Materials Science Forum Vols. 743-744

Abstract: The adsorption experiment was carried out in an enclosed reactor in order to evaluate activated carbon, prepared by brewing yeast, which could remove benzene, toluene, ethylbenzene, and xylene (BTEX) from air. Various experimental parameters were determined, and activated carbon adsorption performance was compared with some commercial activated carbons (CACs). The results showed that lots of carboxyl, amino-groups and hydroxyl were on the surface of activated carbon, which were chemical reaction centers. Adsorption was reached equilibrium after six hours. The isothermal data of biosorption followed the Langmuir and Freundlich Models. When the temperature was 25°C,the maximum adsorption capacity was greater than the commercial activated carbon. These adsorption performances indicate that the activated carbon is a potentially economical adsorbent for BTEX removal.

Abstract: TiO₂ aerogel fibers have been fabricated by electron span combined supercritical drying technique. Polyvinylpyrrolidone (PVP)/TiO₂ composite fibers are prepared by electrospinning PVP and TiO₂ precursor Ti (OC₄H₉)₄. TiO₂ aerogel fibers are obtained by supercritical drying PVP/TiO₂ composite fibers using ethanol as media. Structural of the aerogel fibers was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and N₂ adsorption at 77 K. The effect of mass ratio of PVP/TiO₂ was investigated. SEM shows that pore structure of nanofibers was well developed, with the diameter of nanofibers about 2 μm. N₂ adsorption/desorption data show that the highest surface area of aerogel fibers reached 241.6 m²/g with the average pore diameter about 10 nm. The aerogel fibers were anatase type TiO₂.

Abstract: Chemical bath deposition of CdS thin film for solar cells was investigated in this study. CdS thin films were prepared by chemical-bath deposition (CBD) from a bath containing cadmium acetate, ammonium chloride, ammonium hydroxide and thiourea in aqueous solution on the glass substrate at certain bath temperature. The characterization of samples was conducted by using different methods such as scanning electron microscopy (SEM), X-ray diffraction (XRD) and ultraviolet spectrophotometry (UV). The crystal quality of CdS thin films was improved after CdCl₂ thermal annealing at 400C. The results showed that chemical bath deposited CdS thin film was symmetrical and compact, but depositing rate was low. As a result, the best deposition conditions were summarized, such as the pH value was about 10.5, depositing time was 60 minutes.

Abstract: A series of metal oxides sorbents supported on γ-Al₂O₃ were directly prepared by subcritical water impregnation (SCWI) method using an autoclave reactor. The effects of active components, preparation pressure, temperature, and time on the desulfurization activity of sorbents in hot coal-based gases at mid-temperature were investigated. The samples were characterized by X-ray diffraction (XRD), nitrogen adsorption and atomic absorption spectrophotometer (AAS). The results showed that Mn-based sorbent loaded on γ-Al₂O₃ by SCWI presented a good desulfurization performance. The optimal preparation parameters of sorbent were the temperature of 350 °C, the pressure of 18.9 MPa, impregnation time of 30 min, the precursor solution concentration of 0.287 mol/L and the volume of 100 ml, respectively. The Mn/γ-Al₂O₃ sorbent prepared under the optimal conditions presented a good desulfurization precision and regeneration performance. After regeneration, the mechanical strengths of the sorbents were higher than that of raw support and the breakthrough time at the desulfurization efficiency of above 99% was not obviously decreased.

Abstract: A Cu-SAPO-34/cordierite monolithic catalyst was prepared by in-situ hydrothermal method. The effects of ultrasonic treatment were mainly investigated during the preparing process. The removal of NOX was evaluated using a fixed-bed reactor. X-ray diffraction, scanning electron microscopy were used to characterize the samples showing that the crystallinity of Cu-SAPO-34 molecular sieve have increased after ultrasonic treatment. The Cu-SAPO-34/cordierite prepared by ultrasonic treatment showed higher de-NOx activity and stronger anti-aging property. NOx conversion could reach more than 80% between 440 and 560°C over the fresh Cu-SAPO-34/cordierite catalyst with ultrasonic treatment (600 W, 2 h) and the highest conversion was 86%, however, the highest conversion was only 76% over the Cu-SAPO-34/cordierite catalyst without ultrasonic treatment. After aging (treated for 15 h at 720 °C in the presence of 200 ppm SO₂ and 10% vapor), NOx conversion reached more than 45% between 400 and 520 °C over the catalyst with ultrasonic treatment and the highest conversion was 57%, however, the highest conversion was only 43% over the catalyst without ultrasonic treatment. The XRD and SEM results indicated that the structure and morphology of Cu-SAPO-34/cordierite monolithic catalyst kept in good condition after aging.

