Metal composition of layered double hydroxides (LDHs) regulating ClO4- adsorption to calcined LDHs via the memory effect and hydrogen bonding

A series of calcined carbonate layered double hydroxides （CLDHs） with various metal compositions and different M^2＋/M^3＋ ratios were prepared as adsorbents for perchlorate. Adsorption isotherms fit Langmuir model well, and the adsorption amount followed the order of MgA1-CLDHs 1〉 MgFeCLDHs 〉〉 ZnA1-CLDHs. The isotherms of MgA1-CLDHs and MgFe-CLDHs displayed a two-step shape at low and high concentration ranges and increased with an increase in the M^2＋/M^3＋ ratio from 2 to 4. The two-step isotherm was not observed for ZnA1-CLDHs, and the adsorption was minimally affected by the M^2＋/M^3＋ ratio. The LDHs, CLDHs and the reconstructed samples were characterized by X-ray diffraction, SEM, FT-IR and Raman spectra to delineate the analysis of perchlorate adsorption mechanisms. The perchlorate adsorption of MgA1-CLDHs and MgFe-CLDHs was dominated by the structural memory effect and the hydrogen bonds between the free hydroxyl groups on the reconstructed-LDHs and the oxygen atoms of the perchlorates. For ZnAI-CLDHs, the perchlorate adsorption was controlled by the structural memory effect only, as the hydroxyl groups on the hydroxide layers preferred to form strong hydrogen bonds with carbonate over perchlorate, which locked the intercalated perchlorate into a more confined nano-interlayer. Several distinct binding mechanisms of perchlorate by CLDHs with unique M^2＋ ions were proposed.     

Isolation, identification and arsenic-resistance of Acidithiobacillus ferrooxidans HX3 producing schwertmannite

Schwertmannite, a ubiquitous mineral present in iron oxyhydroxides formed in iron- and sulfate-rich acid media, favors incorporation of some toxic anions in its structure. We reported an iron-oxidizing bacterial strain HX3 from a municipal sludge that facilitates the formation of pure schwertmannite in cultures. Ferrous iron oxidation by the isolated strain HX3 was optimum at an initial pH of 2.0-3.3 and temperature of 28-35°C. Pure schwertmannite was found through bacterial oxidation of ferrous iron at an initial pH 2.8and temperature 28°C. Following 16 S rDNA gene sequence analysis the bacterial strain HX3 was identified as Acidithiobacillus ferrooxidans. The arsenic-resistance A. ferrooxidans HX3 showed the potential of environmental application in arsenic removal from the As（Ⅲ）- and iron-rich acid sulfate waters directly by As（Ⅲ） adsorption or the formation of schwertmannite in the environment.     

Graphene-supported nanoscale zero-valent iron：Removal of phosphorus from aqueous solution and mechanistic study

Excess phosphorus from non-point pollution sources is one of the key factors causing eutrophication in many lakes in China,so finding a cost-effective method to remove phosphorus from non-point pollution sources is very important for the health of the aqueous environment. Graphene was selected to support nanoscale zero-valent iron(nZVI)for phosphorus removal from synthetic rainwater runoff in this article. Compared with nZVI supported on other porous materials,graphene-supported nZVI(G-nZVI) could remove phosphorus more efficiently. The amount of nZVI in G-nZVI was an important factor in the removal of phosphorus by G-nZVI,and G-nZVI with 20 wt.% nZVI(20% G-nZVI)could remove phosphorus most efficiently. The nZVI was very stable and could disperse very well on graphene,as characterized by transmission electron microscopy(TEM) and scanning electron microscopy(SEM). X-ray photoelectron spectroscopy(XPS),Fourier Transform infrared spectroscopy(FT-IR) and Raman spectroscopy were used to elucidate the reaction process,and the results indicated that Fe-O-P was formed after phosphorus was adsorbed by G-nZVI. The results obtained from X-ray diffraction(XRD) indicated that the reaction product between nZVI supported on graphene and phosphorus was Fe3(PO4)2·8H2O(Vivianite). It was confirmed that the specific reaction mechanism for the removal of phosphorus with nZVI or G-nZVI was mainly due to chemical reaction between nZVI and phosphorus.     

