超声波/零价铁(US/Fe)协同降解氯酚类化合物的QSPR研究

在同一反应条件下测定US/Fe协同降解6种氯酚类化合物的降解速率常数(κ).采用软件Chemoffice2005内置的MOPAC2002计算氯酚类化合物的分子结构参数,运用偏最小二乘(PLS)回归分析方法,对氯酚类化合物进行定量结构-性质相关(QSPR)研究,得到预测性较好的模型.模型结果显示,影响US/Fe协同降解性能(logK)的主要因素是Vp、Ehomo、logKow、(Elumo-Ehomo)2和Elumo-Ehomo.推测在US/Fe协同体系中:(1)氯酚类化合物的降解反应不是以空化泡内热解反应为主;(2)Fe表面的吸附作用对降解反应起决定影响,且氯酚化合物与·OH的氧化反应占主导作用.     

Distribution of Redox-sensitive Elements in Bottom Waters,Porewaters and Sediments of Rogoznica Lake (Croatia) in Both Oxic and Anoxic Conditions

Geochemical, mineralogical and sedimentological analyses were carried out to contrast two different sites (respectively characterized by permanently oxic and anoxic conditions) in a small, meromictic, seawater lake. In fact, due to relatively high organic matter content, and reduced water exchange, the Rogoznica Lake has almost permanent anoxic conditions below the depth of 12 m, where sediment can be considered an anoxic–sulphidic sedimentary environment. Different water column and sediments redox conditions affect the distribution and speciation of major redox-sensitive metals (Fe, Mn, Mo), reduced sulphur species (RSS) and dissolved organic C (DOC). Trace metals, especially those that accumulate in anoxic–sulphidic environments (Fe, Mo) showed a marked enrichment in the solid phase, whereas the low solubility of sulphides leads to low porewater concentrations. The relatively high sedimentary enrichment of Mo (up to 81 mg/kg) also confirms highly anoxic conditions within the Rogoznica Lake sediments. Results clearly show that chemical species within the sediments will tend towards equilibrium between porewater and solid phase according the prevailing environment conditions such as redox, pH, salinity, DOC.     

田间增强UV-B辐射对麦田生态系统Fe营养和累积的影响

研究大田栽培和自然光条件下,模拟ＵＶ－Ｂ辐射（ＵＶ－Ｂ,２８０ｎｍ ～３１５ｎｍ ）增强对麦田生态系统Ｆｅ营养和累积的影响．在４ 个生育期中,ＵＶ－Ｂ辐射显著增加叶和穗Ｆｅ含量,显著降低根Ｆｅ 含量,并改变茎Ｆｅ 含量．叶Ｆｅ累积对ＵＶ－Ｂ辐射的响应有明显的生育期之间的差异． 分蘖期无显著变化,拔节期和扬花期显著增加,而成熟期显著降低．在各生育期,ＵＶ－Ｂ辐射显著降低叶、根和穗Ｆｅ累积．ＵＶ－Ｂ辐射显著降低春小麦不同生育期Ｆｅ总累积,在５．３１ｋＪ·ｍ^-2 ＵＶ－Ｂ辐射下,降低最显著．ＵＶ－Ｂ辐射还降低春小麦群体Ｆｅ输出．麦田土壤速效Ｆｅ含量增加是春小麦群体Ｆｅ输出降低的结果,可能导致土壤库中Ｆｅ 储量的增加．     

H2O2／Fe^2＋氧化偶合混凝法处理干膜废水的研究

本文研究了H2O2／Fe^2＋氧化偶合混凝法处理印刷电路板厂干膜废水。讨论了包括过氧化氢浓度、亚铁离子浓度、pH值、时间和混凝pH值等影响因素,试验结果表明,当过氧化氢浓度为457.0mg/L、铁离子浓度为400mg/L、氧化pH值4.0、反温度为40℃、反应时间180min时,COD去除率达84.7%,出水的水质达到排放标准。     

羟基铁柱撑膨润土处理含磷废水的研究

以羟基铁为柱化剂对天然膨润土进行柱撑改性制备了羟基铁柱撑膨润土,研究了其对废水中磷的吸附性能和影响因素。结果表明:羟基铁能够进入到膨润土的层间,使其层间距增大,表面积增加;羟基铁柱撑膨润土对废水中的磷有很好的去除效果,在常温下,当改性膨润土投加量为4 mg/L,溶液pH值为5,反应时间为60 min,处理质量浓度为20 mg/L的含磷废水时,磷的去除率达到93.9%。平衡吸附量与平衡质量浓度之间的关系更好地符合Langmuir等温吸附方程所描述的规律。     

Fe3O4稳定化纳米Pd/Fe对水中2,4-D的催化还原脱氯研究

采用四氧化三铁(Fe3O4)稳定化纳米Pd/Fe催化脱氯水溶液中的2,4-二氯苯氧乙酸(2,4-D),获得了良好的处理效果.实验考察了Fe3O4投加量、pH、钯化率、温度、搅拌速率等因素对2,4-D去除的影响.2,4-D去除率随Fe3O4投加量增加而提高,投加量为4.0 g·L-1时,反应210 min后,2,4-D去除率为93.5%,而未稳定的纳米Pd/Fe,去除率为47.3%.低pH可促进2,4-D还原脱氯,pH为2.6~4.1时,2,4-D在110 min内几乎完全去除.2,4-D去除率随钯化率增加而提高.随着钯化率由0.25%、0.50%增加到0.75%,210 min后,2,4-D的去除率也由51.4%、93.5%提高到99.9%.温度在16.5~30.0℃范围内,反应210 min后,2,4-D去除率均可超过90.0%.温度升高到35.0、40.0℃时,去除率显著下降.2,4-D去除率随着搅拌速率加快而提高.Fe3O4的加入可以使纳米Pd/Fe分散和稳定.此外,Fe0可通过Fe3O4将电子传递给H+和2,4-D,促进2,4-D的还原脱氯.     

