BJH Pore Size Research Articles

Investigating catalytic de-oxygenation of cellulose, xylan and lignin bio-oils using HZSM-5 and Fe-HZSM-5

This study presents a detailed analysis of the liquid and gaseous pyrolytic products of the three principal components of biomass (cellulose, hemicellulose and lignin) using two different catalysts (HZSM-5 and its iron-modification, Fe-HZSM-5). The experiments were conducted in a semi-batch reactor under the same operating conditions for all feed materials. The results allow the determination of the provenance of aromatic compounds, which are essential components of bio-oil to be used as a bio-fuel. Transformation schemes have been proposed for each biomass component so as to better comprehend the formation of these aromatic compounds. BET specific surface area, BJH pore size distribution and FT-IR technologies have been used to characterise the catalysts, while gas chromatography-mass spectrometry (GC–MS), flame ionisation detection (GC-FID) and thermal conductivity detection (GC-TCD) were used to examine the liquid and gaseous pyrolytic products. It was firstly found that HZSM-5 favoured the decarbonylation route (production of CO), whilst Fe-HZSM-5 favoured the decarboxylation one (production of CO2) for the same feed. Then, a competition was seen to arise from the presence of the catalysts: the chemical family present in majority in the oils was the one converted by the catalysts, rather than one single family. Finally, from the transformation schemes, it was seen that even though both catalysts boosted the aromatics production, HZSM-5 produced more aromatics than its iron-modification. It was also observed that HZSM-5 formed more phenols, and hence, more coke, than Fe-HZSM-5.

Synthesis and Characterisation of Rice Husk Ash Silica Drug Carrier for α-Mangostin

The potential of rice husk ash (RHA) silica prepared via sol-gel method (RHA-Si) as a drug carrier was investigated. The nitrogen adsorption-desorption isotherm of RHA-Si indicates the presence of mesopores and some small percentage of micropores. The Brunauer, Emmett and Teller (BET) surface area of RHA-Si was 589 m2 g–1 and the Barrett-Joyner-Halenda (BJH) pore size was 5.1 nm. The adsorption of α-mangostin was confirmed by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The sample containing α-mangostin was labeled as RHA-Si-α. The BET surface area of RHA-Si-α was 110 m2 g–1 with the BJH pore size of 24.4 nm. The X-ray powder diffraction (XRD) showed that the RHA-Si and RHA-Si-α were amorphous. The disappearance of crystallinity of α-mangostin indicates that the solubility and dissolution of α-mangostin have been improved. The drug release profile indicated a burst release corresponding to 47% of the total drug loading in the first 15 min. The burst release was caused by physically adsorbed drug molecules. The findings suggest that RHA silica has potential application as nano drug carrier.

Fabrication and In vitro drug release characteristics of magnetic nanocellulose fiber composites for efficient delivery of nystatin

In the present study, one pot fabrication process was used for the synthesis of magnetic nanocellulose fiber composite (MCFNCs), wherein In situ co-precipitation methodology contains reaction of iron with ammonia in controlled temperature environment and cellulose fibers acts as a capping and stabilizing agent. The crosslinked cellulose fibers helps to dissociate Fe ions and avoid aggregation during the nucleation stages. The Nystatin (Nyst) was used as a model drug for studying the release characteristics of MCFNCs. The preliminary confirmation was done by comparing the FTIR spectra of synthesized MCFNCs with its precursor. The fabricated MCFNCs was characterized by x-ray Diffraction, Vibrating Sample Magnetometry, Particle Size, etc. The surface morphology and internal structure were identified by Scanning and Transmission Electron Microscopic observation of respective samples. It shows porous aggregated structure of synthesized nanocellulose, BET surface area and BJH pore size was determined simultaneously and found to be 13.42 m2 g−1 and 104.48 Å respectively. Due to the porous nature of nanocellulose fiber, it has high loading capacity i.e. around 17.8% amongst porous material category. In vitro drug release characteristics of Nyst loaded MCFNCs compared to pure drug showed sustained delivery for up to 8h time period. The Antifungal activity was evaluated on Candida Albicans and showed prominent inhibitory activity. The biocompatible nature of synthesized nanocomposites obtained from the natural nanocellulose fiber has a huge prospective in magnetically guided drug delivery in various parasitic diseases and have a potential of biomedical applications.

