A 1-dodecanethiol-based phase transfer protocol for the highly efficient extraction of noble metal ions from aqueous phase

A 1-dodecanethiol-based phase-transfer protocol is developed for the extraction of noble metal ions from aqueous solution to a hydrocarbon phase, which calls for first mixing the aqueous metal ion solution with an ethanolic solution of 1-dodecanethiol, and then extracting the coordination compounds formed between noble metal ions and 1-dodecanethiol into a non-polar organic solvent. A number of characterization techniques, including inductively coupled plasma atomic emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis demonstrate that this protocol could be applied to extract a wide variety of noble metal ions from water to dichloromethane with an efficiency of > 96%, and has high selectivity for the separation of the noble metal ions from other transition metals. It is therefore an attractive alternative for the extraction of noble metals from water, soil, or waste printed circuit boards.     

Rose Bengal‐sensitized photooxygenation of chlorohydroxyaromatic contaminants in water: A kinetic study

A kinetic study of the RB‐sensitized photooxygenation of a series of chlorohydroxyaromatic (ClArOH) water contaminants (phenolic and dihydroxybenzene derivatives) has been carried out. In addition, an exhaustive study on the possible interactions of RB electronically excited triplet and singlet states with ClArOH was also developed. The determination of relative rates of oxygen uptake upon sensitized irradiation, employing auxiliar selective quenchers of oxygen active species, indicate the contribution of both singlet molecular oxygen (ca. 71%) and Superoxide ion (ca. 26%) as the reactive pathways for ClArOH degradation. The substitution by chlorine atoms in position meta greatly decrease the photooxygenation rate of the phenolic derivatives. For the dihydroxybenzene series, increase in nuclear chlorination parallels a decrease in the photodegradation rate.

Outdoors sensitized solar irradiation experiments on different ClArOH mixtures leads to measurable levels of oxygen after a few minutes exposure. From the environmental point of view, and ruling out the possibility of direct‐irradiation photoreactions, sensitized photooxygenation appears as an alternative pathway for ClArOH degradation, in competence with other naturally‐occurring photoprocesses involving reactive transient species.     

离子色谱法测定地表水中氟化物的方法探讨

探讨了离子色谱法测定地表水中氟化物的影响因素：水质样品的采集保存；水质样品所含成份；实验用水、试剂纯度、实验器皿的影响；使用离子色谱仪测定过程中对氟化物的影响。认为应切实采取措施，消除干扰。     

Instrument tuning for trace analysis of dioxins and furans for the vg 70s/se gas chromatography/mass spectrometry system using electron impact mode

We present the salient characteristics of tuning procedures that have evolved from our 3 years of experience while producing large amounts of data of the highest quality. Our laboratory routinely analyzes 2,3,7,8‐substituted dioxins and furans at parts per quadrillion levels in 50–100 g of human serum samples using the VG 70S/SE stand‐alone gas chromatography/mass spectrometry (GC/MS) system at 10000 resolution (defined by 5% overlap) in the selected ion recording mode. Trace measurement of dioxins and furans in human biological matrices—for example, whole blood, serum, or adipose tissue‐requires reproducible instrument tuning within day as well as among days for quality results. Additionally, instument‐tuning procedures among operators must be reproducible to minimize operator bias because periodically different operators are used. Instrument tuning is highly subjective and argumentive; therefore, to minimize the ambiguity within our laboratory, we have standardized our technique to reproducibly tune the GC/MS system.     

Adsorption of rhodium(III) from plating solutions by calcined gibbsite

Gibbsite calcined at 400°C (GB400) was prepared, and its ability to adsorb rhodium(III) was investigated. Optimal pH, effect of contact time, temperature, adsorption isotherms, and recovery percentage were evaluated. The optimal pH was 6.3. The adsorption equilibrium was achieved within 24 h. The adsorption rate was found to be of pseudo-first order. The experimental data were fitted to both the Freundlich (r = 0.90–0.93) and Langmuir (r = 0.94–0.96) equations. The amount of rhodium(III) adsorbed decreased with increasing temperature. Rhodium(III) being adsorbed from phosphate or sulfate plating solution was recovered using hydrochloric acid and sodium hydroxide solutions at 1, 10, and 100 mmol L^?1.     

北京市典型区域降水特性及其对细颗粒物影响

通过采集北京市典型区域2016年12月~2017年11月期间大气降水样品,实时监测降水前、期间和后大气非难熔亚微米颗粒物NR-PM₁及其组分浓度,研究了降水的理化特性、典型降水过程离子组分变化特征、以及对大气非难熔亚微米颗粒物NR-PM₁及其组分的影响,同时采用后向轨迹聚类分析法研究了气团长距离传输对降水组分的影响.结果表明,2017年北京市典型区域降水主要集中在夏季,约占总降水量的82.2%,降水主要呈中性或碱性,酸雨发生率很低.降水pH值表现为冬季 > 春季 > 夏季~秋季的季节变化特征.降水中总离子浓度、总阴、阳离子浓度均表现为春季 > 夏季 > 冬季 > 秋季,且呈污染日显著高于清洁日的变化特征.降水中主要水溶性离子年均浓度表现为NH₄⁺ > Ca²⁺ > NO₃^- > SO₄^2- > Na⁺ > Cl^- > Mg²⁺ > F^- > K⁺,其中NH₄⁺、Ca²⁺、NO₃^-和SO₄^2-是降水中最主要的离子组分,占总离子浓度的80%以上,各离子浓度均呈污染日高于清洁日的变化特征.降水期间不同时段,降水中各离子浓度大多表现为：降水初期最高,降水中期显著低于降水初期,降水后期均略有增加.降雨量和降雨速率较小的降水对污染日大气NR-PM₁及其组分的清除作用较强,而降雨量和降雨速率较大的降水对清洁日NR-PM₁及其组分的清除作用较小.值得关注的是在降水不同时段,始终存在2个重要的过程,即污染物的累积和二次污染物的形成过程,以及降水的云下冲刷和云内雨除过程.研究期间,降水主要受到东南和西南方向气团影响,分别约占总降水的60%和23%,且主要发生在夏季,这些气团对降水中离子组分都有不同程度的影响.     

