Porous Ceramic Beads Research Articles

Highly effective catalytic reduction of nitrobenzene compounds with gold nanoparticle-immobilized hydroxyapatite nanowire-sintered porous ceramic beads

A catalytic ceramic bead with micron-sized and interconnected porous channels, adjustable porosity, high catalytic activity, and long-term stability is prepared.

Continuous Bioconversion of Oleuropein from Olive Leaf Extract to Produce the Bioactive Product Hydroxytyrosol Using Carrier-Immobilized Enzyme

Feasibility and stability were evaluated of a continuous multi-batch process for converting oleuropein (OLE) from olive leaf extract to the bioactive product hydroxytyrosol (HT). Carrier beads made of three different materials (calcium alginate, chitosan with deacetylated α-chitin nanofibers (DEChN), or porous ceramic) were investigated for morphology, thermogravimetric, sorption, and viscoelastic properties. Enzymatic hydrolysis of OLE conducted in a packed bed bioreactor containing cellulase immobilized to carrier beads yielded OLE degradation rates of ~ 90% and an average HT yield of ~ 70% over 20 batches. Ultimately, inorganic porous ceramic beads were less costly and exhibited superior performance relative to organic carriers and thus were deemed most suitable for industrial-scale HT production. Systems utilizing enzyme immobilization within packed bed reactors hold promise for achieving efficient production of valuable bioproducts from discarded biomass materials.

Synthesis of doped MnOx/diatomite composites for catalyzing ozone decomposition

The wide applications and unintended generation of ozone stimulate the exploration of catalysts for ozone decomposition. Herein, manganese oxides loaded on porous ceramic beads were prepared via a simple thermolysis method. Doping the composite with Ni, Fe, and Al could tune the oxygen vacancies in the manganese oxide, as evidenced by the X-ray photoelectron spectroscopy (XPS) analysis. The average valance of Mn could also be altered by the dopants. The catalytic properties of the composites doped with Fe, Ni, and Al have been significantly improved. And the Ni doped MnOx with the highest density of oxygen vacancy exhibits the best catalytic activity. The prepared composite catalyst can easily be incorporated into filters for air circulation.

Production of Bio-Based Hydrogen Enriched Methane from Waste Glycerol in a Two Stage Continuous System

In the present work, a continuous process was developed aiming at the production of bio-based hydrogen-enriched methane, from waste glycerol (WG) in a two-stage reactor system. In the first step, biohydrogen production was studied, using an attached mixed acidogenic consortium in an up-flow column bioreactor. Cylindrical porous ceramic beads with a surface area of 600 m2L−1 were used as attachment matrix of bacterial cells. The hydrogen yield, the substrate consumption and the distribution of soluble metabolites were investigated for two different substrate concentrations in the feed, i.e. 20 and 25 g WG/L. SEM pictures of the biofilm formed on the ceramic beads revealed that bacilli dominated in the reactor. Subsequently, RISA methodology showed that Klebsiella sp. and Clostridium sp. were among the dominant microorganisms. In parallel, a methanogenic reactor was started up and operated in continuous mode using initially commercial glycerol, and subsequently WG as carbon sources. In the sequel, the effluent of the hydrogenic reactor was fed to the methanogenic reactor (constituting thus the second stage in a two-stage process), and the effect of organic loading on the methane yield was studied. It was shown that the reactor managed to generate up to 73 % of the theoretically expected methane based on COD removal, corresponding to 256.0 ± 2.6 L CH4/kg WG. Moreover, simulation of the experimental data of the methanogenic reactor via the Anaerobic Digestion Model ADM1 revealed that the model was able to successfully describe the performance of the digester, even under dynamic conditions.

Characteristics of a Ceramic Carrier after Wastewater Treatment Process in the Model Column Cascade with Ethanol Addition

Nitrogen and phosphorus removal from wastewater remains one of the serious environmental problems worldwide. The present study was aimed at combining the both nitrification and phosphorus accumulation processes in the laboratory-scale model system. Synthetic wastewaters (28 mg N-NH L) were treated consequently in the cascade of three columns, which were designed for nitrification and phosphorus accumulation processes, respectively, and were packed with porous ceramic beads. Six treatment cycles of seven days in each column were performed. Addition of 3% ethanol to wastewater increased the efficiency of ammonium removal in the first column of the cascade during the 7 day period to 81.9 %, which was accompanied by a decrease of pH from 7.3 to 6.2. An increase of soluble phosphates was shown in Columns II and III of the cascade. Microbial enzyme activity, number of CFU and diversity of the microbial community differed among the three columns tested. The most active biofilm formation was detected in Column I. The thermal analysis of beads has revealed mass losses of 0.23% and 0.08%, due to decomposition of light volatile organic substances at 173 °C and 481 °C, respectively. In turn, the beads in Column II and III were not covered by thick biofilm, while blue crystals were found on the surface. Accumulation of nitrogen and phosphorus on the beads was detected. Vegetation experiments have revealed some stimulation effect of the beads applied as an amendment to loamy sand soil, to the growth of rye and cress.

