TY - JOUR
T1 - The preferential retention of VIZn over IVZn on birnessite during dissolution/desorption
AU - Qin, Zhangjie
AU - Yin, Hui
AU - Wang, Xiaoming
AU - Zhang, Qin
AU - Lan, Shuai
AU - Koopal, Luuk K.
AU - Zheng, Lirong
AU - Feng, Xionghan
AU - Liu, Fan
PY - 2018/9/1
Y1 - 2018/9/1
N2 - Zn is a common heavy metal in soils and sediments. In this study, the release behaviors of octahedral (VIZn) and tetrahedral (IVZn) Zn complexes on synthesized hexagonal birnessite were explored by solution chemistry method in combination with spectroscopic analysis. In acidic dissolution processes, the release of adsorbed Zn2+ from birnessite occurred into two stages: in the first stage, ~60% of Zn2+ was desorbed rapidly, with only 8% of Mn being released, and the ratio of VIZn/IVZn increased with time; in the second stage, the residual Zn2+ was mostly VIZn and released slowly at a nearly constant rate until complete dissolution of the matrix mineral was observed. During desorption of Zn2+ by Pb2+, the ratio of VIZn/IVZn on birnessite also increased, while the residual percentage of VIZn remained nearly constant. However, it is known that IVZn-triple corner-sharing (TCS) is more stable than VIZn-TCS, suggesting that part of the remaining IVZn-TCS on birnessite might transform to VIZn-TCS immediately when VIZn-TCS is replaced by H+ or Pb2+. Additionally, the possible distribution of Mn3+ and IVZn or the partial charge compensation by protons can lead to the preferential retention of VIZn on birnessite or the preferential re-adsorption of VIZn at the new edge sites. These results can provide new insights into the geochemical behavior of Zn2+ contaminant in soil and aquatic environments.
AB - Zn is a common heavy metal in soils and sediments. In this study, the release behaviors of octahedral (VIZn) and tetrahedral (IVZn) Zn complexes on synthesized hexagonal birnessite were explored by solution chemistry method in combination with spectroscopic analysis. In acidic dissolution processes, the release of adsorbed Zn2+ from birnessite occurred into two stages: in the first stage, ~60% of Zn2+ was desorbed rapidly, with only 8% of Mn being released, and the ratio of VIZn/IVZn increased with time; in the second stage, the residual Zn2+ was mostly VIZn and released slowly at a nearly constant rate until complete dissolution of the matrix mineral was observed. During desorption of Zn2+ by Pb2+, the ratio of VIZn/IVZn on birnessite also increased, while the residual percentage of VIZn remained nearly constant. However, it is known that IVZn-triple corner-sharing (TCS) is more stable than VIZn-TCS, suggesting that part of the remaining IVZn-TCS on birnessite might transform to VIZn-TCS immediately when VIZn-TCS is replaced by H+ or Pb2+. Additionally, the possible distribution of Mn3+ and IVZn or the partial charge compensation by protons can lead to the preferential retention of VIZn on birnessite or the preferential re-adsorption of VIZn at the new edge sites. These results can provide new insights into the geochemical behavior of Zn2+ contaminant in soil and aquatic environments.
KW - Birnessite
KW - Desorption
KW - Dissolution
KW - Extended X-ray absorption fine structure spectroscopy
KW - Zinc coordination
U2 - 10.1016/j.clay.2018.04.017
DO - 10.1016/j.clay.2018.04.017
M3 - Article
AN - SCOPUS:85046042122
SN - 0169-1317
VL - 161
SP - 169
EP - 175
JO - Applied Clay Science
JF - Applied Clay Science
ER -