黄铁矿对水体中腐殖酸的吸附特性

选择富里酸(fulvic acid,FA)和胡敏酸(humilic acid,HA)作为吸附对象,通过铁矿物吸附筛选实验,以黄铁矿(pyrite)为吸附剂研究其对水体中两种典型腐殖酸(humic acid)的吸附特性.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、X-射线光电子能谱(XPS)、红外光谱(IR)、纳米粒度及电位(Zeta)分析仪和比表面仪(BET)对黄铁矿进行组成及结构表征.考察了腐殖酸溶液p H、离子强度和温度等条件对黄铁矿吸附的影响.结果表明,黄铁矿是层状结构,吸附腐殖酸后,在黄铁矿表面形成了大小均匀的分子簇,且黄铁矿晶粒尺寸减小了约10 nm;黄铁矿对FA、HA的最大吸附量分别为11.8 mg·g-1和13.1 mg·g-1.随着p H增加,黄铁矿对腐殖酸的吸附量均表现为先增大后减小;离子强度(NaCl)对吸附的影响较小;随着温度升高,其吸附量不断增大.两种腐殖酸吸附数据与Langmuir吸附模型拟合良好且其吸附动力学规律均符合二级动力学模型,热力学研究表明,黄铁矿吸附两种腐殖酸均属于自发进行的吸热反应.     

零价纳米铁吸附去除水中六价铬的研究

利用液相还原法制备的零价纳米铁(nZVI)进行了去除水中Cr(Ⅵ)的实验研究.结果表明,nZVI对Cr的去除效果明显优于还原铁粉和粉末活性碳;pH值越小、初始Cr浓度越低、nZVI放置时间越短及投加量越大均有利于水中Cr(Ⅵ)的去除,最佳去除率近100%;反应动力学拟合结果表明,nZVI去除六价铬符合准二级动力学模型;反应后nZVI颗粒的扫描电镜及电子能谱结果显示Cr占12.02%(wt),结合对反应溶液中Cr(Ⅵ)和Cr(Ⅲ)分析,说明吸附、还原与共沉淀可能是nZVI去除水中六价铬的主要机理.     

Effect of humic acid and metal ions on the debromination of BDE209 by nZVM prepared from steel pickling waste liquor

As a promising in situ remediation technology, nanoscale zero-valent iron (nZVI) can remove polybrominated diphenyl ethers such as decabromodiphenyl ether (BDE209) effectively, However its use is limited by its high production cost. Using steel pickling waste liquor as a raw material to prepare nanoscale zero-valent metal (nZVM) can overcome this deficiency. It has been shown that humic acid and metal ions have the greatest influence on remediation. The results showed that nZVM and nZVI both can effectively remove BDE209 with little difference in their removal efficiencies, and humic acid inhibited the removal efficiency, whereas metal ions promoted it. The promoting effects followed the order Ni²⁺>Cu²⁺>Co²⁺ and the cumulative effect of the two factors was a combination of the promoting and inhibitory individual effects. The major difference between nZVM and nZVI lies in their crystal form, as nZVI was found to be amorphous while that of nZVM was crystal. However, it was found that both nZVM and nZVI removed BDE209 with similar removal efficiencies. The effects and cumulative effects of humic acid and metal ions on nZVM and nZVI were very similar in terms of the efficiency of the BDE209 removal.     

Removal of decabromodiphenyl ether (BDE-209) by sepiolite-supported nanoscale zerovalent iron

Nanoscale zerovalent iron (nZVI) synthesized using sepiolite as a supporter was used to investigate the removal kinetics and mechanisms of decabromodiphenyl ether (BDE-209). BDE-209 was rapidly removed by the prepared sepiolite-supported nZVI with a reaction rate that was 5 times greater than that of the conventionally prepared nZVI because of its high surface area and reactivity. The degradation of BDE-209 occurred in a stepwise debromination manner, which followed pseudo-first-order kinetics. The removal efficiency of BDE-209 increased with increasing dosage of sepiolite-supported nZVI particles and decreasing pH, and the efficiency decreased with increasing initial BDE-209 concentrations. The presence of tetrahydrofuran (THF) as a cosolvent at certain volume fractions in water influenced the degradation rate of sepiolite-supported nZVI. Debromination pathways of BDE-209 with sepiolite-supported nZVI were proposed based on the identified reaction intermediates, which ranged from nona- to mono-brominated diphenylethers (BDEs) under acidic conditions and nona- to penta-BDEs under alkaline conditions. Adsorption on sepiolite-supported nZVI particles also played a role in the removal of BDE-209. Our findings indicate that the particles have potential applications in removing environmental pollutants, such as halogenated organic contaminants.     