杭州市大气细颗粒物中铁溶解度的变化特征及影响因素

采集了杭州市污染天和非污染天的PM_2.5样品,并进一步获取了PM_2.5中可溶铁(FeS)的浓度及%FeS.研究结果显示,采样期间气溶胶中总Fe(FeT)的浓度为(629±296)ng/m³(150～1167ng/m³),FeS的浓度为(51.4±30.5)ng/m³(4.2～90.5ng/m³),%FeS为(7.8%±3.5%)(1.5%～12.9%).污染天PM_2.5、FeT和FeS的浓度均明显高于非污染天,且污染天%FeS为9.3%,高于非污染天的5.1%.本研究发现%FeS的差异主要与Fe的来源和大气酸化过程相关,污染天Fe受交通排放和工业排放等人为源的影响更大,且污染天大气酸化程度更强.     

Fe2O3纳米棒的制备及其H2S气敏性能研究

为快速检测H2S泄漏,以一步水热法制备的Fe2O3纳米棒为基础,制备了H2S气体传感器。研究表明,该传感器在300℃工作温度下对10μmol/mol的H2S的灵敏度为2左右,响应时间为12s左右,恢复时间约4s。而且该传感器具有优异的稳定性和选择性,对CH4、CO等多种气体响应较差,适合用于长时间快速检测H2S气体的泄漏。     

Mechanisms of photochemical release of dissolved organic matter and iron from resuspended sediments

Photochemical reactions can alter the transformation of sedimentary organic matter into dissolved organic matter (DOM) and affect its ultimate fate in water ecosystems. In the present study, the photorelease of DOM and Fe from resuspended lake sediments was investigated under different O₂ and NO₃^? concentration conditions to study the mechanisms of DOM and Fe photorelease. The amount of photoreleased Fe, which ranged from 0.22 to 0.70 μmol/L, was significantly linearly correlated with the amount of photoreleased DOM. O₂ and NO₃^? could promote the photochemical release of DOM and Fe, especially during the initial 4 h irradiation. In general, the order of the photorelease rates of DOM and Fe under different conditions was as follows: NO₃^?/aerobic > aerobic ≈ NO₃^?/anaerobic > anaerobic. The photorelease rates of DOM and Fe were higher for the initial 4 hr irradiation than these for the subsequent 8 hr irradiation. The photorelease of DOM and Fe is thought to proceed via direct photodissolution and indirect processes. The relative contributions of indirect processes (>60%) was much greater than that of direct photodissolution (<40%). The photoproduced H₂O₂ under aerobic and anaerobic conditions indicated that hydroxyl radicals (?OH) are involved in the photorelease of DOM. Using ?OH scavengers, it was found that 38.7%, 53.7%, and 77.6% of photoreleased DOM was attributed to ?OH under anaerobic, aerobic, and NO₃^?/aerobic conditions, respectively. Our findings provide insights for understanding the mechanisms and the important role of ?OH in the DOM and Fe photorelease from resuspended sediments.     

Evidence for coupled iron and nitrate reduction in the surface waters of Jiaozhou Bay

Iron and nitrate (NO₃^?) are dominant physiologically required nutrients for phytoplankton growth, and iron may also play a key role in the marine nitrogen cycle. In this study, we investigated the temporal and spatial distributions of dissolved iron (DFe) and Fe(II) in the surface waters of Jiaozhou Bay (JZB) from April 2 to July 26, 2017. High concentrations of DFe and Fe(II) predominantly occurred in nearshore and estuarine stations and concentrations were generally higher in April and May. The highest DFe concentration was observed along the coast of Hongdao (51.55 nmol/L) in May, while the lowest concentration was observed in the western coastal region (2.88 nmol/L) in April. The highest and lowest Fe(II) concentrations were observed in the Licun estuary (22.42 nmol/L) and outer bay (0.50 nmol/L) in May, respectively. We calculated the proportions of nitrate, nitrite, and ammonium in dissolved inorganic nitrogen (DIN) as well as the ratio of Fe(II) to DFe in all four months. The mean Fe(II)/DFe ratio was 0.48 in April, 0.43 in May, 0.69 in June, and 0.32 in July. The mean ratio of NO₃^? to DIN was 0.78 in April, 0.54 in May, 0.20 in June, and 0.62 in July. NO₃^?/DIN continuously decreased in the first three months, while Fe(II)/DFe remained high, which suggests that the reduction of iron and nitrate occurred simultaneously in the surface waters of JZB.