Mahoney Geochemical Consulting LLC, Lakewood, Colorado 80226, USA.
Environ Sci Technol. 2009 Dec 15;43(24):9260-6. doi: 10.1021/es901586w.
The diffuse layer model (DLM) database of Dzombak and Morel was developed to quantify the adsorption of dissolved species onto the hydrous ferric oxide (HFO) surface, and contained numerous surface complexation reactions, including surface complexation reactions for uranyl (UO(2)(+2)) consisting of Hfo_sOUO(2)(+) and Hfo_wOUO(2)(+). However, these constants were not based upon experimentally obtained data, but rather were derived from linear free energy relationships (LFER) using log K(MOH) values. When compared to experimental data, the LFER-derived constants for uranyl were shown to overestimate adsorption by a factor of 10 in some cases. At least 14 uranyl HFO data sets have been previously published and were used to re-estimate constants by coupling the geochemical computer code PHREEQC with UCODE_2005, an automated parameter optimization program. Five uranyl-bearing surface complexation reactions were initially evaluated; the constants were optimized by allowing UCODE to incrementally vary selected log K(x)(int) values until the best fit to the experimental data was obtained. Assumptions consistent with the original DLM were retained. Changes to the K(1)(int) and K(2)(int) constants, and addition of uranyl monocarbonate and uranyl dicarbonate surface complexes, will update and correct the uranyl sorption reactions in this widely used database.
弥散层模型 (DLM) 数据库由 Dzombak 和 Morel 开发，用于量化溶解物种在水合氧化铁 (HFO) 表面的吸附，其中包含许多表面络合反应，包括包含 Hfo_sOUO(2)(+) 和 Hfo_wOUO(2)(+) 的铀酰 (UO(2)(+2)) 表面络合反应。然而，这些常数不是基于实验获得的数据，而是使用 log K(MOH) 值从线性自由能关系 (LFER) 推导出来的。与实验数据相比，在某些情况下，LFER 推导的铀酰常数高估了吸附作用 10 倍。至少有 14 个铀酰 HFO 数据集以前已经发表过，并使用耦合地球化学计算机代码 PHREEQC 和 UCODE_2005（一种自动参数优化程序）重新估算常数。最初评估了五个含铀酰的表面络合反应；通过允许 UCODE 逐步改变选定的 log K(x)(int) 值，直到与实验数据获得最佳拟合，来优化常数。保留了与原始 DLM 一致的假设。K(1)(int) 和 K(2)(int) 常数的变化以及添加铀酰单碳酸盐和铀酰二碳酸盐表面络合物，将更新和纠正这个广泛使用的数据库中的铀酰吸附反应。