碳纳米管/羟基磷灰石复合材料对水体F-的去除研究

以碳纳米管（CNT）和羟基磷灰石（HAP）为原料,通过原位合成法制备碳纳米管/羟基磷灰石（CdH）复合材料.利用XRD、FTIR、SEM与氮气吸附-脱附等表征其结构形貌,并通过静态吸附实验考察CdH对氟离子（F^-）的吸附性能.结果表明,室温下,CdH对F^-的吸附容量为11.05mg/g,明显高于HAP（5.02mg/g）.吸附动力学模型、Weber-Morris方程、Langmuir和Freundlich方程拟合结果表明,F^-在CdH表面进行Langmuir单分子层吸附,其吸附过程符合准二级动力学方程,并且颗粒内部扩散起主要作用.pH值为6时有利于CdH对F^-的去除.此外,结合反应前后固样XPS分析可知CdH对F^-的吸附机制主要为离子交换作用.     

稀土元素对38CrMoAl钢离子渗氮工艺的影响

目的缩短38CrMoAl钢离子渗氮工艺周期。方法在离子渗氮过程中,添加稀土金属镧(La)及稀土镧铈合金(La-Ce)。通过显微硬度仪、光学金相显微镜、扫描电镜及能谱分析仪对于离子氮化层的表面硬度、脆性、微观显微组织、稀土元素含量进行检测分析,并和常规离子渗氮工艺进行对比研究。结果在离子渗氮工艺过程中,添加稀土金属镧(La)及镧铈合金(La-Ce)后,氮化层表面硬度提高约130～200 HV,渗氮速度提高了15%～30%,氮化周期显著缩短。稀土催渗离子渗氮层的脆性均为Ⅰ级,比常规离子渗氮更优异。同时,稀土元素的渗入细化了晶粒,使得渗层氮化物组织致密、呈弥散分布,优化了氮化层的相结构组成。结论稀土元素的加入可以有效提高渗氮层的表面硬度和脆性等级,改善了氮化层性能。同时缩短了离子渗氮工艺周期。     

超低排放燃煤电厂颗粒物脱除特性

在京津冀某660 MW超低排放发电机组,通过低压撞击器(DLPI)颗粒物取样系统对选择性催化还原装置(SCR)、低低温省煤器(LLTe)、静电除尘器(ESP)、高效湿法脱硫塔(WFGD)、湿式静电除尘器(WESP)进出口烟气中的颗粒物取样,通过滤膜取样系统对WFGD、WESP进出口颗粒物进行同步取样.获得了超低排放改造后,不同烟气处理设备对PM1、PM1~2.5、PM_(2.5~10)的脱除效率.结果表明,SCR能够明显增加PM1的质量浓度,PM1增加了52.11%;LLTe能够显著提高ESP的脱除效率,尤其是0.1~1μm范围内的颗粒物;WFGD能够协同脱除SO_2和颗粒物,但会增加PM1的排放,PM1质量浓度增加了59.41%,PM10中水溶性Mg2+、Cl-、SO2-4组分增加;WESP对PM1、PM1~2.5、PM_(2.5~10)均有较高的脱除效率,能够进一步降低颗粒物质量浓度.超低排放技术路线下,该燃煤电厂最终排放的PM10质量浓度为2.04 mg·m~(-3).     

黄石市大气PM2.5中水溶性离子浓度特征及来源分析

为研究黄石市大气PM_2.5中水溶性离子组成、质量浓度变化特征及来源,于2012年3月-2013年2月在湖北省黄石市利用MiniVol颗粒物采样器采集PM_2.5样品,用离子色谱分析了9种水溶性离子（NH₄+、Ca2+、Mg2+、Na+、K+、Cl-、NO₃-、SO₄2-、F-）的质量浓度,并采用PMF（正定矩阵因子分析法）模型讨论了不同离子的来源.结果表明:观测期间黄石市大气PM_2.5中ρ（总水溶性离子）的年均值为（61.5±26.8）μg/m3,占ρ（PM_2.5）的63.9%,各离子质量浓度的高低顺序依次为ρ（SO₄2-）> ρ（NO₃-）> ρ（NH₄+）> ρ（Na+）> ρ（Cl-）> ρ（Ca2+）> ρ（K+）> ρ（F-）> ρ（Mg2+）.二次无机离子SNA（为SO₄2-、NO₃-和NH₄+的统称）是水溶性离子的主要成分,占全部所测水溶性离子的74.4%.ρ（NO₃-）/ρ（SO₄2-）范围为0.12~1.29,平均值为0.53±0.30,说明全年观测点附近主要以固定源污染为主.4个季节的SOR（硫氧化率）和NOR（氮氧化率）均大于0.10,说明黄石市PM_2.5中的SO₄2-和NO₃-主要是经二次转化形成的.阴、阳离子相关性研究发现,4个季节阴、阳离子总体相关性（R2为0.98）较好,并且全年PM_2.5组分偏酸性.通过PMF模型源解析发现,黄石市大气PM_2.5中水溶性离子主要来源于燃烧源、二次转化源和土壤/矿物扬尘源.研究显示,黄石市大气PM_2.5中主要水溶性离子成分是SNA,燃烧、二次转化和土壤/矿物扬尘是其主要来源.