Determination of rare earth elements and other trace elements (Y, Mn, Co, Cr) in seawater using Tm addition and Mg(OH)₂ co-precipitation

This paper reports on a novel procedure for determining trace element abundances (REE and Y, Cr, Mn, Co) in seawater by inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The procedure uses a combination of pre-concentration using co-precipitation onto magnesium hydroxides and addition of thulium spike. The validity of the method was assessed onto 25 ml volumes of certified reference materials (NASS- and CASS-4) and in house seawater standard. Procedural blanks were determined by applying the same procedure to aliquots of seawater previously depleted in trace elements by successive Mg(OH)₂ co-precipitations, yielding estimated contributions to the studied samples better than 1.1% for all elements, with the exception of Cr (<3.3%) and Co (up to 8%). The reproducibility of the method over the six month duration of the study was smaller than 11% RSD for all the studied elements. Results obtained for NASS-5 and CASS-4 agree well with published working values for trace elements.     

Improve the catalytic activity of α-Fe2O3 particles in decomposition of ammonium perchlorate by coating amorphous carbon on their surface

Sphere- and pod-like α-Fe₂O₃ particles have been selectively synthesized using NH₃·H₂O and NaOH solution to adjust the pH value of the designed synthetic system, respectively. The sphere-like α-Fe₂O₃ particles with diameter about 25 nm on average were encapsulated into carbon shells to fabricate a novel core-shell composite (α-Fe₂O₃@C) through the coating experiments. The catalytic performance of the products on the thermal decomposition of ammonium perchlorate (AP) was investigated by thermal gravimetric analyzer (TG) and differential thermal analysis (DTA). The thermal decomposition temperatures of AP in the presence of pod-like α-Fe₂O₃, sphere-like α-Fe₂O₃ and α-Fe₂O₃@C are reduced by 72, 81 and 109 °C, respectively, which show that α-Fe₂O₃@C core-shell composites have higher catalytic activity than that of α-Fe₂O₃.     

高氯酸锂甲醇溶液中离子溶剂化和离子缔合现象

通过红外光谱技术探讨了高氯酸锂甲醇溶液中离子与溶剂、离子与离子之间的相互作用。红外光谱分析结果表明:锂离子与溶剂发生了相互作用导致甲醇分子的O-H伸缩振动区蓝移,ClO4-的特征谱带的变化表明了溶液中存在离子缔合。根据密度泛函理论,对不同溶剂化数的配合物结构和两种离子对形式进行优化及热力学性质的计算。     

全自动SPE联合离子色谱质谱法测定化工产业园区周边地表径流中氟乙酸、碘乙酸、羟基乙酸、溴酸盐和高氯酸盐微量残留

目的 实验开发了全自动SPE联合离子色谱质谱法测定化工产业园区周边地表径流中氟乙酸、碘乙酸、羟基乙酸、溴酸盐和高氯酸盐微量残留的分析方法。方法 采集化工产业园区周边地表径流水样1000 mL,置试剂瓶中,去除肉眼可见杂质,滤纸过滤,调节水样PH至近中性;取上述水样500 mL,以流速12 mL/min的速度经固相萃取柱富集、净化,最后用10 mL甲醇溶液洗脱,合并收集的洗脱液,洗脱液置氮吹至近干,用1 mL甲醇溶液溶解残渣,0.22μm滤膜过滤,上离子色谱质谱仪定性、定量检测。结果 氟乙酸、碘乙酸、羟基乙酸、溴酸盐和高氯酸盐在浓度0.005 ~2.0μg/mL范围内,线性良好;检测限分别为0.021、0.023、0.0014、0.025和0.015 μg/L;三水平加标回收率在80%~120.6%范围内;精密度(RSD)在5.0%以内。结论 此方法检出限低、准确度和精密度好,适用于化工产业园区周边地表径流水样的检测分析。     

Simple sonochemical synthesis,characterization of TmVO4 nanostructure in the presence of Schiff-base ligands and investigation of its potential in the removal of toxic dyes

Thulium vanadate (TmVO4) nanorods were successfully prepared by a simple sonochemical approach using Schiff-base ligands. Additionally, TmVO₄ nanorods were employed as a photocatalyst. The most optimal crystal structure and morphology of TmVO4 have been determined and optimized by varying Schiff-base ligands, the molar ratio of H2Salen, the sonication time and power, and the calcination time. A Eriochrome Black T (EBT) analysis revealed that the specific surface area was 24.91 m2/g. A bandgap of 2.3 eV was determined by diffuse reflectance spectroscopy (DRS) spectroscopy, which makes this compound suitable for visible photocatalytic applications. In order to assess the photocatalytic performance under visible light, two anionic dyes (EBT) and cationic dyes (Methyl Violet (MV)) were used as models. A variety of factors have been studied in order to improve the efficiency of the photocatalytic reaction, including dye type, pH, dye concentration, and catalyst loading. Under visible light, the highest efficiency was achieved (97.7%) when 45 mg TmVO4 nanocatalysts were present in 10 ppm Eriochorome Black T at pH = 10.