Steam Activation Research Articles

Gasification of Anthracite in a Pilot-Scale CFB Gasifier and Pore Structure Evolution of Gasification Fly Ash during Steam Activation

Gasification of Anthracite in a Pilot-Scale CFB Gasifier and Pore Structure Evolution of Gasification Fly Ash during Steam Activation

Identifying Middle School Students’ Perceptions of STEAM Careers

The aim of this study was to identify the students' perceptions of STEAM careers. The effect of the STEAM intervention on students’ perceptions was evaluated using one group pretest - posttest experimental design with career questionnaire. The sampling of the study consists of 37 seventh grade middle school students. In the study, STEAM activities were used in the teaching of the Force and Energy unit. First of all, the students were asked about their career choices and their responses were evaluated quantitatively. There was statistically significant difference between the distributions of changes in the number of students choosing STEAM careers. Content analysis also was performed on the findings obtained from the questionnaire. As a result of the study, it was determined that the students increased the percentage of choosing careers in the STEAM career fields such as scientists and engineering. Looking at the interest of students in STEAM fields, one of the biggest changes was in the field of science. One of the important findings of the research was that after the implementation, the majority of the students thought that gender was not important in the success of STEAM career fields. The results of the research revealed that the STEAM education approach can be used a lot to evaluate and improve the academic career choices of middle school students.

Adsorption of ibuprofen from aqueous solution onto a raw and steam-activated biochar derived from recycled textiles insulation panels at end-of-life: Kinetic, isotherm and fixed-bed experiments

This study explores the potential use of recycled textile biochar (RT-BC) and steam-activated biochar (RT-SABC), derived from insulation panels at end-of-life, as sorbents for removing ibuprofen from aqueous solutions. After steam activation, the surface area and micropore volume increased. Subsequently, kinetic and isotherm experiments were investigated at 20 °C, 200 rpm and 50 mg/L ibuprofen solution. Equilibrium was reached after 24 h for RT-BC and 120 h for RT-SABC. The kinetics of RT-BC and RT-SABC followed the pseudo-first-order and Elovich models, respectively. RT-SABC isotherm showed the highest adsorption capacity (53.9 mg g−1), well-fitted into the Sips model. Ibuprofen uptake by RT-SABC was nearly irreversible. Afterward, RT-SABC dynamic performance was evaluated in a fixed-bed column for three bed heights. The breakthrough point (41.7–476.7 h), the volume of effluent treated (0.6–6.4 L at breakthrough) and adsorption capacity (22.09–39.81 mg g−1) increased with bed height (10–30 cm). Thomas and Clark's models simulated the experimental points, confirming second-order kinetics and Sips isotherm. Different functional groups were involved in the adsorption mechanism. Preliminary experiments in tap water on RT-SABC showed a removal (>83 %) due to ionic strength and reduced pH. Therefore, RT-SABC could be an efficient adsorbent for ibuprofen removal from aqueous systems.

Creating a watermill through steam activities for preschool children in the school yard

STEAM (Science, Technology, Engineering, Arts and Mathematics) initiatives engage in classroom and schoolyard activities in early childhood education. In early childhood, learning through play provides children with the resources they need for an enjoyable learning environment, especially when the activities take place in the schoolyard, as this is where children can better concentrate and, at the same time, increase their creativity. This work investigates whether preschool children can create watermills through STEAM activities in the schoolyard. Thirty-four children aged 4-6 years participated in the research, and the results were encouraging as the children liked that the activities were outside. At the same time, the teachers were worried if they would be able to support such activities. Preschoolers have a spontaneous disposition toward science with a sense of curiosity and creativity. More research needs to be done on out-of-class activities with the STEAM app, and this training should be incorporated in all kindergartens.

