Preparation and characterization of ceramic nanofiltration membrane prepared from hazardous industrial waste

Kiln rollers, which are widely used in ceramic tiles production, are usually subjected to surface grinding to remove the contaminations. The resulted fine powder is considered useless waste and a hazardous source of environmental pollution particularly as it contains health-threatening fine free silica. In the present paper, the grind waste from kiln rollers was reused as raw material in the fabrication of nanofiltration ceramic membrane. The samples of produced ceramic membranes were formed into disks by adding 15% (by weight) organic binder solution with 2% concentration, then pressed at 35 MPa, dried and fired at temperatures range from 1100°C to 1300°C for 1 hour soaking time. It was found that the best firing temperature to produce nanofiltration ceramic membrane is 1250°C, where the ceramic membrane provides high removal of turbidity and high monovalent, divalent, and trivalent salts separation percentage.     

Cobalt and nickel aluminate spinels: Blue and cyan pigments

M²⁺-doped aluminate spinels (M=Co or Ni) were prepared by a polymeric route leading to pure phases for synthesis temperatures equal to 800 or 1200 °C and characterized by UV–vis–NIR spectroscopy, ²⁷Al NMR and XRD refinements. Coloration of the synthesized pigments is clearly sensitive to the distribution of doping ions in the aluminate spinel lattice. As the synthesis temperature increased, a color shift from green to blue has been observed for Zn_1−xCo_xAl₂O₄ compound while coloration of Zn_1−xNi_xAl₂O₄ compound remains greenish-gray. Hence, to improve pigment coloration and/or synthesis cost, two different strategies have been proposed: (i) the synthesis of aluminum over-stoichiometric spinel with Zn_0.9Co_0.1Al_2.2O_4+δ formal composition in order to force Co²⁺ to be located in tetrahedral sites and (ii) changing from ZnAl₂O₄ to MgAl₂O₄ as host lattices for Ni²⁺ doping ions in order to force Ni²⁺ to be located in octahedral sites.     

Nickel and cobalt sorption on anaerobic granular sludges: kinetic and equilibrium studies

The kinetics and equilibria of sorption of the divalent metal ions cobalt and nickel onto anaerobic granular sludge are described. Single component and binary equimolar systems were studied at different pH values (pH 6, 7 and 8). The kinetic modelling of metal sorption by anaerobic granular sludge has been carried out using Lagergren equations. On fitting the experimental kinetic data both in first‐ and pseudo‐second‐order equations, the regression analysis of a pseudo‐second‐order equation gave a higher r² value, indicating that both external mass transfer and intra‐particle diffusion are involved in the sorption process. The experimental isotherm data were analysed using the Langmuir, Freundlich and Redlich–Peterson equations. The Redlich isotherm, a combination of the Langmuir and Freundlich equations, was found to have the highest regression correlation coefficients at pH 7. At pH 8, the Langmuir mechanism dominated for cobalt and nickel adsorption. In contrast, at pH 6, the Freundlich equation gave a better correlation coefficient which suggests a more heterogeneous adsorption at that pH. The maximal adsorption capacity of the granular sludge, as determined by the Langmuir equation, for cobalt or nickel in single systems (8.92 mg g^?1 Co TSS; 9.41 mg g^?1 Ni TSS, pH 7) compared with binary systems (8.06 mg g^?1 Co TSS; 8.43 mg g^?1 Ni TSS, pH 7) showed no great difference in the accumulation of these metals onto granular sludge. Copyright © 2004 Society of Chemical Industry     

The effect of acetic acid pretreatment for cobalt catalysts prepared from cobalt nitrate

The effects of acetic acid pretreatment for dried catalysts prepared from cobalt nitrate were investigated. Cobalt catalyst prepared from cobalt nitrate, followed by treatment of 2.2 M acetic acid, namely CoN/2.2Ac catalyst, showed the highest CO conversion as well as the lowest CO₂ and CH₄ selectivities in liquid-phase Fischer–Tropsch synthesis. On the contrary, cobalt catalyst prepared from cobalt acetate exhibited poor catalytic activity due to very low reduction degree of supported cobalt. The higher catalytic activity for CoN/2.2Ac catalyst could be ascribed to the formation of the mixture of cobalt nitrate and cobalt acetate with suitable ratio between them during acetic acid treatment, which led to an optimum balance between the dispersion and reduction degree of supported cobalt, eventually realizing the higher catalytic activity. Various catalysts were characterized by XRD, TPR and H₂ chemisorption.     

