This page has only limited features, please log in for full access.
A thermo-chemical treatment method was used to produce biogenic amorphous silica from South African sugarcane and maize residues. Different fractions of South African sugarcane (leaves, pith, and fiber) were processed for silica production. The biomass samples were leached with either 7 wt% citric acid or 7 wt% sulfuric acid at 353 K for 2 h prior to being rinsed, dried and combusted using a four-step program ranging from room temperature to 873 K in a furnace. The characterization of the pre-treated biomass samples was conducted using thermogravimetric analysis (TG/DTA), X-ray fluorescence analysis (XRF) and elemental analysis (CHN), while the final products were characterized by XRF, X-ray diffraction (XRD), elemental analysis, nitrogen physisorption and scanning electron microscopy (SEM). Citric acid pre-treatment proved to be an attractive alternative to mineral acids. Amorphous biogenic silica was produced from sugarcane leaves in good quality (0.1 wt% residual carbon and up to 99.3 wt% silica content). The produced biogenic silica also had great textural properties such as a surface area of up to 323 m2 g−1, average pore diameter of 5.0 nm, and a pore volume of 0.41 cm3 g−1.
Ncamisile Nondumiso Maseko; Denise Schneider; Susan Wassersleben; Dirk Enke; Samuel Ayodele Iwarere; Jonathan Pocock; Annegret Stark. The Production of Biogenic Silica from Different South African Agricultural Residues through a Thermo-Chemical Treatment Method. Sustainability 2021, 13, 577 .
AMA StyleNcamisile Nondumiso Maseko, Denise Schneider, Susan Wassersleben, Dirk Enke, Samuel Ayodele Iwarere, Jonathan Pocock, Annegret Stark. The Production of Biogenic Silica from Different South African Agricultural Residues through a Thermo-Chemical Treatment Method. Sustainability. 2021; 13 (2):577.
Chicago/Turabian StyleNcamisile Nondumiso Maseko; Denise Schneider; Susan Wassersleben; Dirk Enke; Samuel Ayodele Iwarere; Jonathan Pocock; Annegret Stark. 2021. "The Production of Biogenic Silica from Different South African Agricultural Residues through a Thermo-Chemical Treatment Method." Sustainability 13, no. 2: 577.
This work addresses the advanced textural characterization of biogenic silica obtained from different Si-accumulating biomasses and agricultural waste products like rice, oat and spelt husk as well as horsetail. These materials exhibit a non-uniform, disordered pore structure in a broad size range deviating from well-ordered “artificial” species of porous materials. For the first time in literature, this contribution determines and validates mainly the mesoporosity by means of nitrogen physisorption, positron annihilation lifetime spectroscopy (PALS) and hyperpolarized 129Xenon NMR (HP-129Xe NMR). Nitrogen physisorption and HP 129Xe NMR both were able to describe the pore structure in the mesopore range. In addition, the specific surface area and the mesopore volume were determined by nitrogen physisorption. PALS complemented the results by an assessment of microporosity in biogenic silica. It was shown that biogenic silica contains micropores (1.5 nm–1.9 nm), mesopores in a broad range and indications of macroporosity. In addition, the results led to the assumption that different plant origins and plant species evoke different textural properties and inter-connections between the pores in biogenic silica. This contribution demonstrates that only a combination of all techniques is viable to characterize the non-uniform and complex pore structure of biogenic silica of different origin.
Denise Schneider; Ahmed G. Attallah; Susan Wassersleben; Marianne Wenzel; Jörg Matysik; Reinhard Krause-Rehberg; Dirk Enke. Advanced textural characterization of biogenic silica by nitrogen physisorption, positron annihilation lifetime spectroscopy and hyperpolarized 129Xe NMR spectroscopy. Microporous and Mesoporous Materials 2020, 307, 110515 .
AMA StyleDenise Schneider, Ahmed G. Attallah, Susan Wassersleben, Marianne Wenzel, Jörg Matysik, Reinhard Krause-Rehberg, Dirk Enke. Advanced textural characterization of biogenic silica by nitrogen physisorption, positron annihilation lifetime spectroscopy and hyperpolarized 129Xe NMR spectroscopy. Microporous and Mesoporous Materials. 2020; 307 ():110515.
Chicago/Turabian StyleDenise Schneider; Ahmed G. Attallah; Susan Wassersleben; Marianne Wenzel; Jörg Matysik; Reinhard Krause-Rehberg; Dirk Enke. 2020. "Advanced textural characterization of biogenic silica by nitrogen physisorption, positron annihilation lifetime spectroscopy and hyperpolarized 129Xe NMR spectroscopy." Microporous and Mesoporous Materials 307, no. : 110515.
