纳米Fe3O4磁性粒子合成过程中分散体系的影响

分别采用水体系化学共沉淀法和聚乙二醇体系化学共沉淀法制备了超顺磁性的纳米Fe3O4磁性粒子,并比较了它们在物相组成、磁性能以及分散稳定性等方面的差异．结果显示：在2种体系中制备的纳米Fe3O4磁性粒子都呈现出较好的超顺磁性,其中水体系中制备的纳米Fe3O4磁性粒子结晶度较高,聚乙二醇体系中制备的纳米Fe3O4磁性粒子磁化率和分散稳定性较优．     

包覆层厚度对Fe_3O_4@SiO_2核壳结构纳米粒子磁共振性能的影响

二氧化硅包覆四氧化三铁核壳结构纳米粒子在生物医学领域有着广泛的用途。本文采用单质硅粉水解法,以单分散水溶性Fe3O4纳米粒子为内核,通过改变反应体系中单质硅粉的加入质量,制备了不同包覆厚度的Fe3O4@SiO2纳米粒子,并对SiO2包覆层厚度对Fe3O4纳米粒子磁共振性能的影响进行了研究。结果表明:随着SiO2壳层厚度的增加,横向弛豫效率r2逐渐降低。弛豫效率降低是由水分子与磁性纳米粒子内核之间的距离逐渐增大引起的。     

铁铝氧化物纳米粒子对土壤有机碳矿化作用的影响

目的:了解纳米Fe2O3和纳米Al2O3颗粒对土壤有机碳分解矿化作用的影响.方法:以若尔盖高寒草甸土为研究对象,采用室内培养实验方法,测定不同纳米材料对土壤呼吸强度的影响.结果:在一个培养试验周期内,添加Al2O3纳米颗粒后土壤呼吸作用增强,添加Fe2O3纳米粒子的土壤呼吸作用变化不明显;随纳米材料加入量增加,土壤呼吸强度的变化无显著差异;结论:Al2O3纳米粒子能够一定程度增强土壤有机碳分解矿化作用,Fe2O3纳米粒子对土壤有机碳分解矿化作用的影响不大.     

蒸汽相水解法制备磁性光催化剂Fe_3O_4/SiO_2/TiO_2及其光催化性能

采用蒸汽相水解法,以Fe3O4纳米磁性颗粒为磁核,在其表面包覆一层SiO2来阻止光腐蚀,然后将锐钛矿相纳米氧化钛沉积在Fe3O4/SiO2颗粒表面,从而制得核壳结构的Fe3O4/SiO2/TiO2磁性复合光催化材料。用X射线粉末衍射仪(XRD)、场发射扫描电镜(FE-SEM)、高分辨率透射电子显微镜(HR-TEM)、探针式震动磁强计等手段对所制备的产物的结构、形貌、磁强度性能进行表征。以300W汞灯为光源,用亚甲基蓝和酸性红模拟污水中的有机染料来评价复合光催化剂的性能。结果表明,磁性纳米微球中TiO2的含量越大,其光催化性能越好,含TiO2质量分数50%的F3O4/SiO2/TiO2磁性纳米微球可在180min内降解亚甲基蓝模拟染料废水,降解率达99%,在80min内降解酸性模拟染料废水,降解率达98%。     

Fe_3O_4@SiO_2@PGA磁性吸附材料的制备与表征

首先以共沉淀法制备了磁性纳米颗粒Fe_3O_4并在表面包覆SiO_2,制得Fe_3O_4@SiO_2磁性纳米颗粒.然后由PBLG水解制得PGA为共聚组分,过硫酸铵为引发剂,EGDMA为交联剂,使用自由基共聚制备交联共聚物,同时加入Fe_3O_4@SiO_2纳米颗粒,制备得到Fe_3O_4@SiO_2@PGA磁性纳米粒子.通过核磁(~1H-NMR),红外(FT-IR),X-射线衍射(XRD),动态光散射(DLS)和透射电镜(TEM)等一系列手段对磁性纳米粒子的结构和形貌进行了表征,初步证明了制备的样品具有稳定的结构和良好的磁性.     

