材料期刊网

采用草酸和柠檬酸分别与天然磷灰石共培养以对其改性，并将改性磷灰石用于Pb／Zn复合污染土壤的稳定化修复，借助XRD、FTIR等仪器方法表征改性磷灰石的物相组成及其P结合形态的转变，采用TCLP方法评价改性天然磷灰石对土壤重金属的修复效果．研究表明，草酸改性磷灰石诱导了草酸钙生成，并且32?4％的P由稳定形态转化为水溶态，而柠檬酸改性未能使磷灰石主要成分发生显著变化，仅有0．28％的P转化为水溶态P．与天然磷灰石相比，改性磷灰石提高了对Pb和Zn的稳定性．草酸改性磷灰石可同时有效地稳定土壤中的Pb和Zn，稳定化效率分别为68％—100％和64％—73％，其固定机制主要是形成难溶的磷酸盐沉淀；柠檬酸改性磷灰石对Pb和Zn的稳定化效率分别为＜20％和62％—69％，对Pb和Zn的稳定性主要是通过吸附作用．总之，草酸改性磷灰石对Pb和Zn的稳定化优于柠檬酸改性磷灰石，是一种高效经济的土壤重金属稳定化修复材料．

Natural phosphate rock was modified with oxalic acid and citric acid, respectively, and then applied into contaminated soil for immobilization of Pb and Zn. XRD and FTIR were used to characterize the composition and P species in phosphate rock due to the modification. TCLP method was used to evaluate the effect of modified phosphate rock on the immobilization of Pb and Zn in contaminated soil. The results showed that CaC2 O4·H2 O was formed in phosphate rock with oxalic acid modification, and the soluble P increased by 32. 4%, compared to that in the phosphate rock without modification. However, the composition of phosphate rock remained unchanged after citric acid modification, and the soluble P only increased by 0.28%.Compared to natural phosphate rock, modified phosphate rock enhanced the immobilization of Pb and Zn in soil. Oxalic acid modified phosphate rock simultaneously and effectively immobilized Pb and Zn in soil, and the efficiency was 68%—100% for Pb and 64%—73% for Zn, respectively. The main mechanism was phosphate precipitation between Pb and soluble P. The efficiency of immobilizing Pb and Zn by citric acid modified phosphate rock was less than 20% for Pb and 62%—69% for Zn, respectively. The immobilization of Pb and Zn was mainly through adsorption. In conclusion, oxalic acid modified phosphate rock more effectively immobilized Pb and Zn than citric acid modified one, and it was an efficient and cost?effective repair material for the immobilization of heavy metals in soil.