광미(鑛尾)를 활용(活用)한 다공성 세라믹 비드 제조(製造) 및 촉매(觸媒) 변환기(變換機)로의 응용(應用)

광미를 이용하여 다공성 세라믹 비드를 제조한 후 NOx/SOx 제거용 촉매 변환기로 응용하였다. 변환기 표면에 코팅처리된 촉매 지지체는 합성한 메조포러스 실리카(SBA-15)를 사용하였다. 다공성 세라믹 변환기의 내부 구조는 기공과 기공이 서로 연결되어 있는 3차원 망상구조이며 기공율은 80%로 나타났다. 또한, 촉매 변환기의 비표면적은 SBA-15 코팅 전 0.8 <TEX>$m^2/g$</TEX>에서 코팅처리 후에는 55 <TEX>$m^2/g$</TEX>으로 크게 증가하였다. NOx/SOx 제거 실험은 다공성 세라믹 촉매 변환기 표면에 <TEX>$V_2</TEX><TEX>O_5$</TEX>와 <TEX>$V_2O_5$</TEX>, CuO를 함께 담지한 것으로 실시하였다. NOx 전환율은 <TEX>$V_2O_5$</TEX>/CuO 변환기가 <TEX>$V_2O_5$</TEX> 변환기에 비해 약 10% 정도 높게 나타났다. 또한, <TEX>$V_2O_5$</TEX>/CuO 변환기는 반응온도 <TEX>$350^{\circ}C$</TEX>, 공간속도 10000 <TEX>$h^{-1}$</TEX>, 산소농도 5%에서 NOx 95%, SOx 90% 이상의 전환율을 각각 나타냈다. The porous ceramic beads using mine tailing were prepared and applied to catalytic converter for NOx/SOx removal. Catalytic support was used synthesized mesoporous silica (SBA-15) which coated on surface. Internal structure for porous ceramic beads was composed of three-dimensional network structure and porosity was about 80%. In addition, the specific surface area for mesoporous silica(SBA-15) coated on converter was significantly increased 55 <TEX>$m^2/g$</TEX> compared with 0.8 <TEX>$m^2/g$</TEX> before coating. NOx/SOx removal experiment was performed using <TEX>$V_2O_5$</TEX> and <TEX>$V_2O_5$</TEX>/CuO converter. NOx conversion ratio for <TEX>$V_2O_5$</TEX>/CuO converter was approximately increased 10% compared to <TEX>$V_2O_5$</TEX> converter. In addition, catalytic converter of <TEX>$V_2O_5$</TEX>/CuO was shown to remove 95% of NOx and 90% of SOx at reaction temperature of <TEX>$350^{\circ}C$</TEX>, space velocity of 10000 <TEX>$h^{-1}$</TEX> and <TEX>$O_2$</TEX> concentrations of 5%, respectively.

Determination of mass transfer coefficients for packing materials used in biofilters and biotrickling filters for air pollution control—2: Development of mass transfer coefficients correlations

Correlations that allow determination of gas film mass transfer coefficients ( k G a t , k G a w ) and liquid film mass transfer coefficients ( k L a w ) for packing materials used in biofilters and biotrickling filters for air pollution control are presented. Lava rock, polyurethane foam cubes (PUF), Pall rings, porous ceramic beads, porous ceramic Raschig rings, and various compost–woodchips mixtures were used as packing materials. The functionality of gas and liquid velocity on mass transfer coefficients ( k G a t , k G a w , k L a w ) obtained experimentally (see Part 1 of this paper) was correlated using modified Onda-type equations. The correlation equations helped to better understand the sensitivity of gas and liquid velocities on mass transfer, and the effects of packing wetting. Each packing had a different functionality with gas and liquid velocity and different wetting property, hence different correlation equations were needed for the different packing materials. Most of the fitted data fell within ± 20 % of the experimental values.

