反应吸附脱硫中有序介孔Cu-ZnO-l_2O_3吸附剂提高其饱和硫容（英文）

目前汽柴油中的含硫化合物是造成酸雨和PM2.5的重要原因之一.随着污染的日益严重,对汽柴油的深度脱硫受到越来越多的关注.环境保护组织颁布了较为严格的法律措施,规定硫含量低于10 ppm.然而,传统的加氢脱硫工艺(HDS)很难满足在深度HDS的同时辛烷值损失较少.为了减少辛烷值损失,脱硫技术和催化剂应具有较好的选择性.因此,在FCC汽油升级的过程中,减少辛烷值损失的超深度脱硫工艺是重要研究课题之一.目前,一些新型的深度脱硫技术包括吸附脱硫、氧化脱硫和生物脱硫.其中吸附脱硫具有高选择性、低能耗等优点,而反应吸附脱硫则被广泛研究和工业化生产.常见Ni/ZnO吸附剂利用高空速控制辛烷值损失,但频繁的再生过程影响催化剂的稳定性.目前,一种新型的Cu/Zn O吸附脱硫剂用于固定床中,具有较高的脱硫活性、稳定性和高选择性.目前,铜基吸附剂面临着ZnO的饱和硫容、稳定性及活性组分Cu结焦问题.Al_2O_3作为稳定剂可以提高反应活性和稳定性,其中有序介孔能够提供较大的比表面积、孔径、规整的孔结构和较好的分散活性组分的能力,从而有利于分子之间的扩散.本文利用一步溶剂蒸发自组装法合成了具有有序介孔的Cu-Zn O-Al_2O_3吸附剂.SXRD/WXRD结果,证实合成了具有有序介孔结构的Al_2O_3,且添加Cu和Zn物种后,其结构并未发生改变,但当Zn的添加量达到25 wt%时,其有序介孔结构发生改变.有序介孔的Cu-Zn O-Al_2O_3吸附剂具有较高的比表面积、孔容及孔径,添加过量的Zn O后,其比表面积明显降低.TEM和AADF-STEM结果发现,所制Cu-Zn O-Al_2O_3吸附剂具有规则的介孔结构,并且Cu,Zn,Al和O分散均匀,与XRD和BET结果一致.热重结果表明,有序介孔Cu-Zn O-Al_2O_3吸附剂具有较好的热稳定性.通过与商业Cu-Zn O-Al_2O_3吸附剂进行对比,有序介孔Cu-Zn O-Al_2O_3吸附剂具有较高脱硫活性、饱和硫容及稳定性.     

