Application of orange peel for adsorption separation of molybdenum(VI) from Re-containing industrial effluent

The removal of molybdenum(VI) from an aquatic environment was investigated using Zr(IV)-, La(III)-, Ce(III)- and Fe(III)-loaded orange peel, respectively. Mo(VI) adsorption was found to be favored over the whole hydrochloric acid concentration (1.0 mmol·m−3–3 kmol·m−3) while Pb(II), Fe(III), Zn(II), Mn(II), Ni(II) and Cu(II) removal took place at pH values ranging from 1 to 6. The four gels all exhibited selectivity only for Mo(VI) evidenced by the high value of separation factor of molybdenum and rhenium (βMo/Re = 62.78 ∼ 106). The adsorption isotherm of Mo(VI) from aqueous solution using the four gels was carried out. Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models were applied to describe the adsorption of Mo(VI) onto the gels. In addition, the adsorption mechanism of Mo(VI) as a multispecies onto the Zr(IV) loaded gel was studied. Its excellent adsorption characteristics for Mo(VI) from Re-containing industrial effluent were confirmed by the test of adsorbent reutilization.

► Mo(VI) can be selectively separated from other coexisting base metal ions by using the orange peel gels.
► The maximum adsorption capacity for molybdenum is 1.13 mol/kg
► The adsorption behavior obeys the Langmuir model.
► The endothermic adsorption process followed pseudo-second order kinetics.