A pyrazine based metal-organic framework for selective removal of copper from strongly acidic solutions

● pz-UiO-66 was synthesized facilely by a solvothermal method. ● Efficient capture of copper from highly acidic solution was achieved by pz-UiO-66. ● pz-UiO-66 exhibited excellent selectivity and capacity for copper capture. ● Pyrazine-N in pz-UiO-66 was shown to be the dominant adsorption site. The selective capture of copper from strongly acidic solutions is of vital importance from the perspective of sustainable development and environmental protection. Metal organic frameworks (MOFs) have attracted the interest of many scholars for adsorption due to their fascinating physicochemical characteristics, including adjustable structure, strong stability and porosity. Herein, pz-UiO-66 containing a pyrazine structure is successfully synthesized for the efficient separation of copper from strongly acidic conditions. Selective copper removal at low pH values is accomplished by using this material that is not available in previously reported metal–organic frameworks. Furthermore, the material exhibits excellent adsorption capacity, with a theoretical maximum copper uptake of 247 mg/g. As proven by XPS and FT-IR analysis, the coordination of pyrazine nitrogen atoms with copper ions is the dominant adsorption mechanism of copper by pz-UiO-66. This work provides an opportunity for efficient and selective copper removal under strongly acidic conditions, and promises extensive application prospects for the removal of copper in the treatment for acid metallurgical wastewater.     

Cu/Cr co-stabilization mechanisms in a simulated Al2O3-Fe2O3-Cr2O3-CuO waste system

• Cu and Cr can be mostly incorporated into CuFe_xAl_yCr_2−x−yO₄ with a spinel structure. • Spinel phase is the most crucial structure for Cu and Cr co-stabilization. • Compared to Al, Fe and Cr are easier to be incorporated into the spinel structure. • ‘Waste-to-resource’ by thermal process at attainable temperatures can be achieved. Chromium slag usually contains various heavy metals, making its safe treatment difficult. Glass-ceramic sintering has been applied to resolve this issue and emerged as an effective method for metal immobilization by incorporating heavy metals into stable crystal structures. Currently, there is limited knowledge about the reaction pathways adopted by multiple heavy metals and the co-stabilization functions of the crystal structure. To study the Cu/Cr co-stabilization mechanisms during thermal treatment, a simulated system was prepared using a mixture with a molar ratio of Al₂O₃:Fe₂O₃:Cr₂O₃:CuO= 1:1:1:3. The samples were sintered at temperatures 600–1300°C followed by intensive analysis of phase constitutions and microstructure development. A spinel phase (CuFe_xAl_yCr_2−x−yO₄) started to generate at 700°C and the incorporation of Cu/Cr into the spinel largely complete at 900°C, although the spinel peak intensity continued increasing slightly at temperatures above 900°C. Fe₂O₃/Cr₂O₃ was more easily incorporated into the spinel at lower temperatures, while more Al₂O₃ was gradually incorporated into the spinel at higher temperatures. Additionally, sintered sample microstructures became more condensed and smoother with increased sintering temperature. Cu / Cr leachability substantially decreased after Cu/Cr incorporation into the spinel phase at elevated temperatures. At 600°C, the leached ratios for Cu and Cr were 6.28% and 0.65%, respectively. When sintering temperature was increased to 1300°C, the leached ratios for all metal components in the system were below 0.2%. This study proposes a sustainable method for managing Cu/Cr co-exist slag at reasonable temperatures.     

Effect Of pH on the complexation of U(II) with organic matter dissolved in resh waters

In the present work we study the effect of pH on the complexation of copper with organic matter dissolved in fresh surface waters. Samples collected in rivers of Galicia (NW of Spain) were titrated with copper solution at pH values in the range 5.5–7.5. Copper concentration was measured by DPASV technique. The complexation parameters were obtained from the simple model of 1 : 1 complex formation. The obtained values show a linear increase of the logarithm of the conditional stability constant as the pH increases.     

Potentiometric studies of mixed complexes of cobalt(II) and copper(II) with l‐Asparagine and adenine

A potentiometric titration technique has been used to determine the stability constants for the various complexes of Co(II) and Cu(II) with L‐asparagine and from DNA base, e.g. adenine. Stability constants of ternary systems have been evaluated by the method suggested by Irwing‐Rossotti. In addition, the conditional constants were calculated as a function of pH. The maximum values of the conditional formation constants were found to be in accordance with the mixed‐ligand complex formation constants in a determined pH region. Furthermore, the molar fractions of different species from mixed complexes were calculated by means of formation constants. The values of stability constants of mixed‐ligand complexes at 25°C are as follows: log K= 5.25 for Co(II)‐L‐asparagine‐adenine; log K= 9.30 for Cu(II)‐L‐asparagine‐adenine. The ionic strength was kept constant at I = 0.20 with NaClO₄.     

