ADDITION/CORRECTION pubs.acs.org/est
Copper Stabilization via Spinel Formation during the Sintering of Simulated Copper-Laden Sludge with AluminumRich Ceramic Precursors [Environmental Science & Technology 2011, 45, 3598–3604]. Yuanyuan Tang,† Stephen Sin-Yin Chui,‡ Kaimin Shih,*,† and Lingru Zhang† † Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Honzg Kong SAR, China ‡ Department of Chemistry and HKU-CAS Joint Laboratory on New Materials, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China Through repeating experiments with a new batch of acid wash kaolin, we found that its ability to thermally stabilize copper is higher than what was reported in Tang et al. (Environ. Sci. Technol. 2011, 45, 3598 3604, DOI: 10.1021/es103596k). A compositional analysis of the kaolin was conducted before our first use (Environ. Sci. Technol. 2006, 40, 5077 5083, DOI:
Figure 4. Backscattered electron images of the polished surfaces of the products obtained from reaction using (a) kaolinite and (b) mullite sintered at 1000 °C for 3 h. The grains marked “C” are the residual CuO reactants and the light-color grains marked “A” show the enrichment of both Cu and Al (CuAl2O4 spinel). The dark-color matrix (marked “S”) is strongly dominant by Si (cristobalite).
Figure 3. Variations of weight fractions of Cu- and Al-containing crystalline phases obtained from the CuO sintering reactions with (a) kaolinite, and (b) mullite precursors, and (c) the transformation ratio (TR, %) of Cu into the CuAl2O4 spinel phase.
10.1021/es052324z) and it has been successfully used in subsequent metal incorporation experiments (J. Eur. Ceram. Soc. 2007, 27, 91 99, DOI: 10.1016/j.jeurceramsoc.2006.04.176). However, the particular batch used in Tang et al. (2011) had excess Si content in amorphous form, which reduced the amount of Al content for Cu incorporation in experiments. The Si/Al molar ratio of the Si-excess kaolin material was later confirmed by X-ray fluoresces (XRF) to be around 3.0, instead of 1.0 as originally intended in our work. We reconducted sintering experiments with a new batch of acid wash kaolin with a confirmed Si/Al molar ratio of 1.06, and the same phase quantification method reflected higher copper transformation ratios to CuAl2O4, particularly at its maximum incorporation due 7609
dx.doi.org/10.1021/es202699c | Environ. Sci. Technol. 2011, 45, 7609–7610
Environmental Science & Technology
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to sufficient Al content for the reaction. Figures 3 and 4 of Tang et al. (2011) are now revised with the results obtained from using the new kaolin material. With the same phase distribution trends and lower copper incorporation efficiency than alumina systems, the corrected figures do not affect the main conclusions presented in the paper. DOI: 10.1021/es202699c Published on Web 08/16/2011
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dx.doi.org/10.1021/es202699c |Environ. Sci. Technol. 2011, 45, 7609–7610