This work introduces a cost and time efficient procedure to specifically increase mesopore volume and specific surface area of biogenic silica (specific surface area: 147 m2 g−1 and mesopore volume: 0.23 cm3 g−1) to make it suitable for applications in adsorption or as catalyst support. The target values were a specific surface area of ~500 m2 g−1 and a mesopore volume of ~0.40–0.50 cm3 g−1 as these values are industrially relevant and are reached by potential concurring products such as precipitated silica, silica gel, and fumed silica. The applied process of partial pseudomorphic transformation was carried out as a single reaction step in a microwave reactor instead of commonly used convective heating. In addition, the conventionally used surfactant cetyltrimethylammonium bromide (CTABr) was substituted by the low-cost surfactant (Arquad® 16-29, cetyltrimethylammonium chloride (CTACl) aqueous solution). The influence of microwave heating, type of surfactant as well as the concentration of NaOH and CTACl on the textural and structural properties of the modified biogenic silica was investigated using nitrogen adsorption as well as scanning and transmission electron microscopy. The results show that the textural parameters of the modified biogenic silica can be exactly controlled by the amount of NaOH in the reaction solution. By variation of the NaOH concentration, specific surface areas in the range of 215–1,001 m2 g−1 and mesopore volumes of 0.25–0.56 cm3 g−1 were achieved after reaction at 393 K for 10 min. The presented microwave route using the low-cost surfactant solution decreases the reaction time by 99% and as shown in an example for German prices, lowers the costs for the surfactant by 76–99%.
Denise Schneider; Ralf Kircheis; Susan Wassersleben; Wolf-Dietrich Einicke; Roger Gläser; Dirk Enke. Low-Cost Microwave-Assisted Partial Pseudomorphic Transformation of Biogenic Silica. Frontiers in Chemistry 2019, 7, 575 .
AMA StyleDenise Schneider, Ralf Kircheis, Susan Wassersleben, Wolf-Dietrich Einicke, Roger Gläser, Dirk Enke. Low-Cost Microwave-Assisted Partial Pseudomorphic Transformation of Biogenic Silica. Frontiers in Chemistry. 2019; 7 ():575.
Chicago/Turabian StyleDenise Schneider; Ralf Kircheis; Susan Wassersleben; Wolf-Dietrich Einicke; Roger Gläser; Dirk Enke. 2019. "Low-Cost Microwave-Assisted Partial Pseudomorphic Transformation of Biogenic Silica." Frontiers in Chemistry 7, no. : 575.
The separation of Pd and CeO2 on the inner surface of controlled porous glass (CPG, obtained from phase-separated borosilicate glass after extraction) yields long-term stable and highly active methane combustion catalysts. However, the limited availability of the CPG makes such catalysts highly expensive and limits their applicability. In this work, porous silica obtained from acid leached rice husks after calcination (RHS) was used as a sustainable, cheap and broadly available substitute for the above mentioned CPG. RHS-supported Pd-CeO2 with separated CeO2 clusters and Pd nanoparticles was fabricated via subsequent impregnation/calcination of molten cerium nitrate and different amounts of palladium nitrate solution. The Pd/CeO2/RHS catalysts were employed for the catalytic methane combustion in the temperature range of 150–500 °C under methane lean conditions (1000 ppm) in a simulated off-gas consisting of 9.0 vol% O2, and 5.5 vol% CO2 balanced with N2. Additionally, tests with 10.5 vol% H2O as co-feed were carried out. The results revealed that the RHS-supported catalysts reached the performance of the cost intensive benchmark catalyst based on CPG. The incorporation of Pd-CeO2 into RHS additionally improved water-resistance compared to solely Pd/CeO2 lowering the required temperature for methane combustion in presence of 10.5 vol% H2O to values significantly below 500 °C (T90 = 425 °C).
Dongjing Liu; Dominik Seeburg; Stefanie Kreft; René Bindig; Ingo Hartmann; Denise Schneider; Dirk Enke; Sebastian Wohlrab. Rice Husk Derived Porous Silica as Support for Pd and CeO2 for Low Temperature Catalytic Methane Combustion. Catalysts 2019, 9, 26 .
AMA StyleDongjing Liu, Dominik Seeburg, Stefanie Kreft, René Bindig, Ingo Hartmann, Denise Schneider, Dirk Enke, Sebastian Wohlrab. Rice Husk Derived Porous Silica as Support for Pd and CeO2 for Low Temperature Catalytic Methane Combustion. Catalysts. 2019; 9 (1):26.