Synthesis of mesoporous silicon from industrial waste sodium-based slag

An increasing amount of waste sodium-based slag was generated during the purification process of metallurgical silicon that causes a posed problem to the environment. Here, a simple but effective approach was developed for the synthesis of mesoporous silicon from waste sodium-based slag. The as-received slag was leached and then calcined to fabricate silica as a precursor. Subsequently, the nanostructured silicon was produced through the reduction of the silica in a magnesium (Mg) vapor. The mechanism suggested that the Mg-containing phases (Mg2Si, MgSiO3, and MgO) were performed as an intermediary agent and facilitated the formation of nano-scale silicon. Nitrogen (N2) adsorption study of the final silicon product showed a BET surface area of 75.5 m2/g and a distributional BJH pore size of 3.7 nm. Significantly, the N2 absorption capacity of the mesoporous silicon reached 200 m3/g. The aim of this study is to recycle the waste sodium-based slag and provide an alternative for the synthesis of mesoporous silicon materials.

Fabrication of electrospun Mn1−xZnxMoO4 (x = 2.5%, 5%, and 10% Zn) nanofibers: Microstructure parameters, surface morphology and Kramers-Kronig (KK) analysis

Electrospun Mn1−xZnxMoO4 nanofibers (x = 2.5%, 5% and 10%), have been prepared by controlling the Zn concentration of a polymeric solution followed by calcination. The effects of Zn doping on structural, morphological, chemical characterization, and optical properties of the manganese molybdate nanofibers were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive analysis of X-rays (EDAX), BJH pore size and volume analysis, Fourier Transform Infrared (FTIR), and Reflectance spectrum in the wave length range of 200–1200nm. XRD studies revealed the diffraction peaks are mainly assigned to the orthorhombic structure of the MoO3 phase. The microstructural investigation of the calcinated nanofibers has been achieved from the size-strain plot (SSP) model using X-ray diffraction profile analysis. The SEM images exhibit Zn-doped manganese molybdate ceramic nanofibers with diameters ranged from 60 ± 10 to 90 ± 10nm after calcination at 400°C. The optical property of the prepared nanofibers was also proposed according to the Kramers-Kronig model.

Mesoporous Akaganeite of Adjustable Pore Size Synthesized using Mixed Templates

Mesoporous akaganeite with large and adjustable pore size was synthesized through a co-template method, which was achieved by the combined interaction between PEG2000 and alkyl amines with different lengths of the straight carbon chain. The characterized results indicate that the synthesized samples show comparatively narrow BJH pore size distributions and centered at 14.3 nm when PEG and HEPA was used, and it could be enlarged to 16.8 and 19.4 nm respectively through changing the alkyl amines to DDA and HDA. Meanwhile, all the synthesized akaganeite possess relativity high specific surface area ranging from 183 to 281 m2/g and high total pore volume of 0.98 to 1.5 cm3/g. A possible mechanism leading to the pore size changing was also proposed.

New hybrid adsorbent based on porphyrin functionalized silica for heavy metals removal: Synthesis, characterization, isotherms, kinetics and thermodynamics studies.

The pollution of water resources due to the disposal of toxic heavy metals has been a growing global concern for the last decades. For this purpose, the search for effective and economic material based adsorbents is required, due to the efficiency of the process. In this work, a novel inorganic-organic hybrid material based on silica chemically modified with a porphyrin (SiNTPP), with a high metal removal efficiency, was developed. The new material was characterized using a set of suitable techniques such as 13C NMR of the solid state, elemental analysis, FTIR, nitrogen adsorption-desorption isotherm, BET surface area, BJH pore sizes and scanning electron microscopy (SEM). The new material surface exhibits good chemical and thermal stability based on the obtained thermogravimetric curves (TGA). An adsorption study was accomplished to investigate the effect of porphyrin-silica hybrid on the removal of Pb(II), Zn(II), Cd(II) and Cu(II) from aqueous solutions using a batch method. The effect of various parameters, such as initial metal concentration, pH, temperature, as well as the kinetics and thermodynamics for sorption on SiNTPP were investigated. The studies demonstrate that adsorption is fast, as proved by the equilibrium achievement within 25min. The metals removal from aqueous solution are better adapted to the Langmuir isotherm model than to the Freundlich model. The thermodynamic parameters (ΔG°, ΔH° and ΔS°) disclose that the process was endothermic and spontaneous in nature, and the adsorption process follows a pseudo-second order kinetics. The adsorbent can be regenerated continuously without affecting its extraction percentage. Its effectiveness is highly justified compared to previous described materials.

