The adsorption and desorption of Ni(II) on Al substituted goethite

It is demonstrated that the metal (hydr)oxides are ubiquitous in subsurface sediments, therefore investigation of adsorption and desorption of Ni(II) on aluminium substituted goethite (Al-FeOOH) plays vital role in the understanding of the fate and transport of heavy metals in sub-sediment at their initial sources. The Al-FeOOH nanoparticles were synthesized by chemical co-precipitation method and were characterized by TEM, XRD and potentiometric titration. The characteristic results revealed phase transformation of Al-FeOOH nanoparticles from acicular-like shape to rod-like shape with increasing Al content. The effect of environmental factors (e.g., reaction time, pH, ionic strength and temperature) on the adsorption of Ni(II) on Al-FeOOH nanoparticles was investigated by batch techniques. The kinetic adsorption showed that the adsorption of Ni(II) on Al-FeOOH can be satisfactorily fitted by pseudo-second order kinetic model. The maximum adsorption capacity of Al-FeOOH nanoparticles calculated from Langmuir model at pH 5.0 and T = 298 K is 94.52 mg/g for Ni(II). Approximately 40% and 6% of Ni(II) are desorbed from α-FeOOH and Al-FeOOH at 1200 h, respectively, indicating the strong chemical affinity for Al-FeOOH due to the nanoscale space confinement effect. This study implies that Al-FeOOH nanoparticles could be a promising adsorbent to remove the Ni(II) from aqueous solutions.