Cu0 & Cu

铜基催化剂是工业合成甲醇中常用的催化剂,其主要包含Cu, ZnO, Al2O3三种组分,研究各组分在催化合成甲醇过程中的本质作用及其相互间的协同作用不仅是一个催化基础科学问题,同时对于设计和合成新型高性能的铜基催化剂也有重要指导作用.以往的研究主要针对Cu和ZnO二元组分,关于Al2O3的作用很少有报道,主要观点认为Al2O3起结构助剂的作用.在Cu/Al2O3/ZnO(0001)-Zn模型催化体系的研究中,我们发现Al2O3具有稳定Cu+的能力.为了更接近于实际催化体系,并进一步探索铜基催化剂中载体Al2O3及ZnO的作用,我们制备了负载型的5 wt%Cu/Al2O3及5 wt%Cu/ZnO催化剂,并通过原位傅里叶变换红外光谱(in situ FTIR)、准原位X射线光电子能谱(ex situ XPS)及高灵敏度低能离子散射谱(HS-LEIS),着重考察H2还原及CO2加氢过程中表面吸附物种的转变及催化剂表面结构变化,更深一步理解Cu, ZnO, Al2O3三组分在催化CO2加氢过程中所起的作用及相互间的协同作用.通过XRD, BET和TEM表征,发现采用浸渍负载法制备的、经过焙烧后的5 wt%Cu/Al2O3及5 wt%Cu/ZnO催化剂的结构和形貌有明显差别, Al2O3载体具有较大的比表面积, CuO在其表面分散性较好,而ZnO的比表面积很小、Cu O颗粒也相对较大.ExsituXPS及HS-LEIS显示,经过H2还原后, Cu在Al2O3表面的颗粒粒径略有增大,表面仍有较大比例的Cu+物种.以CO为探针分子的FTIR光谱也表明, H2还原后5 wt%Cu/Al2O3存在一定量的Cu+,而5 wt%Cu/ZnO催化剂还原后形成Cu纳米粒子表面被ZnOx包覆, exsituXPS及HS-LEIS的深度剖析也证实了上述结果.CO2加氢过程中, 5wt%Cu/Al2O3表面能够形成大量碳酸氢盐及碳酸盐物种并在升温过程中逐渐转变为甲酸盐,表面仍有一定量的Cu+;5wt%Cu/ZnO表面形成的碳酸盐及碳酸氢盐物种含量相对较少,但Cu-ZnOx的协同作用形成活化H2的高活性表面,在室温下就可以生成甲酸盐物种,在随后的升温过程中甲酸盐逐渐转变为甲氧基.通过对比负载型Cu/Al2O3及Cu/ZnO催化剂的研究,得以更加深入地理解铜基催化剂中载体在CO2加氢制甲醇过程中所起的作用:Al2O3能较好分散Cu,且能够稳定Cu+;相对于ZnO, Al2O3具有较强的吸附CO2能力,能够在表面形成大量的碳酸氢盐物种及碳酸氢盐物种,与表面Cu作用在升温过程中能够生成大量的甲酸盐物种;对于5wt%Cu/ZnO在H2还原和CO2加氢过程中Cu表面被ZnOx包覆,其高度缺陷的表面结构能在室温下解离H2.这些结果表明,实际CuZnAlO催化剂上CO2加氢制备甲醇的活性位点可能包含Cu+, Cu0及相邻的具有高度缺陷结构的ZnOx包覆层.     

介孔α-Fe2O3表面配合反应平衡常数测定

采用十二胺为模板剂、氨水做沉淀剂成功制备了介孔α-Fe2O3,通过粉末X射线衍射(XRD)、透射电镜(TEM)、N2吸附/脱附技术对样品晶相、形貌和比表面积进行了表征.根据介孔α-Fe2O3悬浮液的酸碱滴定数据,使用FITEQL软件,采用双电层恒电容模型计算得出了介孔α-Fe2O3的表面酸碱反应平衡常数.在此基础上研究了Cu2+,Pb2+,Zn2+在介孔氧化铁表面的吸附行为,使用WinSGW软件模拟得出了相应的表面配合反应平衡常数并讨论了其吸附机理.     

功能化有序介孔碳对重金属离子Cu(Ⅱ)、Cr(Ⅵ)的选择性吸附行为

以三嵌段共聚物F127为模板剂,酚醛树脂为碳源,正硅酸乙酯为硅源,三组分共组装合成介孔碳-氧化硅纳米复合物,再经HF去除氧化硅,得到有序介孔碳(OMC).X射线衍射(XRD)、透射电子显微镜(TEM)、低温N2吸脱附(BET)等测试表明,所得样品具有高度有序的介孔结构,比表面积和孔容分别为1330m2·g-1和2.13cm3·g-1,平均孔径6.4nm.对其先氧化、后氯化、再胺化,得到不同胺基接枝量的胺化介孔碳(C-NH2(m),m为加入的乙二胺的质量(g)).傅里叶变换红外(FT-IR)光谱表征结果证实,胺基官能团成功接枝到有序介孔碳表面.TEM测试表明介孔碳的有序孔道结构得到了较好的保持.以有序介孔碳、胺化介孔碳作吸附剂对Cu(Ⅱ)、Cr(Ⅵ)进行选择性吸附研究.结果表明:功能化修饰前,样品对Cu(Ⅱ)、Cr(Ⅵ)饱和吸附量分别为213.33、241.55mg·g-1;修饰后饱和吸附量可分别达到495.05、68.21mg·g-1.功能化介孔碳表现了较强的选择性吸附Cu(Ⅱ)的能力.     

