http://pubs.rsc.org/en/content/articlelanding/2012/RA/c2ra01347a
Activation of serpentine for CO2mineralization by flux extraction of soluble magnesium salts using ammonium sulfate James Highfield, HuiQi Lim, Johan Fagerlund Ron Zevenhoven RSC Adv., 2012,2, 6535-6541 DOI: 10.1039/C2RA01347A Abstract This paper concerns the growing role of cheap and potentially recyclable ammonium salts in CO2 mineralization. The powerful hyphenated technique TG-FTIR, along with XRD and ICP-AES, were used to shed light on the underlying chemistry and measure the efficiency of magnesium ion extraction from a Finnish serpentinite in contact with molten ammonium sulfate above 300 °C. From micro- and gram-scale tests, flux extraction as epsomite [MgSO4·7H2O] proceeds via the intermediacy of Tutton salts, NH4/Mg double sulfates increasingly rich in Mg. Extraction is effected through the agency of acidic derivatives, principally ammonium bisulfate and sulfamic acid, which are created sequentially from ammonium sulfate in situ. However, sulfamic acid volatilizes and/or decomposes at a significant rate by 400 °C. This loss mechanism is primarily responsible for the modest recovery of Mg (50–60%). An improved process would operate below 400 °C where Mg extraction as efremovite [(NH4)2Mg2(SO4)3] is effective. Future experiments evaluating the use of humid air to stabilize the bisulfate and impede the loss of flux are recommended. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
