Preparation and Properties of Pillared Montmorillonite by Polyhydroxyl-aluminum-manganese Cations

Al-Mn-pillared montmoriUonite ( AMPM ) was prepared by using the artificial Na-montmoril-lonite from the Qingfengshan bentonite mine as starting materials mixed with Al-Mn pillaring solutions at different Al / Mn molar ratios ( R ). The basal spacing and specific surface area of the materials were increased significantly compared with untreated c/ays. When R=0.5, the d(001) value and specific surface area of pillared montmoril-lonite were 1.8987 nm and 146.01 m^2 g^-1, respectively. The thermal stability was determined using calcined tests,X-ray diffraction( XRD ) analysis, thermal gravimetry and differential thermal analysis( TG- DTA ). The formed at initial R = 0. 5 exhibited a high stability, the basal interlayer spacing was stabilized at 1. 7859 nm after calcined for 2 h at 300℃. The adsorption behavior of the materials wets studied by adsorption experi-ments. The results show the AMPM and calcined AI-Mn-pilloTed montmoriUonite (CAMPM) exhibit a strong ca-pacity of adsorbing the Zn ( Ⅱ ) in aqueous solution at pH 10.0.     

Comparison of Conventional and Microwave-assisted Synthesis and Characteristics of Aluminum-pillared Rectorite

The synthesis and characterization of aluminum-pillared rectorite were studied. The synthesis was conducted with both conventional heating and microwave irradiation. Microwave irradiation was found to enhanee the intercalation and ion-exchange during synthesis, and to be able to produce the rectorite with a larger d001 aad a better uniformity. The specific surface area is 180 m^2 / g and basal spacing is 3.2 nm.The texture change and thermal and hydrothermal stability of cross- linked rectorite were examined using XRD, FTIR, nitrogen-adsorption and TGA. The experimental results show that the aluminum-pillared rectorite, after calcined at 800℃ for 3 hours, can keep the basal aluminum-silicate texture and would not disperse in water at room or an elevated temperature. The alumimum-pillared rectorite shows a high specific surface area, good thermal and hydrothermal stability, and is promising in applications as catalyst carriers and adsorbents for waste treatment.     

Preparation and Microstructure of Al-pillared Interlayered Montmorillonite

Al-pillared interlayerad montmorillonite (Al-PILM) was prepared using the artifcial Na-mont-morillonite from the Qingfengshan betonite nime as a starting material mixed with Al-pillared solutions.The micorstructure of the materials was studied by an X-ray powder diffractometer and a Fourier transfomr infrared (FTIR) spectrometer,The results indicated that the basda spacing [d (001) value ] of the mateials was increased significantly to 1.9194 nm relative to Na-montmorillonite (1.2182 nm) ,After calcined for 2 h at 300 ℃ ,the significantly to 1.9194 nm relative to Na-montmorillonite (1.2182nm) ,After calcined for 2 h at 300℃,the basal spacing was stailized at 1.8394 nm and the layered structure of the materials not destroyed .Themal analysis was conduted by a thermal gravimetry and differential thermal analysis (TG-DTA) instrument,it showed that Al-PILM lost physically adsorbed water below 230.6℃ and water formed by dehydorxylation of the pillars at around 497.1℃,with a peak of the phase transformation at 903.0℃.     

Effect of surfactant/silica and hydrothermal time on the specific surface area of mesoporous materials from coal-measure kaolin

Mesoporous materials with the highest surface area were synthesized by hydrothermal treatment from coal-measure kaolin using cetyltrimethylammonium bromide(CTAB)as template.The effect of several factors on surface area of products also had been discussed.The products were characterized by FT- IR,HRTEM and N 2 adsorption and desorption isotherm plot methods.There was typical structure as Si-O,Si- OH and Si-O-Si of mesoporous materials in the framework of synthesized materials;the pore size distributions of the products showed a sharp peak at 3.82 nm.The effect of hydrothermal treatment time and the amount of template on the specific surface area of mesoporous materials was important,when the Surf/Si=0.135,and hydrothermal time=12 h,and the surface area of the product reached up to 1 070 m2/g,which was higher than other products.     

