Enhanced adsorption of antimonate by ball-milled microscale zero valent iron/pyrite composite: adsorption properties and mechanism insight

Understanding the Operating Mode of Fe0/Fe-Sulfide/H2O Systems for Water Treatment

“…Noubactep et al [56] reported exactly the same trend for U VI removal. These results are correctly interpreted as an indication of the synergetic effect of FeS 2 (or more generally Fe-sulfides) on contaminant removal by Fe 0 [44,52,56]. However, the role of Fe-sulfides is limited to inducing pH shift, and thus increasing corrosion, at least during the lag time of the experimental durations ranging from 300 min for Lü et al [18] to 120 days for Noubactep et al [56].…”

“…The intrinsic reactivity of the selected FeS 2 mineral should be known, as well as the kinetics of its long-term dissolution. In other words, there is no need to verify whether pyrite can enhance the efficiency of a Fe 0 /H 2 O system or not [44,100,101]. Instead, there is a need to rationally select both Fe 0 and FeS 2 and their relative mixing ratios to achieve a given remediation goal [57].…”

“…In essence, "reactivity loss" is a misleading term, as reactivity is an intrinsic property of each material and cannot change with operational variables or under given operating conditions [28,[33][34][35][36]. That is the reason why it is restored by appropriate treatments (e.g., acid wash) [15,37] and/or sustained by other additive materials (e.g., using FeS 2 or MnO 2 ) [29,[38][39][40][41][42][43][44]. Despite its misleading nature, the term "reactivity loss" is partly maintained here, for the sake of clarity.…”

“…Despite its misleading nature, the term "reactivity loss" is partly maintained here, for the sake of clarity. Several tools have been introduced to address "reactivity loss" [15,37,[44][45][46][47][48], including the amendment of granular Fe 0 with granular iron sulfide minerals, which is the focus of the current study. Other tools as summarized by Lü et al [18] include using the following: fabrication of (dispersed) nanoscale Fe 0 , multi-metallic materials, weak magnetic field and the fabrication of several Fe 0 -based composites.…”

“…Lipczynska-Kochany et al [38] was probably the first research group to use iron sulfide minerals to sustain the Fe 0 reactivity, thereby increasing the efficiency of conventional Fe 0 /H 2 O systems for water treatment. Accordingly, during the past 25 years, a large number of scientific publications have reported on the enhanced efficiency of Fe 0 /Fe-sulfide/H 2 O systems relative to their Fe 0 /H 2 O counterparts [18,29,44,[47][48][49][50][51][52][53]. However, the mechanisms for this enhancement are still to be established [18,44,52].…”