摘要
结合磷灰石和解磷菌进行农业土壤铅修复是环境修复领域的新兴技术。然而仅靠实验很难全面解析修复过程中的详细反应过程和铅的成矿机制,特别是难以解释目标稳定矿物氟基磷酸铅为何不是主要产物。本文主要利用GWB软件中的React和Act2两个程序模块,基于前人实验数据设置模拟参数,对这一科学问题进行探究。首先用React程序模块的滴定模式(Titration)来研究黑曲霉复合氟基磷灰石的除铅过程,即通过向反应体系中逐步滴加草酸来模拟黑曲霉分泌草酸的过程。反应体系中Pb^(2+)初始浓度为8.4 mmol·L^(-1),草酸总添加量为2.0 g·L^(-1),氟基磷灰石总添加量为8.3 g,其中草酸和氟基磷灰石分为100步添加到体系中。React模拟过程终止后,可得到体系pH值、主要离子浓度(Pb^(2+)、Ca^(2+)、H_2PO-_4^-、F^-和C_2O_4^(2-))以及生成产物随着草酸和氟基磷灰石添加的变化曲线。然后将黑曲霉与氟基磷灰石培养后的浸出液与Pb(NO-_3)_2溶液混合后,用Act2模块模拟其草酸和F^-浓度变化对铅矿物形态的影响。模拟结果表明:草酸引起的pH值变化是影响铅矿化结果的最重要参数,体系中的Pb^(2+)主要以草酸铅形式沉淀,和原实验结果吻合。此外,只有在弱酸或碱性环境下,且溶液中氟离子浓度大于27 mmol·L^(-1)时,体系中才会生成氟基磷酸铅。该结果为利用磷酸盐矿物材料进行土壤铅修复提供了理论指导。
Combination with apatite and phosphate solubilizing microbes is a new technique for lead remediation in soil. However, it is difficult to elucidate the detailed reaction processes and the mechanisms via only experiments, especially in explaining why the fluoropyromorphite is not the major product. In this study, GWB software was applied to stimulate the reaction progress in Pb remediation via the application of fungus Aspergillus niger and geological fluorapatite based on our previous experimental data. The oxalic acid was gradually added to the system(100 steps) to simulate oxalic acid secretion by Aspergillus niger in Titration of React module. The initial concentration of Pb2+was 8.4 mmol·L-1, with the total addition of oxalic acid and fluorapatite of 2.0 g·L-1 and 8.3 g respectively. In React module, the pH value of the system, concentrations of ions(Pb2+、Ca2+、H2PO4-、F- and C2O42-), and formation of products during the addition of oxalic acid and fluorapatite can be tracked. Then, Act2 module was used to simulate the effects of oxalic acid and F- on Pb mineralization, i.e.,during adding Pb cations to the filtered solution incubated with Aspergillus niger and fluorapatite. The results showed that the change of pH caused by oxalic acid was the most significant parameter influencing Pb mineralization. The Pb2+was precipitated mainly as lead oxalate in the system, which was consistent with the previous experimental results. The stable fluoropyromorphite is only formed when the concentration of F- is higher than 27 mmol·L-1 under weak acid or alkaline environments. This study sheds bright light on the theoretical guidance for Pb remediation in soil via phosphate materials.
作者
郑君仪
蒋柳
胡云潇
郭辰萌
唐凌逸
李真
ZHENG Jun-yi;JIANG Liu;HU Yun-xiao;GUO Chen-meng;TANG Ling-yi;LI Zhen(College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095,China;Jiangsu Provincial Key Lab for Organic Solid Waste Utilization,Nanjing Agricultural University,Nanjing 210095,China)
出处
《农业资源与环境学报》
CAS
北大核心
2019年第2期198-205,共8页
Journal of Agricultural Resources and Environment
基金
江苏省自然科学基金(BK20150683)
国家重点基础研究发展计划(973计划)重大专项(2015CB150504)
中央高校基本业务费重点项目(KYTZ201712)
江苏省双创博士计划
南京市留学回国人员科技活动择优项目~~
关键词
铅污染修复
解磷真菌
黑曲霉
氟基磷灰石
GWB
Pb remediation
phosphate solubilizing fungi
Aspergillus niger
fluorapatite
GWB
