Sorption of dissolved lead from shooting range soils using hydroxyapatite amendments synthesized from industrial byproducts as affected by varying pH conditions
Sorption of dissolved lead from shooting range soils using hydroxyapatite amendments synthesized from industrial byproducts as affected by varying pH conditions
复制标题
DOI：
10.1016/j.jenvman.2008.11.004
复制
发表时间：
2009-04-01
影响因子：
8.7
通讯作者：
Sato, Takeshi
中科院分区：
文献类型：
--
作者：
Hashimoto, Yohey;Taki, Tomohiro;Sato, Takeshi
为了使固定化技术取得成功，当修复针对大量污染土壤时，使用容易获得且成本有利的改良剂是重要的。本研究的目的是研究副产物合成的羟基磷灰石是否可以作为射击场土壤中溶解铅的固定化改进剂，并对溶解实验中收集的动力学数据进行建模。在固定pH条件下进行了土壤溶液动力学实验。采用不同羟基磷灰石改良剂对铅污染土壤进行了反应，测定了土壤中铅的溶解速率和矿物产物。使用的三种改进剂分别是纯羟基磷灰石（HA）、从石膏废物（CHA）合成的低结晶羟基磷灰石和从焚烧的家禽垃圾（PHA）合成的羟基磷灰石。在pH 3 ~ 7范围内，随着添加剂的加入，溶解铅浓度降低。在pH为6及以上时，CHA和PHA均比HA更有效地抑制Pb的溶解。根据pH值为6时的热力学计算，预测CHA和PHA处理的溶解pb浓度分别比HA处理低66%和50%。CHA和PHA具有较好的固铅效果，在较高的pH下具有较大的溶解度，这可能促进了绿磷闪石沉淀的形成。在酸性pH范围内，土壤Pb的溶解动力学可以用拟一级和拟二级方程来解释。根据离子交换模型，在反应过程的最初40 min内，实验数据与回归曲线吻合较好，但此后模型预测的准确性下降。根据动力学模型和溶解现象，CHA和PHA改性剂在弱酸到中性ph下比纯羟基磷灰石具有更好的铅吸附能力和快速动力学。(C) 2008 Elsevier Ltd。版权所有。
For immobilization technologies to be successful, the use of readily available and cost advantageous amendment is important when the remediation targets vast amounts of contaminated soils. The objectives of this study were to investigate whether the byproduct-synthesized hydroxyapatite can be used as an immobilizing amendment for dissolved Pb from a shooting range soil, and to model the kinetic data collected from dissolution experiments. A soil-solution kinetic experiment was conducted under fixed pH conditions as a function of time. A Pb-contaminated soil was reacted with various hydroxyapatite amendments to determine the dissolution rate and mineral products of soil Pb. Three types of amendments used were pure hydroxyapatite (HA), and poorly crystalline hydroxyapatites synthesized from gypsum waste (CHA), and synthesized from incinerated poultry litter (PHA). The dissolved Pb concentration decreased with the addition of amendments at pH 3-7. Both CHA and PHA were more effective than HA for attenuating Pb dissolution at pH 6 and above. According to the thermodynamic calculation at pH 6, the dissolved Pb-concentration for CHA and PHA treatments was predicted to be 66% and 50% lower than that of HA treatment, respectively. A better Pb immobilization effect demonstrated by CHA and PHA resulted in their greater solubility at higher pH, which may promote the formation of chloropyromorphite precipitates. Dissolution kinetics of soil Pb was adequately explained by pseudo-first order and pseudo-second order equations in acid pH ranges. According to the ion exchange model, an adequate agreement between the experimental data and regression curves was shown in the initial 40 min of the reaction process, but the accuracy of model predictability decreased thereafter. According to kinetic models and dissolution phenomena, CHA and PHA amendments had better Pb sorption capacity with rapid kinetics than pure hydroxyapatite at weak acid to neutral pH. (C) 2008 Elsevier Ltd. All rights reserved.