石墨炉原子吸收光谱法测定海水中痕量铅

研究了APDC-DDTC/CCI4体系石墨炉原子吸收法测定海水中痕量Pb.在最佳务件测定海水中痕量铅与标准方法有良好的相关性(R=0.9969),统计检验表明,置信度为95%时,两方法之间没有显著差异.本法RSD%=1.1,精密度略优于标准方法,操作简便,节省时间.应用于海水中铅的分析,取得了令人满意的结果.     

X射线荧光光谱法测定土壤样品中铅的不确定度评定

用实例对X射线荧光光谱法测定土壤样品中铅的不确定度进行了评定.测量结果的不确定度由仪器综合稳定性、制样、标准物质、回归工作曲线、重复测量等所引入的不确定度分量组成.在对各个不确定度分量进行量化的基础上,通过合成得到测量结果的标准不确定度,再乘以95%置信概率下的扩展因子2,得到测量结果的扩展不确定度.     

从废弃镍氢电池负极板中回收稀土金属

通过废弃镍氢电池负极板在稀硫酸中的浸出实验,考察了稀硫酸浓度、稀硫酸体积与废弃镍氢电池负极板质量比（液固比）、浸出时间、搅拌转速等因素对稀土金属（RE）浸出率的影响。通过正交实验确定的最佳浸出条件：稀硫酸浓度为2．5mol／L,液固比为10,浸出时间为60min,搅拌转速为800r／min。在此条件下,RE浸出率为92．50％。基于RE的硫酸盐和无水硫酸钠生成RE复盐沉淀的原理,向稀硫酸浸出废弃镍氢电池负极板后得到的硫酸盐溶液中加入无水硫酸钠,得到RE复盐沉淀,通过正交实验确定的最佳沉淀条件为：溶液pH为2．0,无水硫酸钠与浸出液中RE^3＋的摩尔比为4,反应温度为60℃。在此条件下,RE回收率为94．6％。用X射线衍射仪对RE复盐进行了表征。     

Lead immobilization in mechanochemical fly ash recycling

In previous studies, we focused on a mechanochemical process for recycling fly ash for use in cement; this process was expected to immobilize heavy metals in the fly ash, a desirable outcome in light of the fact that recycled fly ash is commonly used in the synthesis of inorganic materials. Here, we investigated the leaching of lead (Pb) from fly ash treated by a mechanochemical process and from cement prepared from the treated fly ash. We used lead oxide (PbO), a typical Pb compound in fly ash, as a model substance. Mechanochemical treatment of the fly ash inhibited Pb leaching by 93%, and further inhibition (more than 99.9%) was observed in cement produced from the treated fly ash. During the mechanochemical treatment, PbO was reduced to Pb by iron from the stainless-steel mill used for processing, and the lower solubility of Pb in water resulted in immobilization of the Pb.     

Kinetic research on the sorption of aqueous lead by synthetic carbonate hydroxyapatite

The sorption of aqueous lead on carbonate-hydroxyapatite (CHAp) is a complicated non-homogeneous solid/water reaction, which from the kinetic point of view has two stages. In the first stage, the reaction rate is so fast and the kinetic pathway so intricate that further research is required. In the second stage, the reaction rate slows down and the reaction process follows that of a first-order kinetic equation. Experimental results show that the relationship between the reaction rate constant k(1) and temperature T agrees with the Arrhenius equation, and that the activation energy of sorption (E(a)) is 11.93 kJ/mol and the frequency factor (A) is 2.51/s. The reaction rate constant k(1) increases with the Pb(2+) initial concentration and decreasing pH, but with increasing CHAp dosage. X-ray diffraction (XRD), scanning electron microscopy with energy dispersion spectrum (SEM-EDS) and toxicity characteristic leaching procedure (TCLP) tests indicate that the main sorption mechanism is dissolution-precipitation, in conjunction with surface sorption.     