Porous Materials from Thermally Activated Kaolinite: Preparation, Characterization and Application.

In the present study, porous alumina/silica materials were prepared by selective leaching of silicon/aluminum constituents from thermal-activated kaolinite in inorganic acid or alkali liquor. The correlations between the characteristics of the prepared porous materials and the dissolution properties of activated kaolinite were also investigated. The results show that the specific surface area (SSA) of porous alumina/silica increases with silica/alumina dissolution, but without marked change of the BJH pore size. Furthermore, change in pore volume is more dependent on activation temperature. The porous alumina and silica obtained from alkali leaching of kaolinite activated at 1150 °C for 15 min and acid leaching of kaolinite activated at 850 °C for 15 min are mesoporous, with SSAs, BJH pore sizes and pore volumes of 55.8 m2/g and 280.3 m2/g, 6.06 nm and 3.06 nm, 0.1455 mL/g and 0.1945 mL/g, respectively. According to the adsorption tests, porous alumina has superior adsorption capacities for Cu2+, Pb2+ and Cd2+ compared with porous silica and activated carbon. The maximum capacities of porous alumina for Cu2+, Pb2+ and Cd2+ are 134 mg/g, 183 mg/g and 195 mg/g, respectively, at 30 °C.

Evaluation of the performance of α-alumina nano-porous ceramic composite membrane for esterification applications in petroleum refinery

The carrier gas permeation performance through α-alumina nano-porous ceramic membrane was investigated in this study. The four carrier gases used for the study were argon (Ar), helium (He), nitrogen (N2) and carbon dioxide (CO2). The experiments was carried out at the gauge pressure drop of 0.10–1.00bar at 80°C. The α-alumina membrane was prepared using the sol-gel dip-coating techniques. The dip-coated membrane exhibited a higher molar flux with He (0.046molm−2s−1) and Ar (0.037molm−2s−1) with a much lower flux for N2 (0.037molm−2s−1) and CO2 (0.035molm−2s−1) at 0.30bar. The membrane recorded a huge decrease of permeance with the four carrier gases in the range of 9.81783E-07molm−2s−1Pa−1 to 1.23237E-06molm−2s−1Pa−1 at 0.50bar. The gas flow rate increased with respect to the pressure drop across the membrane. A plot of the inverse square root of the gases molecular weight showed a linear dependence on the gas permeance. The order of the gas flow rate with respect to the mean pressure was He>Ar>CO2>N2. The membrane was characterised using different methods including liquid nitrogen physisorption (Quantachrome instrument 2013) and scanning electron microscopy (Zeiss EVO LS10 SEM). The liquid nitrogen adsorption isotherm were described using the BET and BJH methods The BET surface area of the 7th dip-coated membrane was found to be higher (5.991m2/g) in contrast to the 8th dipped (3.840m2/g). The BJH pore size distribution of the membrane show a reduction pore size after the modification process. The BET isotherms of the membrane indicated a type IV isotherm with hysteresis on the curve indicating that the membrane can undergo a capillary condensation in the mesoporous region. The SEM/EDAX of support showed a clear surface without evidence of crack while the SEM micrograph of the silica membrane exhibit a bonding on the surface membrane as result of the modification process.

