BET Area Research Articles

Ni/NiO doped chitosan-cellulose based on the wastes of barley and shrimp for degradation of ciprofloxacin antibiotic

A novel nanocomposite including cellulose, chitosan and Ni/NiO was fabricated from barely wastes, shrimp wastes, and Calotropis procera, respectively. It was characterized by TEM, SEM, TGA, DTA, FT-IR, BET, EDAX, and elemental analysis. 5–25 nm of Ni/NiO were dispersed on chitosan and cellulose. The BET isotherms results showed that the Ni/NiO had a pore size of 11.3 nm with a BET area of 13.8 m2 g−1. While, Chit-Cell@Ni/NiO nano-biocomposite had a pore size of 16.087 nm with a BET area of 15.539 m2 g−1. Then, Chit-Cell@Ni/NiO bio-nanocomposite was applied to the photodegradation of ciprofloxacin under sunlight. About 92% of ciprofloxacin could be efficiently degraded within 20 min. Radical quenching experiments confirmed the contribution of active species was in descending order of h+>•OH > •O2− in the Chit-Cell@Ni/NiO system. The possible ciprofloxacin degradation pathway has been proposed according to the intermediates detected by LC-MS. Also, Chit-Cell@Ni/NiO showed high durability and stability after three-cycle ciprofloxacin degradation. In short, this study offers an efficient green methodology to decrease the number of antibiotics in the water system.

Hydrogen Production from MeOH /H2O Using MWCNT/UV100-TiO2 Catalysts

The current work deals with the synthesis of binary composites MWCNT/UV100 - TiO2 nanoparticles by simple mix method and compares their photocatalytic activates for the pristine and impregnated two ratios of MWCNTs using hydrogen production process under UV- light irradiation. X-ray diffraction, UV-visible reflectance and surface area BET were used to characterize binary synthesized Nano composites. The results in this work were related to two causes; the abilities of MWCNTs towards creating more active species with TiO2-UV100 when dispersion in all the surface, which causing reduce in bandgap, leading to a slight shift in the absorption. The second; the XRD has shown that two samples were did not change in crystallized the anatase phase. According to the results MWCNTs can be used to enhance the activates of UV100 for produce high quantiles of H2 as compare with pristine case without impregnated.

Agroindustrial waste conversion into ultramicroporous activated carbons for greenhouse gases adsorption-based processes

Activated carbons (ACs) for greenhouse gases adsorption were developed via KOH activation of waste twigs arising from processing of Ilex paraguariensis branches. The effect of KOH/carbonized twigs mass ratio (R = 1–3) and temperature (873–1073 K) was examined. The ACs showed BET areas between 1000 and 2150 m2 g−1, total pore volumes of 0.3–1.0 cm3 g−1, and completely microporous structures with large presence of ultramicropores (≤1.1 nm). The ACs obtained with R = 2 at 873 K attained the highest CO2 adsorption capacity (5.4 mmol g−1). An unprecedented correlation to estimate CO2 adsorption capacity in terms of ACs properties was developed. For the best sample, dynamic assays for CO2 and CH4 adsorption from single and binary equimolar gaseous streams were conducted at 101.32 kPa and 303 K. Regeneration showed that the ACs almost kept the initial dynamic adsorption capacity of both gases (1.4 mmol CO2 g−1 and 0.4 mmol CH4 g−1) after five adsorption-desorption cycles.

Sodium adsorption isotherm and characterization of biochars produced from various agricultural biomass wastes