Abstract: In order to developing high-value-added products and making full use of phosphate resources, Lithium Iron Phosphate were synthesized in the controlled atmosphere, using electronic grade phosphoric acid from Yunnan province, ferrous oxalate and Lithium carbonate by microwave processing. The variety of particles and distribution in different conditions of the mixing and grinding, the influence of appearance and property of the Lithium Iron Phosphate in different conditions of microwave power, microwave time and reaction temperature were discussed. Based on the experiment the optimized process conditions have been obtained. Some of the samples were characterized by XRD, SEM, electric capacity, chemical analysis, cycle performance and phase analysis. The experimental results show that the microwave synthesis method of Lithium Ferrous Phosphate is feasible.

Abstract: The use of camellia oleifera abel shells as biosorbent has been successfully demonstrated in the removal of Cr (VI) from aqueous solution. The effects of different parameters, such as, contact time, initial concentration of Cr (VI), pH and temperature on Cr (VI) adsorption were investigated. The results showed that the maximum uptake of Cr (VI) was up to 190.69 mg/g at a pH value of around 1.0, under the initial Cr (VI) concentration of 400mg/L and at the temperature of 298 K. The adsorption kinetics could be described by pseudo-first order and pseudo-second order kinetics models.

Abstract: In this thesis, TiO2-pillared montmorillonite was prepared by a sol-gel method. The sample was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the crystal phase of the sample is composed of anatase and montmorillonite. The microstructure of the sample is still layered structure. Furthermore, the XRD results indicate that the interlayer distance of crystal plane (001) of the montmorillonite left-shift obviously. In other words, its interlayer distance increases obviously. The adsorptive ability of the sample was tested with industry wastewater, which containing Pb2+. The results indicate that the adsorptive rate of sample for lead () cationic is 99.9%. After analyzing with the interlayer space, it indicated that the increasing of the interlayer space is good for the adsorptive ability. And the adsorptive ability reached a maximum when the interlayer space was 1.339 nm. The TiO2-pillared montmorillonite absorbed Pb2+ saturatedly was impregnated into nitric acid solution to dissolve the lead cationic. The results show that the concentration of the nitric acid is higher, the leaching rate of the lead cationic is higher. And it reached a maximum when the concentration of the nitric acid is 2 mol/L after leaching for 20 min.Introduction

Abstract: With the development of materials industry, the problem of water pollution is increasingly serious, and therefore it is important to establish an appropriate characterization model of heavy metals in water in China. This paper provides the human toxicity potential factors of several heavy metals, including Hg, Cd, Cr, Pb and As. The result showed that Chinas HTP factors are partial greater than Europe factors, caused by the different industrial situation and the ratio of total human intake to total emissions.

Abstract: In this paper, the sodium alginate (SA)/poly (vinylalcohol)(PVA)/hydroxyapatite (HAp) fiber was prepared via solution spinning. The adsorption properties of SA/PVA/HAp composite fiber were studied,and the adsorption kinetics and isotherms were investigated. The experimental results showed that the adsorption process was fast, in which half-equilibrium and equilibrium was obtained in 5 and 30 minutes, respectively. The pseudo-second-order kinetic model provided a better correlation of the experimental results. Both of Langmuir isotherm and Freundlich isotherm could describe the adsorption behavior of SA/PVA/HAp composite fiber towards cadmium. The positive H° value and increased absolute value of the G° with temperature indicate that high temperature is good to the adsorption process.