溶剂极性对微波辐射老化制备前驱体及CuO/ZnO/Al2O3催化剂结构的影响

在制备CuO/ZnO/Al2O3催化剂的老化过程中,采用微波辐射老化技术,着重研究了溶剂极性对前躯体物相组成,烧后CuO/ZnO/Al2O3催化剂结构及其在浆态床合成甲醇工艺中催化性能的影响。通过XRD、DTG、H2-TPR,FTIR、HR-TEM和XPS对前驱体及催化剂表征表明,沉淀母液在微波辐射条件下进行老化,溶剂的极性对前躯体物相组成及催化剂结构影响显著。随着溶剂极性的增大,Zn2+/Cu2+取代Cu2(CO3)(OH)2/Zn5(CO3)2(OH)6中Cu2+/Zn2+的取代反应增强,使得前躯体中(Cu,Zn)5(CO3)2(OH)6和(Cu,Zn)2(CO3)(OH)2物相的含量增多,结晶度提高,导致烧后CuO/ZnO/Al2O3催化剂中CuO-ZnO协同作用增强,且CuO晶粒减小,表面Cu含量增加,催化剂活性和稳定性提高。水溶剂的极性最大,制备的催化剂活性和稳定性最好,甲醇的时空收率(STY)和平均失活率分别为320 mg.g-1.h-1和0.11%.d-1。     

沉淀温度对CuO/ZnO/Al2O3催化剂前驱体物相及催化水煤气变换反应活性的影响

 用X射线衍射、差热热重测定、程序升温还原、N2吸附、N2O滴定和常压微反活性评价技术考察了沉淀温度对CuO/ZnO/Al2O3系催化剂及其前驱体的物相和催化水煤气变换反应活性的影响. 结果表明,在沉淀温度为60～90 ℃时,催化剂前驱体中主要存在Cu2CO3(OH)2,(Cu,Zn)2CO3(OH)2和(Cu,Zn)6Al2(OH)16CO3·4H2O三种物相. 焙烧后的催化剂样品中形成了较多的CuO-ZnO固溶体,沉淀温度升高有利于CuO-ZnO固溶体的形成及催化剂活性的提高. 水煤气变换反应是一个非结构敏感型反应.     

介孔氧化铝复合材料负载铂催化剂上丙酮酸乙酯的不对称氢化反应

采用固相研磨法制备了有序介孔树脂FDU-14孔道限阈分散的Al2O3复合材料Al2O3@FDU-14.以其为载体,采用浸渍法制备了4.0％ Pt/Al2O3@FDU- 14催化剂,并利用X射线衍射、透射电子显微镜和N2吸附等手段对催化剂进行了表征.结果表明,Pt/Al2O3@FDU- 14催化剂保持了FDU-14的介孔...     

新型功能介孔吸附剂NiNb_2O_6的合成及其吸附性能研究

通过柠檬酸溶胶-凝胶反应,合成了新型功能介孔NiNb2O6吸附剂,通过X-射线粉末衍射仪(XRD)、透射电镜(TEM)和比表面积及孔径分析(BET)对其结构进行表征。通过影响因素实验、吸附动力学实验和等温吸附实验,探讨了NiNb2O6吸附剂对水溶液中亚甲基蓝的吸附性能和机理。结果表明,NiNb2O6介孔吸附剂具有正交相晶体结构,平均粒径为30~200nm,比表面积为66.3m2/g。吸附剂用量、温度和pH值均对吸附行为有一定的影响;在35℃时,亚甲基蓝在吸附剂上吸附行为符合Langmuir方程,吸附动力学符合拟二级动力学方程,初始浓度为40mg/L,pH值为7.03时,0.2g介孔吸附剂NiNb2O6对亚甲基蓝的吸附量最大,吸附过程中液膜扩散为主要速率控制步骤。     