Agricultural biomass wastes, which may pollute the environment yet are inefficiently managed worldwide, can be recycled into biochar, which is subsequently used to remediate salt-affected environments. This creates value-added or dual benefits of treating the wastes while reclaiming saline water/soil for sustainable development. Nevertheless, a lack of knowledge about the linkage between biochar characteristics and sodium adsorption capacity may restrict the wastes from being recycled. The current study aimed to examine physicochemical, nano/microstructural, and functional-group characteristics of biochar and to assess its sodium isothermal-adsorption properties. Four biochars made from rice husk (RH-BC), corn stalks (CS-BC), longan branch (LA-BC), and coconut coir (CC-BC) were used for an isothermal-adsorption experiment. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Brauner-Emmett-Teller surface area (BET area), pore size distribution, and Fourier Transform Infrared spectroscopy (FTIR) were used to characterize biochars, which were additionally analyzed for 9 parameters. RH-BC had the highest BET area (151 m2 g−1) and porosity, whereas LA-BC exhibited the lowest BET area (10.6 m2 g−1), and LA-BC was more condensed. Functional groups, necessary for cation adsorption, were found in biochars. The maximum adsorption capacity of RH-BC (33.9 mg g−1), estimated by the Langmuir isotherm model, was the highest while that of CC-BC (15.5 mg g−1) was the lowest. The Dubinin-Radushkevich isotherm model showed that the Na adsorption mechanism was dominantly a physical process. The current study provides a feasible value-added and sustainable strategy of recycling agricultural biomass wastes with dual benefits of waste treatment and salt-affected environment remediation, applicable worldwide.

Thickness-controlled porous hexagonal NiO nanodiscs electrodes for use in supercapacitors: How nanodiscs thickness influences electrochemical performance

Two-dimensional (2D) nickel oxide (NiO) hexagonal nanodiscs were synthesized via a hydrothermal route, followed by successive calcination. The decisive roles of the [OH−]/[Ni2+] molar ratios, as well as the calcination temperatures, were found in controlling the nanodiscs morphology of the NiO nanostructures. The increase in the concentration of OH− ions in the precursor solution influenced the crystal growth that directed to the formation of the hexagonal nanodisc morphology with increased edge thickness and beyond certain limits transformation from the nanodiscs to complete 3D morphology. The nanodiscs grew with increasing exposed surface size with a high BET area and varied thicknesses from 4 to 20 nm. The increase in calcination temperature improved crystallinity by eliminating crystal defects and voids, while crystals grew along the (200) plane. However, a reduction in the BET area and pore volume occurred at higher calcination temperature because of the collapse in micro-mesopores. The electrochemical performances of NiO electrodes show dependence on the thickness of the nanodiscs, the calcination temperature, and the type of current collector used. A distinct electrochemical feature was observed for NiO nanodiscs over planar conductive carbon fiber paper and 3D porous Ni foam substrates. The hydrothermal approach reported here to produce thickness-controlled NiO nanodiscs with high intrinsic surface area has great potential for developing next-generation battery-type faradic electrodes in conjunction with carbon allotropes and other metal oxide materials for high power and energy density throughput.

Evaluation of the Soil–Water Retention Curve of Arsenic-Contaminated Soil by the Filter Paper Method

Arsenic is a metalloid frequently found in contaminated sites due to its easy mobilization in the environment. This has attracted the researchers who have studied this phenomenon from an environmental engineering perspective. Although there is evidence indicating that soil contamination impacts its geotechnical behavior, there is no available information about the changes in the soil’s suction after its contamination. The objective of this paper was to evaluate the soil–water retention curve of arsenic-contaminated soil. An unsaturated soil sample was contaminated with arsenic at two different concentrations and a filter paper calibration curve was developed for each contaminant concentration. Soil contamination decreased the BET area and increased its pore sizes. At a saturation rate of 0.8, the matric suction of the contaminated soils decreased (from 1681 kPa to 260 kPa), while the osmotic suction increased (from 23 kPa to 530 kPa), compared with the natural soil’s condition. Furthermore, the soil’s suction values obtained with the ASTM D5298 calibration curve were higher than those obtained using the calibration curve developed for the contaminated state. Thus, to avoid misunderstanding the mechanical behavior of the unsaturated soils under contaminated conditions, the osmotic suction should be considered and evaluated with the corresponding calibration curve.

