Specific Surface Area Of Samples Research Articles

Contrasting piezocatalytic and tribocatalytic behavior of BaTiO3

In this work, BaTiO3 with different morphologies is obtained by controlling the Ba/Ti ratio in the precursor, reaction temperature, and reaction time. The effects of the morphology and the specific surface area of samples, as well as friction conditions on piezocatalytic and tribocatalytic performance, are investigated. BaTiO3 exhibits the best piezocatalytic performance when it is composed of a mixed-shape of BaTiO3 rod and particle because in this case there is a balance between the specific surface area and the piezopotetial. However, the tribocatalytic performance is majorly dependent on friction conditions such as the roughness of the reaction vessel and the rotation speed of the stirring rod. Both ⋅O2− and ⋅OH play important roles in the piezocatalytic and tribocatalytic degradation of dyes. Therefore, this work gains significant factors in piezocatalytic and tribocatalytic degradation of dyes and provides a reference for remediation of water pollution in the future.

Study on triphase of polymorphs TiO2 (anatase/rutile/brookite) for boosting photocatalytic activity of metformin degradation

The elution of pharmaceutical products such as metformin at higher concentrations than the safe level in aquatic systems is a serious threat to human health and the ecosystem. Photocatalytic technology using TiO2 semiconductors potentially fixes this problem. This study aims to synthesize triphasic anatase–rutile–brookite TiO2 using ultrasound assisted sol–gel technique in the presence of acid and its application to photodegradation of metformin under UV light irradiation. Based on X-ray diffraction analysis, a TiO2 sample consisted of anatase (76%), rutile (7%), and brookite (17%) polymorph (A76R7B17) that was fully crystallized. Scanning electron microscopy (EM)–energy dispersive X-ray spectra results showed agglomerated triphasic A76R7B17 with irregular spherical clusters. Transmission EM results revealed that the crystal size of A76R7B17 was 4–14 nm. The Brunauer–Emmett–Teller analysis showed the sample's specific surface area of 149 m2 g−1. The degradation test of metformin demonstrated that the A76R7B17 exhibited a 75.4% degradation efficiency after 120 min under UV light irradiation, significantly higher than using biphasic and single-phase TiO2 photocatalysts. This difference could be attributed to the heterojunction effect of triphasic materials that effectively reduced electron–hole recombination rate as well as the combination of effective electron transfer from conduction band of brookite and anatase and the utilization of wider range of UV–visible light using rutile.

Thermochemical energy storage in CaCl2-NH3 pair evaluated by rapid multiple adsorption-desorption cycles controlled with wasted iron induction heating

Energy storing systems can provide leverage to the current supply demand intermittency issue thus increasing energy efficiency. Among many available technologies, thermochemical energy storage is highly promising. In this work, we investigate, experimentally, for the first time, inductive heating as an approach to direct coupling of power systems with thermal energy technologies. This system also allows for versatile measurements in rapid multiple adsorption–desorption cycle control. Adsorption and desorption cycling of the CaCl2-NH3 adducts is realized in a custom-made setup. Iron wires and waste red mud are investigated as potential inductive materials. Material performance is evaluated after 1, 2 and 1000 cycles using differential scanning calorimetry, thermogravimetry, scanning electron microscopy and specific surface area. Waste red mud shows good inductive potential. No material degradation is observed after 1000 cycles in all cases. Samples heated using waste red mud have a higher maximum absorption capacity (0.304 versus 0.154 gNH3/gCaCl2) and desorption enthalpy (716 versus 460 KJ/ kgCaCl2) compared to the ones heated using iron wires. This is found to be related to the average specific surface area of samples containing red mud, which is almost double that of iron ones. We hope the concept presented here can stimulate research in the direction of inductive heating while simultaneously generating new utilization pathways for waste red mud.

