木灰可以用,例如,作为土壤肥料或建筑材料;然而,重要的是要确保这种使用不会导致重金属的扩散和随后对环境的危害。木飞灰(WFA)通常具有比木底灰更高的重金属浓度。本文主要研究从WFA中浸出重金属,特别确定影响浸出的WFA特性以及由环境空气中的水合和碳酸化引起的浸出变化。基于八种不同WFA特征的化学计量学模型表明,Cr和Zn的浸出与K的浓度和SO42-的浸出有关,表明与WFA中常见的可溶性K2(SO4)有关。在衰老过程中,WFA的pH和电导率均降低,表明形成了新的相。Cd的浸出,Cu,Ni,Pb最初较低,老化后下降到不可测量。除其中一种WFA外,锌的浸出也是如此。因此,重金属的一部分,最初是浸出的,建立在新形成的阶段。Cr浸出在时效过程中也表现出普遍下降,然而,而不是同样低的水平。这意味着浸出Cr部分不受时效过程的影响或形成的相含有水溶性Cr。Cr的持续浸出需要更多的关注,因为它可能是有毒和致癌的Cr(IV)。作为WFA的化学和矿物学,包括重金属的流动性,可能会发生变化,需要增加对化学的了解来确定这些变化,以选择无害环境的回收方案。
Wood ashes can be used, e.g., as soil fertilizer or in construction materials; however, it is important to ensure that such use will not cause spreading of heavy metals and subsequent harm to the environment. Wood fly ashes (WFAs) generally have higher concentrations of heavy metals than wood bottom ashes. This paper focuses on the leaching of heavy metals from WFA, specifically identifying WFA characteristics that influence the leaching and changes in leaching caused by hydration and carbonation in ambient air. Chemometric modeling based on characteristics for eight different WFAs suggested that the leaching of Cr and Zn was associated with the concentration of K and the leaching of SO42-, indicating a connection to the soluble K2(SO4) commonly found in WFAs. During the aging, both pH and conductivity of the WFAs decreased showing the formation of new phases. The leaching of Cd, Cu, Ni, and Pb was low initially and decreased to non-measurable after the aging. So did the leaching of Zn except from one of the WFAs. Thus, the part of the heavy metals, which were leaching originally, was built into the newly formed phases. The Cr leaching also showed a general decrease during the aging, however, not to similarly low levels. This means that the leaching Cr fraction was either not influenced by the aging processes or the formed phases contained water-soluble Cr. The continued leaching of Cr needs more attention as it may be the toxic and carcinogenic Cr(IV). As the chemistry and mineralogy of WFAs, inclusive of the mobility of the heavy metals, are subject to changes, increased knowledge on the chemistry determining these changes is needed to choose environmentally sound recycling options.