An Experimental Analysis of Lactic Acid Esterification Process Using Langmuir-Hinshelwood Model

In this study, esterification of lactic acid and ethanol to produce ethyl lactate using different cation-exchange resin catalysts was performed at 100 °C. The catalysts used for the esterification process were amberlyst 16 and dowex 50W8x cation-exchange resins. Two simplified mechanisms based on Langmuir-Hinshelwood model were employed to describe the components that adsorbed most on the surface of the catalysts. Fourier Transform Infrared (Nicolet iS10 FTIR) was employed to verify the rationality of the mechanisms. FTIR of the esterification product reflected C=O, H=O and C=C bonds on the spectra confirming water and ethanol as the most adsorbed components. The kinetic study of the retention time and the peak areas of the esterification produced with the different catalysts were compared using an autosampler gas chromatography/mass spectrometry (autosampler GC-MS). The chromatogram of the esterification product catalysed by amberlyst 16 showed a faster elution at 1.503 mins with the peak area of 1229816403 m2 in contrast to the dowex 50W8x. The BET surface area and BJH pore size distribution of the resin catalysts were determined using liquid nitrogen adsorption (Quantachrome, 2013) at 77 K. The BET surface area results of amberlyst 16 resin catalysts was found to be 1.659m2/g compared to 0.1m2/g for the dowex 50W8x. The BJH results of the catalysts exhibited a type IV isotherm with hysteresis confirming that the materials were mesoporous with pore size in the region of 2 – 50 nm.

Effect of mesoporosity of bimetallic Ni-Ru-Al2O3 catalysts for hydrogen production during supercritical water gasification of glucose

A well-known problem with metal supported alumina catalysts during gasification processes for H2 formation is catalyst deactivation by coke formation and pore plugging. Poorly controlled catalyst structure with low surface area and microporous structure also accounts for low catalyst activity. This work investigated bimetallic Ni-Ru/Al2O3 catalysts that are both effective and durable for glucose gasification in supercritical water with minimal coke formation. Both non-ionic (Pluronic P-123) and cationic (CTAB) templates were examined for mesoporous alumina synthesis with Ni and Ru loadings and compared with a conventional incipient impregnation method. Gas formation during SCWG catalysis was monitored for hydrogen formation while the catalysts were examined both before and after reaction by a variety of physico-chemical techniques including BET surface area, BJH pore size analysis, XRD, TG-DTA, TPR, TPO, Raman spectroscopy & TEM microscopy. The results showed that templating helped disperse both Ni and Ru particles homogeneously inside the pores of mesoporous Al2O3 catalysts; whereas the impregnated catalyst gave poorer dispersion. Comparing with the impregnation method, a six-fold increase of BET surface area was observed using the one-pot synthesis method. Hydrogen production during glucose gasification increased by 25mol% for both templated catalysts, with the CTAB catalyst showing slightly higher activity. This method provided insignificant coke deposition indicating that the new Ru-Ni/Al2O3 templated catalyst is promising for the development of hydrogen production for an emerging biorefinery.

Nanoflower, nanoplatelet and nanocapsule Mg(OH)2 powders for adsorption of CO2 gas

The soft chemical synthesis of self-assembled magnesium hydroxide (Mg(OH)2) nanoplatelets with surface area as high as about 300 m2 g−1 was achieved in the present work. The nanopowders such as MHN, MHCl, MHBr were synthesized at ~30 °C without using any catalyst or surfactant using, respectively, precursor solutions of Mg(NO3)2, MgCl2, MgBr2 and characterized by XRD, BET surface area, BJH pore size analysis, FTIR, FE-SEM, TEM and EDX techniques. It was found that the MHN and MHCl nanopowders comprised of nanoflowers formed by self-assembly of nanoplatelets and porous nanoplatelets, while the MHBr nanopowders comprised of a random assembly of nanocapsules. The powders possessed the technologically important quality of reproducible CO2 adsorption at room temperature and its desorption at a relatively lower temperature of 75 °C. Based on the experimental evidences, the mechanisms of various microstructure formations and CO2 adsorption mechanism were also proposed.