Separation and characterization of pigments from bleached and deodorized canola oil

An analysis of pigments responsible for color formation during bleaching and deodorization of canola oils treated with activated bleaching earth (ABE) or novel mineral-acid/silica (AS) adsorbents is presented. The chromophores are trace glycerides and were concentrated by silica column chromatography. The concentrated color bodies were hydrolyzed and analyzed as free acids or methyl esters by reversed-phase high-performance liquid chromatography with photodiode array and mass spectrometry detection,¹H and¹³C nuclear magnetic resonance and infrared spectroscopies. Absorbance in deodorized oils is mostly from oxygenated C18 and C20 fatty acids with 1 to 4 double bonds. High-wavelength absorbance in AS-bleached oils is from conjugated pentane fatty acids that are not observed for ABE-bleached oils. Thus, both the bleaching agent and the deodorization treatment affect the distribution and concentration of such stable chromophores.     

Synthetic resins: II: Preparation and characterization of resins prepared from aminoacetophenone

A number of resins were prepared by condensing m-aminoacetophenone with substituted aromatic compounds and formaldehyde in the presence of acids and bases as catalyst. The resins were characterized by infrared spectra. The solubility parameters were calculated from Small's group contribution which agreed well with the experimental value. The bacteriocidal properties of the resins have been studied.     

CdZnS半导体颜料的制备与表征

以Cd(AC)2、Zn(AC)2、Na2S等为原料,采用共沉淀法制备CdZnS半导体颜料,详细讨论了反应温度、反应液pH值、保温熟化时间等共沉淀反应参数对CdZnS半导体颜料合成的影响,确定了CdZnS半导体颜料合成的最佳反应参数。最后采用XRD、EDS、SEM等手段对颜料结构、成分、形貌进行表征,测试了CdZnS半导体颜料的粉体电阻率。     

Polyurethane coatings prepared from CNSL based polyols: Synthesis,characterization and properties

Conventional polyurethane chemistry based on polyol and isocyanate chemistry is widely used for many applications ranging from plastics to coatings, constructions, pharmaceuticals, foods, etc. The growing concern over depletion of petrochemical materials and their rising prices has led to search for environment friendly renewable materials. Cardanol derived from cashew nut shell liquid is one such renewable material which has reactive phenolic group and aliphatic double bond that could be tailor-made to produce novel functional materials for polymer and coating applications. This has previously been used for preparation of phenolics, epoxy resins and phenalkamine hardners. Diglycidyl ether of cardanol which is commercially available, is used as epoxy resin or modifier in epoxy formulations. In the present work, this was modified by simple one step ring opening reaction to produce polyols with different number of functionalities. The various polyols prepared were cured with polyisocyanate cross-linkers and applied on metallic substrates. The cured coatings were evaluated for physical, mechanical, chemical and thermal properties. The study conducted showed that the prepared polyols could be used as sole binder for coating formulation with overall excellent properties.     

Activated carbons prepared from biogas residue: characterization and methylene blue adsorption capacity

BACKGROUND: In China, some biogas residue, which cannot be utilized by microbes in the anaerobic process, has been used as fertilizer. More has been deposited in biogas plants or on land around the plants. This has an effect on the environmental protection of the biogas plant, especially if the high lignin content in the biogas residue is not handled properly. RESULTS: In this study biogas residue has been used for the preparation of activated carbons by phosphoric acid activation. Textural characterization and feasibility of employing the prepared activated carbon to remove methylene blue (MB) from aqueous solution were investigated. The results show that the activated carbons have high surface area (1950 m² g^?1) and pore volume (1.232 cm³ g^?1). Equilibrium data were best described by the Langmuir isotherm model, with a maximum monolayer adsorption capacity of 344.83 mg g^?1 at 25 °C. Among the kinetic models studied, the pseudo‐first‐order model was found to be the most applicable to describe the adsorption of MB. CONCLUSIONS: The adsorption performance of activated carbons prepared from biogas residues (BR‐AC) was comparable with that of commercial material and other adsorbents reported in earlier studies and presents a high value added application for biogas residues. Copyright © 2010 Society of Chemical Industry     

工业钛钨粉制备选择性催化还原催化剂的对比研究

以国产和进口专用于制备脱硝选择性催化还原（selective catalytic reduction,SCR）催化剂的工业钛钨粉为原料,采用浸渍法在不同条件下制备了V2O5-WO3/TiO2催化剂,测试了催化剂的脱硝性能,并且采用低温N2吸附法、X射线衍射（XRD）和扫描电子显微镜/X-射线能谱（SEM/EDX）对其结构和组成进行了表征,为提高国产钛钨粉的质量提供依据。实验结果表明,相同条件下国产钛钨粉制备的催化剂脱硝性能稍差于进口,其原因除了原料组成之外,还在于国产钛钨粉制备的催化剂孔容低于进口,活性组分的负载量较低;国产的钛钨粉中有少量的金红石,而且晶粒度较小,烧结程度较进口的大。提高国产钛钨粉的质量,除其组成适当外,还应考虑增大孔容,避免金红石的形成。     

