Die Bleisulfidhalogenide Pb2SJ2 und Pb2SBr2

The Science of Nature -     

可见光-芬顿降解甲基橙效果的正交试验研究

在节能灯光照条件下,Fe2+/C2O2-4/H2O2体系对甲基橙具有较好的降解效果,并通过正交试验得出降解1 000 mL 100 mg/L甲基橙溶液的最佳条件是:H2O2浓度为7.8 mmol/L,Fe2+浓度为0.8 mmol/L,草酸钠浓度为74.6 mmol/L,反应时间60 min.     

Ti/RuO2-TiO2-IrO2-SnO2电极电解氧化含氨氮废水

研究了含氨氮(NH4 -N)废水在循环流动式电解槽中的电化学氧化,其中阳极为Ti/RuO2-TiO2-IrO2-SnO2网状电极,阴极为网状钛电极.考察了出水放置时间、进水流量和电流密度对氨氮去除的影响,并对能耗、阳极效率和瞬时电流效率(ICE)进行分析.结果表明,在氯离子浓度为400 mg/L,初始氨氮浓度为40 mg/L时,进水流量对氨氮去除的影响不大,电流密度的影响比较大.在进水流量为600 mL/min,电流密度为20 mA/cm2,电解时间为90 min时,氨氮去除率为99.37%,去除1 kg氨氮的能耗和阳极效率为500 kW·h和2.68 h·m2·A,瞬时电流效率(ICE)为0.28.表明电解氧化含氨氮废水具有较好的应用前景.     

MnO2/TiO2改性沸石去除矿井水中Fe2+和Mn2+的试验研究

针对矿井水中Fe2+、Mn2+浓度超标及处理效果不稳定等问题,通过溶胶-凝胶法将纳米MnO₂和纳米TiO₂负载于天然斜发沸石表面制备出MnO₂/TiO₂改性沸石滤料,并分析了沸石改性前后的微观形貌和孔隙结构. 采用单因素动态吸附试验和Thomas模型拟合探究了MnO₂/TiO₂改性沸石对模拟矿井水水样中Fe2+、Mn2+的去除效果及机理,并考察水流速度、滤层厚度、溶液pH及硬度对去除效果的影响. 结果表明:较天然沸石而言,MnO₂/TiO₂改性沸石的比表面积、孔径、孔体积和阳离子交换量明显增大. 当水流速度为7 m/h、进水pH为9.5、水质硬度为350 mg/L、滤层厚度为110 cm时,改性沸石对Fe2+、Mn2+的最大吸附量分别为44.810、6.549 mg/g,且Thomas模型能较好地拟合改性沸石对Fe2+、Mn2+的吸附动力学特征. 反冲洗试验结果表明,反冲洗强度为13 L/(m2·s),反冲洗时间大于7 min时,改性沸石的再生效果良好,可重复使用. 研究显示,本文制备的MnO₂/TiO₂改性沸石吸附滤料可为同步去除矿井水中Fe2+、Mn2+污染提供一种解决办法.      

铁屑/焦炭/H2O2法预处理焦化废水的试验研究

采用铁屑/焦炭/H2O2法对焦化废水进行处理,通过单因素试验法考察了铁炭比、铁炭用量、H2O2用量、废水pH以及反应时间对处理效果的影响,并确定了最适工艺条件。结果表明,铁屑/焦炭/H2O2法与常规的铁屑内电解法相比,可显著提高焦化废水的预处理效果,并缩短反应时间。铁屑/焦炭/H2O2法处理焦化废水的最适条件为:铁炭比为4,铁炭用量为300mg/L铁屑+75mg/L焦炭,H2O2用量为1000mg/L,pH为3,反应时间20min。在此条件下,COD、色度、NH3-N和CN-的去除效率分别可达61.2%、74.0%、56.2%和74.3%,B/C比由处理前的0.189提高到0.387,处理水可生化性良好。铁屑/焦炭/H2O2可作为焦化废水的一种有效的预处理方法。     

Inhibition of photosynthesis and leaf conductance interactions induced by SO2, NO2 and SO2 + NO2

Effects of 2-h exposures to 0–1 μmol mol⁻¹ SO₂, NO₂ and (1:1) SO₂ + NO₂ on CO₂ uptake by standardized snap bean leaves were studied. Interactions resulting from pollutant-induced changes in leaf conductance were evaluated. Minimum exposure concentrations required to depress CO₂ exchange rates (CER) under the test conditions were:0.17 μmol mol⁻¹ SO₂, 0.38 μmol mol⁻¹ NO₂, and 0.08 μmol mol⁻¹ of each pollutant in the 1:1 mixture. Treatments with 1 μmol mol⁻¹ NO₂ reduced CER 10% without affecting leaf conductance. One μmol mol⁻¹ SO₂ depressed CER by 50%. Leaf conductances increased in SO₂-treated leaves showing 30% inhibition of CER. Greater inhibition led to subsequent stomatal closure. Inhibition caused by the individual pollutants (applied singly) was linear over the range of concentrations investigated. The dual-pollutant mixture produced a synergistic response that was most pronounced at the lower pollutant concentrations. The potentiated effect was correlated with marked stomatal closure.Experimental plants for this study were grown under low moisture stress conditions to enhance stomatal opening in the plant stock material and reduce (damp) the potential for further SO₂-induced stimulation of stomatal opening. The experiments were designed to obtain limiting data for the test conditions.