高气体阻隔石墨/环氧纳米复合材料的可控制备

针对无内衬复合材料压力容器的气体渗漏问题,提出了一种具有高气体阻隔性能的石墨/环氧微结构有序复合材料的制备方法。采用湿化学沉淀的方法将Fe3O4磁性纳米粒子吸附到石墨微片(GNPs)的表面,实现石墨微片的表面磁性修饰(mGNPs)。在分析磁性片状粒子代表单元在磁场条件下的受力情况的基础上,确定了定向排列m-GNPs所需最小磁场强度40mT。将m-GNPs引入到环氧树脂中,通过外加磁场诱导定向排列,制备出了石墨/环氧微结构有序复合材料(m-GNPs/EP)。氦检漏试验结果表明,1%质量分数的m-GNPs/EP的氦漏率较纯树脂提高了1个数量级,较GNPs随机排列的复合材料氦漏率提高了69%。     

水溶性磁性Fe_3O_4纳米粒子对小麦生长影响的研究

水溶性磁性Fe_3O_4纳米颗粒由于其良好的生物相容性、超顺磁性等特征,在生物领域常被用来作为磁性载体材料,其广泛的生产和应用增加了它们在环境中释放的可能性,需对其环境生物安全性进行评价.首先合成了水溶性磁性Fe_3O_4纳米纳米粒子,并用透射电子显微镜和马尔文粒度分析仪对其进行形貌分析和表征.然后在不同的浓度下(0、0.72、1.44、3.6 mg/mL)研究了水溶性磁性Fe_3O_4纳米粒子对小麦生长的影响,结果显示随着浓度的增加,磁性Fe_3O_4纳米纳米粒子对小麦生长的抑制越明显,造成生长抑制和根结构损伤.结果证明了水溶性磁性Fe_3O_4纳米颗粒对小麦植物存在一定的生物毒性,其环境排放应该严格限制.     

氧化沉淀法制备纳米Fe_3O_4及其类Fenton催化活性

通过化学氧化沉淀法制备出球形和八面体形貌的Fe3O4纳米颗粒,对其进行XRD、Raman和SEM等表征。以合成的纳米Fe3O4催化H2O2氧化降解橙黄Ⅱ,考察了不同形貌Fe3O4的类Fenton催化活性。结果表明:使用化学氧化沉淀法制备Fe3O4,在低pH(8⁹)条件下所得到的产物呈类球形,高pH(13)条件得到的产物为八面体形貌,其粒径均在210nm左右,并且结晶良好。Fe3O4/H2O2体系能有效降解橙黄II,并且催化反应主要发生在Fe3O4表面,最佳催化条件为pH 3.0、温度40℃。类球形Fe3O4纳米颗粒的催化活性高于八面体Fe3O4,并且Fe3O4具有良好的化学稳定性,重复使用4次效果稳定。     

Fe_3O_4水基磁流体的合成及其在油田污水处理中的应用

采用反滴加-化学共沉淀法,以Fe Cl3·6H2O和Fe SO4·7H2O为原料、H2O为基液、Na OH为沉淀剂、聚乙二醇(PEG)为表面活性剂合成Fe3O4水基磁流体,通过正交实验优化,得到最适宜的反应条件。通过XRD、AGM、TEM、TGDSC等对磁性纳米粒子进行表征。结果表明:当Fe3+和Fe2+的浓度为0.3 mol·L-1、n(Fe3+)/n(Fe2+)为1.5、体系p H值为12、反应温度为50℃、反应时间为60 min、PEG质量浓度为60 g·L-1时,产品的粒度平均为31.98 nm,饱和磁强度平均为55.82 emu/g;水基磁流体与聚铝、聚丙烯酰胺复配使用,结合磁分离装置,净水效果和处理效率明显提高,处理后的污水油含量小于1 mg·L-1,除油率可达99%,悬浮物含量降至3 mg·L-1以下,水质达到回注A级标准。     

磁性纳米探针流动注射化学发光检测肿瘤细胞

将人B淋巴瘤细胞(Ramos)的核酸适体TE02和钴纳米粒子(CoNPs)标记的DNA按1∶10的比例组装到金磁核壳结构Au@Fe3O4上,得到一种新型磁性生物条形码纳米探针(TE02/CoNPs/Au@Fe3O4)。通过适体TE02与96孔板上捕获探针的部分杂交,将所构建的磁性纳米探针固定到96孔板上。进一步利用Ramos细胞表面蛋白与适体TE02的特异性识别,将TE02/CoNPs/Au@Fe3O4纳米探针结合到Ramos细胞表面。磁性分离后,加入连接DNA,通过链取代反应将Ramos细胞表面的TE02/CoNPs/Au@Fe3O4纳米探针解离下来,进而作为信号放大的中转站,通过稀硝酸溶解,释放大量二价钴离子(Co2+)。基于Co2+催化鲁米诺-过氧化氢化学发光反应体系,采用流动注射进样技术,实现对Ramos细胞的高灵敏度、高选择性分析检测,线性范围为100¹0 000个Ramos细胞,检测限可达86个Ramos细胞,并成功应用于血清样品中Ramos细胞的分析测定。     