The production of activated carbon from Acacia erioloba seedpods via phosphoric acid activation method for the removal of methylene blue from water

Wastewater treatment requires a lot of granular activated carbon to absorb the dissolved organic components. This article describes a low-cost process for making highly active adsorption activated carbons from biomass, which could be used for wastewater treatment. A one-step carbonization and chemical activation with phosphoric acid at 500 °C produced low-cost acacia-derived porous activated carbons. The activated carbons' moisture, ash, volatile matter, and fixed carbon content were determined using proximate analysis. The activated carbon's adsorption qualities were also determined by studying its bulk density, surface morphology, power of hydrogen, iodine number, and methylene blue number index. To test the produced activated carbons for water treatment, batch adsorption dynamics were performed at room temperature for the removal of methylene blue from aqueous solution. Compared to activation using H2SO4, H3PO4 proves superior in generating well-developed pores, leading to a mesoporosity and microporosity structure with a larger surface area and high adsorption capacity. Brunauer–Emmett–Teller determined the sample's specific surface area, which was found to be 387 m2/g. The iodine number for 50, 100, and 200 μm activated carbon particles size was 620, 592, and 632 mg/g, respectively. The adsorption of MB on AC material better fits with Langmuir's adsorption isotherm; hence, particles are adsorbed on well-pronounced heterogeneous surfaces. The sips model is found to best represent the equilibrium data with R2 values of 0.994, suggesting the heterogeneous surface adsorption of MB on AC. Therefore, the adsorption of AC by MB involves physical and chemical processes. The produced AC hence appears to remove dissolved organic contaminants from raw water.

Ultrasound-assisted sol-gel synthesis and characterization of highly efficient OTES-Functionalized ZnO/GO nanocomposite for a novel purification of phosphoric acid using sonophotocatalytic process: Box-Behnken Design optimization

Octyltriethoxysilane-Functionalized Zinc Oxide/Graphene Oxide nanocomposites (OTES@ZnO/GO NCs) were synthesized via the ultrasound-assisted sol-gel synthesis technique. The surfaces of the ZnO/GO NCs were modified by grafting the organosilane agent, octyltriethoxysilane. The structure, morphology and elemental compositions of the samples were characterized using XRD, FESEM, TEM and EDX. The surface charge and specific surface area of samples were measured using Zeta potential and BET analysis, respectively. The various chemical functional groups and, absorption spectroscopy were performed using FTIR and RS spectrum, and UV-Vis spectrophotometer, respectively. Photoluminescence (PL) measurements have been used to investigate the fate of electron-hole and the performance of charge carriers trapping. Patterns of XRD showed a good agreement with the hexagonal structure and the crystalline size of ZnO NPs and OTES@ZnO/GO NCs were obtained as 21 and 16 nm, respectively. Response Surface Methodology (RSM) based on Box–Behnken Design (BBD) was applied to optimize the phosphoric extraction. The optimal conditions were found in 21.04 % of HCl concentration, a reaction time of 5 min and 6 of liquid-to-solid ratio to achieve 96.87% extraction efficiency. Based on the FTIR spectrum, the combination of UV/US irradiation in the degradation process resulted in the efficient removal of Ca2+ ions in 120 min.

Generic CD-MUSIC-eSGC model parameters to predict the surface reactivity of iron (hydr)oxides

The surface reactivity of iron (hydr)oxides plays a crucial role in controlling their interfacial reactions, for which various surface complexation models have been developed. The diversity of mineralogical properties of iron (hydr)oxides has resulted in a redundancy of model parameters, which hampers the modeling of iron (hydr)oxides in soils and sediments, where goethite, hematite and ferrihydrite dominate the iron (hydr)oxide mass fraction. To capture their combined surface reactivity, optimized generic protonation parameters of the Charge Distribution-Multisite Complexation (CD-MUSIC) extended-Stern-Gouy-Chapman (eSGC) model were derived by reanalyzing literature datasets and tested with some newly synthesized iron (hydr)oxides. It was observed that the proton and monovalent ion affinity constants of the different iron (hydr)oxides were located in a narrow range. For the singly- and triply-coordinated hydroxyl sites the obtained generic log(affinity constants) were 8.3 and 11.7 for the protonation reaction and -0.5 for the reaction with the monovalent background ions. Their combination with fixed site densities of singly-/triply-coordinated hydroxyl sites of 3.45/2.70, 5.00/2.50, and 5.80/1.40 sites/nm2 for goethite, hematite, and ferrihydrite, respectively, provided good results. The Stern layer capacitances of the inner and outer Stern layers were set equal and could be acquired by an empirical correlation with the sample specific surface area (SSA). The CD-MUSIC-eSGC model with the generic model parameters enables good quality predictions of the proton reactivity of iron (hydr)oxides in 1:1 electrolyte solutions regardless of the sample heterogeneity. The advantages of the generic CD-MUSIC-eSGC model are twofold: (1) protonation of iron (hydr)oxides can be described without making use of spectroscopic measurements and proton titrations, and (2) the model calculations are greatly simplified.

