The effects of CaO addition on structure and arsenic immobilization in xCaO-(100-x) (30Na2O-2.8B2O3-25.2Fe2O3-42P2O5)(x=0,5,10,20 mol%)(sodium-iron-boron-phosphorous, SIBP) glasses are studied and the results indicate that the addition of 20 mol% CaO in the SIBP glasses decreases the leaching concentration of arsenic from 3.14 mg/L to 0.99 mg/L, and the ratio of arsenic immobilized in the glass increases from 60.78 % to 88.87 %. The Q2 bridge oxygen structure can be broken by the addition of CaO, which leads to depolymerization of SIBP glasses network. Simultaneously, CaO added in the glasses can depolymerize the phosphate chains and participate in the network by forming chemical bonds such as Ca-O-P, Ca-O-As bonds in the glasses which will strengthen the glass structure and compact the glass density. Moreover, with the increase of CaO, the SIBP glasses transition temperature (Tg) and △T exhibit tendency of increasing, which demonstrates that the SIBP glasses structure has been strengthened. Besides, the cross-linking between non-bridging oxygen of phosphate and Ca2+ also has great impacts on the arsenic immobilization in the SIBP glasses.%研究了CaO对xCaO-（100-x）（30Na2O-2.8B2O3-25.2Fe2O3-42P2O5）（x=0、5％、10％、20％，指摩尔分数）玻璃结构及固砷效果的影响，研究表明加入20%（摩尔分数）CaO砷浸出浓度由3.14 mg/L降低至0.99 mg/L，固化率从60.78%增加到88.87%；CaO的加入，会破坏钠铁硼磷玻璃固砷体系中Q2桥氧结构，玻璃网络化程度降低，结构加强；同时，加入体系中的CaO 能够进入玻璃固砷体的网络结构中，使桥氧解聚，并对非桥氧结构产生集聚作用的同时，形成Ca-O-As、Ca-O-P等化学键，使玻璃体系的结构增强，致密度增加；随着CaO摩尔分数增加，Tg、△T呈现增大的趋势，玻璃结构得到增强，同时 Ca2+对非桥氧磷酸盐之间的交联，对固砷效果也有较大的影响.
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