改性磁性材料处理油田废水的研究

以改性Fe3O4磁粉为磁种、改性Fe3O4磁粒为滤料,采用磁种-磁滤-砂滤联合工艺处理江苏油田废水,考察了磁种投加量、搅拌强度、磁感应强度及磁滤速度对除油效果的影响.结果表明,改性后的Fe3O4磁粉对油田废水有良好的除油效果,除油率比未改性的Fe3O4磁粉平均提高了17.5%.在磁种投加量为300 mg/L、搅拌强度为250 r/min、磁感应强度为0.081 9 T、磁滤速度为25 m/h的最佳工艺条件下,当进水平均含油量为111.5 mg/L时,出水平均含油量降为8.3mg/L,平均除油率达92.5%,达到了<污水综合排放标准>(GB 8978-1996)的二级标准.     

Fe2O3有机物光催化降解有机染料的研究进展

探讨了Fe2O3/H2O2体系在可见光下降解有机染料的研究进展,采用Fe2O3/H2O2体系,对大红4BS、甲基橙等染料进行了光氧化降解实验,得出Fe2O3/H2O2/太阳光体系和Fe2O3/H2O2/UV体系在不同pH值条件下的光降解效率。     

Discoloration and mineralization of Reactive Red HE-3B by heterogeneous photo-Fenton reaction

Discoloration and mineralization of Reactive Red HE-3B were studied by using a laponite clay-based Fe nanocomposite (Fe-Lap-RD) as a heterogeneous catalyst in the presence of H2O2 and UV light. Our experimental results clearly indicate that Fe-Lap-RD mainly consists of Fe2O3 (meghemite) and Fe2Si4O10(OH)2 (iron silicate hydroxide) which have tetragonal and monoclinic structures, respectively, and has a high specific surface area (472 m2/g) as well as a high total pore volume (0.547 cm3/g). It was observed that discoloration of HE-3B undergoes a much faster kinetics than mineralization of HE-3B. It was also found that initial HE-3B concentration, H2O2 concentration, UV light wavelength and power, and Fe-Lap-RD catalyst loading are the four main factors that can significantly influence the mineralization of HE-3B. At optimal conditions, complete discoloration of 100 mg/L HE-3B can be achieved in 30 min and the total organic carbon removal ratio can attain 76% in 120 min, illustrating that Fe-Lap-RD has a high photo-catalytic activity in the photo-assisted discoloration and mineralization of HE-3B in the presence of UV light (254 nm) and H2O2.     

亚硝酸盐对含氯盐砂浆内钢筋钝化膜组成的影响

采用X射线光电能谱仪(XPS)研究了NaNO_2对含氯盐砂浆内钢筋钝化膜微结构的影响,阐明了亚硝酸盐阻锈作用下砂浆内钢筋钝化膜的微结构变化规律及其特征.研究结果表明:NaNO_2在碱性环境下与Fe元素反应生成中间产物Na_2FeO_2和(NaFeO_2)_2,进一步促进Fe_3O_4的生成,提高了阻锈效果;NaNO_2的掺入促进了反应式向正向移动,提高了钝化膜中Fe_3O_4的含量;当普通碳钢钝化膜内5nm处Fe~(3+)/Fe~(2+)的百分比大于表层的Fe~(3+)/Fe~(2+)百分比时,钝化膜内部的致密性优于表面.NaNO_2不参与钝化膜的组成,但参与生成钝化膜的反应过程,该反应过程为缓慢的动态平衡过程,可通过改变反应物的含量控制钝化膜厚度.     

花状MoS2/Fe3O4材料的制备及其吸波性能研究

通过水热法制备花状MoS2/Fe3O4吸波材料,利用SEM,XRD及VSM对其进行微观形貌、物相组成及磁性表征,并对其吸波性能进行研究。结果表明,MoS2花状饱满,同时,Fe3O4纳米微球分散在MoS2花瓣边缘和纳米片间隙中。当样品与石蜡质量比为3:7,匹配厚度1.97mm时,在11.34GHz时最小反射损耗为-54.21dB,其有效吸收带宽为3.2GHz,该材料表现出优异的吸波性能。     