Synergetic effect of oxygen vacancies and morphology of ZnO photocatalyst prepared by non-hydrolytic sol-gel route for the photo-oxidation of 2-propanol in a gas-solid system

The effects of the nature of some carboxylic acids (oxalic, malic, citric, and tartaric acid) and of the annealing temperature in the preparation of the ZnO photocatalyst by a non-hydrolytic sol-gel route (using zinc acetate as the precursor) have been studied for oxidation of 2-propanol in air as probe reaction in a gas-solid regime. The physico-chemical characterization by XRD, SEM/EDX and UV–vis-DRS revealed a synergetic effect of the presence of oxygen vacancies and morphology of ZnO on the reaction performance. Oxygen vacancies were found to increase with decreasing annealing temperature, and this result indicates the possibility of their production in situ without the addition of a doping agent.XRD results showed that ZnO samples present a pure wurtzite structure with an average crystal size ranging from 21 nm to 42 nm. The specific surface area of samples ranged from 3.0 m2·g–1 to 18 m2·g–1and SEM observation indicated the presence of different agglomeration of both faceted and non-faceted particles. The lowest band gap energy of ZnO was 3.2 eV. The photocatalytic oxidation of 2-propanol in gas-solid regime was carried out in oxygen atmosphere. An increase of acid concentration during the ZnO preparation caused a decrease on the activity of the photocatalyts. An increasing amount of zinc acetate with respect to acid during the preparation of the photocatalysts enhanced the oxygen vacancies in the solid, which induced an increase of the 2-propanol oxidation rate constant. The increasing of the annealing temperature decreased the oxygen vacancies and hence the photocatalytic activity of ZnO. The highest 2-propanol oxidation rate (kapp = 4.00·10–2 min–1) was obtained by using the ZnO sample prepared with a 1:2 molar ratio of zinc acetate:oxalic acid, and annealed at 400 °C. This photocatalyst showed an oxidation rate 80 times higher than that of the least active photocatalyst (kapp = 5.00·10–4 min–1) obtained using zinc acetate:tartaric acid at 1:1 molar ratio and annealed at 500 °C.

Modification of CeNi0.9Zr0.1O3 Perovskite Catalyst by Partially Substituting Yttrium with Zirconia in Dry Reforming of Methane.

Methane Dry Reforming is one of the means of producing syngas. CeNi0.9Zr0.1O3 catalyst and its modification with yttrium were investigated for CO2 reforming of methane. The experiment was performed at 800 °C to examine the effect of yttrium loading on catalyst activity, stability, and H2/CO ratio. The catalyst activity increased with an increase in yttrium loading with CeNi0.9Zr0.01Y0.09O3 catalyst demonstrating the best activity with CH4 conversion >85% and CO2 conversion >90% while the stability increased with increases in zirconium loading. The specific surface area of samples ranged from 1–9 m2/g with a pore size of 12–29 nm. The samples all showed type IV isotherms. The XRD peaks confirmed the formation of a monoclinic phase of zirconium and the well-crystallized structure of the perovskite catalyst. The Temperature Program Reduction analysis (TPR) showed a peak at low-temperature region for the yttrium doped catalyst while the un-modified perovskite catalyst (CeNi0.9Zr0.1O3) showed a slight shift to a moderate temperature region in the TPR profile. The Thermogravimetric analysis (TGA) curve showed a weight loss step in the range of 500–700 °C, with CeNi0.9Zr0.1O3 having the least carbon with a weight loss of 20%.