Morphology-Controllable Graphene-Modified Cu-Benzene-1,3,5 Tricarboxylic Acid Composites for Volatile Organic Compounds and CO2 Adsorption Property

Volatile organic compounds (VOCs) are the one kind of pollution, which lead to the severe atmospheric contamination problem. Metal organic frameworks (MOFs) and graphene are promising candidates to collect VOCs. In this study, composites which consist of graphene sheets and Cu-BTC (benzene-1,3,5 tricarboxylic acid) are prepared by the hydrothermal method to adsorb VOCs and CO. Moreover, the morphology of the resulting graphene material in the composites can be controlled by adjusting the pH value, reaction time and surfactant during the hydrothermal process, which further determines the adsorption ability for different gas molecules. According to the pore distribution features of various composites, the morphology of graphene exerts a fatal influence on the observed adsorption performances. Furthermore, the polarity of the as-prepared composites is another important determinant to selective adsorption for various VOCs. The stability of these composites under high temperature is also tested, and the results demonstrate that the adsorbents can be used in a wide temperature range. Moreover, the large BET areas and high stability of the composites in the water endow them a potential application in the sewage clarification field. After the corresponding optimization, the adsorption amounts of methanol and ethanol reach 13.6[Formula: see text]mmol[Formula: see text]g[Formula: see text] and 9.68[Formula: see text]mmol[Formula: see text]g[Formula: see text], respectively.

Effect of N-vinylimidazole comonomer on blood plasma protein and endogenous toxin adsorption on mesoporous copolymer beads

N-vinylimidazole-divinylbenzene (VI-DVB) copolymer beads with a N-vinylimidazole (VI) weight content ranging from 7% to 15% were studied as possible adsorbents for hemoperfusion and compared with the cross-linked polystyrene beads from commercial devices. All the beads had a large volume fraction of mesopores with diameters of 2–50 nm, quantified by nitrogen adsorption, and BET areas from 500 to 1000 m²/g. Metal-chelate adsorption of copper (II) ions on VI-DVB was high in 0.15 M NaCl (up to 40 μmol/mL), and low in blood plasma (< 1 μmol/mL). Reversible adsorption of blood plasma proteins was high (> 100 mg/mL beads) on all the bead types. Irreversibly adsorbed proteins eluted by 2% SDS included albumin, fibrinogen, fibronectin, and transferrin. Metal chelating contributed to the irreversible adsorption. Unlike the beads from commercial devices, VI-DVB beads adsorbed the LPS endotoxin from plasma. Adsorption of bilirubin and IL-6 was high on all the beads tested, but VI-DVB beads were better adsorbents of bile acids. VI-DVB are promising as components of multifunctional devices for blood purification applicable to treatment of diseases where conventional devices have lower or negligible adsorption capacity.

Insight into the role and mechanism of polysaccharide in polymorphous magnesium oxide nanoparticle synthesis for arsenate removal

The low cost and non-toxic of magnesium oxides make it a potential eco-friendly material for arsenic removal. Polysaccharide is a kind of green modifier to obtain nanoscale MgO particles with a higher adsorption affinity. In this study, the impact of chain structures of polysaccharides on the morphology features and arsenate removal efficiency of MgO-NPs were investigated. Pullulan and starch facilitated the synthesis of flower-like MgO-NPs, and pectin facilitated the synthesis of plate-like ones. Although the two kinds of flower-like MgO-NPs undergone similar time to reach equilibrium, the one obtained from the starch-synthesis route showed a higher arsenate adsorption capacity (98 mg g−1), due to that their bushy and smaller petals on the surface provide more active sites for arsenic adsorption. The pectin-synthesis route also produced MgO-NPs with higher arsenate adsorption capacity (101 mg g−1), ascribed to stacking of nano-plates on their surfaces facilitated to form defect surfaces. However, due to their lower BET area, the plate-like MgO-NPs took twice times to reach equilibrium for arsenic adsorption compared with the others. In the stage for the hydrolysis of MgO, hydroxyl groups on the polymer chain provide active sites to physically trap or bond with MgO particles and then to produce hydrolyzed precursors. The poly chain containing inter- and intra-hydroxyl groups directed MgO molecular growing into hydroxide crystals with 3D frameworks during their nucleation and growth. However, pectin only provides inter-hydroxyl groups and directs to form hydroxides with 2D frameworks. Furthermore, the rapid-nucleation vs. slow-growth model in the stage of pyrolysis of hydroxide crystals successfully interprets the thinner petals and complex chemical phases of the final nanoparticles obtained from the pullulan-synthesis route. This work may provide direction and perspectives for the rational design of well-performing MgO materials for arsenate removal.