Removal of copper from industrial wastewaters by activated carbon prepared from periwinkle shells

The present study aims at the removal of copper from industrial wastewater by using a low-cost adsorbent. Activated periwinkle shell carbon (PSC) was prepared and characterized for various physiochemical properties. To determine copper removal capacity, the performance of PSC was compared with commercial activated carbon (CAC) and a mixture of activated periwinkle shell carbon and commercial activated carbon (PSC:CAC) in a ratio 1:1. The effect of adsorbent dose, contact time, pH, agitation speed and adsorbent particle size was studied for adsorption of copper from wastewater under batch conditions. The result obtained showed that PSC competes favourably with CAC. The maximum adsorption capacity was observed for PSC:CAC with 88.12% removal at an optimal pH of 8. The PSC and CAC had 84.19% removal and 85.15% removal, respectively. The equilibrium data obtained fitted both the Langmuir and the Freundlich models. Good correlation coefficients were obtained for the pseudo-second-order kinetic model.     

Structural investigation and optical properties of cobalt aluminate pigments derived from thermal decomposition of mixed-metal nitrate co-crystals

In this study, the coloration mechanism of cobalt aluminate spinel materials derived by thermal decomposition of the co-crystallized mixed-metal precursors has been reported. The structural alteration of cobalt aluminates, along with the origins of chroma values at the different calcination temperatures from 600 °C to 1200 °C were thoroughly investigated by combining XRF, XRD, XAS, UV-VIS DRS, FT-IR, and FT-Raman techniques. In-depth analyses of structural information and corresponding optical properties suggested that the coloration can be modified by controlling Co²⁺/Co³⁺ contents and their site occupancies in the spinel structure by adjusting calcination temperatures and selecting the counter ions with appropriate oxidizing power. The interplays among (1) the oxidation process at low temperatures, (2) the deoxidation process at high temperatures, (3) the reduction in the degree of spinel inversion (toward the emerging of normal-spinel CoAl₂O₄ structure), and (4) the existence of the minor Al₂O₃ domains are found to be key imperatives for tailoring the color appearances of cobalt aluminate powders in the broad range from black, dark-green, green, greenish-blue, dark-blue, towards bright-blue. Herein, we reveal the correlation between the synthetic parameters and the structural features of the obtained spinel-based materials, which could further exhibit the crucial procedure to control the coloration of inorganic pigments systematically.     

Colouring of opaque ceramic glaze with zircon pigments: Formulation with simplified Kubelka-Munk model

In this study a simplified Kubelka-Munk model is proposed for colour matching purposes. Opaque glazes were prepared to determine the absorption optical constants from the reflectance curves measured with a spectrophotometer. After the physical and chemical characterization of the glaze components (frit and pigments), to analyze the spectrophotometric results a simplification of the Kubelka-Munk model was suggested. To experimentally verify the model, two target green colour were reproduced in laboratory by adding in an opaque glaze a yellow praseodymium-doped zircon ((Zr,Pr)SiO₄) and blue vanadium-doped zircon ((Zr,V)SiO₄) pigments. The results were in good agreement with the experimental reflectance curves and the prediction of colour green glazes was possible with a reduced number of experiments.     

Synthesis and characterization of homo- and copolyimides prepared from two-step polymerization

Homopolyamic acids and copolyamic acids were prepared from four dianhydrides and three diamines. Copolyimides could be arranged in sequence through different reaction processes, such as alternating, block, and random. Polyamic acids were subsequently converted into corresponding polyimides by the solid-phase imidization. Polyimide derivatives were characterized by viscosity, thermal stability, mechanical properties, and solubility. The extent of polymerization might be influenced by the nucleophilicity of a diamine and the electrophilicity of a dianhydride. In gel permeation chromatography, molecular weight distribution of polymers was 2.5–3.0. The thermal stability of polymers decreased with increasing the ratio of a more flexible component, and alternating copolyimides showed slightly better than corresponding random and block ones. The melting temperatures of all polyimide derivatives did not exist on the differential scanning calorimetry curves, and the results were proof that the X-ray diffraction curves. Polymers derived from bis[4-(3-amino phenoxy)phenyl]sulfone dissolved well in some polar solvents. Alternating copolymers represented a better solubility than the corresponding random and block ones. All polymers had good mechanical properties, both tensile and elongation. The kinetics of imide formation could be also dependent on the structure and reactivity of reagents. The kinetics of cyclo-dehydration was described by the first-order kinetics up to relatively high conversion but deviated from the first-order kinetics at high conversion followed by the second-order kinetics. © 1996 John Wiley & Sons, Inc.     