Sorption-photocatalytic performance of NbOx nanocrystals synthesized via heat-stimulated oxidation of niobium carbide

In this work, nano-sized niobium oxides with different crystal structures can be produced by thermal treatment of nonstoichiometric nanocrystalline niobium carbide (NbCy) and serve as effective sorbents and photocatalytic materials. Differential thermal analysis of initial NbCy powder was carried out, and temperatures of thermal treatment for the were chosen. The nanopowders were studied using powder X-ray diffraction, scanning electron microscopy, low-temperature N2 adsorption–desorption, X-ray photoelectron spectroscopy and diffuse reflectance electron spectroscopy methods. The specific surface area of samples annealed at 100, 200, 300, 400, 500 °C was about 224, 255, 273, 224 and 47 m2/g, respectively. The photocatalytic activity of the obtained nanopowders was analyzed during the oxidation of an aqueous solution of methyl orange on exposure to visible light. The photocatalytic activity of nanopowders grows with the annealing temperature increasing from 100 to 500 °C and reaches the maximum value for the higher niobium oxide Nb2O5. The time of complete decoloration of dye was 165 min. The tests performed to establish the sorption equilibrium between catalyst and dye in the dark revealed that the nanopowder produced during annealing at 300 °C possesses a high sorption capacity of 76.5%, which allows it to be considered as an effective sorbent.

Facile Construction of Magnetic Ionic Liquid Supported Silica for Aerobic Oxidative Desulfurization in Fuel

With the rapid growth in fuel demand, deep desulfurization of fuel oil is vitally necessary for the sake of health and environmental protection. In this work, a kind of magnetic ionic liquid supported silica is prepared by a facile ball milling method, and applied in the aerobic oxidative desulfurization of organosulfurs in fuel. The experimental results indicated that ball milling procedure can increase the specific surface area of samples, which is beneficial to oxidative desulfurization process. Under the optimal reaction conditions, the prepared materials can have an entire removal of aromatic sulfur compounds as well as a good recycling ability. Moreover, the introduction of Fe3O4 did not decline the desulfurization performance, but help the catalyst to be easily separated after reaction.

Comparative study on properties of zinc ferrite and its purified products

In this paper, aimed at the zinc ferrite products from the gossan bearing-zinc ore by direct roasting and their sulfuric acid leaching products, the differences of related products in element composition, mineral composition, specific surface properties and particle morphology were studied. The results show that the XRD diffraction peaks of low content zinc ferrite products are more complex and have more impurity peaks than those of high content zinc ferrite products and less impurity peaks. The XRD patterns of leaching residue have little difference after sulfuric acid leaching purification, but the high content zinc ferrite products have higher crystallinity, the diffraction peak of zinc ferrite from leaching residue is stronger. That is to say, the content of zinc ferrite in the roasted product will not affect the final purification effect by sulfuric acid leaching purification. The phase composition of the purified product is similar, which the main component is zinc ferrite, and contains impurities such as gangue minerals. The adsorption-desorption curves of two purified zinc ferrite products are of type III, but the curves of two products are different. The specific surface area of sample 1 is 9.66 times that of sample 2. The Pore volume and average pore diameter are 8.14 times and 1.97 times, respectively. Therefore, the purified zinc ferrite products with low content of zinc ferrite will have more application potential as adsorbents. There are relatively few soluble impurities in the high content zinc ferrite products, so the micro-morphology of the samples has little change after leaching. However, there are more soluble impurities in the low content of zinc ferrite. After leaching purification by sulfuric acid, the position of the soluble impurities becomes pore, the large particles are decomposed and the particles become finer.

Investigation on the adsorption characteristics and influencing factors of diesel engine exhaust particulate matter.