TiO2-Al2O3复合氧化物载体焙烧温度对Au-Pd催化剂加氢脱硫性能的影响

 采用溶胶-凝胶法制备了介孔TiO2-Al2O3复合氧化物载体,考察了载体的焙烧温度对负载型Au-Pd双金属催化剂加氢脱硫性能的影响,并采用X射线衍射、吸附吡啶的程序升温脱附、程序升温还原、红外光谱和N2物理吸附等技术对载体及催化剂进行了表征. 结果表明,不同温度焙烧的TiO2-Al2O3复合载体都具有介孔结构,其中773 K焙烧制得的TiO2-Al2O3复合载体的比表面积和孔容较大, B酸中心较多,以其为载体的Au-Pd 催化剂具有较好的加氢脱硫活性. 表征结果表明, 773 K焙烧制得的Au-Pd/TiO2-Al2O3催化剂中Au-Pd活性组分与载体的相互作用较强,催化剂上形成的AuxPdy合金的晶粒较小且数量较多,催化剂的酸量和活性组分的分散度较大,并且其上进行的加氢脱硫反应的活化能较低,这些因素均有利于催化剂活性的提高.     

催化裂化USY／ZnO／Al2O3脱硫添加剂的高温水热失活

 对USY／ZnO／Al2O3汽油催化裂化脱硫添加剂经高温水热老化处理前后的脱硫性能进行了考察，发现老化后添加剂的脱硫性能大幅度下降．采用XRD和IR等技术对USY／ZnO／Al2O3添加剂在高温和高温水热条件下失活的原因进行了研究．结果表明，在高温下，ZnO可与USY沸石中的铝发生固相反应生成ZnAl2O4尖晶石，从而造成USY晶体结构崩塌，转变成无定形状态．在ZnO含量较高的条件下，ZnO可继续与USY晶体结构崩塌后生成的无定形的硅和铝的氧化物反应，生成Zn2SiO4硅锌矿和ZnAl2O4尖晶石结构．这一方面使添加剂失去了可形成硫化物吸附中心的ZnO，另一方面破坏了硫化物的裂化活性组分USY，从而造成添加剂脱硫性能下降甚至失去脱硫活性．ZnO对USY的破坏作用主要与温度有关．在USY／ZnO／Al2O3体系中，ZnO被ZnO与Al2O3之间形成的锌铝尖晶石膜固定并与USY隔离，单纯的高温条件对添加剂的破坏不显著，而水蒸气可以促进ZnO的移动，有利于ZnO与USY的接触，因此在高温和有水蒸气存 在的条件下添加剂的结构易遭到破坏．     

Synthesis of Fe<Superscript>3+</Superscript> doped ordered mesoporous TiO<Subscript>2</Subscript> with enhanced visible light photocatalytic activity and highly crystallized anatase wall

Fe³⁺ doped mesoporous TiO₂ with ordered mesoporous structure were successfully prepared by the solvent evaporation-induced self-assembly process using P123 as soft template. The properties and structure of Fe³⁺ doped mesoporous TiO₂ were characterized by means of XRD, EPR, BET, TEM, and UV–vis absorption spectra. The characteristic results clearly show that the amount of Fe³⁺ dopant affects the mesoporous structure as well as the visible light absorption of the catalysts. The photocatalytic activity of the prepared mesoporous TiO₂ was evaluated from an analysis of the photodegradation of methyl orange under visible light irradiation. The results indicate that the sample of 0.50%Fe–MTiO₂ exhibits the highest visible light photocatalytic activity compared with other catalysts.     

