十二烷基磺酸根插层Ni^2＋-Fe^3＋/Co^2＋-Ni^2＋-Fe^3＋ LDHs及其结构研究

应用水热技术制备了二元Ni^2＋-Fe^3＋-CO3^2- LDHs和三元Co2＋-Ni2＋-Fe3＋-CO32- LDHs,以十二烷基磺酸根离子作为插层客体,通过离子交换反应在酸性溶液中实现了十二烷基磺酸根插层Ni2＋-Fe3＋ LDHs和Co2＋-Ni2＋-Fe3＋-LDHs。十二烷基磺酸根在Ni2＋-Fe3＋LDHs层间出现了2种空间导向和排列：即十二烷基磺酸根以单层垂直方向排布和以双层垂直方向排布在层间;十二烷基磺酸根在三元组分Co2＋-Ni2＋-Fe3＋-LDHs层间只有一种空间排列方式,即十二烷基磺酸根以单层垂直方向排布于Co2＋-Ni2＋-Fe3＋-LDHs层间。     

A highly active oxygen evolution electrocatalyst: Ni-Fe-layered double hydroxide intercalated with the Molybdate and Vanadate anions

Efficient low-cost electrocatalysts in the oxygen evolution reaction (OER) are important components of renewable energy technologies, e.g. solar fuel synthesis and water splitting for powering fuel cells. A great deal of attention has been attracted toward LDHs due to their electrical power and they are potentially applied in the field of electrocatalysts. The present paper reports synthesis of the Ni-Fe-Molybdate and Ni-Fe-Vanadate layered double hydroxides (LDHs) using a simple co-precipitation method. Powder X-ray diffraction, Fourier transform infrared spectra, Transmission electron microscopy, and X-ray energy dispersive spectroscopy spectrum provide successful intercalation of the Vanadate and Molybdate anions. Compared to the bare glassy carbon electrode, in alkaline media, the as-obtained Ni-Fe-MoO₄-LDH represents superior electrocatalytic activity toward water oxidation with the overpotential of 491 mV at10 mA/cm² and a low Tafel slope of 23 mV/dec. Ni–Fe-MoO₄-LDH exhibits good OER activity, which is stated as low onset overpotential, small Tafel slope, and large exchange current density. The current density of the Ni–Fe-MoO₄-LDH nanosheets is about 10 mA cm⁻² at the overpotential of 0.491 (V vs SCE). This value is much larger than that of the Ni–Fe-NO₃-LDH and Ni–Fe-VO₃-LDH nanoparticles.     

[O{MoO( O2)2｝2]2-插层LDHs对软PVC协同阻燃效果的研究

采用共沉淀法制备了MgAl-CO3-LDHs、ZnAl-CO3-LDHs及ZnMgAl-CO3-LDHs,然后采用离子交换法制备了[O{MoO(O2)2}2]2-插层的LDHs;将制得的LDHs样品分别与软PVC共混,并对其阻燃性能与机械性能进行了测试。结果表明,当LDHs阻燃剂的添加量不高于5份时,所得软PVC复合材料的氧指数均随着添加量的增大而增大,其中添加了5份[O{MoO(O2)2}2]2-插层ZnMgAl-LDHs阻燃剂后,软PVC的氧指数由27.5%提高到30.5%,其阻燃性能优于其他几种LDHs阻燃剂,表现出较好的协同阻燃效果。     

多元层状双羟基金属复合氧化物用作阻燃填料制备阻燃纸

以氯化镁(MgCl2.6H2O)、氯化铝(AlCl3.6H2O)、氯化锌(ZnCl2.6H2O)、氯化铁(FeCl3.6H2O)和碳酸钠(Na2CO3)为原料,采用共沉淀法制备了双羟基金属复合氧化物(LDHs,又称水滑石),包括二元Mg-Al-CO23--LDHs、三元Mg-Al-Zn-CO23--LDHs和四元Mg-Al-Zn-Fe-CO23--LDHs;将LDHs作为阻燃填料,用浆内添加法制备了一系列新型阻燃纸;通过红外光谱(FT-IR)、力学性能、燃烧性能等测试对LDHs和阻燃纸进行了表征。结果表明,采用多元LDHs作为阻燃填料所制备的阻燃纸,阻燃性能得到了明显改善,而且随着LDHs元素的增多,其阻燃性能更好。当三元Mg-Al-Zn-CO23--LDHs用量为30%时,阻燃纸可达到难燃级,氧指数达到25.3%。当四元Mg-Al-Zn-Fe-CO23--LDHs用量25%时,阻燃纸即可达到难燃级,氧指数高于25.0%;当四元-Al-Zn-Fe-CO23--LDHs用量30%时,阻燃纸的续燃时间为5 s,灼燃时间为30 s,炭化长度为95 mm,阻燃纸达到GB/T14656—2009的要求。     

Effective removal and fixation of Cr(VI) from aqueous solution with Friedel's salt