Fabrication of waste-derived porous geopolymer by community-scale carbonization and steam activation with potential copper adsorption

An integrated system for solid waste management in rural regions is presented in this study. Waste charcoal and activated carbon (AC) products were used for the production of absorbable geopolymers by subjecting municipal solid waste (MSW) and beachside waste (BSW) to a carbonization process (400 °C for 3 h) and steam activation (700, 800, and 900 °C for 1 h). The material characterization, mechanical property analysis, and copper adsorption performance were investigated. The results showed that the waste charcoal yields from MSW and BSW were 31.4% and 39.5%, respectively. The AC product yields of MSW and BSW were approximately 13.9–19.8% and 18.1–26.2%, respectively. Additional ingredients for geopolymer production are coal fly ash (FA) and rice husk bottom ash (RA). The results showed that the 45FARA10MSW and 50FA50BSW geopolymers had maximum compressive strengths of 188.78 and 130.94 ksc, respectively. The absorbable geopolymers 45FARA10MSW-AC and 50FA50BSW-AC, produced from waste charcoal-derived AC, exhibited Cu2+ removal performances of 68.5% and 98.3%, respectively. The high adsorption performance was owing to improved physical properties such as the surface area, pore size, and average porosity of the AC products. In summary, absorbable geopolymer products from waste could be a promising green materials for environmental applications.

Bamboo-Activated Carbon Synthesized by One-Pot Pyrolysis and FeCl2 Activation for the Removal of Cr(VI) in Aqueous Solutions

The present study utilized a FeCl2-based environmentally sustainable activation technique to produce activated carbon from bamboo. The research aimed to evaluate the influence of activation temperature on the physical and chemical characteristics of the activated carbon and its ability to adsorb Cr(VI). The results of the experiment indicated that the yield of activated carbon prepared by this method was in the range of 25.5–37.5%, which was comparatively higher than the yield obtained through traditional KOH and steam activation techniques. Moreover, this method resulted in a well-developed pore structure with pore sizes primarily ranging from 0.5 nm to 1.0 nm. A gradual increase in the specific surface area and pore volume was observed with an increase in the activation temperature. The maximum values of 1290.9 m2/g and 0.67 m3/g for specific surface area and pore volume, respectively, were achieved at an activation temperature of 900 °C. The adsorption capacity of Cr(VI) was subject to variation in correspondence with alterations in the pore structure of activated carbon. The maximum adsorption capacity recorded was 13.65 mg/g. This suggested that the adsorption capability was predominantly influenced by the pore configuration. The study of kinetics and isothermal adsorption indicates that the quasi-second-order kinetic model was a more effective approach for characterizing the adsorption process of Cr(VI) on activated carbon. Additionally, the Freundlich model demonstrated superior fitting performance compared to the Langmuir model.

Insights on the dual role of low-rank coal with high mineral catalysis index (LRC-HMCI) during blending coal for activated carbon production and low-temperature NH3-SCR of NO

The mineral catalysis index (MCI), reflecting the activity of mineral composition in coal, could be used as a meaningful reference to indicate the coal’s application potential. To elucidate the role of low-rank coal with high MCI (LRC-HMCI) on the AC preparation and application, in this investigation, ACs are produced by steam activation after blending Fugu (F) coal, Yangchang (Y) coal and Xiangyuan (X) coal. The as-prepared ACs’ textural evolution and performance were investigated by a series of characterization and low-temperature NO removal tests. The results show that LRC-HMCI promotes the as-prepared AC’s weight loss and burn-off and lowers its yield. The LRC-HMCI could promote the generation of micropores and the transformation from micropores to mesopores/macropores. 6Y-1X-3F-AC’s total BET specific surface area and micropore specific surface area is up to 880 m2/g and 629 m2/g, and the total volume reaches 0.42 cm3/g. LRC-HMCI decreases the AC’s graphitization degree. Meanwhile, LRC-HMCI favors incrementing as-prepared AC’s COO, CO and π–π*. LRC-HMCI also enhances NO removal, and 7Y-1X-2F-AC shows the highest denitrification activity. 2 h’s NO removal rate reaches 45.5%, which is 77.1% higher than 25.7% of Y-AC. The enhanced denitrification is mainly due to the dual role of LRC-HMCI: LRC-HMCI optimizes micropore porosity and improves the surface chemistry properties of AC, which eventually promote the NO and NH3 adsorption; Minerals from LRC-HMCI, particularly Fe-, Ca-, Mg- containing components, could catalyze the NH3-SCR reaction, thus improves the NO removal. The results of this research could guide cost-effective and high-performance AC production through coal blending based on MCI.