Highly ordered molecularly imprinted mesoporous silica for selective removal of bisphenol A from wastewater

Selective removal of bisphenol A from wastewater is quite challenging primarily because of its low concentration and matrix complexity. To this end, according to the molecular structure of bisphenol A, we designed a functional monomer for the preparation of molecularly imprinted mesoporous silica using click chemistry reaction. The resultant bisphenol A imprinted mesoporous silica was characterized by transmission electron microscopy, small angle X‐ray diffraction, and N₂ adsorption–desorption experiments. The results indicated that the bisphenol A imprinted mesoporous silica possessed a highly ordered periodic hexagonal mesostructure with the Brunauer–Emmett–Teller surface area of 944.28 m²/g. The bisphenol A imprinted mesoporous silica showed fast adsorption kinetics and the saturated adsorption capacity reached up to 88.6 mg/g at pH 6.5, and with relative selectivity factors ranged from 1.06 to 3.20. The adsorption efficiency of the bisphenol A imprinted mesoporous silica was above 97.96% after five extraction/elution cycles. The bisphenol A imprinted mesoporous silica was further applied to the selective removal of bisphenol A from real wastewater samples and showed great promise in practical applications.     

Synthesis of nano‐sized magnetite mesoporous carbon for removal of Reactive Yellow dye from aqueous solutions

In this study, core‐shell structures of magnetite nanoparticles coated with CMK‐8 ordered mesoporous carbon (Fe₃O₄@SiO₂‐CMK‐8 NPs) have been successfully synthesized for the first time by carbonizing sucrose inside the pores of the Kit‐6 mesoporous silica. The nano‐sized mesoporous particles were characterized by X‐ray diffraction, Fourier transform‐infrared spectroscopy, scanning electron microscope, dynamic light scattering, vibrating‐sample magnetometer, Brunauer–Emmett–Teller (BET) and transmission electron microscopy instruments. The obtained nanocomposite was used for removal of Reactive Yellow 160 (RY 160) dye from aqueous samples. The N₂ adsorption–desorption method (at 77 K) confirmed the mesoporous structure of synthesized Fe₃O₄@SiO₂‐CMK‐8 NPs. Also, the surface area was calculated by the BET method and Langmuir plot as 276.84 m²/g and 352.32 m²/g, respectively. The surface area, volume and pore diameter of synthesized nanoparticles (NPs) were calculated from the pore size distribution curves using the Barrett–Joyner–Halenda formula (BJH). To obtain the optimum experimental variables, the effect of various experimental parameters on the dye removal efficiency was studied using Taguchi orthogonal array experimental design method. According to the experimental results, about 90.0% of RY 160 was removed from aqueous solutions at the adsorbent amount of 0.06 g, pH 3 and ionic strength = 0.05 m during 10 min. The pseudo‐second order kinetic model provided a very good fit for the RY 160 dye removal (R² = 0.999). The Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models were applied to describe the equilibrium isotherms, and the Langmuir isotherm showed the best fit to data with the maximum adsorption capacity of 62.893 mg/g. Furthermore, the Fe₃O₄@SiO₂‐CMK‐8 NPs could be simply recovered by external magnet, and exhibited recyclability and reusability for a subsequent six runs.     

The influence of isothermal aging,surfactant and inorganic precursors concentrations on pore size and structural order of mesoporous bioactive glass

Ordered hexagonal mesoporous bioactive glasses (MBGs) are synthesized by an evaporation-induced self-assembly (EISA) method using tetraethylorthosilicate (TEOS), calcium nitrate tetrahydrate (Ca(NO₃)₂.4H₂O) and triethyl phosphate (TEP) as the silicon, calcium, phosphorous sources, respectively, and pluronic P123 as the structure directing agent. The influences of P123, TEOS, TEP, and Ca(NO₃)₂.4H₂O on the structural order and pore size of MBGs at different environmental conditions are studied. The prepared MBGs are characterized by the small angle X-ray diffraction (SXRD), N₂ adsorption-desorption isotherms, and transmission electron microscopy (TEM). The study revealed that polymerization degree of inorganic precursors should be low enough at the initial assembling stage of inorganic species with organic surfactants to form highly ordered mesoporous structure. Concentration of Ca(NO₃)₂ governs the formation of ordered mesostructure in MBGs by complexation of Ca²⁺ with the hydrophilic group of surfactant P123. Isothermal aging also plays an important role in the formation of highly ordered MBGs as it permits formation of rigid inorganic framework.     