Relationships Between Copper Species and Forms,Hydrographic and Biomass Parameters in the Taiwan Erhjin Chi Coastal Area

The first incident of green oysters (Crassostrea gigas) was reported in Taiwan in the Charting coastal area in January, 1986 and mortality was reported three months later. the cause of the greened oysters was identified as copper pollution. the copper content of the green oysters was extremely high - 2100 ppm, 2225 ppm, and 4400 ppm dry weight, in January, 1986, February 1987, and January 1989, respectively. in this paper we summarize the seasonal and regional distributions of copper species (complexed by inorganic and organic ligands, labile and non-labile, polar and non-polar) and forms (dissolved and particulate) and the hydrographic and biomass parameters (mainly particulate organic carbon, chloropyll -α, adenosine triphosphate and primary production) in sea water in the Erhjin Chi coastal area. in general, high concentrations of particulate material (0.24 to 724 ppb) and non-labile organic copper (0.03 to 21.5 ppb) were observed. Low values of polar organic copper (<0.02 to 16.5 ppb) indicated that non-polar organic complexes (0.3 to 20.4 ppb) from man-made organic pollutants were the major complexes in the area studied. On the basis of this data, the cause of greening and mortality in oysters is evaluated in relation to the bioavailable copper (sum of particulate and labile copper) and copper assimilative capacity (detoxicant). Finally, the correlations between the species and forms of copper, hydrographic and biomass parameters are also discussed.     

铜和镉对蝌蚪的联合毒性研究

研究了铜和镉对蝌蚪的急性毒性和联合毒性，结果表明，Cu^2 对蝌蚪的24h，48h、96h和LC50分别为0.201,0.138和0.118mg/L；Cd^2 对蝌蚪的24h，48h和96h的LC50分别为32.1、23.3和18.9mg/L,Cu^2 和Cd^2 共存对蝌蚪的24h,48h和96h联合毒性相加指数（AI）分别为1.03、1.12和1.20。     

落叶中DOM和NDOM对紫色土中Cu迁移的影响

以黄葛榕落叶中可溶性有机质(DOM)和不可溶性有机质(NDOM)为研究对象,分析用DOM、NDOM和DOM+NDOM改良碱性(Al-P)、中性(Ne-P)和酸性紫色土(Ac-P)后,土中Cu的形态变化。结果表明：随着老化时间的增加,各改良紫色土中离子交换态Cu含量均明显降低,碳酸盐结合态Cu含量基本保持不变,铁锰氧化物结合态和有机结合态Cu含量均逐渐增加。老化后,供试改良紫色土中Cu表现为有机结合态≈铁锰氧化物结合态＞碳酸盐结合态＞离子交换态的趋势,Cu迁移能力整体降低,降低幅度为44.22%~68.99%。     

原子吸收法测定铜检出限的测量不确定度评估

对原子吸收法测定铜检出限的测量不确定度进行分析探讨,建立了不确定度的评估方法。影响铜检出限测量不确定度的主要因素包括标准溶液不确定度;拟合曲线不确定度;检测仪器不确定度;吸光值量化误差不确定度等,提供了上述各因素的计算方法及过程。     

预浓缩与GC-MS联用分析垃圾填埋场恶臭气体

采用预浓缩与气相色谱-质谱联用,建立了垃圾填埋场几种恶臭气体的分析方法。该法用SUMMA罐采集垃圾填埋场臭气,经预浓缩系统冷凝浓缩后,用GC-MS分析测定。几种臭气的检出限均低于3.0×10-3mg/m3,经6次重复测定,其相对标准偏差低于10%。该法已用于西安市江村沟垃圾填埋场臭气的采样分析。该法的应用增强了西安市对臭气的监测分析能力。     

环境空气中VOC_S在线监测法与SUMMA罐采样气相色谱-质谱法比对研究

定性比较了环境空气VOCs在线监测法和SUMMA罐采样GC-MS法的基本原理、检测化合物种类和适用范围,并对标样实验、日均浓度、小时浓度从统计学角度进行了定量比对.研究表明,VOCs在线监测法监测结果与实验室方法有较好可比性,可用于相关领域VOCs的连续监控.