졸겔법으로 제조한 탄소피복된 SiOx/ZnO 복합체의 합성 및 전기화학적 특성

수명특성이 우수한 실리콘 음극재를 제조하기 위해 졸겔법을 통해 <TEX>$SiO_x/ZnO$</TEX> 복합체를 제조하였고, 제조된 복합체는 PVC를 탄소 전구체로 하여 탄소를 피복하였다. 복합체에 포함된 ZnO를 HCl로 제거하여 내부에 빈 공간을 만들어 충 방전에 따른 실리콘의 부피변화를 완화할 수 있게 하였다. 합성된 복합체의 결정구조와 형상을 파악하기 위해 XRD, SEM, TEM 분석을 실시하였다. 탄소 피복된 복합체에 포함된 탄소함량을 TGA를 통해 알아보았으며, 복합체의 기공구조를 확인하기 위해 BET 비표면적 분석과 BJH 기공분포를 확인하였다. 탄소의 추가로 향상된 전기전도성을 측정하였으며, 전기화학적 특성은 AC 임피던스 측정과 충 방전 및 수명특성을 확인하였다. <TEX>$SiO_x/ZnO$</TEX>시료에 탄소를 피복할 경우에 전기전도도가 증가하였으며, 방전용량도 증가하였다. 염산으로 ZnO를 제거한 시료의 경우에 표면적은 증가하였으나, 전지의 방전용량은 오히려 감소하였다. 탄소를 피복하지 않은 <TEX>$SiO_x/ZnO$</TEX> 시료의 경우에 방전용량이 매우 낮았으며, 탄소를 피복한 후의 시료는 높은 충방전용량을 나타내었다. 수명특성의 경우, <TEX>$C-SiO_x/ZnO$</TEX> 복합체(Zn : Si : C = 1 : 1 : 8)가 0.2 C의 전류량에서 50 사이클에서 <TEX>$815mAh\;g^{-1}$</TEX>의 용량으로 기존 흑연계 음극재보다 높은 용량을 나타내었다. <TEX>$SiO_x/ZnO$</TEX> composites were prepared from sol-gel method for excellent cycle life characteristics. The composites were coated by PVC as a carbon precursor. ZnO removal to create a void space therein was able to buffer the volume change during charge and discharge. To determine the crystal structure and the shape of the synthesized composite, XRD, SEM, TEM analysis was performed. The carbon contents in the composites were confirmed by TGA. The pore structure and pore size distribution of the composite was measured with the BET specific surface area analysis and BJH pore size distribution. Enhanced electric conductivity by carbon addition was determined from powder resistance measurement. Electrochemical properties were measured with the AC impedance and the charge and discharge cycle life characteristics. When carbon was coated on the <TEX>$SiO_x/ZnO$</TEX> sample, the electrical conductivity and the discharge capacity were increased. After removal of ZnO with HCl the surface area of the sample was increased, but the discharge capacity was decreased. <TEX>$SiO_x/ZnO$</TEX> sample without acarbon coating showed very low discharge capacity, and after carbon coating the sample showed high discharge capacity. For cycle life characteristics, <TEX>$C-SiO_x/ZnO$</TEX> composite (Zn : Si : C = 1 : 1 : 8) with a capacity of <TEX>$815mAh\;g^{-1}$</TEX> at 50 cycle and 0.2 C has higher capacity than existing graphite-based anode materials.

Study on photocatalyst Zinc Oxide annealed at different temperatures for photodegradation of Eosin Y dye

Mesoporous photocatalyst Zinc Oxide (ZnO) nanoparticles have been synthesized via co-precipitation method. The effect of different annealing temperatures (300 °C and 700 °C) on the samples have been investigated by characterization techniques like High Resolution X-Ray diffraction (HR-XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectra (EDXS), Ultraviolet Visible spectroscopy (UV–Vis), Room Temperature Photoluminescence (RTPL) and Braunner Emmett Teller (BET) measurement. The reduction in recombination centers, increase in porosity and size have been observed for the ZnO photocatalyst annealed at higher temperature (700 °C). The photocatalytic activity of the products have been evaluated by photodegradation of Eosin Y dye under solar irradiance. The results depict sample annealed at 700 °C temperature has higher photonic efficiency due to reduced defect states and meso-porosity as evidenced by the RTPL spectra and BJH pore size distribution analysis. The study on photocatalytic activity of the two samples annealed at different temperatures shows the effect of certain significant parameters on the degradation process of EY dye. The synthesized sample annealed at 700 °C has good potential for application in photovoltaics.

