Parameter estimation for trace element sorption on a new granular iron oxide

Surface complexation of Pb(II) on amorphous iron oxide and manganese oxide: Spectroscopic and time studies

“…The best-fit D s was 2.5 × 10 −15 cm 2 s −1 suggesting a slow and rate-limiting process for Pb sorption to HFO. Results from many studies support that intraparticle diffusion is the rate-limiting step in metal sorption to microporous oxides [17,24,[31][32][33][34][36][37][38]58]. The D s of this study (2.5 × 10 −15 cm 2 s −1 ) is consistent with the range obtained by Fan et al [38] for Pb sorption in HAO, HMO, and HFO (10 −16 -10 −14 cm 2 s −1 ).…”

“…Pb adsorption on amorphous Mn oxide, one exhibiting no long-range order, has not yet been reported in literature. Meanwhile, although intraparticle diffusion into inner surfaces of soil has been observed [17,24,[28][29][30][31][32][33][34][35][36][37][38], few studies [17,24,39] have been conducted in identifying the nature of internal sites especially for Pb/HFO and HMO systems. Pb(II) sorption mechanisms were found to be invariant with time on γ -Al 2 O 3 [17] and 2-line ferrihydrite [24]; in both studies, there was no evidence of Pb precipitation.…”

Chromate Removal by an Iron Sorbent: Mechanism and Modeling

“…Apparently, the influent pH within this range has little effect on adsorptive mass transfer rates in fixed beds of the iron sorbent, with differences in column performance captured by the equilibrium model. Solidphase loadings achieved compare favorably to those reported for granular iron oxides and commercial sorbents (Gao et al, 1995;Theis et al, 1994). It is also useful to point out that even though the equilibrium relationship used to update C s,z is derived from the pH adsorption edges (that is, batch experiments), it is considered to provide a representative approximation of equilibrium at the particle surface in dynamic column calculations (see eq 11).…”

“…Hexavalent chromium was then recovered by desorption using a pH 9.5 solution. Another granular iron oxide, prepared by cementation of goethite using a proprietary binding material, achieved an adsorption capacity of 3.3 mg/g for chromate in a fixed bed (Theis et al, 1994).…”