Preparation and characterization of glazes from combinations of different industrial wastes

The work reported here involves the preparation and characterization of ceramic glazes made from combinations of different industrial wastes. The wastes were float glass, granite and lime shale (a raw material waste from the oil shale industry in São Mateus do Sul, state of Paraná, Brazil), which were used to replace natural raw materials in a proportion of up to 50% in weight. The compositions were formulated using the Seger method and prepared by conventional ceramic processing. The stabilized suspensions were applied in commercial wall tile and porcelain stoneware tile, which were sintered at temperatures of 1080 °C and 1150 °C, respectively, using two different heating cycle. Three compositions were developed, two of which yielded opaque glazes and one a transparent glaze. Linear thermal expansion coefficients (α) of 80.10^?7 °C^?1 to 100.10^?7 °C^?1, and glaze softening temperatures of 600–700 °C were characterized by dilatometric analysis. The glaze compositions showed chemical resistance against acid and alkaline attack after 96 h, showing a mass loss of less than 0.1% in weight. The surface hardness of the glazes determined by the Mohs scale, Vickers microhardness and abrasion resistance (PEI indices) were between 6–7, 3–3.7 GPa and 3–4, respectively. These properties are compatible with those of commercial glazes for wall tiles and porcelain stoneware ceramics.     

Hydrogen evolution in alkaline water on cobalt electrodeposits prepared from baths containing different anions

Electrolytic cobalt deposits, as electrocatalytic materials, were prepared from baths containing chloride, sulphate or acetate. Electrodeposition was conducted at 200 A m^–2 with or without oxygen bubbling at the cathode. The hydrogen evolution reaction (h.e.r.) on the cobalt electrodes was performed in 30 wt % KOH at 25, 40, 50, 60 and 70 °C. Without oxygen bubbling during deposition, the cobalt electrodes prepared from the acetate bath gave superior performance for h.e.r. than electrodes deposited from the other baths. With oxygen bubbling, however, the lowest h.e.r. over-potential was obtained on the cobalt prepared from the chloride bath.     

Electrochemical and structural characterization of cobalt recycled from cathodes of spent Li-ion batteries

In this work, cobalt from spent Li-ion batteries of cellular phones was recycled using electrochemical techniques. The efficiency, structure and morphology of deposits were influenced by the pH solution and charge density. Maximum efficiency is obtained for pH = 5.40 for all charge densities analyzed. The presence of the cobalt hcp phase for both pH solutions (5.40 and 2.70) and charge density conditions (10.0 and 50.0 C cm⁻²) used in the electrodeposition process was detected by X-ray diffraction. The growth of the cobalt deposit is favored in the crystallographic direction [002] for pH = 5.40 and in the direction [110] for pH = 2.70 when the charge density is 10.0 C cm⁻². The [100] and [101] crystallographic directions of hcp phase were detected by X-ray diffractogram for both pH conditions when the charge density was increased to 50.0 C cm⁻². The potentiodynamic dissolution of the cobalt depends on its structural composition.     

High-porosity whisker-mullite/corundum membrane support prepared from recycled industrial waste coal cinder

Recycled coal cinder was utilized as a raw material for the preparation of a high-porosity and low-cost whisker-mullite/alumina membrane support via in situ synthesis of mullite whiskers with MoO₃ and AlF₃ as additives. The effects of the sintering temperature and additives on the physical properties (porosity, shrinkage, phase composition, microstructure, pore size, nitrogen permeation, and tortuosity factor) of the porous mullite-based membrane supports were investigated in detail. Based on the synergistic effect of AlF₃ and MoO₃, the porosity of the as-synthesized membrane supports was as high as 60%. This is attributed to the reduction in the viscosity of the solid phase reaction interface between the mullite precursors by the MoO₃ additives, thus promoting the formation of mullite grains, while the AlF₃ additive effectively promoted the anisotropic growth of whisker-mullite via vapor deposition. This whisker-mullite membrane support with a cross-interlocking structure has an inherently unimodal pore-size distribution and low tortuosity factor (~0.4).     

Formulation and characterization of UV-light-curable electrically conductive pastes

UV-light-curable electrically conductive pastes have been formulated from granular silver particles and flake-shaped silver and epoxyacrylate, ethylene glycol and photo-initiator in this study. These conductive pastes were analyzed using photo-DSC, TGA and conductivity metry for reaction rate during photo-polymerization process, thermal resistance and conductivity, respectively. It is shown that (1) the rate of photo-polymerization can be regulated by varying the exposure dose and time depending on the particle size and particle loading; (2) the resistance of the paste containing 60 wt% silver with mean particle size from 0.6 to 1.5 μm is reduced to 5.63 × 10^?7 Ωcm; and (3) with granular-shaped silver with 0.6 to 3.5 μm in diameter the decomposition temperature of electrically conductive paste is 424°C, while the temperature of thermal decomposition is 397°C for the same solid content of flake shape silver with length 0.5 to 5 μm, after photo-polymerization using a radiation dose of 500 mJ/cm².