Chicago/Turabian StyleDongjing Liu; Dominik Seeburg; Stefanie Kreft; René Bindig; Ingo Hartmann; Denise Schneider; Dirk Enke; Sebastian Wohlrab. 2019. "Rice Husk Derived Porous Silica as Support for Pd and CeO2 for Low Temperature Catalytic Methane Combustion." Catalysts 9, no. 1: 26.
Biomasses are a sustainable, CO2 neutral source used in biorefining. Si-accumulating plants can be used for the production of biogenic silica in a biomass valorisation process. This study examines the production of high-grade porous silica from different plant parts like rice, oat and spelt husk, rice straw and horsetail using a generalized procedure for all. The silica materials were produced by a 2-step method. First, the biomasses were pretreated with water and then subjected to leaching with citric acid. As a second step, a sequential burning program was applied. The characterization of the untreated biomasses was carried out by X-ray fluorescence (XRF) analysis and thermal analysis (TG–DTA). The biogenic silica samples were subjected to XRF, carbon content analysis, low temperature nitrogen physisorption, scanning and transmission electron microscopy as well as X-ray diffraction. Independent of the initial composition of the plant part, the established method resulted in amorphous, biogenic silica with up to 99.7% purity, mesopores between 2 and 30 nm with pore volumes of up to 0.46 cm3 g−1 and specific surfaces of up to 303 m2 g−1. It was shown that the generalized method developed works not only for all the biomasses separately, but also if treated in the same batch. The produced biogenic silica can be considered as sustainable alternative to other silica products like precipitated silica, silica gel and fumed silica which are produced in highly energy consuming processes.
Denise Schneider; Susan Wassersleben; Michael Weiß; Reinhard Denecke; Annegret Stark; Dirk Enke. A Generalized Procedure for the Production of High-Grade, Porous Biogenic Silica. Waste and Biomass Valorization 2018, 11, 1 -15.
AMA StyleDenise Schneider, Susan Wassersleben, Michael Weiß, Reinhard Denecke, Annegret Stark, Dirk Enke. A Generalized Procedure for the Production of High-Grade, Porous Biogenic Silica. Waste and Biomass Valorization. 2018; 11 (1):1-15.
Chicago/Turabian StyleDenise Schneider; Susan Wassersleben; Michael Weiß; Reinhard Denecke; Annegret Stark; Dirk Enke. 2018. "A Generalized Procedure for the Production of High-Grade, Porous Biogenic Silica." Waste and Biomass Valorization 11, no. 1: 1-15.
Pre-shaped mesoporous amorphous rice husk ash (RHA) and MCM-41 derived from RHA as a silica source were transformed into MFI-type zeolites using two different structure-directing agents. Tetrapropylammonium hydroxide (TPAOH) was utilized as an alkali source for silica dissolution and structure control during the direct transformation of RHA into zeolite. A monopropylamine (PA)-containing alkaline solution (NaOH) was used for the pseudomorphic transformation of RHA or MCM-41 into zeolite. The hydrothermal conversion of RHA or MCM-41 into MFI-type zeolites was investigated as a function of reaction time at 175 °C. With PA as template, the crystallization took place inside and on the outer surface of RHA or MCM-41 without losing the original shape of the initial silica sources, while TPAOH led to the formation of conventional MFI-type zeolite crystals due to the complete dissolution of RHA. The final products were characterized by X-ray diffraction, nitrogen adsorption, scanning electron microscopy, and optical emission spectroscopy.
Hallah Ahmad Alyosef; Hans Roggendorf; Denise Schneider; Alexandra Inayat; Julia Welscher; Wilhelm Schwieger; Tom Münster; Gert Kloess; Suzan Ibrahim; Dirk Enke. Comparative Study between Direct and Pseudomorphic Transformation of Rice Husk Ash into MFI-Type Zeolite. Molecules 2017, 23, 1 .
AMA StyleHallah Ahmad Alyosef, Hans Roggendorf, Denise Schneider, Alexandra Inayat, Julia Welscher, Wilhelm Schwieger, Tom Münster, Gert Kloess, Suzan Ibrahim, Dirk Enke. Comparative Study between Direct and Pseudomorphic Transformation of Rice Husk Ash into MFI-Type Zeolite. Molecules. 2017; 23 (1):1.
Chicago/Turabian StyleHallah Ahmad Alyosef; Hans Roggendorf; Denise Schneider; Alexandra Inayat; Julia Welscher; Wilhelm Schwieger; Tom Münster; Gert Kloess; Suzan Ibrahim; Dirk Enke. 2017. "Comparative Study between Direct and Pseudomorphic Transformation of Rice Husk Ash into MFI-Type Zeolite." Molecules 23, no. 1: 1.