Key Factors for Activated Carbon Adsorption of Pharmaceutical Compounds from Wastewaters: A Multivariate Modelling Approach

Projection to Latent Structures (PLS) regression, a generalization of multiple linear regression, is used to model two datasets (40 observed data points each) of adsorption removal of three pharmaceutical compounds (PhCs), of different therapeutic classes and physical–chemical properties (carbamazepine, diclofenac, and sulfamethoxazole), from six real secondary effluents collected from wastewater treatment plants onto different powdered activated carbons (PACs). For the PLS regression, 25 descriptors were considered: 7 descriptors related to the PhCs properties, 10 descriptors related to the wastewaters properties (8 related to the organic matrix and 2 to the inorganic matrix), and 8 descriptors related to the PACs properties. This modelling approach showed good descriptive capability, showing that hydrophobic PhC-PAC interactions play the major role in the adsorption process, with the solvation energy and log Kow being the most suitable descriptors. The results also stress the importance of the competition effects of water dissolved organic matter (DOM), namely of its slightly hydrophobic compounds impacting the adsorption capacity or its charged hydrophilic compounds impacting the short-term adsorption, while the water inorganic matrix only appears to impact PAC adsorption capacity and not the short-term adsorption. For the pool of PACs tested, the results point to the BET area as a good descriptor of the PAC capacity, while the short-term adsorption kinetics appears to be better related to its supermicropore volume and density. The improvement in these PAC properties should be regarded as a way of refining their performance. The correlations obtained, involving the impact of water, PhC and PAC-related descriptors, show the existence of complex interactions that a univariate analysis is not sufficient to describe.

Efficient synthesis of high quality double walled carbon nanotubes and their cost-effective properties

The excellent capacitance performance of DWCNTs with high BET area and electrical conductivity far exceeds that of MWCNTs and they are cost-effective compared to SWCNTs on the market.

Synthesis and photocatalytic activity of Cu2O hollow nanospheres/TiO2 nanosheets by an in-situ water-bath method

In this work, a simple in-situ water-bath method is used to load Cu2O hollow nanospheres (named as H-Cu2O) on TiO2 nanosheets (named as TiO2-NS). H-Cu2O of 160–250 nm in diameter is uniformly supported on the surface of TiO2-NS. H-Cu2O has a novel hollow core-shell structure with a double shell. Specifically, the diameters of inner hollow spheres are 80–90 nm and the thickness of the outer shell and inner shell are about 40 nm and 25 nm, respectively. It is conjectured that the outer and inner shells of H-Cu2O can both provide adsorption and reaction sites, favoring the photocatalytic reaction. The UV–visible diffused reflectance spectra show that compared with TiO2-NS, the H-Cu2O/TiO2-2 sample with adding 80 mg of TiO2-NS shows a stronger visible light absorption. Furthermore, the steady-state photoluminescence (PL) and photocurrent spectra show that H-Cu2O/TiO2-2 has a weaker PL intensity at about 370 nm and 6 times higher photocurrent intensity than TiO2-NS, demonstrating that H-Cu2O/TiO2-2 has higher charge separation efficiency. Compared with TiO2-NS, the photocatalytic activity of H-Cu2O/TiO2-2 under UV light (λ ≤ 400 nm) increase by 6.3 times for the degradation of methyl orange. The improved photocatalytic activity can be attributed to the enlarged BET areas (6.1 m2 g-1/H-Cu2O/TiO2-2 vs. 3.8 m2 g-1/TiO2-NS), the enhanced light adsorption, and the improved charge separation efficiency. The reported in-situ water-bath method is simple, mild, and general, which could be extended to other novel composite materials.