Determination of mass transfer coefficients for packing materials used in biofilters and biotrickling filters for air pollution control. 1. Experimental results

Gas film mass transfer coefficients ( k G a t , k G a w ) and liquid film mass transfer coefficients ( k L a w ) for packing materials used in biofilters and biotrickling filters for air pollution control were determined experimentally. Lava rock, polyurethane foam cube (PUF), Pall ring, porous ceramic beads, porous ceramic Raschig rings and compost–woodchips mixtures were investigated. The experiments were performed at gas velocities ranging from 100 to 8000 m h - 1 and liquid velocities of 0.1 – 12 m h - 1 , i.e., a wide range that covers most biofilters and biotrickling filters. k G a t in biofilter packings ranged from about 500 to 2500 h - 1 , while k G a w and k L a w in biotrickling filters ranged from 100 to 8000 h - 1 , and 1 to 300 h - 1 , respectively, depending on the packings and the conditions. This is markedly lower than mass transfer coefficients usually observed for conventional wet scrubbing. The gas film mass transfer coefficient ( k G a t ) of 50:50% vol compost–woodchips mixture, a common biofilter packing, was greater than this of a 20% vol compost and 80% woodchips mixture, though the mass transfer was not increased by increasing further the volume fraction of compost. All compost mixtures exhibited a greater gas film mass transfer coefficient than lava rock or other synthetic materials. The mass transfer coefficients of compost mixtures was also influenced by packing method and it was directly proportional to the surface area of the bulking agents added. The gas film mass transfer coefficient ( k G a w ) of five biotrickling filter packing materials increased linearly with gas velocity. The effect of liquid on the gas film mass transfer coefficient was not significant. Of all the biotrickling filter packings, the porous ceramic beads had the highest gas and liquid film mass transfer coefficients followed by lava rock, porous ceramic rings, 1 in Pall ring and PUF cubes. The liquid film mass transfer coefficient ( k L a w ) was directly proportional to liquid velocity and the effect of gas velocity was negligible. Several correlations allowing prediction of mass transfer coefficients are presented in Part 2 of this paper.

Maintenance of fungal strains on cryopreservative-immersed porous ceramic beads

The applicability of a bacterial storage method (maintenance after absorption on cryopreservative-immersed ceramic beads) was tested for different fungal strains of biotechnological importance: Aspergillus, Mucor, Phaffia, Rhizomucor and Saccharomyces. Polyethylene glycol (100ml of 30% or 45% solutions) added after the transfer of cells into the vial increased the safety of storage.

Packed bed bioreactor with porous ceramic beads for animal cell culture

A packed bed bioreactor was investigated as means for the cultivation of mammalian cells. The packed bed is comprised of porous ceramic particles with pores sufficiently large for cell immobilization as well as for intraparticle convective flow. In this way, the transport of limiting nutrients such as oxygen can be significantly enhanced, allowing maintenance of cell viability and productivity in an environment protective of adverse shear effects. The extent of intraparticle convective medium flow was experimentally quantified relative to the reactor operating conditions, and was found to be the dominant mechanism of nutrient transport to cells immobilized in the particle interior. An approximate linear relationship was obtained between overall reactor productivity and the extent of intraparticle convection. As the latter can be controlled at the single-particle level through total flow rate control, this relationship is a useful scale-up tool for the design of bioreactors. The high cell densities and the high volumetric productivities achieved by using small lab-scale reactors underline the potential of this simple bioreactor configuration for large-scale cell culture applications.

Promotive action of ceramics on yeast ethanol production, and its relationship to pH, glycerol and alcohol dehydrogenase activity

A yeast strain, Saccharomyces cerevisiae KPY32 isolated from pito, a traditional West-African alcoholic beverage, was immobilized in porous ceramic beads as a means of improving its ethanol production. Stationary fermentation cultures at different temperatures were made using semi-synthetic medium and fermentation parameters including ethanol production, sugar consumption, cell growth and pH were monitored. Glycerol production, and the activity of alcohol dehydrogenase (ADH) of the various systems were monitored. It was found that immobilization of the yeast resulted in improved ethanol production, at conversion rates above 93% of the theoretical value. The pH of the immobilized systems was also stabilized at around 4.0, glycerol production was higher, and the ADH activities were higher than those of free-cell systems. Ethanol production at the high temperature of 37° C was also improved by immobilization. The promotive action was found to be related to the pH, presence of glycerol and the enhancement of ADH activity.

Kinetics of immobilized sucrose phosphorylase

Sucrose phosphorylase was immobilized on porous ceramic beads with 3-aminopropyltriethoxysilane and glutaraldehyde. It was determined experimentally that under laboratory conditions there was no diffusional resistance to the enzyme-catalyzed reaction. The half-life of the immobilized enzyme varied from about 35 days at 30 degrees C to about 5 days at 40 degrees C. The pH optimum was found to be between 6.5 and 7.0. The activation energy for the reaction was found to be about 12.5 kcal/mol. Eleven independent kinetic constants in the complete rate equation for the previously proposed ping-pong mechanism were found to be in good agreement with those for the soluble enzyme.