Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong SAR, China.
Chemosphere. 2012 Feb;86(8):817-21. doi: 10.1016/j.chemosphere.2011.11.043. Epub 2011 Dec 23.
The feasibility and mechanism of incorporating simulated lead-laden sludge into low-cost ceramic products was investigated by observing the reaction of lead with two kaolinite-based precursors under sintering conditions. To investigate the phase transformation process of lead, lead oxide (PbO) mixed with a kaolinite or mullite precursor were fired at 500-950°C for 3h. Detailed X-ray diffraction analysis of sintered products revealed that both precursors had crystallochemically incorporated lead into the lead feldspar (PbAl(2)Si(2)O(8)) crystalline structure. By mixing lead oxide with kaolinite, lead feldspar begins to crystallize at 700°C; maximum incorporation of lead into this structure occurred at 950°C. However, two intermediate phases, Pb(4)Al(4)Si(3)O(16) and a polymorph of lead feldspar, were detected at temperatures between 700 and 900°C. By sintering lead oxide with the mullite precursor, lead feldspar was detected at temperatures above 750°C, and an intermediate phase of Pb(4)Al(4)Si(3)O(16) was observed in the temperature range of 750-900°C. This study compared the lead leachabilities of PbO and lead feldspar using a prolonged leaching test (at pH 2.9 for 23d) modified from the toxicity characteristic leaching procedure. The results indicate the superiority of lead feldspar in stabilizing lead and suggest a promising and reliable strategy to stabilize lead in ceramic products.
采用烧结条件下观察铅与两种高岭土基前体反应的方法，研究了将模拟含铅污泥掺入低成本陶瓷制品中的可行性和机理。为了研究铅的相变过程，将氧化铅（PbO）与高岭土或莫来石前体混合，在 500-950°C 下煅烧 3h。对烧结产物的详细 X 射线衍射分析表明，两种前体都将铅晶化学地掺入到长石铅（PbAl(2)Si(2)O(8))晶体结构中。通过将氧化铅与高岭土混合，长石铅在 700°C 开始结晶；在 950°C 时，铅最大程度地掺入到该结构中。然而，在 700-900°C 之间的温度下，检测到两种中间相，Pb(4)Al(4)Si(3)O(16)和长石铅的多晶型物。通过将氧化铅与莫来石前体烧结，在 750°C 以上的温度下检测到长石铅，并且在 750-900°C 的温度范围内观察到 Pb(4)Al(4)Si(3)O(16)的中间相。本研究通过对毒性特征浸出程序进行修改（在 pH 2.9 下浸出 23d），使用延长浸出试验比较了 PbO 和长石铅的铅浸出率。结果表明长石铅在稳定铅方面具有优势，并提出了一种在陶瓷制品中稳定铅的有前途且可靠的策略。