Zn2+对铁氧化物吸附苄嘧磺隆的影响

研究2种人工合成的铁氧化物对磺酰脲类除草剂--苄嘧磺隆(bensulfuron-methyl,BSM)的吸附,以及Zn2 对供试样品吸附苄嘧磺隆的影响.实验结果表明,用Langmuir、Freundlich、Temkin等方程对供试样品加入Zn2 后吸附BSM的数据进行了拟合,发现供试样品吸附苄嘧磺隆的等温曲线较好地符合Freundlich方程.加入Zn2 后,铁氧化物吸附苄嘧磺隆的量较未加Zn2 有较大幅度的增加,但在苄嘧磺隆的平衡质量浓度较低(＜4 mg/L)时,氧化物吸附苄嘧磺隆的量不随Zn2 浓度的增加而增加;在苄嘧磺隆的平衡质量浓度较高(＞6 mg/L)时,氧化物吸附苄嘧磺隆的量随Zn2 浓度的增加而增加.这可能是Zn2 和苄嘧磺隆被吸附时存在竞争和协同交互作用的结果.     

骆马湖泥-水界面磷铁硫原位同步变化特征

利用薄膜梯度扩散（DGT）原位采样装置获取了骆马湖全湖8个典型湖区泥-水界面（SWI）活性磷（P）、铁（Fe）、硫（S）垂向分布信息，据此定量估算三者交换通量.结果表明，骆马湖沉积物剖面P、Fe、S浓度范围分别为0~2.05，0~11.10和0.01~0.63mg/L，并在微小尺度呈高度空间异质性.在水平方向上活性P、Fe主要表现为西北湖区高于东南湖区，而活性S则未表现出明显的分布规律；就垂直剖面而言，活性P、Fe、S自界面向下呈升高趋势，并在60mm深度内出现峰值，且活性P和Fe剖面呈明显的同步变化特征；活性P、Fe在多数点位具有显著的正相关性（r>0.65，P<0.01），且各采样点沉积物中的总铁与总磷比值[w（∑Fe）/w（∑P）]均高于15，这表明Fe的地球化学循环过程对于骆马湖内源磷释放起重要控制作用；8个采样点样品中活性P、Fe、S交换通量分别为0.066~0.698，1.671~5.592和0.007~0.071mg/（m²·d），表明P、Fe、S由沉积物向水体释放.西北湖区表现出较高的P通量和活性P浓度，这可能会增加南水北调过程中水质污染的风险，应予以重视.以上结果支持了P、Fe耦合释放机制，明确了骆马湖SWI的活性P、Fe、S迁移特征.     

含铜黄连素废水的铁碳微电解预处理及铜回收研究

利用铁碳微电解技术对含铜黄连素制药废水进行预处理,通过单因素试验确定了反应时间,铁粉和废碳投加量,pH等因素对处理效果的影响,并设计了回收金属铜的工艺流程.结果表明:采用铁碳微电解工艺处理初始Cu2+浓度约为20000mg/L,黄连素浓度为1 700～1 900mg/L的含铜黄连素制药废水,当废水pH为2.0～3.0,...     

天铁:高效能推进节能减排力争在好字优先上走在前列

2007年,炼钢厂实现负能炼钢,全集团吨钢综合能耗同比降低100 kg,万元产值能耗降到1.4 t标煤.2008年一季度,吨钢综合能耗降到570 kg,万元产值能耗降到了2.21 t标煤.尤其是3月份降到了514 kg,创历史最好水平.     

酸性Fe(Ⅲ)溶液催化氧化S(Ⅳ)机理研究进展

烟道气SO2是大气污染的主要污染物之一.酸性Fe(Ⅲ)溶液催化氧化SO2是研究最早、最多、应用最广的一项烟气脱硫技术,但对其机理一直以来都存在争议.通过综述国内外的酸性Fe(Ⅲ)溶液催化氧化S(Ⅳ)机理研究进展,总结得出其机理为配位催化氧化;指出了机理研究中存在的问题.为我国湿法烟气脱硫技术及其机理研究的发展提供了理论依据.     

共沉淀—原子吸收法分析铁强化盐中的铁

本文采用原子吸收分光光度法,测定铁强化盐中微量铁。用数理统计方法检证了方法的可靠性。     

高铁酸盐多功能水处理剂的制备及除污染技术

该发明涉及一种多功能水处理剂的制备与除污染技术。采用廉价的亚铁盐，经过改性处理得到反应活性较高的三价铁，再经过氧化过程制备高铁酸盐。本法工艺简单，能耗低，产品质量稳定，成本低廉。采用该发明制备的高铁酸盐产品，由于具有强氧化性并同时具有絮凝剂的特点，对天然水体中的多种污染物有广谱的去除作用。高铁酸盐预氧化处理具有氧化、吸附、共沉淀、消毒、杀菌、除藻等多功能的净水效能。