Experimental investigation on NO emission and burnout characteristics of high-temperature char under the improved preheating combustion technology

In order to avoid the formation of NO from the nitrogen-containing pyrolysis components in the main combustion zone under preheating combustion technology, an improved preheating combustion technology was proposed. A two-stage drop-tube furnace was built to study the NO emission and combustion characteristics of high-temperature char (HTC) under the improved preheating combustion technology. The char was first heated to the initial pyrolysis temperature(600℃,800℃ and 1000℃) in the upper furnace under the atmosphere of nitrogen, before being burned in the second furnace. The influence of important operating parameters such as HTC temperature(600℃,800℃ and 1000℃), combustion temperature (1200℃,1300℃ and 1400℃)and excess air ratio (0.6 ∼ 1.4)were analyzed. The results show that raising the HTC temperature helps to reduce NO emissions. The maximum NO reduction efficiency is 21.1 % when the excess air ratio(α) = 1.0, which differs from the reported literature results of room-temperature char (RTC). In HTC, there is no absolute correlation observed between the BET area and NO reduction. The release of C and N is altered by pre-ignition of char at HTC; additionally, the evolution of nitrogen functional groups during the pyrolysis process is more key influencing factors. The stoichiometric ratio has a considerable influence on the effects of combustion temperature on NO emission. When there is a lack of oxygen, NOx emissions decrease as the temperature rises, whereas under oxygen-rich situations the converse is true. With the increase in HTC temperature from 600 °C to 1000 °C, the critical excess air ratio steadily increases from 0.75 to 0.85. The carbon concentration of fly ash can be reduced by increasing both the HTC and the combustion temperature. The largest reduction in carbon content in fly ash is 28.6 % at α = 1.0.

Oxidation-absorption process for simultaneous removal of NOx and SO2 over Fe/Al2O3@SiO2 using vaporized H2O2

3% Fe/Al2O3 and 3% Fe/Al2O3@SiO2 were prepared to investigate the performance in simultaneous removal of NOx and SO2 using vaporized H2O2. Certain paraments were changed to explore the activity of catalysts, including temperature, H2O2 concentration, GHSV and coexistence gases component. A 24-h durability test was conducted on 3% Fe/Al2O3@SiO2. Moreover, a series of characterizations were employed to analyze the physical and chemical properties of catalysts, including XRD, BET, SEM, TEM, FTIR and XPS. Compared with 3% Fe/Al2O3, 3% Fe/Al2O3@SiO2 exhibited more excellent catalytic activity, which could achieve the peak removal efficiency of 100% for SO2 and 93.76% for NOx. Moreover, 3% Fe/Al2O3@SiO2 kept stable simultaneous removal efficiency in a 24-h test. The characterization results indicated that the BET area was greatly improved and the core-shell structure was synthesized with the formation of more micropores and mesopores by the coating of SiO2, which could improve the activity of catalyst at high temperature and high SO2 concentration. Besides, the mechanism of SO2 molecules on simultaneous removal was investigated. On one hand, a part of H2O2 was consumed by SO2 molecules without catalyst, which resulted in the drop of NOx removal by the decrease of oxidants. The main products were sulfites and bisulfites, which were broken down into SO2 over the catalyst. On the other hand, the presence of SO2 was beneficial for NOx removal by increasing oxygen vacancies on the catalyst surface and facilitating the absorption of NO2 by NaOH solution.

Hybrid Metal-Organic Framework-Cellulose Materials Retaining High Porosity: ZIF-8@Cellulose Nanofibrils

Metal-organic frameworks have attracted a great deal of attention for future applications in numerous areas, including gas adsorption. However, in order for them to reach their full potential a substrate to provide an anchor may be needed. Ideally, this substrate should be environmentally friendly and renewable. Cellulose nanofibrils show potential in this area. Here we present a hybrid material created from the self-assembly of zeolitic imidazolate framework (ZIF-8) nanocrystals on cellulose nanofibrils (CNF) in aqueous medium. The CNF/ZIF-8 was freeze dried and formed free standing materials suitable for gas adsorption. A BET area of 1014 m2 g−1 was achieved for the CNF/ZIF-8 hybrid materials ZIF-8@cellulose which is comparable with reported values for free standing ZIF-8 materials, 1600 m2 g−1, considering the dilution with cellulose, and a considerable enhancement compared to CNF on its own, 32 m2 g−1.

