Removal of Cr(VI) using mesoporous alumina with different kinds of pore structures

Three kinds of aluminas with different pore structures, synthesized using different methods, were investigated for the removal of Cr(VI) by batch adsorption tests. And commercial alumina was investigated to compare the removal efficiency. To understand the adsorption process, kinetics studies were performed and the results showed that the kinetics rate was fitted well by the pseudo-2nd-order kinetic model. The adsorption isotherm studies showed that Langmuir adsorption isotherm model fit the experimental data better. Their adsorption rate and capacities of the four kinds of adsorbents were furthermore compared and analyzed. It showed that the adsorption performance varied and depended on the characteristics, surface area, pore type and the surface modification of the adsorbents. The uniform mesopore structures with well-ordered channels have greater advantages over the disordered pores, and meanwhile, the surface area of the adsorbents also played an important role in the adsorption performances.     

Preparation of ordered porous carbon from tea by chemical activation and its use in Cr(VI) adsorption

Ordered porous carbon was prepared from a new carbon precursor??the tea leaves, the most widely used beverage worldwide by a chemical activation process. We obtained well developed spherical interlinked meso and micro pores with uniform pore morphology and high surface area from green, black and waste tea by NaOH as well as H₃PO₄ activation process. The carbon obtained from green tea by H₃PO₄ activation had the highest BET surface area of 1,285?m²g^?1 with total pore volume of 0.6243?mL?g^?1. The as prepared porous carbon showed high adsorption efficiency of Cr(VI) adsorption from aqueous solution.     

Synthesis of an ordered mesoporous carbon with graphitic characteristics and its application for dye adsorption

An ordered mesoporous carbon (OMC) was prepared by a chemical vapor deposition technique using liquid petroleum gas (LPG) as the carbon source. During synthesis, LPG was effectively adsorbed in the ordered mesopores of SBA-15 silica and converted to a graphitic carbon at 800 °C. X-ray diffraction and nitrogen adsorption/desorption data and high-resolution transmission electron microscopy (HRTEM) of the OMC confirmed its ordered mesoporous structure. The OMC was utilized as an adsorbent in the removal of dyes from aqueous solution. A commercial powder activated carbon (AC) was also investigated to obtain comparative data. The efficiency of the OMC for dye adsorption was tested using acidic dye acid orange 8 (AO8) and basic dyes methylene blue (MB) and rhodamine B (RB). The results show that adsorption was affected by the molecular size of the dye, the textural properties of carbon adsorbent and surface-dye interactions. The adsorption capacities of the OMC for acid orange 8 (AO8), methylene blue (MB) and rhodamine B (RB) were determined to be 222, 833, and 233 mg/g, respectively. The adsorption capacities of the AC for AO8, MB, and RB were determined to be 141, 313, and 185 mg/g, respectively. The OMC demonstrated to be an excellent adsorbent for the removal of MB from wastewater.     

Aminopropyl-modified mesoporous silica nanospheres for the adsorption of Cr(VI) from water

Journal of Porous Materials - Aminopropyl-functionalized mesoporous silica spherical particles were obtained through post-synthetic route. The suitability of this material as an adsorbent for heavy...     

Synthesis of functionalized SBA-15 with ordered large pore size and its adsorption properties of BSA

SBA-15, mesoporous material, is a very excellent candidate for drug delivery system because its pore size is easy to control according to synthesis conditions and the presence of swelling agent. In this study, a known swelling agent, 1,3,5-trimethylbenzene (TMB), was used to increase the pore size with increased aging temperature and prolonged aging time. Furthermore, 3-aminopropyltriethoxysilane (APTES) was incorporated on SBA-15 surface via post synthesis method to separate protein effectively. The samples were characterized by X-ray diffraction (XRD), nitrogen adsorption and desorption analyses, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier Transform Infrared (FT-IR). Adsorption capacity increased with temperature at the isoelectric point (pI) of bovine serum albumin (BSA) regardless of the pore size of SBA-15 samples. Release studies were carried out in the range of pH from neutral to basic solution on unmodified and amine-modified samples. In addition, the adsorption mechanism was investigated by employing the pseudo-first order, pseudo-second order, and intraparticle diffusion models.     