Friedel's salt (3CaO·Al₂O₃·CaCl₂·10H₂O or Ca₄Al₂(OH)₁₂Cl₂(H₂O)₄) is a calcium aluminate hydrate formed by hydrating cement or concrete in seawater at a low cost. In the current study, we carefully examined the adsorption behaviors of Friedel's salt for Cr(VI) from aqueous solution at different concentrations and various initial pHs. The adsorption kinetic data are well fitted with the pseudo-first-order Lageren equation at the initial Cr(VI) concentration from 0.10 to 8.00 mM. Both the experimental and modeled data indicate that Friedel's salt can adsorb a large amount of Cr(VI) (up to 1.4 mmol Cr(VI)/g) very quickly (t_1/2 = 2–3 min) with a very high efficiency (>99% Cr(VI) removal at [Cr] < 4.00 mM with 4.00 g/L of adsorbent) in the pH range of 4–10. In particular, the competitive adsorption tests show that the Cr(VI) removal efficiency is only slightly affected by the co-existence of Cl⁻ and HCO₃⁻. The Cr(VI)-fixation stability tests show that only less than 0.2% adsorbed Cr(VI) is leaching out in water at pH 4–10 for 24 h because the adsorption/exchange of Cr(VI) with Friedel's salt leads to the formation of a new stable phase (3CaO·Al₂O₃·CaCrO₄·10H₂O). This research thus suggests that Friedel's salt is a potential cost-effective adsorbent for Cr(VI) removal in wastewater treatment.     

新型受阻胺类光稳定剂N-烯丙基四甲基哌啶醇的合成和表征

在Mg-Al水滑石(Mg-Al LDHs)催化哌啶醇和烯丙基溴反应,合成了一种新型受阻胺类光稳定剂,产物通过IR、MS、元素分析等进行了表征。     

纳米层状双金属氢氧化物的制备及光催化性能研究进展

半导体光催化剂因其高效、生态友好、成本低等优点,可用于解决能源与环境问题。层状双金属氢氧化物(LDHs)是一类由两种或两种以上金属阳离子组成的金属氢氧化物,结构由主体层板和层间的插层阴离子及水分子相互交叠构成。LDHs纳米材料具有带隙可调、比表面积大、种类多样、成本低廉并且易与其他材料复合实现功能化等优点,因此LDHs纳米材料在光催化领域中表现出良好的应用前景。本文系统综述了近年来LDHs纳米材料的制备方法及其在光催化分解水制氢、吸附和降解有机染料,以及光催化还原二氧化碳等光催化领域的最新研究进展,为未来高性能LDHs基纳米催化材料的制备及催化性能调控提供了一定的参考。     

LDHs对碳酸盐激发胶凝材料早期水化反应与力学性能的影响

碳酸盐激发胶凝材料具有低环境影响、易操作、良好材料性能等特点,但也存在抗压强度发展慢等问题,限制其在实际工程中的应用。本研究以层状双氢氧化物(LDHs)为关键改性材料,探究LDHs掺入后碳酸钠激发矿渣的早期性能,结合等温量热法、XRD、TG-DTG、SEM和压汞仪(MIP)等材料表征测试方法,系统分析LDHs对碳酸盐激发胶凝材料水化反应及产物的影响规律。研究结果发现,随着LDHs掺量的增加,碳酸钠激发矿渣早期水化反应速率显著提升。LDHs可作为纳米晶核位点促进水滑石和C-S-H凝胶生长,加快碳酸盐激发胶凝材料早期主要水化产物的生成。水化早期试样孔隙结构得到改善,其1 d抗压强度最高可达22 MPa。     

Zn~(2+)-Ni~(2+)-Fe~(3+)-LDHs新型催化剂的制备及其酸性研究

以Ni(NO3)2?6H2O、Zn(NO3)2?6H2O、Fe Cl3?6H2O为原料,采用均相沉淀法制备了层状形貌的Zn~(2+)-Ni~(2+)-Fe~(3+)-LDHs催化剂材料。吡啶作为分子探针,通过原位红外技术对Zn~(2+)-Ni~(2+)-Fe~(3+)-LDHs的酸性中心和酸量进行了研究。研究表明该材料同时存在路易斯酸(L酸)和布朗克(B酸)酸性中心,其酸量分别为4.4 mmol/g、2.6 mmol/g,L酸酸强度强B于酸。     

荧光类水滑石的细菌检测及杀菌性能

通过阴离子交换法制备万古霉素改性的铕掺杂锌铝类水滑石,并考察该材料对革兰氏阴性细菌的检测识别和对革兰氏阳性细菌的抑菌活性。所制备的产品通过X射线衍射,透射电镜,荧光等进行了表征。结果表明万古霉素改性的铕掺杂类水滑石纳米片层材料的粒径在50nm左右,而且材料具有较好的荧光性能。利用材料的荧光性质和万古霉素与大肠杆菌之间的作用实现了对大肠杆菌的荧光标记检测;同时,该材料可以利用万古霉素的抗菌性实现对革兰氏阳性细菌的杀灭。结果显示,万古霉素改性的铕掺杂类水滑石具有较好的荧光标记细菌性能和杀菌作用。该材料的合成对于致病菌的快速、方便检测和控制有着重要意义。