A new one step approach for the preparation of MFI-type zeolites through direct trans-formation of pre-modified diatomite is reported. Two diatomite species modified by calcination and acid treatment were used as silica and alumina sources. The progress of the transformation was investigated by analyzing samples after different crystallization times at 453 K. Tetrapropylammonium hydroxide was utilized for the first time as bi-functional molecule for silica dissolution in diatomite and structure directing agent during zeolite formation. In this way, the use of an additional alkaline source, such as sodium hydroxide, for silica dissolution was not necessary. The applied diatomite samples contained amorphous silica in combination with impurities like feldspar, anatase and quartz. This allowed the systematic investigation of the influence of modification procedure, amorphous silica content and crystalline impurities of the different diatomite samples on the direct transformation in MFI-type zeolites. During the transformation process, the feldspar was totally dissolved. The quartz content was reduced to <10 wt% in the final products as compared with the modified diatomite starting material. X-ray diffraction, nitrogen adsorption, scanning electron microscopy and optical emission spectroscopy were used to characterize these materials.
Hallah Ahmad Alyosef; Hans Roggendorf; Denise Schneider; Alexandra Inayat; Julia Welscher; Wilhelm Schwieger; Tom Münster; Gert Kloess; Suzan Ibrahim; Dirk Enke. MFI-type zeolites from natural materials: a comparative study of MFI-type zeolites generated from different diatomite species (part I). Journal of Porous Materials 2016, 23, 1609 -1618.
AMA StyleHallah Ahmad Alyosef, Hans Roggendorf, Denise Schneider, Alexandra Inayat, Julia Welscher, Wilhelm Schwieger, Tom Münster, Gert Kloess, Suzan Ibrahim, Dirk Enke. MFI-type zeolites from natural materials: a comparative study of MFI-type zeolites generated from different diatomite species (part I). Journal of Porous Materials. 2016; 23 (6):1609-1618.
Chicago/Turabian StyleHallah Ahmad Alyosef; Hans Roggendorf; Denise Schneider; Alexandra Inayat; Julia Welscher; Wilhelm Schwieger; Tom Münster; Gert Kloess; Suzan Ibrahim; Dirk Enke. 2016. "MFI-type zeolites from natural materials: a comparative study of MFI-type zeolites generated from different diatomite species (part I)." Journal of Porous Materials 23, no. 6: 1609-1618.
In the present study, the possibility of extracting biogenic silica from various European biomass materials was investigated. High-purity biogenic silica (>90 wt % SiO2) was obtained from energy crops (miscanthus), agro wastes (wheat straw), and other crop residues (cereal remnant pellets). Three different morphological forms of biogenic silica materials (ash) were obtained by a thermo-chemical treatment of these biomass sources. The wet biomass materials were leached using 5 M sulfuric acid for a defined period of time. After washing and drying the biomass materials, the leached samples were subjected to a heat treatment in a furnace with three sequential temperatures and time stages to determine the minimum combustion temperature of the organic compounds in the biomass materials. The final products were characterized by X-ray diffraction, X-ray fluorescence, carbon content analysis, differential thermal analysis, low temperature nitrogen adsorption, mercury intrusion porosimetry, and scanning electron microscopy. The obtained silica materials had a microstructure composed of accessible, interconnected, and intraparticle meso- and macropores with sizes ranging from 3 to 1500 nm.
Hallah Ahmad Alyosef; Denise Schneider; Susan Wassersleben; Hans Roggendorf; Michael Weiß; André Eilert; Reinhard Denecke; Ingo Hartmann; Dirk Enke. Meso/Macroporous Silica from Miscanthus, Cereal Remnant Pellets, and Wheat Straw. ACS Sustainable Chemistry & Engineering 2015, 3, 2012 -2021.
AMA StyleHallah Ahmad Alyosef, Denise Schneider, Susan Wassersleben, Hans Roggendorf, Michael Weiß, André Eilert, Reinhard Denecke, Ingo Hartmann, Dirk Enke. Meso/Macroporous Silica from Miscanthus, Cereal Remnant Pellets, and Wheat Straw. ACS Sustainable Chemistry & Engineering. 2015; 3 (9):2012-2021.
Chicago/Turabian StyleHallah Ahmad Alyosef; Denise Schneider; Susan Wassersleben; Hans Roggendorf; Michael Weiß; André Eilert; Reinhard Denecke; Ingo Hartmann; Dirk Enke. 2015. "Meso/Macroporous Silica from Miscanthus, Cereal Remnant Pellets, and Wheat Straw." ACS Sustainable Chemistry & Engineering 3, no. 9: 2012-2021.