Leachability of printed wire boards containing leaded and lead-free solder

Due to environmental concerns and regulatory initiatives, electronics manufacturers are replacing the tin/lead solder commonly used on printed wire boards (PWBs) with alternative solders. To determine the potential waste management impacts of the alternative solders versus the tin/lead solder, two leaching tests on PWBs manufactured with five alternative types of solder were performed: the toxicity characteristic leaching procedure (TCLP) and the synthetic precipitation leaching procedure (SPLP). These tests are commonly used in the US regulatory community to assess pollutant leachability in different disposal scenarios. The article discusses the application and limitations of these tests. The five types of solders investigated were 63Sn/37Pb, 99.3Sn/0.7Cu, 95.5Sn/4Ag/0.5 Cu, 96Sn/2.5Ag/1Bi/0.5Cu, and 42Sn/1Ag/57Bi. The leaching tests were conducted on four PWB sections, each with a unique configuration and solder density. The largest lead concentrations were observed from the PWBs containing Sn/Pb solder, with concentrations exceeding the hazardous waste toxicity characteristic (TC) in TCLP leachates. Silver, the other regulated element used in the solders, was rarely detected, with none of the samples exceeding the TC limit for silver. High copper concentrations were observed and were determined to result from the PWB itself, not from the copper-containing solders.     

微波消解ICP-AES法测定废气中铅镉砷

采用微波消解电感耦合等离子体发射光谱法同时测定废气中的铅、镉、砷,在优化的试验条件下,方法在0 mg/L～5.00 mg/L范围内线性良好,铅、镉、砷的检出限分别为0.250 μg/m3、0.125 μg/m3、0.375 μg/m3(按采样体积400 L、定容体积50 mL计),空白滤筒平行测定6次的RSD为2.3％～10.5％,加标回收率为83％ ～ 112％,与标准方法的测定结果无显著差异.     

铅冶炼企业周边大气降尘中铅、镉、砷量及其对土壤的影响

通过在2012年5月-2013年4月1个周期年内,对修复基地和对照点每月大气降尘中铅、镉、砷沉降量的监测,结果表明：修复基地大气降尘中铅、镉、砷含量明显较对照点高,年总沉降量分别是对照点的17．6倍、16．3倍和14．1倍,表明铅冶炼企业对基地大气降尘中铅、镉、砷含量影响显著;大气降尘中铅、镉、砷沉降量受位置和时间影响较大,在相距不到100 m的测点间,沉降量相差1倍以上,冬季主导风明显、地面植被少、二次扬尘大,使处于铅冶炼企业下风向的基地降尘中铅、镉、砷沉降量较大。沉降量时空不均匀与土壤污染不均匀现状一致,也验证了铅冶炼企业是基地大气和土壤重金属污染的主要来源。以降尘缸模拟土壤进行测算,结果表明大气降尘中镉对土壤污染速度最快,风险最大。     

废锂电池放电及正极片分离回收处理

研究了废锂电池放电及正极片分离回收处理工艺。实验结果表明:经质量浓度30 g/L NaCl溶液浸泡9.0 h可实现电池放电,残余电压在0.5 V以下;在60℃恒温水浴振荡、NaOH质量浓度40 g/L、废锂电池质量与NaOH溶液体积的比为15 g/L的优化条件下,集流体完全与活性物质分离,回收得到的黑色粉末为LiCoO2活性材料,未见铝杂质的特征峰;通过硫酸中和的方法回收碱浸溶液中的铝,当体系pH为10.0时,可获得最大量的Al(OH)3沉淀,沉淀物颗粒表面光滑,粒径大小不一。     

Algae (Raphidocelis subcapitata) mitigate combined toxicity of microplastic and lead on Ceriodaphnia dubia

• Micro-plastics (MPs) significantly increase Pb toxicity. • Algae reduce the combined toxicity of MP and Pb. • The toxicity increase comes from high soluble Pb and MP-Pb uptake. • The toxicity reduction might come from energy related pathway. Microplastics (MPs) have been recognized as a new class of emerging contaminants in recent years. They not only directly impact aquatic organisms, but also indirectly impact these organisms by interacting with background toxins in the environment. Moreover, under realistic environmental conditions, algae, a natural food for aquatic organisms, may alter the toxicity pattern related to MPs. In this research, we first examined the toxicity of MPs alone, and their effect on the toxicity of lead (Pb) on Ceriodaphnia dubia (C. dubia), a model aquatic organism for toxicity survey. Then, we investigated the effect of algae on the combined toxicity of MPs and Pb. We observed that, MPs significantly increased Pb toxicity, which was related to the increase in soluble Pb concentration and the intake of Pb-loaded MPs, both of which increased the accumulation of Pb in C. dubia. The presence of algae mitigated the combined toxicity of MPs and Pb, although algae alone increased Pb accumulation. Therefore, the toxicity mitigation through algae uptake came from mechanisms other than Pb accumulation, which will need further investigation.