Iron and manganese oxides enhance electron output efficiency of Clostridium pasteurianum

[Background] Fermentative dissimilatory metal-reducing bacteria, which are capable of reducing metallic oxides, get energy from fermentation. Little is known about how metallic oxides affect electron output efficiency of fermentative dissimilatory metal-reducing microorganisms. [Objective] This study was conducted to explore the influence of iron and manganese oxides (Fe_2O_3/MNO_2) on electron output efficiency. [Methods] Different concentrations of Fe_2O_3/MNO_2 were added into fermented system containing glucose and inoculated 5% C. pasteurianum. Electrochemical activity of C. pasteurianum was detected. The concentrations of Fe(Ⅱ) and Mn(Ⅱ) were measured by ferrozine spectrophotometry and formaldoxime method. Fermentation substrate and metabolites of C. pasteurianum were detected by gas chromatography and high performance liquid chromatography. Lastly, we calculated the electron output efficiency. [Results] The current density peaked with the value of about 0.93 mA/m~2. The concentrations of Fe(Ⅱ) and Mn(Ⅱ) gradually accumulated. The consumption of glucose was increased by 9.4%/7.7%, Meanwhile, acetate production was increased by 37.5%/25.0%, and butyrate production was increased by 22.7%/6.8%. Additionally, hydrogen production was increased by 21.6%/9.8%, and the total electron output efficiency was increased by 24.27%/10.82%, respectively. The pH values between experimental group and control are no significant difference. [Conclusion] This study shows that iron and manganese oxides can improve the electron output efficiency of C. pasteurianum by increasing glucose consumption and buffering pH value. The results provide evidence for revealing the effects of multivalent metal oxides on the electron output of fermentative dissimilatory metal-reducing bacteria, and further expand our understanding of the interaction mechanism between multivalent metal oxides and fermentative dissimilatory metal-reducing bacteria.</p

Humic acid from leonardite for cadmium adsorption and potential applications

以碱溶酸析＂法从新疆风化煤中提取的胡敏酸为研究对象,对其理化性质和表面形态进行表征,并通过吸附试验探究反应时间、溶液pH、镉离子（Cd（2＋））质量浓度对胡敏酸吸附Cd（2＋）的影响.结果表明：风化煤提取的胡敏酸碳元素质量分数高达58.68%,羧基的质量摩尔浓度为5.81mol/kg,等电点为2.7;该胡敏酸含Cd量为0.15mg/kg,符合国家土壤环境质量标准.胡敏酸对Cd（2＋）的吸附在8h内达到平衡,吸附量随Cd（2＋）质量浓度（0～100mg/L）和溶液pH升高而增加,到pH=6.0时最大,之后胡敏酸开始溶解导致吸附量降低.Langmuir方程比Freundlich方程能更好地拟合胡敏酸对Cd（2＋）的吸附等温线,显示出单分子层吸附的特点.在pH=5.0时,胡敏酸对Cd（2＋）的饱和吸附量达137.37mg/g,相当于用去了酸度系数（pKa）为3的羧基含量的71%.在pH=4.3、Cd（2＋）初始质量浓度为80mg/L的同等条件下,新疆风化煤提取的胡敏酸对Cd（2＋）的吸附量为86.97mg/g,高于国际腐殖质协会胡敏酸标样1R106H对Cd（2＋）的吸附量（73.49mg/g）.风化煤来源广、储量大、价格低,以它为原料制备获得的胡敏酸产量高、吸附能力强、环境友好、施用安全,有望作为吸附剂用于含重金属废水处理,以及作为钝化剂和土壤调理剂用于重金属污染土壤的修复

Humic nanoparticles for remediation of Cd- contaminated soils

Extraneous humic substances could alter the dynamics of Cd in soils. An insoluble humic acid, produced from a leonardite, was used in laboratory experiment as an adsorbent to immobilize Cd in a silt-loam soil near a smelting plant and a Cd-spiked and aged sandy-loam soil, whereas a soluble peat-derived potassium humate was employed as a washing agent to mobilize Cd in, and remove it out of, the contaminated soils. Addition of 2% humic acid could reduce CaCl_2 extractable Cd in a soil (0.103 mg·L~(-1)) by 19.7%. This immobilization effect was greater in sandy-loam soil than in silt-loam soil. Similarly, Cd removed from the contaminated soils increased with washing agent dosage. A single washing at 10 g·L~(-1) of potassium humate removed up to 38.1% of the total Cd in soils. Fourier transform infrared spectroscopic analysis indicated the formation of Cd-carboxyl complex. This study suggests that Cd-contaminated soils can be remediated by humic substances through either an immobilization or mobilization process. The key to the success is to select humic substances with a suitable solubility: water insoluble humic acid for Cd immobilization and water soluble potassium humate for effective removal of Cd out of soils

一种用于重金属钝化的土壤调理剂及其制备方法

本发明涉及一种用于重金属钝化的土壤调理剂及其制备方法。该制备方法为：由富含腐殖酸的物料和强碱溶液混合，加热后提取的腐殖酸经联合絮凝方法得到用于重金属钝化的土壤调理剂。本发明利用分布广泛、储量丰富、廉价易得的褐煤和风化煤为原料，经环境友好过程提取，用首创的联合絮凝法制得用于重金属钝化的土壤调理剂。本发明的土壤调理剂由腐殖酸钙组成，富含羧基、羟基等功能基团，能有效吸附重金属，从而降低它们的生物有效性，可用于包括酸性土壤在内的重金属污染农田的调理和修复

Humic acid from leonardite for cadmium adsorption and potential applications

以碱溶酸析"法从新疆风化煤中提取的胡敏酸为研究对象,对其理化性质和表面形态进行表征,并通过吸附试验探究反应时间、溶液pH、镉离子(Cd~(2+))质量浓度对胡敏酸吸附Cd~(2+)的影响.结果表明:风化煤提取的胡敏酸碳元素质量分数高达58.68%,羧基的质量摩尔浓度为5.81mol/kg,等电点为2.7;该胡敏酸含Cd量为0.15mg/kg,符合国家土壤环境质量标准.胡敏酸对Cd~(2+)的吸附在8h内达到平衡,吸附量随Cd~(2+)质量浓度(0~100mg/L)和溶液pH升高而增加,到pH=6.0时最大,之后胡敏酸开始溶解导致吸附量降低.Langmuir方程比Freundlich方程能更好..

奇奇核~(90)Nb的高自旋态研究

用能量为80MeV的19F束通过反应76Ge(19F,5n)90Nb布居了90Nb的高自旋态.通过在束γ测量分析90Nb退激γ射线的符合级联关系,发现了19条新的属于90Nb的γ跃迁,建立了90Nb的高自旋态能级纲图.通过经验壳模型计算指定了部分能级的组态,并结合实验DCO比值和与相邻N=49核素的系统比较,确认了新能级的自旋和宇称