Production of AC from Bamboo, Orange, and Paulownia Waste-Influence of Activation Gas and Biomass Maturation.

The production of agricultural waste is associated with environmental problems and risks to public health. The general interest demands, as an ecological alternative, the proper management of waste generated by industrial activity through its transformation into value-added products. Carbonization/activation (2 h/2 h) at 700 °C in a vertical furnace (20 K/min), to produce biochar and activated carbon (AC) from bamboo, orange, and paulownia residue, was carried out in a laboratory facility with physical activation by CO2 and steam. The characterization of the carbonaceous material obtained was based on the determination of the N2 adsorption-desorption isotherms at 77 K, the specific surface area with the BET procedure, and its internal structure by means of SEM images. The BET surface area values obtained as a function of the CO2/steam agent used were 911/1182 m2/g, 248/388 m2/g, and 800/1166 m2/g for bamboo, orange, and paulownia, respectively. The range of variation of porosity in paulownia residue generated after steam activation was 485-1166 m2/g, varying depending on the degree of maturity of the biomass used. Research has shown that both the type of activation agent used to produce AC and the degree of plant maturation of the precursor residue affect the quality and characteristics of the final product.

John - Sivanandan Achari Isotherm Method for the Determination of Surface Area of Porous Materials: Analysis of Granular Activated Carbons

John –Sivanandan Achari isotherm equationlog log Ce= C+n log qe,has many advantages for the structural characterization of porous materials. Linear plot of log logCe versus log qe conform to a straight line and subsequent extrapolation of amount adsorbed (qe), to the xaxis. This way one can directly determine the monolayerqm(J-SA) and hence the specific surface area (SA m2 /g) of the material.This can be analytically proved by applying the method in any type of solid-liquid equilibrium adsorption data. In this study, adsorption of methylene blue (MB) dye molecules on modified granular activated carbon (GAC) has been attempted to determine the porosity, and surface area by the new method. The solids are GAC 383 (native carbon- coconut shell based), GACO383 (native carbon oxidized) and a new carbon (GACOLaO1273). This carbon is prepared in the laboratory by steam activation after incorporating GAC383with Lanthanum(La 3+) ions. Carbons are tested in batch reactors with fixed MB concentrations by adsorptive techniques. The isotherm model behavior of the carbons are hereby reported using John - Sivanandan Achari isotherm (J-SA) equation using specific adsorption data. Porous material category as IUPAC type, constants and parameters are further evaluated with Langmuir, Freundlich, Dubinin - Radushkevich isotherms. It is seen that the isotherm followed the features of micro porous materials on using John – Sivanandan Achari (J-SA) isotherm. Porosity and surface area determined are found to give agreeing results on comparing with other isotherm models. This research is intended to highlight the significance of John and John-Sivanandan Achari (J-SA) isotherms as a tool for material characterization studies- a model originated as Indian analytical scientific skill.

Fabrication and electrochemical performance of Si@Polyaniline-based activated-carbon composites

Si@polyaniline-based activated-carbon (Si@P-AC) composites, consisting of porous polyaniline-based carbon layers, were synthesized via in-situ polymerization, high-temperature sintering, and steam activation utilizing silicon and aniline. Our experimental results demonstrate that Si@P-AC60 composites, prepared via steam activation at 700[Formula: see text]C for 60 min, exhibit superior rate and cycling performance. At current densities of 100, 200, 300, 500, and 1000 mA⋅g[Formula: see text], the discharge-specific capacities of Si@P-AC60 are 1617, 1133, 1005, 855, and 679 mAh⋅g[Formula: see text], respectively. Additionally, the specific capacity retention rate reaches 75.5% when the current density returns to 100 mA⋅g[Formula: see text], with the specific capacity recovering to 1221 mAh⋅g[Formula: see text]. This extraordinary electrochemical performance can be attributed to the improved electron and ion transport channels provided by the polyaniline-based activated-carbon (P-AC) coating on the surface of silicon particles.

