Laboratory of Applied Physical Chemistry and Environmental Technology, Department of Chemical Engineering, K.U. Leuven, W. De Croylaan 46, B-3001 Leuven, Belgium.
Waste Manag. 2012 Feb;32(2):278-86. doi: 10.1016/j.wasman.2011.09.018. Epub 2011 Oct 27.
Development of treatment methods to reduce Sb leaching from municipal solid waste incinerator (MSWI) bottom ash, such as accelerated carbonation, is being complicated by insufficient understanding of Sb geochemistry. The leaching of antimonate (Sb(V)) and antimonite (Sb(III)) in MSWI bottom was studied as a function of pH and degree of carbonation. While total (Sb(V)+Sb(III)) leaching was lowest (1.2 mg kg(-1)) at the natural pH (i.e. 10.6) of uncarbonated bottom ash, HPLC-ICP-MS analysis showed that acidification and carbonation increased Sb(V) leaching, but decreased Sb(III) leaching, probably because Sb(III)(OH)(4)(-) became less stable. PHREEQC geochemical modelling suggested that Sb(V) concentrations approached equilibrium with the romeites, i.e. calcium antimonates, Ca(1.13)Sb(2)(OH)(0.26)·0.74H(2)O at pH=10.6 and CaSb(OH)(6) at pH=8. It is hypothesised that not interaction with ettringite but dissolution of romeite controls antimonate leaching in the pH range 8-11 in MSWI bottom ash, because while Ca is preferentially leached from romeite, the mineral structures containing more Ca at higher pH are less soluble. A model was proposed where acidification and carbonation both lead to lower Ca(2+) and/or hydroxyl concentration, which removes Ca(2+) and hydroxyls from the romeite structure and leads to comparably higher Sb(V) concentration in equilibrium with romeite. Sb solubility depends on pH and Ca(2+) availability in this model, which has implications for bottom ash valorisation and risk assessment.
开发减少城市固体废物焚烧（MSWI）底灰中锑浸出的处理方法，如加速碳酸化，由于对锑地球化学的理解不足而变得复杂。研究了 MSWI 底灰中锑酸盐（Sb(V)）和锑（Sb(III)）的浸出率随 pH 值和碳酸化程度的变化。虽然未碳酸化底灰的自然 pH（即 10.6）下总（Sb(V)+Sb(III)）浸出率最低（1.2mgkg(-1)），但 HPLC-ICP-MS 分析表明酸化和碳酸化增加了 Sb(V)的浸出，但降低了 Sb(III)的浸出，可能是因为 Sb(III)(OH)(4)(-)变得不太稳定。PHREEQC 地球化学模型表明，Sb(V)浓度在 pH=10.6 时与方锑矿（romeite）即 Ca(1.13)Sb(2)(OH)(0.26)·0.74H(2)O 接近平衡，在 pH=8 时与 CaSb(OH)(6)接近平衡。推测在 MSWI 底灰中，控制 Sb(V)浸出的不是与钙矾石的相互作用，而是方锑矿的溶解，因为虽然 Ca 优先从方锑矿中浸出，但在较高 pH 值下，含有更多 Ca 的矿物结构的溶解度较低。提出了一种模型，其中酸化和碳酸化都会导致 Ca(2+)和/或氢氧根浓度降低，从而将 Ca(2+)和氢氧根从方锑矿结构中去除，导致与方锑矿平衡时 Sb(V)浓度较高。在该模型中，Sb 的溶解度取决于 pH 值和 Ca(2+)的可用性，这对底灰的增值和风险评估有影响。