In the exhaust pipe, the adsorption process of diesel exhaust particulate matter (PM) is affected by the combination of its adsorption capacity and the environment. A diesel exhaust particle collection system was established to collect samples with different environmental conditions. The adsorption capacity of the samples was characterized by an isothermal adsorption test. Changes in sample characteristics were investigated by scanning electron microscope and thermogravimetric analyzer. The correlation analysis of the factors influencing the adsorption process was performed. The results showed that the diesel exhaust particulate matter has adsorption capacity, the pore diameter is distributed continuously in the range of 8 to 80 nm, and the specific surface area and pore structure parameters are similar to carbon black and belong to the category of mesopores and macropores. As the engine speed increased from 1500 to 3600 r·min-1, the specific surface area of samples increased from 65.408 to 101.885 m2·g-1, and the pore volume expanded from 0.093 to 0.152 mL·g-1, with a more complex pore structure and enhanced adsorption capacity. The samples at the outlet of the exhaust pipe had increased box dimension (DB), moisture, and soluble organic fraction (SOF) content compared to the samples at the inlet of the exhaust pipe. The activation energies (E) of the three samples were reduced by 34.77 kJ∙mol-1, 38.88 kJ∙mol-1, and 47.43 kJ∙mol-1, respectively. Among the influencing factors, the increase of hydrocarbon concentration contributes to the increase of adsorption volume and the reduction of E. The increase of the average temperature inhibits the increase of the DB, and the increase of the temperature difference between the inlet and outlet facilitates the adsorption of water and SOF by samples. The reduction of adsorption time is one of the main reasons for delaying the increase of DB. Average pore diameter has the largest positive correlation with the variation amount of DB, and the growth of the specific surface area and pore volume is the dominant reason for the improvement of adsorption capacity and oxidation activity.

Study on the kinetics of process for obtaining cobalt nanopowder by hydrogen reduction under isothermal conditions

The kinetics of metallic cobalt nanopowder synthesizing by hydrogen reduction from Co(OH)2 nanopowder under isothermal conditions were studied. Co(OH)2 nanopowder was prepared in advance by chemical deposition from aqueous solutions of Co(NO3)2 cobalt nitrate (10 wt.%) and NaOH alkali (10 wt.%) at room temperature, pH = 9 under continuous stirring. The hydrogen reduction of Co(OH)2 nanopowder under isothermal conditions was carried out in a tube furnace in the temperature range from 270 to 310 °C. The crystal structure and composition of powders was studied by X-ray phase analysis. The specific surface area of samples was measured using the BET method by low-temperature nitrogen adsorption. The average particle size of powders was determined by the measured specific surface area. Particles size characteristics and morphology were investigated by transmission and scanning electron microscopes. Kinetic parameters of Co(OH)2 hydrogen reduction under isothermal conditions were calculated using the Gray–Weddington model and Arrhenius equation. It was found that the rate constant of reduction at t = 310 °C is approximately 1.93 times higher than at 270 °C, so the process accelerates by 1.58 times for 40 min of reduction. The activation energy of cobalt nanopowder synthesizing from Co(OH)2 by hydrogen reduction is ~40 kJ/mol, which indicates a mixed reaction mode. It was shown that cobalt nanoparticles obtained by the hydrogen reduction of its hydroxide at 280 °C are aggregates of equiaxed particles up to 100 nm in size where individual particles are connected to several neighboring particles by contact isthmuses.

Impact of Geological Factors on Marine Shale Gas Enrichment and Reserve Estimation: A Case Study of Jiaoshiba Area in Fuling Gas Field

Geological factors are key elements to control shale gas enrichment and influence the accurate estimation of shale gas reserve. However, the impact of the main geological factors, such as porosity, mineralogy, and organic matter, on marine shale gas enrichment and reserve calculation has not yet been fully clarified. Herein, we measured gas adsorption, porosity, mineralogical composition, and total organic carbon content of the marine shale samples from the Jiaoshiba area of Fuling gas field in Sichuan Basin, South China, and investigate the relationships between the geological factors and the adsorbed gas content. The results show that adsorbed gas content is positively correlated with total organic carbon and porosity; the larger specific surface area of samples with more clay minerals essentially contributes to shale gas enrichment. Additionally, the sealing of faults imposes a significant impact on shale gas accumulation. The probability volume method was applied to calculate the shale gas reserve. The reserves of P90 (the most pessimistic reserve), P50 (the most likely reserve), and P10 (the most optimistic reserve) were calculated, respectively, which provides useful information to reduce the risk in shale gas development.

