Abstract

Simple fixed bed models such as the Bohart–Adams and Thomas equations are often used to describe the breakthrough characteristics of water and air contaminant adsorption in fixed bed adsorbers. However, these popular models are confined to correlating highly symmetric breakthrough curves. The present study explores the feasibility of using two probability distributions (normal and log-normal) to track asymmetric breakthrough curves for water and air contaminant adsorption in fixed bed columns (ciprofloxacin, ammonium, hydrogen chloride, and hydrogen sulfide). The normal and log-normal probability distributions provided accurate fits to the slightly asymmetric ciprofloxacin breakthrough curve. They also provided a good representation of the overall shape of the ammonium breakthrough curve, but failed to describe the leakage of ammonium during the initial period of column operation. The log-normal distribution was able to match the asymmetric HCI and H₂S breakthrough curves. The normal distribution, by comparison, failed to describe these two asymmetric breakthrough curves. Because the log-normal distribution has a floating inflection point, it was very effective in describing the asymmetric HCI and H₂S breakthrough curves that were sharp initially and then broadened significantly as the column approached saturation. The ability of the normal distribution to track such asymmetric breakthrough data was impeded by its invariant inflection point.

摘要

简单的固定床模型，例如 Bohart-Adams 和 Thomas 方程，通常用于描述固定床吸附器中水和空气污染物吸附的突破性特征。然而，这些流行的模型仅限于关联高度对称的突破曲线。本研究探讨了使用两种概率分布（正态分布和对数正态分布）来跟踪固定床柱（环丙沙星、铵、氯化氢和硫化氢）中水和空气污染物吸附的不对称突破曲线的可行性。正态和对数正态概率分布提供了对稍微不对称的环丙沙星突破曲​​线的精确拟合。他们还很好地体现了铵突破曲线的整体形状，但未能描述塔运行初期的氨泄漏情况。对数正态分布能够匹配非对称 HCI 和 H₂ S 突破曲线。相比之下，正态分布无法描述这两条不对称的突破曲线。由于对数正态分布具有浮动拐点，因此它非常有效地描述不对称的 HCI 和 H ₂ S 突破曲线，这些曲线最初很尖锐，然后随着色谱柱接近饱和而显着变宽。正态分布追踪这种不对称突破数据的能力因其不变的拐点而受到阻碍。