Influence of coexisting ions on the electron efficiency of sulfidated zerovalent iron toward Se(VI) removal

Review of Advances in Engineering Nanomaterial Adsorbents for Metal Removal and Recovery from Water: Synthesis and Microstructure Impacts

“…To address surface passivation, recent studies have developed several useful strategies by the mediation of the iron oxide shell structure . For example, sulfidation of nZVI (S-nZVI) can not only mitigate its passivation but also create more active sites to facilitate the binding interaction between S-nZVI and metals, resulting in an improved adsorption performance for metal removal. − In addition, Hu et al demonstrated a liquid nitrogen activation approach (Figure a) to improve the Cr­(VI) removal ability of nZVI. This approach yields abundant fractures and provides suitable mass transfer channels for the adsorption and/or reduction of Cr­(VI).…”

Quantifying the efficiency and selectivity of organohalide dechlorination by zerovalent iron

“…where n j is the stoichiometry of the formed product j from reduction of a non-target contaminant or oxidant, and p j is the molar quantity of that product. With this approach, 3 e can be calculated using eqn (16).…”

“…The electron efficiency for reduction involving cocontaminants or other oxidants that contribute to NRD can be written with similar equations, for example as was done for nitrate in competition with NDMA 20 and chromate against TCE. 37 The approach represented by eqn (16) has several advantages over the approaches that rely on solid phase characterization. First, this approach requires only solution phase measurements, which are generally more accessible and sensitive than specialized instrumentation requiring signicant mineralogical transformation for detection.…”

“…79 Another possible explanation is that the PCE is concentrated on the AC support, leading to a signicantly higher PCE to ZVI ratio and therefore greater selectivity and electron efficiency. It was previously shown that the reaction of TCE was increasingly favored over the reaction of water as the initial TCE concentration increased relative to the nZVI concentration, simply due to TCE outcompeting water for reduction reaction sites and/or for adsorbed H. 80 In a recent laboratory study, the 3 e of PCE dechlorination by Carbo-Iron® was determined using eqn (16). 21 The 3 e value increased from 27 to 60% with decreasing particle concentration from 5 to 1.25 g L À1 at pH 8.5 and PCE concentration of 33 mg L À1 .…”

“…), [9][10][11][12] some of which address the efficiency and selectivity of those processes. [13][14][15][16][17][18] Because the science and engineering of contaminant degradation, especially dechlorination, in the Fe-water system are relatively mature, most current research is now focused on higher-level issues like the optimization of the process to maximize its efficiency for contaminant degradation (e.g., electron efficiency). [19][20][21] Throughout this manuscript, the term "efficiency" is used in a precise technical sense (i.e., the relative quantity of inputs to outputs in a process 22 ), rather than the common but casual and not entirely accurate use of the term as a synonym for the rate of contaminant removal (e.g., "removal efficiency" 5 and "degradation efficiency" 23 ).…”