碳化与氯盐对混凝土孔溶液中钢筋钝化的影响

采用X射线衍射(XRD)、X射线光电子能谱(XPS)和扫描电子显微镜(SEM),研究了碳化与氯盐腐蚀作用下,混凝土孔溶液中钢筋锈蚀物的组成和微结构特征,阐明了腐蚀因素作用下钢筋的腐蚀机理.结果表明:含氯盐混凝土孔溶液中钢筋表面钝化膜和锈蚀物共存,锈蚀物表面较为致密,主要组成为FeOOH和FeO;碳化混凝土孔溶液中钢筋表面有黄黑色锈蚀物生成,锈蚀物呈疏松多孔棒状,主要组成为FeOOH、Fe_3O_4和Fe_2O_3;碳化与氯盐复合混凝土孔溶液中钢筋表面有大量黄褐色锈蚀物生成,锈蚀物表面呈分层剥落状,主要组成为FeOOH、Fe_3O_4和FeCl_3,其中FeOOH含量高达60%以上;从含氯盐混凝土孔溶液到碳化混凝土孔溶液再到碳化与氯盐复合混凝土孔溶液,钢筋锈蚀物中Fe的XPS扫描峰值逐渐增强,Fe的氧化物含量增多,钢筋腐蚀越来越严重.     

Zero-valent iron reduction of nitrate in the presence of ultraviolet light,organic matter and hydrogen peroxide

This paper describes the use of metallic iron (Fe(0)) powder for nitrate removal in a well-mixed batch reactor. Important variables explored include Fe(0) dosage (1-3g/L), UV light intensity (64-128 W), and the presence of propanol (20 mg/L as DOC) and H(2)O(2) (100-200 mg/L). Accumulation of ferrous ions released from the Fe(0) surface can be expressed by an S-curve, which involves lag growth phase, exponential phase, rate-declining phase, and saturation phase. The removal of nitrate increases with increasing Fe(0) dosage; however, the removal makes no difference as the Fe(0) dosage is greater than 2 g/L. UV irradiation retards the dissolution of ferrous ion and the removal of nitrate. The species of propanol, which has a functional group of -OH, plays a role of organic inhibitor for Fe(0) corrosion. The presence of H(2)O(2) appears to inactivate all reactions as the Fe(0) of 10 microm was used; the final H(2)O(2) remains intact throughout the entire reaction period, and there were no removal of nitrate and no dissolution of ferrous ion. Surprisingly, with the use of a larger Fe(0) particle size of 150 microm, the H(2)O(2) was seen to decompose rapidly through Fenton reaction. Nevertheless, the rate of ferrous accumulation or nitrate removal is slow.     

Cationic polymer and clay or metal oxide combinations for natural organic matter removal.

The effect of adding suspended matter in the form of clay or metal oxide when a cationic polymer was employed as the primary coagulant was found to be beneficial. The solids provide both an adsorbent for natural organic matter (NOM) and a nucleating species for precipitating the NOM-polymer complex. Metal oxides in conjunction with a cationic polymer were more promising than clay, with effectiveness in the order Fe2O3 > Fe3O4 > Al2O3 > MnO2. Magnesium oxide at a much lower dose was nearly as effective as ferric oxide, but of course raised the pH level significantly. A simpler and more convenient way of having reactive solids present was to add alum to form flocs; for one of the waters studied the alum dose could be reduced by 67% by adding 1 mg/L of polymer, to give equal or better performance than alum alone at the optimum dose.     

As(III) removal by hydrous titanium dioxide prepared from one-step hydrolysis of aqueous TiCl4 solution

Hydrous titanium dioxide (TiO₂·xH₂O) nanoparticles were synthesized by a low-cost one-step hydrolysis process with aqueous TiCl₄ solution. These TiO₂·xH₂O nanoparticles ranged from 3 to 8 nm and formed aggregates with a highly porous structure, resulting in a large surface area and easy removal capability from aqueous environment after the treatment. Their effectiveness on the removal of As(III) (arsenite) from water was investigated in both laboratory and natural water samples. The adsorption capacity on As(III) of these TiO₂·xH₂O nanoparticles reached over 83 mg/g at near neutral pH environment, and over 96 mg/g at pH 9.0. Testing with a As(III) contaminated natural lake water sample confirmed the effectiveness of these TiO₂·xH₂O nanoparticles in removing As(III) from natural water. The high adsorption capacity of the TiO₂·xH₂O nanoparticles is related to the high surface area, large pore volume, and the presence of high affinity surface hydroxyl groups.     

瓷釉用棕色尖晶石颜料

ZnO-Fe2O3-Cr2O3系统是合成陶瓷工业用的大部分棕色颜料的基本三元系统。介绍了如下几种类型的棕色颜料的制备:1ZnFeCrO4,2ZnFeCrO4中部分ZnO被FeO或FeO+NiO置换,3ZnFeCrO4中部分Fe2O3、Cr2O3或Fe2O3+Cr2O4被Al2O3置换;借助X-射线衍射法和热分析,阐述了色料的形成和晶体结构;通过色釉试验,并参照色度测定的数据讨论了色料的组成与结构对色釉颜色的影响。