Statistical validation of sulfate quantification methods used for analysis of acid mine drainage

Turbidimetric method (TM), ion chromatography (IC) and inductively coupled plasma atomic emission spectrometry (ICP-AES) with and without acid digestion have been compared and validated for the determination of sulfate in mining wastewater. Analytical methods were chosen to compare the performance of a portable field turbidimetric instrument and to validate the underlying assumption utilized in conversion of total sulfur to sulfate during ICP-AES analysis. Accuracy and precision of analytical techniques were compared to one another using control and field samples collected from a mine site using the Bonferroni multiple comparison test. Effects of sample dilution, filter pore size and acidification on sulfate quantification were also studied. The results showed that IC and ICP-AES with and without acid digestion provided excellent recoveries in the case of control samples (within 90-110%). These analytical methods also showed lower relative standard deviation for both control and field samples. On the other hand, performance of the turbidimetric method was severely affected by sample dilution and acidification, and also revealed poor sulfate recoveries for control samples ranging from 0 to 83.5%. Analysis of variance (ANOVA) was used to evaluate the response (sulfate concentration) obtained from factorial design. Analytical method had significant effect (P < 0.0001) on the sulfate quantification. The interaction between determination method and sample dilution was more significant than other two-way interactions.     

Oxygen dependent oxidation of trimethoprim by sulfate radical: Kinetic and mechanistic investigations

Trimethoprim (TMP) is a typical antibiotic to treat infectious disease, which is among the most commonly detected antibacterial agents in natural waters and municipal wastewaters. In the present study, the impacts of dissolved oxygen (DO) on the oxidation efficiency and pathways of TMP by reaction with sulfate radicals (SO₄⁻) were investigated. Our results revealed that the presence of DO was favourable for TMP degradation. Specifically, TMP would react initially with SO₄⁻ via electron-transfer process to form a carbon-centered radical. In the absence of oxygen, the carbon-centered radical could undergo hydrolysis to produce α-hydroxytrimethoprim (TMP−OH), followed by the further oxidation which generated α-ketotrimethoprim (TMP=O). However, in the presence of oxygen, the carbon-centered radical would alternatively combine with oxygen, leading to a sequential reaction in which peroxyl radical and a tetroxide were formed, and finally generated TMP−OH and TMP=O simultaneously. The proposed pathways were further confirmed by density functional theory (DFT) calculations. The results obtained in this study would emphasize the significance of DO on the oxidation of organic micro-pollutants by SO₄⁻.     

水中硫酸根及其总硬度的EDTA滴定法——采用计滴微型毛细管滴定管

用EDTA微量滴定法测定了水中硫酸根及总硬度，测定过程在氨性缓冲介质中进行，采用络黑T作指示剂，用一种自制的聚乙烯微型毛细管滴定管进行滴定，滴定反应所耗的滴定剂用计滴法计数。从微滴管流出的每一小滴滴定剂的体积（通常在0．01～0．02mL之间）用重量法校正，每次滴定所耗滴定剂一般在50～200小滴之间。此方法的扩展不确定度，对硫酸根测定为0．94％与重量法相当，而精密度则优于重量法，对总硬度测定为0．82％优于常量滴定法。此方法的特点为分析快速、准确，消耗试剂少且便于携带，适合于现场或野外分析应用。     

再生水环境中304不锈钢生物膜腐蚀电化学特征

研究了以再生水作为循环冷却系统补水的北京某热电厂冷却塔底粘泥中分离纯化培养出来的硫酸盐还原菌(SRB)生长特性.采用原子力显微镜(AFM)、扫描电镜(SEM)、能谱分析仪(EDS)和电化学交流阻抗(EIS)方法研究了304不锈钢(SS304)表面生物膜特征及其主要成分和不锈钢/生物膜界面电化学行为.结果显示,再生水环境下304不锈钢表面形成的生物膜是由吸附的SRB菌体及以含碳有机物为主的胞外聚合物和FeS腐蚀产物构成.浸泡前期(前7 d)SS304电极表面阻抗值主要由SS304表面钝化膜的贡献;浸泡后期(14 d后),电极体系阻抗值由不锈钢表面钝化膜和生物膜共同贡献.     

Unusual cytotoxic sulfated cadinene-type sesquiterpene glycosides from cottonseed (Gossypium hirsutum)

Two new sulfated cadinene-type sesquiterpene glycosides, 13-hydroxy-7-O-(6′-O-sulfate-β-d-glucopyranosyl)-desoxyhemigossypol (1) and 13,15-dihydroxy-7-O-(6′-O-sulfate-β-d-glucopyranosyl)-desoxyhemigossypol (2), have been isolated from whole cottonseed (Gossypium hirsutum). Their structures, which possess an unusual 6-O-sulfate-glucopyranosyl moiety, were determined through the interpretation of 2D NMR spectral data and H/D exchange ESI-MS experiments. Compounds 1 and 2 were screened for their toxicity on Jurkat cells. Both compounds inhibited cellular proliferation with IC₅₀ values of 8.1 and 4.2 μg, respectively.     

Use of factorial experimental design for the rapid evaluation of main and interactive factors affecting linearity in calibration curves for sulfate analysis by ion chromatography

Analytical results of anion determination by suppressed ion chromatography are significantly affected by calibration curve calculation. In this paper, as expected, eluent pK_a is shown to influence calibration linearity in the range 1–20 mg/l sulfate, with A carbonate-hydrogencarbonate mixture producing a larger non-linearity than NaOH. Evidence is given for very large errors (about 30–40%) in estimating sample sulfate concentration when linear regression is used instead of a quadratic calibration curve. This study was performed following a 2⁴ run full factorial experimental design, including eluent pK_a, counterion type, solution composition and current level for background suppression as main variables.     

Die Kristallstruktur von Dikalium-trikobalt(II)-dihydroxid-trisulfat-dihydrat,K2Co3(OH)2(SO4)3·2H2O

Crystals of K₂Co₃(OH)₂(SO₄)₃·2H₂O were synthesized under hydrothermal conditions. The crystal structure [a=17.945 (4) Å,b=7.557 (2) Å,c=9.760 (3) Å, space group Cmc2₁,Z=4] was determined by direct methods and refined with single crystal X-ray data. The H atoms were located byFourier syntheses. Their structural parameters were refined, too. The finalR-values areR=0.025 andR _w =0.028 (w=1/) for 612 reflections withF ₀>3 (F ₀). Both Co(II) atoms are octahedral six coordinated and form zigzag chains running parallel [001]. These chains are connected via sulfate groups to built up sheets parallel (100). The KO₉ polyhedron and one of the four hydrogen bonds link these sheets.

     

还原浊度法测定溴化锂－铬酸锂混合液中的硫酸根

还原浊度法测定溴化锂－铬酸锂混合液中的硫酸根谢家理，冯易君，王劲榕（四川大学化学系成都６１００６４）关键词硫酸根，溴化锂，铬酸锂，比浊法由于溴化锂致冷剂不污染环境将得到推广应用，以取代氟里昂。因此控制微量杂质硫酸根的测定是必要的。若用离子色谱法测定，...