铁(Ⅲ)-草酸盐配合物的光化学性质及其对天然水相中有机物光降解的作用

本文综述了天然水相（大气水相、地表水等）中Ｆｅ（Ⅲ）－草酸盐配合物的含量与分布、光化学性质、对天然水相中有机物的降解、及其在废水光化学处理中的应用研究及前景。     

不同Mn/Fe摩尔比对Mn-Fe复合催化剂催化氧化NO的影响

采用溶胶凝胶法制备了四种不同比例的Mn-Fe催化剂。研究了四种催化剂在100℃~400℃温度范围内的NO催化氧化活性,并采用BET、XRD和H2-TPR手段对催化剂的表征进行测试。结果表明,Mn/Fe=1:1的催化剂在低温段(100℃~300℃)活性更高,表征结果表明,Mn/Fe=1:1的催化剂的比表面积大、结晶度低、氧化还原能力强,这都是Mn/Fe=1:1的催化剂活性较高的原因。     

长江口潮滩芦苇根表铁膜磁性特征及其环境意义

湿地植物根表铁膜对包括重金属在内的物质迁移转化具有重要作用,其氧化铁组成研究备受重视,但利用环境磁学方法进行表征的研究还未见报道.本文对长江口潮滩植物芦苇根系及周边沉积物进行了磁学分析,并结合沉积物粒度、漫反射光谱等测试,对芦苇根表铁膜的磁性矿物组成进行了系统研究.结果表明,芦苇根表铁膜磁性矿物主要包括磁铁矿和赤铁矿.由于沉积物不同深度氧化还原环境的不同,铁膜磁性矿物组成存在垂向差异.研究柱样24 cm深度以上,由于相对氧化的环境,铁膜磁性矿物除磁铁矿外,还有较多的赤铁矿贡献;24 cm深度以下,因根系处于相对还原的环境,磁性矿物以磁铁矿为主.与沉积物相比,24 cm以上深度铁膜中亚铁磁性矿物含量较低,24 cm深度以下则相反,反映铁膜和沉积物磁性矿物来源不同.本项研究表明,磁性测量方法有助于认识湿地植物根表铁膜的矿物组成,对湿地生物地球化学过程研究具有重要价值.     

纳米Pd/Fe催化甲醇/水中2,2',4,4'-四溴联苯醚(BDE-47)还原脱溴

构建了纳米Pd/Fe催化还原甲醇/水中2,2’,4,4’-四溴联苯醚(BDE-47)反应体系,常压下采用单因素实验系统考察了纳米Pd/Fe催化还原甲醇/水中2,2’,4,4’-四溴联苯醚(BDE-47)的主要影响因素,并分析了BDE-47还原反应的中间产物及终产物.结果表明,纳米Pd/Fe的反应活性随Pd负载率的提高而先升后降;甲醇-水体积比高于50∶50后,BDE-47去除率随甲醇-水体积比升高而降低;在25～40℃内,BDE-47去除率随反应温度的升高而升高,随BDE-47初始浓度的增加而降低,增加纳米Pd/Fe量可提高反应速率;酸性及弱碱性条件有利于BDE-47还原.BDE-47还原主要为脱溴反应,是一个从n溴到(n-1)溴联苯醚的逐步脱溴过程,反应进行90min后,BDE-47分子中溴原子完全被脱除,反应终产物为二苯醚.     

钙钛矿型La1.4FeO3.6处理餐厨废水的湿式氧化催化性能研究

Fe元素不易产生生物毒性,以氧化物所形成的钙钛矿型结构有氧空位产生或消除为基础进行可逆氧化-还原过程的特征。采用新型的钙钛矿型La1.4FeO3.6催化剂,对餐厨废水进行湿式催化氧化处理,考察钙钛矿型La1.4FeO3.6催化剂的催化性能。研究表明,在140℃氧分压为0.6 MPa的条件下催化剂对高浓度餐厨废水具有较高的催化活性,但由于催化剂本身的缺陷,存在催化剂流失的问题。     

土壤理化性质对Fe~0还原硝基苯的影响

采用零价铁（Fe0）还原降解土壤中的硝基苯,考察土壤理化性质对还原效果的影响。结果显示,当2 g土壤中NB含量约为2.5×10-6mol/g,铁粉用量为50 mg,土壤含水量为75%时,控温25℃条件下反应1 h,硝基苯在松砂土和中壤土中的还原率分别可达到82.9%和91.1%。硝基苯在2种土壤中的还原率表现出中壤土〉松砂土的规律;土壤微生物和土壤有机质含量升高有利于反应进行;粒径偏小的中壤土中硝基苯还原较彻底。NB在土壤中的老化时间对Fe0还原效果影响较小。     

Fe(II)-mediated transformation of schwertmannite associated with calcium from acid mine drainage treatment