Promoted Ni–Co–Al2O3 nanostructured catalysts for CO2 methanation

15 wt.%Ni-12.5 wt.%Co–Al2O3 catalysts promoted with Fe, Mn, Cu, Zr, La, Ce, and Ba were prepared by a novel solid-state synthesis method and employed in CO2 methanation reaction. BET, XRD, EDS, SEM, TPR, TGA, and FTIR analyses were conducted to identify the chemicophysical characteristics of the prepared samples. The addition of Fe, Mn, La, Ce, and Ba was effective to improve the catalytic performance of the 15 wt%Ni-12.5 wt%Co–Al2O3 due to the higher CO2 adsorption capacity of the promoted catalysts. Among the studied promoters, the Fe-promoted catalyst possessed the highest catalytic activity (XCO2 = 61.2% and SCH4 = 98.87% at 300 °C). Also, the effect of calcination temperature, feed composition, and GHSV on the performance of the 15 wt%Ni-12.5 wt%Co-5wt%Fe–Al2O3 catalyst in CO2 methanation reaction was assessed. The outcomes confirmed that the 15 wt%Ni-12.5 wt%Co-5wt%Fe–Al2O3 catalyst with the BET area of 122.4 m2/g and the highest pore volume and largest pore diameter had the highest catalytic activity. Also, the catalytic performance in the methanation of carbon monoxide was studied, and 100% conversion of carbon monoxide was observed at 250 °C.

Ingenious ambient temperature fabrication zirconium-metal organic framework laden polysaccharide aerogel as an efficient glyphosate scavenger

Developing superior adsorbents to remove pollutants from aqueous solution is increasingly becoming urgent with respect to grave water pollution and public health consequences. Herein, a metal organic framework (MOFs)-decorated shapeable aerogel (CS-CNC@UiO-66-NH2) prepared by in situ growth of Zr-MOF (UiO-66-NH2) on chitosan/cellulose nanocrystal (CS-CNC) hybrid aerogel at room temperature was developed to remove glyphosate (Gly) from water. The aerogel possessed highly porous structure and excellent water stability upon introduction of cellulose nanocrystals extracted from cotton. Besides, the loading ratio of UiO-66-NH2 of the proposed ambient growth strategy (37.72%) was higher than conventional solvothermal method (10.91%) because of the structure integrity of polysaccharide aerogels at room temperature. Further, the BET area and porosity of CS-CNC@UiO-66-NH2 aerogel increased from 21.65 m2 g−1 to 231.60 m2 g−1 and 87.47–93.03% due to the synergy of UiO-66-NH2. Owing to these virtues, the separation-free aerogel exhibited a high adsorption capacity of 133.7 mg/g in batch adsorption and displayed high recyclability over four consecutive adsorption-desorption cycles. Moreover, the Zr-OH/oxygen-containing moieties of the aerogel, electrostatic attraction and hydrogen-bonding accounted for driving Gly adsorption. Considering practical application, the aerogels were packed in glass column for fixed-bed test which revealed that the aerogels could decontaminate Gly with column adsorption capacity of 44.99 mg/g. Consequently, the CS-CNC@UiO-66-NH2 aerogel with highly porous structure exhibited good Gly adsorption and simple separation, offering a novel strategy to synchronously improve adsorption capacity of polysaccharide-based adsorbent and MOFs shaping for pollutant removal.

Design of Ni/La2O3 catalysts for dry reforming of methane: Understanding the impact of synthesis methods