Laminar mesoporous structure of modified montmorillonite clays and its formation mechanism

Zr-pillared clays were prepared by heating and ultrasonic methods in intercalation process.The resultants were characterized by XRD,N2 adsorption-desorption,SEM,and TG/DTA analysis.Ultrasonic technology accelerated the pillaring process effectively and obtained better ordered structure than by heating method.The specific surface area and pore volume of the Zr-pillared clays increased by about 13 and 3 times respectively.Rare earth metal(Ce)was introduced into Zr-pillared clays by co-intercalation and dipping method.The specific surface area was increased by co-intercalation approach,but it was decreased dramatically by dipping method.Thermal stability of Ce modified samples prepared by co-intercalation method was enhanced in comparison with Zr-pillared clays.Modification mechanism and "corrugation-like" structural mode of intercalation process was proposed basing on the double XRD peaks in small-angle range of pillared clays,which was related to the deformation of silicate layer.     

Water vapor adsorption in activated carbon modified with hydrophilic organic salts

Five different kinds of hydrophilic organic salts were used to modify commercial activated carbon in order to prepare hydrophilic carbon materials. Properties of the samples were analyzed by surface area analyzer and SEM-EDX. The hydrophilic organic salts with different properties were introduced into activated carbon and significantly affected the properties of the samples.During adsorption experiments, the water vapor adsorption amount in modified samples increases by 0.57-17.12 times in temperature range from 303 to 323 K and at relative pressure below 0.50. Water molecules combined with surface hydrophilic groups through H-bonding exhibit good thermo stability. The effects of temperature, oxygen content and properties of the hydrophilic organic salts on water vapor adsorption were studied. It is indicated that water vapor adsorption in modified samples is mainly affected by the surface oxygen content. The carboxylate radicals in the hydrophilic organic salts greatly affect the micropore structure of the modified samples, while the metal ions in them exhibit limited influence. Different adsorption capacity of modified samples can be explained with the electronegativity of elements presented by Pauling.     

Preparation of a cationic azobenzene dye-montmorillonite intercalation compound and its photochemical behavior

Montmorillonite/cationic azobenzene dye （GTL） intercalation compounds were prepared by the conventional ion exchange method. As compared with that of pure GTL, the thermal stability of the intercalated GTL was greatly enhanced, and the absorption band corresponding to azobenzene group in intercalated GTL shifted towards a longer wavelength by 55 nm, which could be ascribed to the strong conjugation of GTL supramolecular order structure （J cluster） confined in a nanoscale space of montmorillonite interlayer gallery. The microstructures of the resulting intercalation compounds could be successfully controlled by varying the amount of dye loaded as evidenced by the basal spacing of the intercalation compounds. The intercalated azo dye in the montmorillonite interlayer space exhibited reversible trans-to-cis photoisomerization and thermal cis-to-trans reaction. FTIR proved the successful intercalation of GTL into the silicate layer.     

Preparation of activated carbons from mesophase pitch and their electrochemical properties

The influences of molar ratio of KOH to C and activated temperature on the pore structure and electrochemical property of porous activated carbon from mesophase pitch activated by KOH were investigated. The surface areas and the pore structures of activated carbons were analyzed by nitrogen adsorption, and the electrochemical properties of the activated carbons were studied using two-electrode capacitors in organic electrolyte. The results indicate that the maximum surface area of 3 190 m2/g is obtained at molar ratio of KOH to C of 5:1, the maximum specific capacitance of 122 F/g is attained at molar ratio of KOH to C of 4:1, and 800 ℃ is the proper temperature to obtain the maximum surface area and capacitance.     

Effect of thermal oxidation on microstructures and mechanical properties of nanoporous coppers

Nanoporous copper oxides were formed by thermal oxidation of nanoporous copper at 150°C–270°C. The oxidation process of nanoporous copper was investigated by using XRD, SEM, nitrogen adsorption, HRTEM and nanoindentation. The variation of microstructures and mechanical properties was analyzed. The results showed that the content of copper oxides increased, the ligament gradually coarsened, and the mechanical properties of nanoporous structure were improved with the increase of oxidation temperature. When the oxidation temperature was below 210°C, the ligament surface was oxidized to Cu_2O, and the composite structure of Cu_2O@Cu was formed. The formation of CuO occurred since 220°C, and the composite structure of CuO/Cu_2 O@Cu was formed. CuO nanowires were grown on the ligament surface at 250°C; the specific surface area, elastic modulus and hardness of nanoporous structure are 1.37, 3.31 and 7.58 times that of the nanoporous copper, respectively.     