Green Synthesis and Application of ZSM-5 Zeolite

A ZSM-5 molecular sieve composite with a wide pore prepared by the solid phase in-situ synthesis method and fluid catalytic cracking, and an FCC catalyst additive prepared by the same ZSM-5 molecular sieve for increasing the amount of light olefin yield were investigated. The samples were characterized by XRD, N2 adsorption/desorption, SEM, and NH3-TPD, respectively. The results showed that the structure of the ZSM-5 molecular sieve composite prepared by solid phase in-situ synthesis method was pure MFI-type zeolite material. The crystallinity of ZSM-5 molecular sieve was 59.8 wt%. The synthesized ZSM-5 molecular sieve had more acid content and a wide-pore structure. The average pore size was 5.9 nm, and BET specific surface area and micropore specific surface area of sample were 213 m2 g–1 and 124 m2 g–1, respectively. The evaluated results indicated that the FCC catalyst additive had good selectivity for LPG, propylene, and butene, increasing propylene and butene yields by 2.28 wt% and 2.15 wt%, respectively, as well as had better heavy oil cracking capability and coke selectivity.

Peculiarities of palladium-containing MFI-type zeolites as catalysts of isomerization of linear alkanes

Platinum group metals are widely used as a hydrogenating-dehydrogenating component of a number of petroleum refining and petrochemical catalysts, in particular for isomerization of linear alkanes. The main direction in improving the preparation of these catalysts is to reduce their cost by optimizing the metal component amount. However, insufficient attention was paid to the method of introduction of an active metal into the carrier; at the same time, this issue is especially important in case of zeolite catalysts, for which ion exchange can be used in addition to traditional impregnation. Therefore, the purpose of this work was to compare the catalytic efficiencies of Pd-containing MFI zeolites in which metal was introduced by two methods: impregnation from a solution of palladium chloride and ion exchange from tetraamminepalladium(II) chloride in the amount of 0.5 wt.% in terms of pure metal. Study of texture characteristics by nitrogen low-temperature adsorption/desorption technique showed that the specific surface area of samples and the total sorption volume remained practically unchanged, regardless of the procedure of metal component introduction. A significant decrease in average pore size was observed only in case of ion-exchange metal introduction; this indicated the localization of palladium mainly in zeolite pores, which was confirmed by transmission electron microscopy. The stage of transformation from ammonium form to hydrogen one strongly affects the activity of samples, this stage should precede the final stage of metal recovery. The highest yield of hexane isomers of about 46.5 wt.% with the selectivity of 88.7% was observed over a catalyst with Pd introduced by ion-exchange method with the smallest palladium particles (3–7 nm).

The Synthesis and Electrochemical Performance of Si Composite with Hollow Carbon Microtubes by the Carbonization of Milkweed from Nature as Anode Template for Lithium Ion Batteries

It has been reported that improving electrical conductivity and maintaining stable structure during discharge/charge process are challenge for Si to be used as an anode for lithium ion batteries (LIB). To address this problem, milkweed (MW) was carbonized to prepare hollow carbon microtubes (HCMT) derived from biomass as an anode template for LIB. In order to improve electrical conductivity, various materials such as chitosan (CTS), agarose, and polyvinylidene fluoride (PVDF) are used as carbon source (C1, C2, and C3) by carbonization. Carbon coated HCMT@Si composits, HCMT@Si@C1, HCMT@Si@C1@C2, and HCMT@Si@C1@C3, have been successfully synthesized. Changes in structure and crystallinity of HCMT@Si composites were characterized by using X-ray diffraction (XRD). Specific surface area for samples was calculated by using BET (Brunauer–Emmett–Teller). Also, pore size and particle size were obtained by particle and pore size analysis system. The surface morphology was evaluated using high resolution scanning electron microscopy (HR-SEM), Field Emission transmission electron microscopy (TEM). The thermal properties of HCMT@Si composites were analyzed by thermogravimetric analysis (TGA). Our research was performed to study the synthesis and electrochemical performance of Si composite with HCMT by the carbonization of natural micro hollow milkweed to form an inner space. After carbonization at 900 °C for 2 h in N2 flow, inner diameter of HCMT obtained was about 10 μm. The electrochemical tests indicate that HCMT@Si@C1@C3 exhibits discharge capacity of 932.18 mAh/g at 0.5 A/g after 100 cycles.

