LAUSR

Abstract A new adsorbent obtained from alkaline treatment of black cumin seeds (BCS) has been developed for the adsorption of cation pollutants cobalt [Co(II), lead Pb(II), copper Cu(II) and nickel Ni(II)] from aqueous solutions. The alkaline treated black cumin seeds were labeled; base treated black cumin seeds (BT-BCS), acid treated black cumin seeds (AT-BCS) and untreated black cumin seeds (UT-BCS). The absorbents were analyzed by scanning electron microscope (SEM), fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction spectroscopy (XRD). The SEM images showed that UT-BCS is composed of spherical shaped particles. AT-BCS and BT-BCS images showed irregular surface morphology. AT-BCS and BT-BCS –IR spectra observed new bands. Pseudo First Order kinetic (PFO) model gave consistent fit in describing the adsorption of all the cations. The PFO good fit suggest that the adsorption mechanism involved, Van der Waal forces. The estimated pore adsorption (EPA) was more dominant than estimated surface adsorption (ESA). Equilibrium data had a good fit for Langmuir isotherm model for all cations this indicates that adsorption took place on active sites having equal affinity for these ions and further suggests that monolayer adsorption occurred on adsorbents surface at the end of adsorption process. BT-BCS was the best performing adsorbent with capacity of 190.7 mg/g for Cu(II), AT-BCS and UT-BCS with capacities of 180.1 and 135 mg/g respectively for Pb(II). Adsorption trend is BT-BCS > AT-BCS > UT-BCS. Reusability data suggests that (BCS) adsorbents retained ≥ 90% of their initial cations adsorption, these adsorbents may be reusable in wastewater treatment.