准确检测植物体内的氟含量有助于预测氟化物的生态环境效应。植物中的氟含量低,通常不超过300μg/g,应用离子选择电极法测量氟需选择样品分解效率高的前处理方法使氟不受到损失,获得离子成分简单、空白低的溶液,同时加入适量的缓冲液增...准确检测植物体内的氟含量有助于预测氟化物的生态环境效应。植物中的氟含量低,通常不超过300μg/g,应用离子选择电极法测量氟需选择样品分解效率高的前处理方法使氟不受到损失,获得离子成分简单、空白低的溶液,同时加入适量的缓冲液增强氟离子的强度和掩蔽干扰。本文采用微波消解法处理植物样品,离子选择电极法测定氟的含量,通过优化实验条件确定了缓冲液的浓度。结果表明,在25℃、p H=6.5的样品溶液中加入147 g/L总离子强度缓冲溶液（TISAB）10 m L,避免了溶液中的阳离子与氟离子生成稳定的不溶絮状物,显著降低了沉淀物的产生。本方法检出限为0.242μg/g,精密度（RSD）小于8.5%,回收率为92.0%-108%,能满足地球化学样品分析中对植物样品中低含量氟的检测要求。展开更多
A new cathode material, LiVPO4F, has been synthesized through two steps of solid-state reactions. In the first step, vanadium pentoxide, ammonium dihydrogen phosphate, and a high surface area carbon were pre-heated at...A new cathode material, LiVPO4F, has been synthesized through two steps of solid-state reactions. In the first step, vanadium pentoxide, ammonium dihydrogen phosphate, and a high surface area carbon were pre-heated at 300 ℃ and reacted at 750 ℃ under an inert atmosphere to yield the trivalent vanadium phosphate VPO4. In the second step, the product LiVPO4F was synthesized by the reaction with VPO4 and LiF. The LiVPO4F was characterized by X-ray diffraction, scanning electron microscopy, cyclic voltammetry and charge/discharge testing measurements. The LiVPO4F is triclinic crystalline system. At 0.1 C rate, the first charge/discharge capacities were 150.1 mAh·g-1 and 132.6 mAh·g-1; At 0.2 C rate, the first charge/discharge capacities were 142.9 mAh·g-1 and 125.2 mAh·g-1. The LiVPO4F from this work has higher charge/discharge voltage 4.3 V and 4.1 V, respectively.展开更多
文摘准确检测植物体内的氟含量有助于预测氟化物的生态环境效应。植物中的氟含量低,通常不超过300μg/g,应用离子选择电极法测量氟需选择样品分解效率高的前处理方法使氟不受到损失,获得离子成分简单、空白低的溶液,同时加入适量的缓冲液增强氟离子的强度和掩蔽干扰。本文采用微波消解法处理植物样品,离子选择电极法测定氟的含量,通过优化实验条件确定了缓冲液的浓度。结果表明,在25℃、p H=6.5的样品溶液中加入147 g/L总离子强度缓冲溶液（TISAB）10 m L,避免了溶液中的阳离子与氟离子生成稳定的不溶絮状物,显著降低了沉淀物的产生。本方法检出限为0.242μg/g,精密度（RSD）小于8.5%,回收率为92.0%-108%,能满足地球化学样品分析中对植物样品中低含量氟的检测要求。
文摘A new cathode material, LiVPO4F, has been synthesized through two steps of solid-state reactions. In the first step, vanadium pentoxide, ammonium dihydrogen phosphate, and a high surface area carbon were pre-heated at 300 ℃ and reacted at 750 ℃ under an inert atmosphere to yield the trivalent vanadium phosphate VPO4. In the second step, the product LiVPO4F was synthesized by the reaction with VPO4 and LiF. The LiVPO4F was characterized by X-ray diffraction, scanning electron microscopy, cyclic voltammetry and charge/discharge testing measurements. The LiVPO4F is triclinic crystalline system. At 0.1 C rate, the first charge/discharge capacities were 150.1 mAh·g-1 and 132.6 mAh·g-1; At 0.2 C rate, the first charge/discharge capacities were 142.9 mAh·g-1 and 125.2 mAh·g-1. The LiVPO4F from this work has higher charge/discharge voltage 4.3 V and 4.1 V, respectively.