Experimental research on semi-coke for blast furnace injection

The combustion properties and grindability of Shenmu low-rank coal (SM) and its four different semi-cokes were studied by the self-designed equipment and Hardgrove method. The four semi-cokes were obtained under the pyrolysis temperature of 400, 500, 600 and 700 °C, named as SM-400, SM-500, SM-600 and SM-700, respectively. The analyses of nitrogen adsorption, Fourier-transform infrared spectroscopy (FTIR) spectra and Raman spectra were carried out to explain the change in combustion ratio and grindability. The result showed that the specific surface area of samples had an essential effect on the combustion ratio of SM-400 and SM-500. Meanwhile, the grindability depended on the strength of coal matrix, and the augment of pore amounts would increase the grindability. The functional groups and graphitization degree of the same sample were identical with the combustion ratio. With the pyrolysis upgrading temperature increasing, the combustion ratio of sample decreased, corresponding to the decrease in the benzene ring and the increase in graphitization degree. In addition, the thermogravimetric analysis was carried out, and the result was compared against what was shown in the data of combustion ratio. For pulverized coal injection, the combustion ratio was more intuitive and more accurate than combustibility.

Hierarchical flower-like NiCo2O4 applied in n-butanol detection at low temperature

In this work, hierarchical flower-like NiCo2O4 assembled by hexagonal sheets was prepared in one-step hydrothermal method, in which 2-mIM (2-Methylimidazole) acted as the structure-directing agent. The amount of 2-mIM had a great influence on the morphology and the composition of products, which further influenced the n-butanol gas-sensing performance. In addition, the systematic gas tests were carried out. It was concluded that compared with other corresponding samples, the hierarchical NiCo2O4 prepared with 18 mmol 2-mIM (NC-2) presented the highest gas sensitivity (240 %) and selectivity to 100 ppm of n-butanol at a low operation temperature 165 °C, with a response/recovery time of 68 s/107 s and an excellent long-term stability. Furthermore, the detailed analyses of the gas sensing mechanism were discussed in this paper. The best gas sensing performance of NC-2 based sensor was attributed to its unique hierarchical structure, which can provide more active sites for the process of oxygen adsorption. In addition, the content of chemical adsorbed oxygen species and the specific surface area of samples had an intimate relationship with the response for sensing materials. In summary, this research provided a simple way in designing n-butanol sensor based on hierarchical flower-like NiCo2O4 at a low operation temperature.

Combined mechanical grinding and enzyme post-treatment leading to increased yield and size uniformity of cellulose nanofibrils

The low yield and size nonuniformity of cellulose nanofibrils (CNFs) prepared by mechanical grinding restrict their extensive application in many fields. In this study, microfibrillated cellulose (MFC) with varying grinding time (0–2.5 h) was post-treated with endoglucanase (EG) to improve the yield and size uniformity of the CNFs. With the same grinding time, the yield of the CNFs post-treated with EG increased approximately one-fold, and the diameter of the microfibrils decreased according to the SEM and TEM images. The yield of the CNFs ground for 0.5 h and post-treated by EG was similar to that of the sample ground for 2.5 h, and approximately 26.1 kWh/kg mechanical grinding energy were saved by the EG post-treatment while obtaining the same CNF yield. There was an abundance of micropores that affected the specific surface area of samples, and the width of the micropores was centered between 1.3 and 2.0 nm. The crystallinity index (CrI) of the MFC decreased gradually from 74.90 to 69.30% with prolonged grinding time, whereas the CrI of the samples post-treated by EG slightly increased between 1.7 and 3.0%. The tensile strength and elongation at break of the films prepared by the EG post-treated samples slightly decreased, while the Young’s modulus and transmittance increased. This study provides a valid and an eco-friendly biological method to improve the yield and size uniformity of CNFs and reduce energy consumption.