Investigation on the removal of Mo(VI) from Mo–Re containing wastewater by chemically modified persimmon residua

Persimmon waste was chemically modified by crosslinking with concentrated sulfuric acid to obtain a novel kind of adsorption gel, which was termed as crosslinked persimmon tannin (CPT), hereinafter. The adsorption behaviors of Mo(VI) with other coexisting metal ions onto the CPT gel were investigated. The gel exhibited selectivity only for Mo(VI) ions evidenced by the high value of separation factor of molybdenum and rhenium (βMo/Re = 164.37), and the adsorption mechanism of Mo(VI) as a multispecies was studied. The molybdenum adsorption behavior conforms to the Langmuir model with a remarkably high adsorption capacity of 0.56 mol/kg. A kinetic study for the adsorption of molybdenum at various temperatures confirmed that the endothermic adsorption process followed pseudo-second order kinetics. Moreover, its excellent adsorption properties and applicability for Mo(VI) were demonstrated by the removal and separation of Mo(VI) from different Mo–Re containing industrial wastewaters.

► The persimmon waste gel exhibited selectivity only for molybdenum with a high capacity for Mo(VI) (0.56 mol/kg dry gel).
► The adsorption mechanisms of molybdenum on the persimmon waste gel have been determined for deferent molybdenum species.
► The effectiveness of removal and separation of molybdenum from different actual Re-containing industrial wastewaters was confirmed.