Nanorod-pillared mesoporous rGO/ZnO/Au hybrids for photocatalytic Cr (VI) reduction: Enhanced Cr(VI) adsorption and solar energy harvest

Herein, we fabricated mesoporous ternary hybrids composed of Au-functionalized ZnO nanorods grown on rGO nanosheets. The ZnO nanorods distributed on the rGO nanosheets can act as a pillaring layer to avoid the agglomeration of rGO, leading to the formation of abundant mesopores within the hybrids. The high-surface-area, mesoporous hybrids can offer sufficient active sites and transport channels for efficient adsorption and diffusion of Cr(VI), which was favorable for its photocatalytic reduction due to the adsorption enrichment effects. Moreover, the plasmonic-induced visible-light absorption of Au nanoparticles and efficient charge separation by rGO synergistically contributed to the significantly improved solar-light-driven photocatalytic Cr(VI) reduction properties of the ternary hybrids.     

有序介孔碳和活性炭对阿莫西林的吸附研究

阿莫西林是废水中一类典型的药品与个人护理品类新型有机污染物,会对周围环境和人体健康造成潜在威胁。以蔗糖为碳源、以SBA-15为模板制备有序介孔碳（OMC）。采用动态吸附法研究其对阿莫西林的吸附行为,并与常规吸附材料商用活性炭（GAC）作对比。探讨了废水中阿莫西林的初始浓度、温度及流速对动态吸附的影响。结果表明：在同等条件下,OMC的吸附能力远强于GAC,以OMC为吸附剂可有效去除废水中的阿莫西林类新型有机污染物。     

氙常温吸附性能与多孔碳材料孔径分布关联分析

以多孔碳材料为研究对象,测量分析了材料孔径分布和氙吸附性能,讨论了氙吸附性能与材料孔径分布之间的关联关系。结果表明,多孔材料的微孔孔容与其比表面积呈正相关;大气氙常温吸附集中于多孔材料的微孔孔道内,氙吸附能力与材料中孔无显著关联;氙常温吸附能力与碳材料5.0～7.0?的微孔孔体积相关性较显著,大于10.0?微孔孔容关联较小。     

Synthesis of ordered small pore mesoporous silicates with tailorable pore structures and sizes by polyoxyethylene alkyl amine surfactant

Ordered mesoporous silicates with tailorable pore structures and small pore sizes have been synthesized by using polyoxyethylene alkyl amine surfactant PN-430 [CH₃(CH₂)₁₇N(EO)_x(EO)_y, x + y = 5] as a structure-directing agent under acidic condition. Two-dimensional (2-D) hexagonal (p6mm) mesoporous silicates have been prepared via an evaporation-induced self-assembly (EISA) process. The N₂ sorption isotherms show that the product has a small uniform pore size distribution of 1.8 nm by BJH model, a BET surface area of 730 m²/g and a pore volume of 0.36 cm³/g. 3-D cubic (Pm-3n) mesoporous silicate with small uniform pore size (1.76 nm) can also be prepared at high concentration of PN-430 by EISA method in tetrahydrofuran solvent. The solvothermal post-treatment by n-hexane at 70 °C for 3 d to the above material results in the phase transition of the mesostructure from Pm-3n to P6₃/mmc based on XRD and TEM analyses. In comparison, by using nonionic oligometric alkyl-ethylene oxide surfactant such as Brij 78 (C₁₈H₃₇EO₂₀) or Triton X-100 (CH₃C(CH₃)₂CH₂C(CH₃)₂C₆H₄ EO₁₀) as co-templates, high-quality hexagonal (p6mm) small pore mesoporous silicates have also been prepared in ethanol media. Our results show that the blend templates composed of PN-430 and a small amount of nonionic surfactant can increase the efficiency of organic and inorganic hybrid species assembly, improve the quality of the structural regularity, and decrease the pore size to about 1.65 nm.     