Cu-ZnO-Al2O3复合催化剂上甘油选择氢解合成丙二醇

分别采用均匀共沉淀法、沉积-沉淀法和传统的共沉淀法制备了3种具有相似组成的Cu-ZnO-A1₂O₃催化剂（CZA-HP,CAZ-DP和CZA-CP）Ε同时还采用均匀共沉淀法制备了Cu-ZnO催化剂（CZ-HP）以用于比较.X射线衍射表征结果表明,以上方法制备的Cu-Zn-Al碱式碳酸盐前体中Cu²⁺,Zn²⁺和Al³⁺的混合均匀程度的顺序为CZA-DP3+分散程度的提高和A1₂O₃与ZnO的紧密接触使得Cu-ZnO-A1₂O₃催化剂中金属Cu和ZnO具有更小的粒径.但ZnO-A1₂O₃间紧密接触也阻隔了Cu-ZnO-A1₂O₃催化剂中金属Cu与ZnO之间的相互作用.因此A1₂O₃的添加使得CZA-HP样品上的Cu粒子表现出最强的氧化还原能力.在473 K和6.0 MPa H₂的反应条件下,以上三种Cu-ZnO-A1₂O₃催化剂均高选择性地催化甘油氢解为丙二醇（30%甘油转化率下的选择性>90%）.Cu-ZnO-A1₂O₃催化剂表面单位Cu原子的本征活性顺序为CZA-DP2O₃的添加还显著地抑制了Cu粒子在反应过程中的聚集,提高了催化剂的稳定性.经6次循环使用后,CZ-HP中Cu粒子的粒径从13.2增至45.2 nm,活性相应下降了45%:而CZA-HP中Cu粒子的粒径从8.3增至19.0 nm,活性仅下降了10%.     

High-temperature hydrothermal synthesis of magnetically active, ordered mesoporous resin and carbon monoliths with reusable adsorption for organic dye

Magnetically active, thermally stable, and ordered mesoporous resin (MOMR-200) and carbon (MOMC-200) monoliths were prepared by one-pot hydrothermal synthesis from resol, copolymer surfactant, and iron cations at high-temperature (200 ^°C), followed by calcination at 360 ^°C and carbonization at 600 ^°C. X-ray diffraction results show that both MOMR-200 and MOMC-200 have ordered hexagonal mesoporous symmetry, and N₂ isotherms indicate that these samples have uniform mesopores (3.71, 3.45 nm), high surface area (328, 621 m²/g) and large pore volume (0.31, 0.43 cm³/g). Transmission electron microscopy shows that iron nanoparticles, which are superparamagnetic in nature, are dispersed in the network. More importantly, the high temperature (200 ^°C) products exhibit much better stability than the samples synthesized at low temperature (100 ^°C). Interestingly, MOMC-200 has higher adsorption capacity for organic dyes when compared with commercial adsorbents (activated carbon and macroporous resin: XAD-4). Combining the advantages such as magnetically active, thermally stable networks, ordered and open mesopores, high surface area, large pore volume, adsorption of pollutants in water and desorption in ethanol solvent, MOMC-200 is potentially important for water treatments.     