Alcohol‐Induced Strong Metal‐Support Interactions in a Supported Copper/ZnO Catalyst

AbstractTuning the strong metal‐support interaction (SMSI) in metal catalysts is a promising strategy to improve their catalytic performance. In this article, we systematically investigated the influences of different alcohol/water mixtures on the evolution of the interfacial structure of Cu/ZnO catalysts in the reduction stage. A series of in situ characterization and theoretical simulation studies were performed to elucidate the various mechanisms of alcohol induced SMSI. It was found that when methanol/water is added to H2 during the reduction pretreatment, more oxygen vacancies are formed on the ZnO support, which facilitates the dissociation of H2O and the hydroxylation of ZnO species. Such promotion eventually favors the SMSI between Cu and ZnO and increases the catalytic activity for the methanol steam reforming reaction. In contrast, the addition of ethanol/water and 1‐propanol/water during reduction leads to a physical blockage of the catalyst by alcohol molecules, poisoning the active Cu sites and limiting the migration of ZnO species.

Alcohol-Induced Strong Metal-Support Interactions in a Supported Copper/ZnO Catalyst.

Tuning the strong metal-support interaction (SMSI) in metal catalysts is a promising strategy to improve their catalytic performance. In this article, we systematically investigated the influences of different alcohol/water mixtures on the evolution of the interfacial structure of Cu/ZnO catalysts in the reduction stage. A series of in situ characterization and theoretical simulation studies were performed to elucidate the various mechanisms of alcohol induced SMSI. It was found that when methanol/water is added to H2 during the reduction pretreatment, more oxygen vacancies are formed on the ZnO support, which facilitates the dissociation of H2 O and the hydroxylation of ZnO species. Such promotion eventually favors the SMSI between Cu and ZnO and increases the catalytic activity for the methanol steam reforming reaction. In contrast, the addition of ethanol/water and 1-propanol/water during reduction leads to a physical blockage of the catalyst by alcohol molecules, poisoning the active Cu sites and limiting the migration of ZnO species.

Evolution of pore structures and fractal characteristics of coal-based activated carbon in steam activation based on nitrogen adsorption method

To investigate the structures and fractal characteristics of micro- and mesopores during steam activation, a series activated carbons were prepared from Datong bituminous coal by physical activation at 750 and 850 °C. Low-temperature nitrogen adsorption and Frenkel-Halsey-Hill model were employed to determine the fractal dimensions of pore structures. The results demonstrate that micro- and mesopore structures were fully developed during steam activation, and activation at 750 °C was conducive to the development of pore structures, especially mesopores. The samples had similar pore size distributions that the micropore diameters mainly centered at 0.4–0.8 nm and 1.2–1.8 nm, and the mesopores mainly distributed in the range of 2–9 nm. The variation of surface and structure fractal dimensions for activated carbons with different burn-offs indicated that the surface roughness and structure complexity changed during activation process. The fractal dimensions of micropore surface (D1) and micropore structure (D2) had positively linear correlation with Smic/SBET and Vmic/Vtot, respectively. While the mesopore surface fractal dimensions (D1’) have a negative association with Sext/SBET, and the structure fractal dimensions (D2’) have a negative but weak association with Vmes/Vtot.

Configuration of coupling methanol steam reforming over Cu-based catalyst in a synthetic palladium membrane for one-step high purity hydrogen production

Methanol steam reforming coupled with an efficient hydrogen purification technology to produce high purity hydrogen that feeds for hydrogen fuel cells is an attractive approach to realizing distributed power generation. However, the harmony of catalytic reforming and hydrogen separation with respect to thermodynamics is still an issue. In this work, in order to construct an integrated methanol steam reforming (MSR) reactor for high purity hydrogen production, CuCe/Al2O3 was synthesized by a hydrothermal-impregnated method and a Pd membrane supported by a porous ceramic using the electroless plating method. The results revealed that the catalytic activity and high temperature stability for methanol steam reforming were evidently improved by tuning the copper dispersion, porous structure and the crystal phase. The coupling range with palladium membrane operating temperature was widened. CuCe/Al2O3 presented an excellent stability with a better carbon deposition resistance for the long-term tests than Cu/Al2O3, which exhibited 836.68 μmol/gcat. min of H2 production with low carbon deposition (3.38 wt%) and lower CO emission (0.48 vol%). A 10 μm thick Pd membrane that was deposited on the ceramic support displayed dense and even surface morphology. The effect of palladium membrane structure on hydrogen separation was analyzed. In addition, the influence of temperature on coupling was discussed. Ultimately, high purity of H2 (99.36 vol%) was achieved at 400 °C by integrating the Pd membrane reactor with methanol steam reforming. The internal temperature distribution of the reactor and the effects of feeding conditions were also investigated. This work might offer certain reference for the development of the future distributed integrated hydrogen power generation system, especially in the application of electric vehicles and on-site electricity.