A facile and controllable multi-templating approach based on a solo nonionic surfactant to preparing nanocrystalline bimodal meso-mesoporous titania

In this work, a facile and controllable multi-templating approach based on a solo nonionic surfactant P123 and peroxotitanic acid (PTA) was reported for the preparation of bimodal meso-mesoporous titania (BMM-TiO2) with high surface area (150–243 m2 g−1), high pore volume (0.3–0.6 cm3 g−1), large mesopore sizes spanning from 8 to 16 nm (BJH pore size), and high & tunable crystallinity (Anatase or Anatase + Rutile). The BMM-TiO2 was shown to be a homogeneous ‘mixture’ of two series of wormhole mesostructures with two modes of mesopore sizes that depend on both the contents of P123 and synthetic conditions. The formation of BMM structures was proposed to arise from both the formation of differentiated micellar structures of P123 (dual soft-templating) and their subsequent different mesostructural shrinkages driven by prolonged drying process (i.e., 100 °C for 12 h) in the presence of PTA. The low-temperature crystallization behaviours of PTA, unusual hard-templating effect of P123 and its carbon derivatives (3rd fold templating), large mesopores relative to the surrounding TiO2 crystals are all believed to be responsible for the high thermal stability of the obtained BMM-TiO2. To our knowledge, it is for the first time reported that P123 plays such multiple templating roles (three folds in this work) in the preparation of meso-TiO2, not to mention that P123 was also confirmed to be a prerequisite for the formation bi-crystalline BMM-TiO2. In the photodegradation test of Rhodamine B in water by UV irradiation, other than the high surface area and synergistic effect between anatase and rutile phases, the BMM structures were also found to be advantageous to enhance the photocatalytic properties of mesoporous TiO2.

Adsorption of methylene blue by porous ceramics prepared from electrolytic manganese residues

The present work developed and analyzed an appropriate conversion method for electrolytic manganese residues (EMR) into a porous ceramics adsorbent for methylene blue (MB), which is simple in preparation and regeneration process, low in price, convenient in separation process, good reproducibility and environmentally friendly. The physicochemical properties of the electrolytic manganese residue-based porous ceramics (EMR-based ceramics) were characterized by X-ray diffraction, scanning electron microscopy, FT-IR, BET specific surface area, and BJH pore size distribution measurement. The effects of the contact time, temperature, initial concentration of MB, and pH on the adsorption process were studied. The kinetics, isotherm, thermodynamics, and mechanism analysis were investigated in detail. The results showed that the adsorption kinetics suitability used the pseudo-second-order kinetic model, and the adsorption isotherm data were fitted well to the Freundlich isotherm model. The thermodynamic parameters indicated that the adsorption process was a spontaneous, endothermic, and entropic-adding process. In conclusion, the EMR-based porous ceramics could be utilized as an adsorbent for the removal of MB effectively and repeatedly.

Effect of TiO2Photoanode Porosity on Dye Diffusion Kinetics and Performance of Standard Dye-Sensitized Solar Cells

Low-cost water-based P25-TiO2pastes were formulated and used to produce porous TiO2films in application to the fabrication of dye-sensitized solar cells. The structural properties of the films were characterized using a variety of techniques such as stylus profilometry, FEG-SEM imaging, BET surface area, and BJH pore size analyses. These were compared to films produced from a commercial paste, DSL 18 NR-AO (Dyesol). The major difference was in the fraction of macroporosity: 23% of the total pore volume for films produced with the commercial material and 67–73% for the P25-TiO2films owing to the vast difference in dispersion and size distribution of the particles in the two types of pastes. The macroporosity was found to have a dramatic effect on the dye diffusion kinetics measured usingin situUV-Vis reflectance spectroscopy. The sensitization of P25-based films was much faster for heavily macroporous P25-TiO2films (&gt;90% saturation at 15–35 mins) than for their commercial analogue (&gt;90% saturation at 110 mins). DSC devices built with optimized P25-TiO2photoanodes showed better performance at short dye immersion time (30 mins and 1 hr) due to faster percolation of the dye molecules through the film.

Utilization of Electrolytic Manganese Residues in Production of Porous Ceramics

Electrolytic manganese residues (EMR) are one of industrial by‐products generated during the production of electrolytic manganese metal. To reduce the EMR hazard to environment and invent value‐added materials, porous ceramics were prepared by the pore‐forming method with EMR and various additives. The influences of the incorporation of different additives, sintering temperature, and molding pressure on properties of porous ceramics were investigated. Properties such as apparent porosity, water absorption, bulk density, and compression strength have been measured. The EMR‐based porous ceramics were also characterized by XRD, SEM, BET‐specific surface area, and BJH pore size distribution measurement. It revealed that the appropriate mode was the sample containing 20 wt% carbon powder, 7.5 wt% dolomite, and 5 wt% kaoline, under which the ceramics with the properties of high apparent porosity (69.70%), high compressive strength (6.97 MPa), and good acidity–alkali stability were obtained successfully. The comprehensive performance of EMR‐based porous ceramics makes them advantageous to use as nonhazardous and valuable materials showing promising potential applications, which not only is a promising new approach to improve the resource utilization of EMR but also can promote the manganese industry's sustainable and healthy development and protect and improve ecological environment.

