/g dry beads. Materials after adsorption were also studied desorption for reuse.