Eco-friendly wood plastic composites with biomass-activated carbon-based form-stable phase change material for building energy conversion

Phase change materials (PCM) can store heat energy through the process of phase change and keep the ambient temperature in a comfortable range, thus reaching the aim of energy conservation and emission reduction. To improve the latent heat capacity, activated carbon (AC) with a dendritic pore structure was used as the carrier, and polyethylene glycol (PEG) was loaded by vacuum adsorption method. A dendritic pore structure with a nesting pattern of macropores, mesopores, and micropores was formed through the steam activation process of waste wood chips, leading to a high load capacity (70%) and uniform distribution, which showed high heat storage performance (ΔHm reached 116 J/g). Then the form-stable phase change material with satisfactory performance (AC/PEG-70) was combined with wood flour/ high-density polyethylene (WF/HDPE) through blending and hot pressing to fabricate phase change heat storage wood-plastic composite material (A-WPC). When the AC/PEG-70 content was 50%, the elongation at break increased by 167% (20%), and the rigidity of the material enhanced. ΔHm of A-WPC-50 was 19 J/g, undoubtedly at this point, achieving the expected thermal performance. Thus, we prepared an eco-friendly wood-plastic composite with high latent heat capacity and high stability by using the dendritic pore structure of biomass activated carbon-based form-stable PCM, which has great significance in promoting energy conservation and emission reduction, responding to green technological innovation and promoting the development of the green and low-carbon industry.

Novel oral spherical activated carbon with ultrahigh specific surface area for adsorption of endogenous toxins

Oral adsorbents can treat chronic kidney disease by removing endogenous toxins from the gastrointestinal tract. Herein, a novel polystyrene-based spherical activated carbon adsorbent with an ultrahigh specific surface area (2125.18 m2·g−1) and a good particle strength (30 N) was successfully prepared via air-oxidation and steam activation. The spherical activated carbon adsorbent possessing hierarchically porous structure presented high creatinine adsorption capacity (up to 300.37 mg·g−1) and excellent adsorption selectivity for different molecular weight adsorbates. Moreover, the pH variation had little effect upon the adsorption capacity of creatinine on the adsorbents. Finally, the mechanism of creatinine adsorption on spherical activated carbon adsorbents was proposed. Van der Waals force and hydrogen bond were considered the driving forces of adsorption for creatinine.

Simple and green synthesis of high-quality macroscopic mesoporous carbon spheres facilitated by graphitic crystallite nanomaterials

Macroscopic mesoporous carbon spheres have many potential applications in separation, catalysis and energy storage. However, the synthesis of high-quality macroscopic carbon spheres remains challenging because carbonaceous gel spheres often suffer from a violently thermo-chemical conversion process in the carbonization and/or activation steps. Herein, we report a simple, efficient, environmentally friendly and scalable method to synthesize high-quality millimeter-sized mesoporous carbon spheres without the need for any surfactants, organic solvents and templates. For the synthesis of carbonaceous spheres, a mixed solution of a recently reported graphitic crystalline nanomaterials (GCNs), resorcinol (R) and formaldehyde was added dropwise into methyl silicone oil using a programmed heating process. The resultant carbonaceous spheres have an isotropic and homogeneous texture, and thus can withstand the drastic change triggered by the subsequent carbonization and steam activation steps at a high temperature. Consequently, the as-synthesized millimeter-sized mesoporous carbon spheres possess perfect shape, high strength and highly developed mesopores, depending on the GCNs dosage used. At a GCNs/R weight ratio of 1:4, the resultant millimeter-sized mesoporous spheres possess not only perfect shape and high hardness, but also a surface area of 1225 m2/g and mesopore volume of 1.3 cm3/g, which are predominantly distributed in the range of 5–25 nm. The adsorption results demonstrate that the as-synthesized millimeter-sized mesoporous carbon spheres exhibit excellent performance as blood purification materials.