Simultaneous adsorption of aniline and Cr(VI) ion by activated carbon/chitosan composite

Activated carbon/chitosan composite has been used as an adsorbent to remove aniline and Cr(VI) ions from aqueous solutions simultaneously. The effects of preparation conditions such as the ratio of activated carbon to chitosan, crosslinking reagents, crosslinking time, and adsorption conditions including adsorbent dosage, pH value of solution, and contact time on simultaneous adsorption of aniline and Cr(VI) ion were investigated. Experimental results showed that epichlorohydrin was the proper crosslinking reagent, and the ratio of activated carbon to chitosan was kept at 1. When the adsorbent dosage was 4.0 g/L, and the concentrations of aniline and Cr(VI) were lower than 50 and 100 mg/L, respectively, both aniline and Cr(VI) were simultaneously removed at natural pH with high removals (>95%). The presence of Cr(VI) enhanced the adsorption of aniline, while the presence of aniline almost had no influence on the adsorption of Cr(VI). The adsorption processes of both aniline and Cr(VI) followed the pseudo‐second‐order kinetics model, but the sorption of Cr(VI) was preferential to that of aniline by this composite. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39903.     

Synthesis and characterization of ruthenium-containing ordered mesoporous carbon with high specific surface area

A Ru-containing ordered mesoporous carbon with a high specific surface area of 2186 m²/g was synthesized through evaporation-induced multi-constituent co-assembly method, wherein soluble resol polymer is used as the carbon precursor, silicate oligomers as the inorganic precursor, triblock copolymer as the template, and RuCl₃ · 3H₂O as the Ru precursor. The resultant sample was characterized by X-ray diffraction, nitrogen sorption, transmission electron microscopy and scanning electron microscopy. The results showed that the carbon material exhibited highly ordered mesoporous structure, and the ruthenium particles with sizes of ∼2 nm were uniformly distributed in the carbon matrix. The sample was used to catalyze benzene hydrogenation, which displayed high efficiency for this reaction.     

Different N-containing functional groups modified mesoporous adsorbents for Cr(VI) sequestration: Synthesis, characterization and comparison

Ordered mesoporous SBA-15 has been functionalized by aminopropyl, imidazole and triazole groups by one or two-step post-grafting route and investigated as adsorbents of hexavalent chromium in aqueous solutions. XRD, N₂ adsorption–desorption measurements, FT-IR, solid state NMR and element analysis techniques have been employed to prove the ordered mesoporous structures of the functionalized SBA-15 and the successful immobilization of the organic functional moieties on SBA-15. The Cr(VI) adsorption behavior on the resultant adsorbents were examined by a batchwise method. The results show that all adsorbents exhibit the fast adsorption rate and the excellent adsorption capacity. Electrostatic interaction between the adsorbents and adsorbate plays an important role in the adsorption process. Equilibrium data were well fitted to the Langmuir and Freundlich adsorption models.     

Synthesis and characterization of mesoporous carbon with narrow pore size distribution derived from rare earth–macromolecule complexes

Mesoporous carbon with narrow pore size distribution was novelly derived from rare earth–macromolecule complexes, which were formed by the coordination between grafted novolac‐type phenolic resin and rare earth ions (Ce³⁺). The as‐made resins or carbons were characterized by infrared spectrum, thermogravimetry, carbon tetrachloride adsorption, nitrogen adsorption, and scanning electron microscope. The results showed that the rare earth–macromolecule complexes were formed successfully, which could promote the dispersion of rare earth elements in the precursor and further control the pore structure and pore size distribution of as‐made mesoporous carbon during steam‐activation process. The as‐made mesoporous carbon exhibited typical mesoporous structure and relatively narrow pore size distribution, and the mesoporosity of it was up to 88%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of mesoporous carbon and its adsorption property to biomolecules