Schwertmannite is an important Fe(III)-oxyhydroxysulfate in acid mine drainage (AMD) polluted areas and its stability depends on surrounding environmental factors and previously bound elements. The treatment and neutralization of AMD normally involve the use of lime, which leads to the discharge of abundant Ca in the mining area. Such an environmental disturbance brings up an important and less considered problem of how the reductive transformation of schwertmannite associated with coexisting Ca occurred. Here, the Fe(II)-mediated transformation of Ca-adsorbed schwertmannite and subsequent Ca repartitioning behaviors were investigated. Results showed that adsorbed Ca had a weak inhibitory effect on Fe(II)-mediated schwertmannite transformation. Release of SO₄²⁻ and SEM images both indicated that transformation rates of schwertmannite decreased under the influence of adsorbed Ca. XRD patterns indicated that adsorbed Ca altered schwertmannite transformation pathways and product compositions upon treatment with 0.4 mmol/L Fe(II). The end products of Sch notably contained both goethite and lepidocrocite; however, transformation products of SchCa only contained goethite all along. Approximately 33.5% of the surface adsorbed-Ca was released into solution within 6 hr after Fe(II) injection. Aqueous Ca behaved in a “first release and then im-mobilization” manner, which indicated dissolution and secondary mineralization drove Ca migration during the Fe(II)-mediated transformation of SchCa. Adsorbed Ca blocked the surface sites for subsequent Fe(II) adsorption, limited the Fe(II)-Fe(III) ETAE, and decreased the transformation rates. This work sheds light on the complex geochemical behavior of schwertmannite under the influences of environmental perturbations in AMD environments.     

Nonylphenol photodegradation by novel ternary MIL-100（Fe）/ZnFe2O4/PCN composite under visible light irradiation via double charge transfer process

Nonylphenol（NP） residues, as a typical endocrine disrupting chemical（EDC）, frequently exist in sewage, surface water, groundwater and even drinking water, which poses a serious threat to human health due to its bioaccumulation. In order to remove NP, a series of MIL-100（Fe）/Zn Fe₂O₄/flake-like porous carbon nitride（MIL/ZC） was synthesized through in-situ synthesis at room temperature. High performance of ternary MIL/ZC is used to degrade NP under visible light irradiation. ...     

Trends in sediment metal concentrations in the River Avoca, South-East Ireland

Variation in sediment metal concentrations in the River Avoca, which is severely polluted by acid mine drainage (AMD) discharged from the abandoned sulphur and copper mines in Avoca, is reported. A survey of surface and subsurface sediments was repeated after seven years during exceptionally low flow conditions in 2001. The present study found that the reference (up-stream) site used in the original 1994 study was itself impacted by AMD, showing sediment metal enrichment by AMD to be greater than originally thought. The new reference site contained elevated Pb (570 µg g^–1) in the subsurface sediment due to abandoned Pb-Zn mines 25 km further upstream. Concentrations of Cu (43 µg g^–1), Zn (349 µg g^–1) and Fe (4.0%) were normal for uncontaminated rivers. All the downstream sites showed sediment metal enrichment arising from the AMD (Cu and Zn p < 0.001; Fe p < 0.01). Subsurface concentrations of metals immediately below the mixing zone were Cu 904 µg g–1 (sd 335), Zn 723 µg g–1 (sd 93), Fe 6.3% (sd 1.5) and Pb 463 µg g^–1 (sd 279). Monthly variation in metal concentrations at sites was not significantly different (p > 0.05). Although surface sediment metal concentrations were more variable, they followed similar trends to subsurface sediment. There were no significant differences in the subsurface sediment concentrations for either Cu or Zn over the period 1994 and 2001 immediately below the mines, although at the lowest site Zn had decreased by 35% over the period (p < 0.01). However there was a significant (p < 0.01) decrease over the period in the Fe concentration at all the impacted sites. This corresponds to a reduction in Fe concentration in the AMD and indicates that some remediation has occurred in the river since 1994.     

Structure relationship for catalytic dechlorination rate of dichlorobenzenes in water

Three isomers of dichlorobenzene (o-, m- and p-DCB) were dechlorinated by Pd/Fe catalyst in aqueous solutions through catalytic reduction. The dechlorination reaction took place on the surface site of the catalyst via a pseudo-first-order kinetics, and resulted in benzene as the final reduction product. The rate constants of the reductive dechlorination for the three dichlorobenzenes (DCBs) in the presence of Pd/Fe as a catalyst were measured experimentally. In all cases, the reaction rate constants were found to increase with the decrease in the Gibbs free energy of the formation of DCBs. The reaction rate constant for o-, m- and p-DCBs in the presence of 0.020% (w/w) Pd/Fe at 25 °C was determined to be 0.0213, 0.0223, and 0.0254 min⁻¹, respectively. While the activation energy of each dechlorination reaction was measured to be 102.5, 96.6 and 80.0 kJ mol⁻¹ for o-, m- and p-DCBs, respectively. The results demonstrated that p-DCBs were reduced more easily than o- or m-DCBs, and the order of the tendency of the dechlorination was p-DCB > m-DCB > o-DCB. The presented data show the catalytic reduction using Pd/Fe as a catalyst is a fast and easy approach for the dechlorination of DCBs.