Adsorption behavior of Pb^2＋ and Cd^2＋ ions on bauxite flotation tailings

The adsorption behavior of Pb^2＋ and Cd^2＋ ions on bauxite flotation tailings was investigated to demonstrate the adsorptivity of the bauxite flotation tailings. The adsorption percentage of Pb^2＋ and Cd^2＋ ions as a function of adsorbent dosage, solution pH value and shaking time were determined by batch experiments. The maximum adsorption percentage of 99.93% for Pb^2＋ ions and 99.75% for Cd^2＋ ions were obtained by using bauxite flotation tailings as adsorbent. The methods, such as zeta potentials, specific surface area measurements and the analysis of adsorption kinetics, were introduced to analyze the adsorption mechanisms of the Pb^2＋ ions on bauxite flotation tailings. The isoelectric point of bauxite flotation tailings shifts from 3.6 to 5.6 in the presence of Pb^2＋ ions. The specific surface area of bauxite flotation tailings changes from 12.57 to 20.63 m^2/g after the adsorption of Pb^2＋ ions. These results indicate that a specific adsorption of the cation species happens on the surface of bauxite flotation tailings. Adsorption data of Pb^2＋ ions on the surface of bauxite flotation tailings can be well described by Langmuir model, and the pseudo-second-order kinetic model provides the best correlation for the adsorption data of Pb^2＋ and Cd^2＋ ions on bauxite flotation tailings.     

Synthesis and characterization of montmorillonite inorgano-intercalation compound assisted by microwave irradiation

A montmorillonite inorgano-intercalation compound(MIIC) was synthesized by using a purified Na-exchanged bentonite (PNaB) as a matrix and Al-pillaring ion as an intercalating reagent under microwave irradiation. The synthesized products were characterized by X-ray diffraction (XRD), ²⁷Al magic angle sample-spinning nuclear magnetic resonance (²⁷Al MAS NMR), specific surface area (BET) measurement, and adsorption density determination. The results show that, at 5% solid (PNaB) concentration and 7 minutes irradiation in a 130 W microwave oven, the basal spacing d ₍₀₀₁₎ of the synthesized MIIC increases to 1.740 nm from the original 1.218 nm of PNaB. The MIIC has much higher adsorptive densities to F⁻ and Cr⁶⁺ from aqueous solution than the PNaB. The adsorption isotherm of F⁻ on the MIIC follows the Freundlich equation, and the increased adsorption is mainly due to the porous structure of the MIIC which created larger adsorption surfaces. The adsorption isotherm of Cr⁶⁺ on MIIC follows the Langmuir equation and the adsorption is mainly monolayer as a result of chemisorptions.     

Adsorption of D113 resin for dysprosium(III)

The adsorption behavior and mechanism of D113 resin for Dy(III) was investigated by using the method of resin adsorption. Experimental results show that the optimum medium pH of adsorption of D113 resin for Dy³⁺ is pH=6.00 in the HAc-NaAc medium. The static adsorption capacity of D113 resin for Dy³⁺ is 292.7 mg·g⁻¹. The optimum eluant is 0.5 mol·L⁻¹ HCl. The adsorption rate constant is k ₂₉₈=6.8×10⁻⁶s⁻¹. The apparent activation energy of D113 resin for Dy(III) is 14.79 kJ·mol⁻¹. The adsorption behavior of D113 resin for Dy(III) obeys the Freundlich isotherm. The adsorption parameters of thermodynamic are ΔH=14.48 kJ·mol⁻¹, ΔS=54.69 J·mol⁻¹·K⁻¹, ΔG=−1.82 kJ·mol⁻¹.The adsorption mechanism of D113 resin for Dy³⁺ was confirmed by chemical analysis and IR spectra. Funded by the Natural Science Foundation of Zhejiang Province (No.201027), Foundation of Zhejiang Provincial Education Bureau (No.20040551) and Zhoushan Science Technology Bureau (No.04114)     

Synthesis of 1,4-benzenedicarbonyl thiourea resins and their adsorption properties for Ag（I）

Several 1,4-benzenedicarbonyl thiourea resins (BTR) were synthesized through interfacial polymerization between 1,4-benzenedicarbonyl diisothiocyanate and polyamine. Their structures were confirmed by FT-IR. The adsorption properties (including the effect of adsorption time, pH, initial concentrations and temperature) of BTR-1, BTR-2 and BTR-3 for Ag(I) were investigated by batch tests. The results show that the adsorption equilibria of BTR-1, BTR-2, BTR-3 for Ag(I) are achieved after about 10 h. Their equilibrium adsorption capacities are 7.11, 6.75 and 6.23, respectively, and the adsorption process accords with G. E. Boyd equation and Langmuir adsorption isotherm as well. The adsorption capacities increase with the increase of pH (the highest uptake values are observed at pH being about 6–7). The thermodynamic parameters of BTR-1 were calculated. The results show that ΔH ^Θ; and ΔS ^Θ are 6 958.8 J/mol and 64.28 J/(mol·K), respectively, and ΔG ^Θ at 20, 30, 40 and 50 °C are −11.79, −12.52, −13.16 and −13.8 kJ/mol, respectively. The silver-loaded resins can be quantitatively eluted by a solution containing 6% thiourea in 1 mol/L HNO₃.     

