有机膦酸盐对碱矿渣胶凝材料铅离子固化性能的提升作用

The Enhanced Lead(Ⅱ)Ions Stabilization of Alkali-activated Slag-based Materials with Appropriate Addition of Phosphonate

有机膦酸盐是一种极强的金属螯合剂,在溶液环境中可有效固化重金属离子。然而,目前关于有机膦酸盐改性水泥基材料重金属离子固化性能的研究较少。本工作研究了羟基乙叉二膦酸四钠(HEDP-4Na)和温、湿度交替变化的养护环境对碱矿渣胶凝材料(Alkali-activated slag-based materials,AASM)铅离子固化性能的影响,并分析了其物相组成、孔隙结构和微观形貌。结果显示:HEDP-4Na显著提升了AASM的铅离子固化性能,当其掺量为0.3%时,标准养护至28 d的AASM铅离子浸出浓度相比未掺入HEDP-4Na的对照组降低了34.6%,这与HEDP-4Na促进了AASM低钙硅比水化产物的生成,提升了水化产物吸附、封裹铅离子并形成C-Pb-S-H的能力,改善了其微观孔隙结构有关;温、湿度交替变化养护环境下,AASM的劣化加速,导致其铅离子固化性能下降,但掺HEDP-4Na的AASM铅离子浸出浓度仍显著低于未掺入HEDP-4Na的对照组。温、湿度交替变化养护时铅离子固化性能下降主要与AASM水化产物的生成受抑制,以及基体孔隙率的提高有关。

Organo-phosphonate is a kind of strong metal chelating agent,which shows great potential in the stabilization of heavy metal ions in solution environment.However,the current understanding of the stabilizing effect of organic-phosphonate on heavy metal ions in cement-based materials is still limited.The effect of tetrasodium hydroxyethylidene diphosphonate(HEDP-4Na)and curing environment with alternating temperature and humidity on lead ions stabilization of alkali-activated slag-based materials(AASM)were studied,and the phase compositions,pore structures and micro morphology were analyzed in this study.The results show that HEDP-4Na significantly improved the lead stabilization of AASM.Under standard curing condition,the 28 d lead ions leaching concentration of AASM with 0.3%HEDP-4Na decreased by 34.6%compared with the control group without HEDP-4Na,which was related to HEDP-4Na promoting the formation of AASM hydration products with low Ca/Si ratio,enhancing the ability of hydration products to adsorb,encapsulate lead ions and synthesize C-Pb-S-H,and improving the pore structures of AASM.Under the curing environment with alternating temperature and humidity,the deterioration of AASM was accelerated,resulting in the decrease of the lead stabilization.However,the lead ions leaching concentration of AASM with HEDP-4Na was still lower than that without HEDP-4Na.The decrease of the lead stabilization under the curing environment with alternating temperature and humidity was mainly related to the inhibition of the formation of AASM hydration products and the increase of matrix porosity.