Infrastructural injustices in community‐driven afterschool STEAM

AbstractThis article offers a qualitative analysis of infrastructural in/justice in a community‐partnered design intervention focused on developing high‐tech low‐cost Science, Technology, Engineering, Art, and Math (STEAM) projects. We examined the kinds of infrastructural injustices that were present in three afterschool programs and how it shaped STEAM education designs and opportunities for learning with technology to take hold. Combining insights and methods from studies of science and technology with Critical Race Theory, we developed the concept of infrastructural in/justice to illuminate the challenges of organizing STEAM for justice. Infrastructural injustices were identified at the level of dominant narratives that shaped the ideas, resources, and values that undergirded programming and pedagogical practices. We found that community educators were central to creating more just STEAM infrastructures. They drew out unjust infrastructural narratives, created counternarratives that allowed young people of color space to expand their technology and STEAM practices, and connected these practices to their everyday lives, identities, and emerging interests. We detail how working‐class community educators of color are dreaming and enacting new ways to engage with STEAM and STEAM education alongside young people. As we have shown, their ideas and practices combined with the young people's visions for the future challenged neoliberal and racialized narratives of STEAM. Despite community educators' of color critical expertise, their jobs remained precarious within informal STEAM infrastructures. To design for and sustain more just community‐driven STEAM activities we argue that the field must attend not only to how the work of infrastructuring to how community‐driven STEAM is done but also by whom. These activities, organized by community educators of color, must be valued and protected through the classification systems within informal STEAM infrastructures in order to design and sustain more just community‐driven STEAM initiatives.

Pyrolysis-reforming of cellulose over Ni/mordenite for production of hydrogen and heavier organics: The distinct impacts of Ni and mordenite on nature of coke

In-situ steam reforming of small organics in bio-oil while retainment of heavy ones may be a strategy to maximize utilization of organics in bio-oil. In this study, pyrolysis-reforming (pyro-reforming) of cellulose over Ni/mordenite is conducted at 400 to 600 °C, aiming to understand the influence of nickel and mordenite on the nature of the coke formed. The results show that pyro-reforming of cellulose can produce hydrogen through steam reforming of sugar derived aliphatics while retain anhydrate sugars and phenolics but only at 600 °C. Mordenite shows almost no activity in steam reforming but it can effectively promote the aromatization of aliphatic organics and the formation of amorphous aromatic coke. By contrast, nickel species on Ni/mordenite interfere with aromatization via promoting cracking, forming aliphatic coke at 400 or 500 °C. However, at 600 °C, main routes for coke formation shift to steam reforming over Ni/mordenite, producing carbon nanotubes with highly aromatic nature.

Preparation and characterization of polyethylene-based activated carbon fibers stabilized at low temperatures

This study introduces a method for preparing low-temperature-stabilized high-density polyethylene (HDPE)-based activated carbon fibers (HDPE-ACFs) by using a hybrid crosslinking method involving electron beam irradiation and sulfuric acid crosslinking. The HDPE fibers were primary crosslinked with an electron beam at radiation doses of 1000–2000 kGy before being secondarily crosslinked in sulfuric acid at 100 °C for 30–120 min. The hybrid crosslinked fibers were carbonized at 700 °C for 1 h and then formed into activated carbon fibers upon steam activation at 900 °C for 40–70 min. The surface morphology and structural characteristics of the HDPE-ACFs were observed via field-emission scanning electron microscopy, spherical aberration-corrected field-emission transmission electron microscopy, and X-ray diffraction analysis. The pore characteristics were analyzed by using Brunauer–Emmett–Teller and Barrett–Joyner–Halenda equations. As the activation time increased, the specific surface area and total pore volume increased by up to 2090 m2/g and 1.30 cm3/g, respectively. Thus, activated carbon fibers with a high tensile strength value of up to 78 MPa and specific surface area of at least 2000 m2/g were successfully prepared.