Desulfurization of Diesel over Ni/ZnO Adsorbent Prepared by Coprecipitation

Ni/ZnO adsorbents with various Ni/Zn molar ratios were prepared by coprecipitation; their adsorption capacity in reactive adsorption desulfurization (RADS) of diesel oil was investigated. Ni/ZnO exhibits much higher adsorption performance than pure Ni and pure ZnO. The Ni content plays a crucial role in determining RADS activity over Ni/ZnO; the sulfur capacity depends on the ZnO content in Ni/ZnO. The Ni₄/Zn₆ adsorbent shows the optimal performance; the sulfur content in diesel oil is reduced to less than 5 ppm in first 60 h and less than 15 ppm in next 68 h.     

Sol–gel synthesis of mesoporous silicas containing albumin and guanidine polymers and its application to the bilirubin adsorption

The organic–inorganic composite materials based on mesoporous silica were synthesized using sol–gel method. The surface area of silicas was modified by bovine serum albumin (BSA) and guanidine polymers: polyacrylate guanidine (PAG) and polymethacrylate guanidine. The mesoporous silicas were characterized by nitrogen adsorption–desorption analysis, Fourier transform infrared spectroscopy, transmission electron microscopy. The obtained materials were used as adsorbents for selective bilirubin removal. It was shown that the structural properties and surface area of modified materials depend on the nature of polymers. Incorporation of polymers in silica gel matrix during sol–gel process leads to the formation of mesoporous structure with high pore diameter and a BET surface area equals to 346 m²/g for SiO₂/BSA and 160 m²/g for SiO₂/PAG. Analysis of adsorption isotherms showed that modification of silica by BSA and guanidine polymers increases its adsorption ability to bilirubin molecules. According to Langmuir model, the maximum bilirubin adsorption capacity was 1.18 mg/g.     

Synthesis of mesoporous maghemite with high surface area and its adsorptive properties

Mesoporous maghemite (γ-Fe₂O₃) with high surface area was prepared by the thermal decomposition of Fe–urea complex ([Fe(CON₂H₄)₆](NO₃)₃) with the aid of cetyltrimethyl ammonium bromide (CTAB), and its adsorption ability for the removal of fluoride was investigated. X-ray diffraction (XRD), nitrogen adsorption–desorption measurements, transmission electron micrograph (TEM) observations, and magnetic measurements show that the γ-Fe₂O₃ has a mesoporous structure and its crystallite size, specific surface area, and magnetic properties can be controlled by varying the content of CTAB in [Fe(CON₂H₄)₆](NO₃)₃. The maximum adsorption capacity of the mesoporous γ-Fe₂O₃ for fluoride is estimated to be 7.9 mg/g, which suggests that the mesoporous γ-Fe₂O₃ is an excellent adsorbent for fluoride.     

Biomolecule-Assisted Synthesis of Hierarchical Multilayered Boehmite and Alumina Nanosheets for Enhanced Molybdenum Adsorption

The effective utilization of various biomolecules for creating a series of mesoporous boehmite (γ-AlOOH) and gamma-alumina (γ-Al₂O₃) nanosheets with unique hierarchical multilayered structures is demonstrated. The nature and concentration of the biomolecules strongly influence the degree of the crystallinity, the morphology, and the textural properties of the resulting γ-AlOOH and γ-Al₂O₃ nanosheets, allowing for easy tuning. The hierarchical γ-AlOOH and γ-Al₂O₃ multilayered nanosheets synthesized by using biomolecules exhibit enhanced crystallinity, improved particle separation, and well-defined multilayered structures compared to those obtained without biomolecules. More impressively, these γ-AlOOH and γ-Al₂O₃ nanosheets possess high surface areas up to 425 and 371 m² g⁻¹, respectively, due to their mesoporous nature and hierarchical multilayered structure. When employed for molybdenum adsorption toward medical radioisotope production, the hierarchical γ-Al₂O₃ multilayered nanosheets exhibit Mo adsorption capacities of 33.1–40.8 mg g⁻¹. The Mo adsorption performance of these materials is influenced by the synergistic combination of the crystallinity, the surface area, and the pore volume. It is expected that the proposed biomolecule-assisted strategy may be expanded for the creation of other 3D mesoporous oxides in the future.