Reaction Activity of Kaolinite Surfaces：Quantum Chemistry Calculations

The anion-kaolinite surface infractions and AuS - adsorption onto the surfaces of kaolinite were studied using the self-consistent-field discrete variation ( SCF - Xα - DV) method. Electronic structure and energies of the system of anion AuS- adsorbed on an atomic cluster of kaolinite were calculated. The results show that the systems with lower total energy are those AuS- adsorbed on the edge surfaces, which indicates that the systems of adsorption of AuS- on the edges are more stable relative to those adsorbed on the basal plane. On the other hand, bond order data suggest that significant shifting of atomic charge and the overlapping of electronic cloud between Au ( Ⅰ ) of the AuS- and the surface ions of kaolinite would take place in the systems with AuS - being adsorbed on the edges, especially at the she near A1 octahedra. Therqrore, it can be concluded that edge sites will dominate the complexation reactions of the surfaces of kaolinite, with negligible contributions from other fimctional groups on the basal plane, which are dominated by either siloxane sites in silica layers or aluminol sites in gibbsite layers.     

Thermal deformation behavior and microstructure of nuclear austenitic stainless steel

Gleeble-1500D thermal simulation tester was employed in the hot-compression investigation of as-cast nuclear 304 austenitic stainless steel under conditions: deformation temperature 950―1200℃; deformations 30% and 50%; deformation rates 0.01 and 0.1 s?1. The results show that the flow stress decreases with temperature rise under the same strain rate and deformation, that the flow stress increases with deformation under the same temperature and strain rate, and that the flow stress increases with strain rate...     

Removal of Cr (VI) from aqueous solution using ultrafine coal fly ash

Coal fly ashes WSRA and BQRA were ball milled for 5 h to produce their ultrafine coal fly ashes WSUA and BQUA, respectively. Batch kinetic, isotherm and pH effect on adsorption were studied to evaluate removal of Cr (VI) from aqueous solutions by ultrafine coal fly ashes comparing with raw coal fly ashes. The kinetics of adsorption indicates the process to be intraparticle diffusion controlled and follows the Lagergren first-order kinetics for all coal fly ashes. The first-order rate constants (k ₁) of Cr (VI) adsorption onto WSRA, WSUA, BQRA and BQUA are 1.981, 1.497, 2.119 and 1.500 (×10⁻²) min⁻¹, respectively. The adsorption capacities of WSUA and BQUA are much better than those of WSRA and BQRA. Equilibrium adsorption data of all coal fly ashes well satisfy the Langmuir isotherm. The adsorbed amounts of Cr (VI) onto WSUA and BQUA decrease from pH 2 to pH 6 and then increase up to pH 12.     

Photocatalytic H2 evolution activity of CuO/ZrO2 composite catalyst under simulated sunlight irradiation

Zirconia-supported CuO (CuO/ZrO₂) composite photocatalysts were successfully synthesized via citric acid-assisted sol-gel technique. For comparison, CuO/ZrO₂ materials were also prepared by solid state reaction and co-precipitation method. The as-prepared powders were characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), and thermogravimetric-differential thermal analysis (TG-DTA). The photocatalytic activity of CuO/ZrO₂ catalyst was investigated based on the H₂ evolution from oxalic acid solution under simulated sunlight irradiation. The effects of molar ratio of CuO to ZrO₂, preparation method, phase change with the calcination temperature and the durability on the photocatalytic activity of the photocatalyst were investigated in detail. It is found that the optimal activity of photocatalytic H₂ evolution (2.41 mmol·h⁻¹μ⁻¹) can be obtained when CuO/ZrO₂ composite photocatalyst is synthesized by sol-gel technique and the mole ratio of CuO to ZrO₂ is 40%. The activity of copper oxide supported on monoclinic ZrO₂ calcined at higher temperature is much higher than that on tetragonal ZrO₂ calcined at lower temperature, and the best calcination temperature is 900 °C.