氧电极用膜中氧的渗透性和扩散系数。

Permeability and diffusion coefficient of oxygen in membranes for oxygen electrodes.

作者信息

Evans N T, Quinton T H

出版信息

Respir Physiol. 1978 Oct;35(1):89-99. doi: 10.1016/0034-5687(78)90044-0.

Abstract

Oxygen diffusion coefficient and permeability in thin membranes of low-density polythene and laminated polytetrafluorethylene (PTFE) are measured over the temperature range of about 20 to 30 degrees C. The diffusion coefficient is estimated from the time response of a large area platinum electrode covered with the membrane material and exposed to a sudden change in PO2. outside the membrane. The electrode is operated at a very low polarising voltage so that consumption of oxygen at the cathode surface is made negligible. This method is considered to be more reliable than that based on operating the electrode at more normal polarising voltages at which the boundary condition for oxygen tension at the cathode surface is often ill-defined. Oxygen permeability is estimated from the flux of oxygen across an area of membrane separating a nitrogen gas stream from one containing oxygen, the oxygen being measured with a platinum/zirconium oxide reversible cell. Diffusion coefficient in the membranes is very temperature dependent, whereas oxygen solubility is only weakly so. The diffusion coefficient at 25 degrees C is 0.28 +/- 0.06 . 10(-6) and 1.0 +/- 0.2 . 10(-6) cm2 . sec-1 for PTFE and polythene respectively. The corresponding values for permeability are 0.80 +/- 0.08 . 10(-7) and 0.43 +/- 0.04 . 10(-7) ml O2 atm-1 . cm-1 . sec-1.

摘要

在约20至30摄氏度的温度范围内，测量了低密度聚乙烯和层压聚四氟乙烯（PTFE）薄膜中的氧扩散系数和渗透率。扩散系数是根据覆盖有膜材料并暴露于膜外PO2突然变化的大面积铂电极的时间响应来估算的。电极在非常低的极化电压下工作，以使阴极表面的氧气消耗可忽略不计。这种方法被认为比基于在更正常极化电压下操作电极的方法更可靠，在更正常极化电压下，阴极表面氧张力的边界条件通常不明确。渗透率是根据穿过将氮气流与含氧气流隔开的膜面积的氧气通量估算的，氧气用铂/氧化锆可逆电池测量。膜中的扩散系数对温度非常敏感，而氧溶解度对温度的依赖性较弱。对于PTFE和聚乙烯，25摄氏度时的扩散系数分别为0.28±0.06×10⁻⁶和1.0±0.2×10⁻⁶ cm²·sec⁻¹。渗透率的相应值分别为0.80±0.08×10⁻⁷和0.43±0.04×10⁻⁷ ml O₂ atm⁻¹·cm⁻¹·sec⁻¹。