The potential leaching and mobilization of trace elements from FGD-gypsum of a coal-fired power plant under water re-circulation conditions

Experimental and geochemical modelling studies were carried out to identify mineral and solid phases containing major, minor, and trace elements and the mechanism of the retention of these elements in Flue Gas Desulphurisation (FGD)-gypsum samples from a coal-fired power plant under filtered water recirculation to the scrubber and forced oxidation conditions. The role of the pH and related environmental factors on the mobility of Li, Ni, Zn, As, Se, Mo, and U from FGD-gypsums for a comprehensive assessment of element leaching behaviour were also carried out. Results show that the extraction rate of the studied elements generally increases with decreasing the pH value of the FGD-gypsum leachates. The increase of the mobility of elements such as U, Se, and As in the FGD-gypsum entails the modification of their aqueous speciation in the leachates; UO₂SO₄, H₂Se, and HAsO₂ are the aqueous complexes with the highest activities under acidic conditions. The speciation of Zn, Li, and Ni is not affected in spite of pH changes; these elements occur as free cations and associated to SO₄² in the FGD-gypsum leachates. The mobility of Cu and Mo decreases by decreasing the pH of the FGD-gypsum leachates, which might be associated to the precipitation of CuSe₂ and MoSe₂, respectively. Time-of-Flight mass spectrometry of the solid phase combined with geochemical modelling of the aqueous phase has proved useful in understanding the mobility and geochemical behaviour of elements and their partitioning into FGD-gypsum samples.     

The potential leaching and mobilization of trace elements from FGD-gypsum of a coal-fired power plant under water re-circulation conditions

Experimental and geochemical modelling studies were carried out to identify mineral and solid phases containing major, minor, and trace elements and the mechanism of the retention of these elements in Flue Gas Desulphurisation (FGD)-gypsum samples from a coal-fired power plant under filtered water recirculation to the scrubber and forced oxidation conditions. The role of the pH and related environmental factors on the mobility of Li, Ni, Zn, As, Se, Mo, and U from FGD-gypsums for a comprehensive assessment of element leaching behaviour were also carried out. Results show that the extraction rate of the studied elements generally increases with decreasing the pH value of the FGD-gypsum leachates. The increase of the mobility of elements such as U, Se, and As in the FGD-gypsum entails the modification of their aqueous speciation in the leachates; UO₂SO₄, H₂Se, and HAsO₂ are the aqueous complexes with the highest activities under acidic conditions. The speciation of Zn, Li, and Ni is not affected in spite of pH changes; these elements occur as free cations and associated to SO₄ ² in the FGD-gypsum leachates. The mobility of Cu and Mo decreases by decreasing the pH of the FGD-gypsum leachates, which might be associated to the precipitation of CuSe₂ and MoSe₂, respectively. Time-of-Flight mass spectrometry of the solid phase combined with geochemical modelling of the aqueous phase has proved useful in understanding the mobility and geochemical behaviour of elements and their partitioning into FGD-gypsum samples.     

过硫酸钾消解-离子色谱法测定地表水中总氮的研究

用国标方法HJ636-2012测定地表水中总氮的过程中,过硫酸钾和氢氧化钠在220 nm对吸光度有干扰.为了消除其影响,建立过硫酸钾消解-离子色谱法测定地表水中总氮的新方法.用碱性过硫酸钾消解,采用离子色谱法测定水中总氮的浓度.总氮校准曲线线性关系良好,线性相关系数r达0.999 0,相对标准偏差(RSD％)为0.67,加标回收率为94.8％～105％,方法检出限为0.01 mg/L.该方法的精密度和准确度都能满足需求,适用于地表水中总氮的测定.     

含硫气田采气污泥无害化处理技术研究

含硫气田在天然气开采、管道批处理、气田污水处理过程中,由于高压气流携带井底岩屑、单质硫析出、工艺添加的化学药剂反应产生沉淀物等因素,会产生一些成分复杂、有恶臭气味的固态物质,统称为采气污泥,影响生产安全和工艺参数调配,需要及时清理并无害化处置。结合固废减量化、无害化、资源化的处置原则,立足于企业自行处置的目的,本文就含硫气田采气污泥特性以及无害化处理的方法进行研究,对处理效果进行了分析,对废物综合利用进行了有益的尝试,为今后含硫气田污泥处理提供了一条可借鉴的思路。     

工业废气中异丁酸的测定

建立了用离子色谱法测定工业废气中异丁酸的新方法。废气中异丁酸经淋洗液吸收,0．45μm微孔滤膜过滤后离子色谱法分析,时间定性,峰高定量,其异丁酸回收率为93．5％～104．2％,消采样体积为20L的条件下,异丁酸最低检出质量浓度为0．02mg／m^3。     

石墨炉原子吸收光谱法测定土壤中痕量铋

建立了微波消解土壤、石墨炉原子吸收法测定土壤中痕量铋的方法。采用磷酸二氢铵作为基体改进剂,热解涂层石墨管,塞曼扣背景。此方法对测定土壤中铋的灵敏度、准确度都有很大的提高。方法的最低检出浓度为0.02μg/g,加标回收率为94.5%~103.8%,能够满足环境监测分析的要求。     

离子色谱法快速分析污水中的无机阴离子研究

采用Dionex ICS-900型离子色谱仪对污水中氟离子、氯离子、亚硝酸根离子、硝酸根离子、硫酸根离子等五种阴离子进行测定。在戴安公司提供的色谱条件的基础上,对其进行了修改和改进,实验对淋洗液组分、浓度和流速进行了筛选,使方法的分析效能大大提高,达到了快速分析的要求。按改进后的色谱条件,五种阴离子的分离度达到了3.06,测定结果的相对标准偏差均小于1.533%。并且,对有标准值的样品进行质量控制考核,结果表明各离子的测定结果均在考核范围之内。     

原子荧光光度法测定海水中硒的不确定度评定研究

通过实例对原子荧光法测定海水中硒的不确定度进行评定。根据(JJF 1059-1999)《测量不确定度评定与表示》中对测量和评定不确定度的要求评估了不确定度。测量不确定度的产生包括标准溶液的逐级稀释、工作曲线的非线性和原子荧光光度计的测量性能及取样体积。结果表明取样体积是导致该方法不确定度产生的主要影响因素,在测定时应加强这方面的控制,从而提高测量结果的准确性。当海水中硒的含量为1.99μg/L时,硒含量的扩展不确定度为0.40μg/L,置信水平为95%。     

气相色谱法测定环境空气中异丙醇研究

建立了用气相色谱法测定环境空气中异丙醇的方法。环境空气中异丙醇以蒸馏水吸收,用(DB-624)弹性石英毛细管柱分离,直接进样分析,氢火焰离子化检测器检测。本方法以时间定性,峰面积定量,对实际样品进行分析,其异丙醇加标回收率为94.9%~104.5%,当采样体积为40 L,异丙醇最低检出质量浓度为0.05mg/m3。本方法前处理简便,分离度好干扰少,分析灵敏度高,不使用有机试剂以减少环境污染,满足环境分析要求。     

超声波萃取-毛细管气相色谱法测定土壤和底质中的25种有机氯农药研究

建立了超声波萃取、Florisil柱净化,SPB-5毛细管柱分离,ECD检测器测定土壤和底质中25种有机氯农药的方法.该方法的检出限为0.079 μg/kg ～1.2 μg/kg,加标回收率为73.1％ ～ 126.5％,相对标准偏差为3.3％ ～9.7％.实验结果证明,该方法灵敏度高、精密度高,操作快速简便,满足土壤和底质中有机氯农药的测定要求.