Removing polybrominated diphenyl ethers in pure water using Fe/Pd bimetallic nanoparticles

Polybrominated diphenyl ethers (PBDEs) have been widely used as fire-retardants. Due to their high production volume, widespread usage, and environmental persistence, PBDEs have become ubiquitous contaminants in various environments.Nanoscale zero-valent iron (ZVI) is an effective reductant for many halogenated organic compounds. To enhance the degradation efficiency, ZVI/Palladium bimetallic nanoparticles (nZVI/Pd) were synthesized in this study to degrade decabromodiphenyl ether (BDE209) in water. Approximately 90% of BDE209 was rapidly removed by nZVI/Pd within 80 min, whereas about 25% of BDE209 was removed by nZVI. Degradation of BDE209 by nZVI/Pd fits pseudo-first-order kinetics. An increase in pH led to sharply decrease the rate of BDE209 degradation. The degradation rate constant in the treatment with initial pH at 9.0 was more than 6.8 × higher than that under pH 5.0. The degradation intermediates of BDE209 by nZVI/Pd were identified and the degradation pathways were hypothesized. Results from this study suggest that nZVI/Pd may be an effective tool for treating polybrominated diphenyl ethers (PBDEs) in water.     

蔗糖改性纳米铁原位反应带对硝基苯污染的模拟修复研究

在一维模拟装置中创建改性纳米铁原位反应带,研究反应带对硝基苯污染的修复情况,并通过反应带渗透性变化对其可持续修复能力进行评估.模拟试验结果表明:不同条件下硝基苯的去除率为45%~80%;反应带渗透性变化过程按时间分为3个阶段,分别是0~10d的快速下降期、10~30d的缓慢下降期和30~60d的稳定期,平均下降了53.2%,堵塞现象未发生,反应带可持续修复能力较好.较大的介质粒径和浆液浓度使污染物降解效率增加,硝基苯去除率可分别提高23.7%和13.7%;较高的地下水流速和污染物浓度不利于污染物的去除,硝基苯去除率均下降约46.8%.各反应带中实际参与反应的铁与硝基苯的物质的量比值分别为11.2、17.9、12.6、3.3和25.7,改性纳米铁颗粒的实际利用率较低,实际应用中浆液需要过量注入.     

黄河干流表层沉积物铁形态的分布特征及相关性分析

应用颗粒物中铁的连续浸提技术研究了黄河干流表层沉积物中铁形态的分布特征及相关性,研究结果表明:表层沉积物中总铁(∑Fe)含量范围在14.01~30.98g/kg,最小值和最大值分别出现在黄河柳林段(H13)和渤海近海(H21);各形态铁中以残渣态(Fe-6)含量最高,占∑Fe比率92.55%~98.44%,有效态铁(BFe)含量仅占1.56%~6.98%,与∑Fe呈现显著正相关,并且三者含量高低沿程变化趋势一致;有机质(OM)与BFe、铁锰氧化物态铁(Fe-4)呈现显著正相关系,BFe与Fe-4呈现极显著正相关系,说明BFe含量主要受Fe-4和有机质的控制;黄河水体总颗粒物(TPM)浓度增高,如黄河中游大禹渡段H15和三门峡段H17,表层沉积物∑Fe与Fe-1含量高,TPM浓度降低,如黄河上游乌海段H7和三盛公段H8,表层沉积物∑Fe与Fe-1含量低,说明黄河流域广泛的人工筑坝,导致水体TPM浓度改变,对黄河铁循环产生了不可忽视的影响.     

Removal of arsenic by Acidothiobacillus ferrooxidans bacteria in bench scale fixed-bed bioreactor system

In the present study arsenic contaminated simulated water and groundwater was treated by the combination of biological oxidation of tri-valent arsenite [As (III)] to penta-valent arsenate [As (V)] in presence of Acidothiobacillus ferrooxidans bacteria and its removal by adsorptive filtration in a bioreactor system. This method includes the immobilisation of A.ferrooxidans on Granulated Activated Carbon (GAC) capable of oxidising ferrous [Fe (II)] to ferric [Fe (III)]. The Fe (III) significantly converts the As (III) to As (V) and ultimately removed greater than 95% by the bed of GAC, limestone, and sand. The significant influence of Fe (II) concentration (0.1–1.5?gL^?1), flowrate (0.06–0.18?Lh^?1), and initial As (III) concentration (100–1000?µgL^?1) on the arsenic removal efficiency was investigated. The simulated water sample containing the different concentration of As (III) and other ions was used in the study. The removal of other co-existing ions present in contaminated water was also investigated in column study. The concentration of arsenic was found to be <10?µgL^?1 which is below Maximum Contaminant Level (MCL) as per WHO in treated water. The results confirmed that the present system including adsorptive-filtration was successfully used for the treatment of contaminated water containing As (III) ions.     

浅议碳排放与废钢铁的节能减排功效

二氧化碳是导致全球气候变暖、人类生存环境恶化的主要原因。简要介绍世界钢铁工业二氧化碳排放情况,针对我国钢铁工业碳排放的具体情况,提出发展我国废钢产业,提高废钢铁的供应能力,是我国钢铁工业摆脱危机,实现低碳发展、绿色发展的主要途径。     

克黄灵注射液与颗颗灵栓剂的配合施用

本文讨论了克黄灵注射液和颗颗灵栓剂配合施用问题，两者配合施用有助于颗颗灵的溶解，叶片转缓时间比单施颗颗灵提前且维持时间更长．