引用本文:王侠,王欣,杜艳艳,何香艳,彭渤,谭长银,等.改性纳米零价铁对稻田土壤As污染的修复效能[J].环境科学研究,2017,30(9):1406-1414.
WANG Xia,WANG Xin,DU Yanyan,HE Xiangyan,PENG Bo,TAN Changyin,et al.Remediation Efficiency of Arsenic-Contaminated Paddy Soil with Modified Nano-Zero-Valent Iron[J].Reserrch of Environmental Science,2017,30(9):1406-1414.]
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改性纳米零价铁对稻田土壤As污染的修复效能
王 侠, 王 欣, 杜艳艳, 何香艳, 彭 渤, 谭长银
湖南师范大学资源与环境科学学院, 湖南 长沙 410081
摘要:
为实现对稻田土壤As污染的高效修复,通过制备C-NZVI(壳聚糖基稳定化纳米零价铁),分析其对还原态亚砷酸〔As(Ⅲ)〕的吸附动力学和等温吸附特征,阐明典型竞争性阴离子/分子对C-NZVI吸附As(Ⅲ)效率的影响;在此基础上,重点研究淹水和拮抗性肥料对稻土As的强化溶出效应,揭示C-NZVI对稻土液相As的异位吸附去除与原位补充钝化作用.结果表明:准一级动力学和Langmuir等温吸附模型能很好地描述C-NZVI对As(Ⅲ)的吸附过程特征,该材料对As(Ⅲ)的最大吸附量为145.09 mg/g;当竞争性K2HPO4、H3BO3、Na2SiO3和CH3COOH的摩尔浓度为0.05~0.50 mmol/L时,C-NZVI对As(Ⅲ)的去除率依然高达99%. 在对稻田土壤进行淹水和依次施用NH4H2PO4、(NH4)2C2O4、Na2SiO3三种拮抗性肥料条件下,稻土中累积溶出w(水溶态As)(18.1 mg/kg)达到土壤w(As)的30.0%;对强化溶出反应后的淹水稻土进行排水并利用C-NZVI对各步分离获得的含As液相进行异位吸附,As去除率为91.3%~99.8%,该过程使稻土中w(As)减少43.4%~52.6%;进一步利用1%和5%的C-NZVI对强化溶出后的稻土进行补充钝化,可使稻土中w(非专性吸附态As)降低94.7%~100%. 研究显示,淹水强化条件下,利用C-NZVI对稻田土壤As污染进行异位去除与原位钝化的联合修复可为有效减控稻田土壤As生物有效性提供有益途径.
关键词:  壳聚糖稳定化纳米零价铁(C-NZVI)  亚砷酸〔As(Ⅲ)〕  拮抗  异位去除  原位钝化
DOI:
分类号:
基金项目:湖南省自然科学基金项目(2017JJ2180);湖南省地理学重点学科项目;湖南省教育厅优秀青年项目(17B157)
Remediation Efficiency of Arsenic-Contaminated Paddy Soil with Modified Nano-Zero-Valent Iron
WANG Xia, WANG Xin, DU Yanyan, HE Xiangyan, PENG Bo, TAN Changyin
College of Resources and Environmental Science, Hunan Normal University, Changsha 410081, China
Abstract:
Abstract: To achieve effective remediation of As contamination in paddy soils, chitosan-based nanoscale zero-valent iron (C-NZVI) was prepared by liquid phase reducing method using biodegradable chitosan as the stabilizer. The adsorption kinetics and adsorption isotherms of As(III) with C-NZVI were studied. The effects of typical competitive anions and molecules on As(III) adsorption efficiency by C-NZVI were also tested. On this basis, the fortification effects of flooding and antagonistic fertilizers on As dissolution in paddy soil were addressed. C-NZVI was then employed for ectopic adsorption of soluble As in effluent from flooded paddy soils followed by complementary in situ immobilization of soil residual As. The results showed that the process of As(III) adsorption with C-NZVI could be well described by pseudo-first-order kinetics and Langmuir isothermal adsorption. The maximum adsorption capacity of C-NZVI towards As(III) was 145.09 mg/g. With the presence of K2HPO4, H3BO3, Na2SiO3 and CH3COOH at 0.05-0.50 mmol/L, the efficiency of As(III) adsorption by C-NZVI was still as high as 99%. When the tested paddy soil was subject to flooding and subsequent application of NH4H2PO4, (NH4)2C2O4 and Na2SiO3, the cumulative level of soil soluble As (18.1 mg/kg) accounted for 30.0% of the total soil As concentration. Up to 91.3%-99.8% of the effluent As from submerged paddy soil could then be removed with C-NZVI, which reduced the total soil As level by 43.4%-52.6%. To further stabilize soil As in the labile pool, 1% and 5% C-NZVI was applied, and the non-specifically bound As was decreased remarkably by 94.7%-100%. The results highlighted that the combination of ex situ removal and in situ passivation of soil As with C-NZVI under flooding condition can provide a useful strategy for efficient remediation of As contamination in paddy soil.
Key words:  chitosan-stabilized nanoscale zero-valent iron  arsenite  antagonism  ex situ removal  in situ immobilization