Mesoporous carbon (MC) with high surface area and large pore volume was synthesized using mesophase pitch as a carbon precursor and nanosized MgO as an additive. The maximum surface area, largest pore volume and highest mesoporous ratio of as-prepared MC were up to 1400 m²/g, 2.8 cm³/g and 89%, respectively. The mesoporous structures (3–40 nm) of MC were directly observed under SEM and TEM. The adsorption capacity and adsorption rate of MC to vitamin B₁₂ (VB), chicken egg white albumin (CEWA) and bovine serum albumin (BSA) were proportional to the mesopore volume and average pore size. MC (PM4-OC) exhibited the maximum adsorption capacity to the typical biomolecules, 486, 140 and 176 mg/g for VB, CEWA and BSA, respectively. In contrast, Maxsorbs (commercial activated carbons) with a surprising surface area gave a very low adsorption to such biomolecules. The research indicates that MC may be potential in the selective adsorption and separation of biomolecules, based on a molecule sieve effect.     

生物质吸附材料对Cr(VI)的吸附还原研究进展

重金属污染是当今工业发展所面临的一个重要环境问题,传统处理含铬废水的方法具有工艺简单、操作方便等优点,但存在二次污染、处理成本高等问题。寻找成本低、去除效率高的重金属废水处理方法是当下研究的一个重要方向。本工作介绍了生物质吸附法对含铬废水的处理研究,简述了生物质材料在金属吸附回收领域的优势,分析了当前生物质吸附材料的研究内容和发展现状,归纳了目前常用的物理、化学改性方法,并详细介绍了改性生物质材料对Cr(VI)的吸附效果,然后根据吸附剂表面活性基团与吸附质之间相互作用的类型,分析总结了生物质吸附材料对Cr(VI)的四种吸附机理以及在吸附过程中氨基、羟基、硫醇等活性基团作为电子供体对Cr(VI)的还原机理。最后,从研究与应用的角度,对生物质吸附材料吸附还原Cr(VI)的未来研究方向做出展望。     

新型介孔碳的制备及对罗丹明B的吸附动力学研究

采用SBA-15氧化硅分子筛为模板制备有序介孔碳CMK-3,研究了CMK-3作为吸附剂在水溶液中对罗丹明B的吸附作用,同时研究了初始浓度、pH和温度对吸附的影响.结果表明随着初始浓度的增大、pH增加和温度升高,吸附量增大,但是在较低的pH下,吸附量增加的较小,当pH较高时,吸附量增加的较多.分别采用拟一级反应和拟二级反应模型考察了吸附动力学,并计算了这些动力学模型的速率常数.拟二级反应模型和实验数据之间有较好的相关性.     

Studies of adsorption behavior of crosslinked chitosan for Cr(VI), Se(VI)

In this work, it was found that crosslinked chitosan (CCTS) had strong adsorption ability for some anions under certain conditions. Cr(VI) and Se(VI) existed in anion forms in aqueous solution, and their adsorption rates by CCTS were 97% for Cr(VI) at pH 3.0 and 95% for Se(VI) at pH 4.0. In addition, the adsorption balance time and isotherm of CCTS for Cr(VI) and Se (VI) were discussed and adsorption mechanism was explained. This research will be useful for designing CCTS‐based adsorption for metallic toxin removal and preconcentrating Cr(VI) and Se(VI) in their trace analysis. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3216–3219, 2000     

酚醛树脂对介孔碳孔结构及有序性的影响

以酚醛树脂为碳前体,三嵌段聚合物F127作为模板剂,采用溶剂挥发自组装法制备了有序介孔碳材料。采用凝胶渗透色谱测定了不同合成温度酚醛树脂的分子量;使用X射线衍射、透射电镜和N2吸/脱附等手段对有序介孔碳进行了表征。研究了合成酚醛树脂的温度对介孔碳孔径分布及有序性的影响。结果表明,随着合成酚醛树脂的温度从75℃升到95℃,介孔碳的有序性先增后减:酚醛树脂的合成温度为85℃时,所得介孔碳有较好的有序性,介孔孔容和比表面积分别为0.115cm3/g和127m2/g,平均孔径为3.41nm。