A comparison of experimental methods for describing shale pore features — A case study in the Bohai Bay Basin of eastern China

To compare experimental methods for describing shale pore features, we performed a series of parallel experiments on typical continental shales from the Bohai Bay Basin of eastern China, including scanning electronic microscopy (SEM), focused ion beam scanning/field emission scanning electron microscopy (FIB/FE-SEM), low-temperature nitrogen adsorption/desorption (LTNA), mercury intrusion porosimetry (MIP) and nuclear magnetic resonance (NMR) techniques. The results show that artificial peaks located at 3 to 5nm, affected by the tensile strength effect (TSE), are clearly seen in the BJH pore size distributions (PSDs) calculated using the low-temperature nitrogen desorption curve of shale with narrow-neck pores (e.g., ink-bottle pores). Although the LTNA technique cannot completely reveal large pores, the adsorption/desorption curve and the PSD acquired from it can still indicate the relatively high or low extent of development of large pores in different shales. Shale within the “oil window” primarily contains inorganic pores, as organic nanopores are generally formed during the high or over-mature stage of organic matter. During the mercury intrusion, high pressures forcing liquid mercury to enter small pores (less than 40 to 70nm) will cause pores in the samples to crack, especially for shale with slit-shaped and wedge-shaped pores. Unlike LTNA, MIP measures only pore throats and does not detect pore bodies; therefore, the effective pore size revealed by the LTNA method may be up to 300nm instead of only 50nm when LTNA is combined with MIP to reveal the PSD of shales with narrow-necked pores. NMR and LTAN can be complemented by each other, and the PSD results revealed by them are anastomotic, which suggests that the combination of NMR and LTAN is an ideal method for revealing the PSD of shale.

Enhanced NO2 gas sensing performance of bare and Pd-loaded SnO2 thick film sensors under UV-light irradiation at room temperature

NO2 gas sensing performance of bare and Pd-loaded SnO2 thick film sensors were measured under UV-light irradiation, using a UV-LED of 365nm wavelength and light intensities ranging from 0 to 137mWcm−2 at room temperature (30°C). Template free conventional and microwave-assisted hydrothermal methods were applied to synthesize SnO2 powder with different specific surface areas and morphologies (rod-shape and nanoparticle). Two different Pd-loaded SnO2 (0.03 and 0.1wt%) powders were also prepared by a simple wet-impregnation method. XRD, FE-SEM/SEM, XPS, BET surface area and BJH pore size distribution measured with N2 adsorption isotherms were utilized to characterize structural and morphological characteristics of all the samples. The results clearly confirmed that the presence of a low amount of Pd could effectively enhance the response value to 5ppm NO2 gas and shorten the recovery time under the UV-light irradiation so that the sensor loaded with 0.1wt% Pd (0.1Pd_MH1_400 sensor) showed the largest improvement in response value (almost 11 times) and recovery time (around 27s) compared with the bare SnO2 sensor (MH1_400) at an UV-light intensity of 79mWcm−2. This enhancement is most likely due to the role of Pd in facilitating the sensing reactions via producing additional NO2 adsorption sites on the SnO2 surface. Moreover, in the present study, the SnO2 sensor which was fabricated from as-synthesized, i.e. uncalcined, powder (MH1) showed the highest response (over 3000) compared with other sensors under an UV-light intensity of 7mWcm−2 with a recovery time of about 48s. The drastic decrease in the resistance in air of this sensor under the UV-light irradiation may be a possible reason for the highest response value. It was also revealed that high NO2 response could be achieved only at the optimum conditions of both the number of the NO2 adsorption sites (optimum specific surface area) and the electron density in the bulk under the UV-light irradiation.