Fine-tuning of materials properties, particularly the catalytic properties, through innovative synthesis procedures has gained an increased research interest in the last decades. It is well known that synthesis procedures have considerable impact on the physio-chemical properties of the synthesized materials even if the chemical composition is maintained. Herein, we investigated the impact of selected synthesis methods on the catalytic performance of Ni/La2O3 for the dry reforming of methane (DRM), a challenging reaction known for severe coking. Although this catalyst has been frequently studied for DRM, however, tuning the structure-activity relationship by varying the synthesis routes has not been reported. Herein, the chosen synthesis techniques; for example the solution combustion synthesis (Ni/La-SC), sol-gel (Ni/La-SG), homogeneous precipitation (Ni/La-HP), solvothermal (Ni/La-ST), and modified oleylamine-assisted synthesis (Ni/La-ME); considerably affected the morphology, metal support interaction (MSI), and surface area of Ni/La2O3 catalysts leading to variation in their performance for DRM. The investigated catalysts were thoroughly characterized by using SEM-EDX, TEM, N2-physisorption, XRD, XPS, and H2-TPR to understand the structural properties. Their catalytic performance towards the DRM was evaluated by varying the temperature between 550 and 800 °C. DRM experiments demonstrated that among the studied catalysts, Ni/La-SC showed the best performance for DRM with a high catalytic activity and coking resistance. For instance, Ni/La-SC revealed the highest CO2 and CH4 conversions i.e. 97.9 ± 1.5% and 96.6 ± 1.8%, respectively at 800 °C. The same sample revealed the highest hydrogen yield i.e. 71.9% and the highest H2/CO ratio i.e. 1.03 ± 0.013 at the same temperature. The results revealed that Ni/La-SC demonstrated the lowest increment (20.9%) in the Ni crystallite size after DRM reaction, highest durability, and the lowest rate of coke formation (42 ± 5.2 mg C/gcatalyst) over an operating period of 100 h at 800 °C. The outstanding performance of Ni/La-SC catalyst was credited to the small crystallite size of Ni, high Ni0/Ni2+ ratio, high BET area, and a good dispersion of nickel sites over the La2O3 support. The obtained results may open new frontiers for size and shape-controlled synthesis of nanostructured metals/metal oxides catalysts with controllable morphologies and dispersion that can lead to desirable catalytic properties.

Effect of pressure on the structure and reactivity of demineralized coal during O2/H2O thermal conversion process

Pressure can strongly affect the thermal conversion characteristics of coal. This work used a pressurized horizontal furnace to study the pyrolysis (Ar) and O2/H2O (10 vol%/25 vol%) thermal conversion characteristics of demineralized coal under different pressure (0.1–1.5 MPa) and at 1000 °C. The changes of carbon conversion, pore structure, carbon skeleton structure, and surface functional group structure of different pressure pyrolysis char and its combustion residual char were obtained by using N2 adsorption, Raman and X-ray Photoelectron Spectroscopy (XPS) test methods. A micro fluidized bed reaction analyzer was then used to test the reactivity of the char to explore the influence of pressure. Pressure can increase the yield of pyrolysis char from 64.81% to 68.78% and promote the conversion of char in O2/H2O conditions from 27.78% to 78.58%. For the pore structure of char, pressure and O2/H2O atmosphere have a positive promotion effect, and have a similar effect on the degree of graphitization and the relative content of C–C and C–H bonds. Largest BET area of char is 234.72 m2/g at 1.5 MPa of pyrolysis and 793.43 m2/g at 1.0 MPa of O2/H2O combustion, respectively. For the reactivity of char prepared in O2/H2O combustion, the pore structure is dominant compared to chemical structure.

Use of dirty plastic waste as precursors for activated carbon production—A contribution to the circular economy

AbstractThe production of activated carbons (ACs) from dirty plastic wastes derived from the mechanical/biological treatment of urban solid wastes, disposable plastics and plastics used in agriculture is reported. The use of these precursors is innovative and contributes to the circular economy by the valorization of dirty plastics that are usually disposed in landfills. ACs were produced by physical activation, with air or CO2, and chemical activation, with KOH or K2CO3. ACs presented a BET (N2) area and pore volume up to 723 m2/g and 0.32 cm3/g. Selected samples were tested for the 2,4‐dichlorophenoxyacetic acid (MCPA) and 4‐chloro‐2‐methyl‐phenoxyacetic acid (2,4‐D) removal from the liquid phase. PB‐K2CO3‐1:1–700 presented an apparent maximum adsorption capacity of 245 and 289 mg g−1 for MCPA and 2,4‐D, respectively.