磷酸锆基陶瓷材料的制备与性能研究

利用共沉淀法制备了磷酸锆,用差热分析法(DTA)研究了Zr2P2O7的热稳定性情况,并进一步研究了烧结助剂的量、烧结温度等对其性能的影响。

蓝绿色长余辉材料ZrP_2O_7:Mn^(2+),Sr^(2+)的制备与性能研究

利用高温固相法制备了蓝绿色长余辉发光材料ZrP_2O_7:Mn^(2+),Sr^(2+).通过X射线衍射对产物的相结构进行分析,通过荧光光谱和热释光谱研究其发光本质,并探究了Sr^(2+)掺杂量对余辉性质的影响.结果表明:制备的样品的结构与ZrP_2O_7相同.样品位于489 nm处有发射峰,由Zr4+所贡献,521 nm及545 nm归属于Mn^(2+)的~4T_(1g)-~6A_(1g)跃迁,为蓝绿色发光材料.当Sr^(2+)掺杂量为0.5 mol%时,样品的发光性能最佳.样品经过紫外光照射后,在暗室中目测其余辉时间约3 h.热释光谱分析表明,掺杂Sr^(2+)可以增加晶体中Vo¨氧空位缺陷浓度,从而改善样品的余辉时间.

pH、富里酸和温度对铀酰在ZrP_2O_7上的吸附影响

采用质量滴定法和静态法分别研究了ZrP2O7的零电荷点(pHPZC)和铀酰离子在ZrP2O7上的吸附及解吸行为.铀酰离子在ZrP2O7上的吸附受体系pH、固液比、电解质种类及富里酸(FA)强烈影响,离子强度对铀酰离子在ZrP2O7上吸附的影响较小;随着固液比(m/V)和pH增大,吸附边界向左偏移;磷酸根与硫酸根对吸附有相反的影响;在低pH下,富里酸(FA)促进铀酰离子在ZrP2O7上吸附;柠檬酸根对吸附有非常大的影响;温度升高有利于吸附.采用Langmuir和Freundlich模型对吸附等温线进行拟合研究,表明Freundlich模型可以更好地拟合铀酰离子在ZrP2O7上的吸附.通过对热力学数据如(△H0,△S0和△G0)的计算可知吸附过程是自发和吸热过程.铀酰离子在ZrP2O7上吸附为不可逆吸附.

Effect of pH,fulvic acid and temperature on the sorption of uranyl on ZrP_2O_7

The sorption of UO22+ onto ZrP2O7 was studied using the batch technique and the point of zero charge of ZrP2O7 was obtained through mass titration.The results indicated that sorption of UO22+ onto ZrP2O7 was strongly affected by pH,solid-to-liquid ratio (m/V),the species of electrolyte in solution and fulvic acid (FA),but was insensitive to ionic strength.The sorption of UO22+ increased with increasing pH and m/V.The presence of FA enhanced UO22+ sorption onto ZrP2O7 at low pH.The presence of phosphate or sulfate caused opposite effects on the sorption of UO22+ onto ZrP2O7.Addition of citrate also significantly affected UO22+ sorption.The sorption of UO22+ increased as the temperature of the system increased.The Langmuir and Freundlich models were used to simulate the sorption isotherms of UO22+ onto ZrP2O7 at different temperatures.The results indicated that the Freundlich model described UO22+ sorption better than the Langmuir model.Thermodynamic parameters for the sorption process were calculated from the temperature dependent sorption isotherms.The results suggested that the sorption process of UO22+ onto ZrP2O7 is spontaneous and endothermic.The desorption process of UO22+ from ZrP2O7 was also investigated and it was found that sorption onto ZrP2O7 was irreversible.