Showing papers on "BET theory published in 2014"
TL;DR: The enhanced surface area of the MPC, as well as its graphite-like structure, may contribute to the adsorption capacity of TC, which could be effectively separated by applying a magnetic field.
326 citations
TL;DR: In this paper, an Activated Carbon (AC) with high purity and surface area was synthesized from rice husk (RH) using alkali leaching at room temperature, and the maximum surface area obtained from the BET analysis was 2696m2g−1 for the KOH activated carbon at 850°C with an impregnation ratio of 1:5 under nitrogen flow.
262 citations
TL;DR: In this paper, a modified exfoliated vermiculite (La5EV) was fabricated, characterized, and investigated for phosphate removal in batch tests for the first time, and the effect of initial phosphate concentration, contact time, temperature, pH, and coexisting ions on the adsorption capacity of La5EV was investigated in detail.
255 citations
TL;DR: In this article, low cost activated carbon was prepared from the grape stalk by chemical activation with ZnCl2 in CO2 atmosphere and its characteristics were determined by proximate-ultimate analysis, including surface area, total pore volume, iodine number, pHzpc, SEM-EDX and particle size distribution.
241 citations
TL;DR: In this paper, Mg-Al and Zn-Al layered double hydroxides (LDHs) were synthesized by co-precipitation method at a constant pH of 9-10.
239 citations
TL;DR: In this article, an activated carbon produced from buriti shells (AC b ) using ZnCl 2 as activating agent and its ability to remove methylene blue dye (MB) from aqueous solutions was reported.
193 citations
TL;DR: The chromium terephthalate metal-organic framework, MIL-101 (MIL, Material Institut Lavoisier), is comprised of trimeric chromium(III) octahedral clusters interconnected by 1,4-benzenedicarboxylates, resulting in a highly porous 3-dimentional structure as discussed by the authors.
Abstract: The chromium terephthalate metal–organic framework, MIL-101 (MIL, Material Institut Lavoisier), is comprised of trimeric chromium(III) octahedral clusters interconnected by 1,4-benzenedicarboxylates, resulting in a highly porous 3-dimentional structure. The large pores (29 and 34 A) and high BET surface area (>3000 m2 g−1) with a huge cell volume (≈702 000 A3) together with the coordinatively unsaturated open metal sites that can be subjected to diverse post-synthesis functionalization or guest encapsulation, and excellent hydrothermal/chemical stability, make MIL-101 particularly attractive for applications, such as selective gas adsorption/separation, energy storage and heterogeneous catalysis. This paper reviews the current status of research and development on the synthesis, functionalization and applications of MIL-101 for adsorption/catalytic reactions.
189 citations
TL;DR: A new metalloporphyrin-based conjugated microporous polymer, NiP-CMP, was constructed via a homo-coupling polymerization reaction and exhibits outstanding performance for the reversible adsorption of iodine in solution.
187 citations
TL;DR: In this article, a sub-pilot scale process of synthesis of Na-P1 zeolite from coal fly ash was presented, which has a specific BET surface area (88 m2/g) c.a. six times higher than the fly ash from which it has been derived.
Abstract: This paper presents a sub-pilot scale process of synthesis of Na-P1 zeolite from the coal fly ash. After establishing the appropriate synthesis conditions (20 kg of fly ash, 12 kg of NaOH, 90 dm3 of water, the reaction temperature: 80 °C and reaction time: 36 h), the high-purity (81 wt%) Na-P1 zeolite product was obtained. Its chemical, mineralogical, and textural properties were determined (by means of XRD, XRF, SEM–EDS and ASAP 2020). The synthesized material has a specific BET surface area (88 m2/g) c.a. six times higher than the fly ash from which it has been derived (15 m2/g). The pore-size distribution indicates a mesoporous character of the obtained zeolite, with the following pores size contents: micropores (2.76 %), mesopores (61.81 %), and macropores (35.43 %). The presented technological/production line is fully automated and allows to regulate the conditions of the synthesis process, therefore different types of zeolite materials (including: Na-X, Linde-A, and Na-P1) can be obtained using the same equipment.
187 citations
TL;DR: In this article, low-cost activated carbons with textural properties, chemical functional groups and a capacity for toluene adsorption comparable to that of activated carbonons obtained with KOH or NaOH were produced from vegetable-tanned leather wastes by means of K 2 CO 3 chemical activation.
185 citations
TL;DR: In this paper, the authors used H3PO4 activation (WHAC) to eliminate Pb(II) in water hyacinth and showed that the adsorption behavior follows pseudo-first order kinetic and Langmuir isotherm.
TL;DR: In this paper, the deactivation by coke deposition of Ni and Co catalysts in the steam reforming of ethanol has been studied in a fluidized bed reactor under the following conditions: 500 and 700°C; steam/ethanol molar ratio, 6; space time, 014g catalyst ǫ/g ethanol, partial pressure of ethanol in the feed, 011bar, and time on stream up to 20h The decrease in activity depends mainly on the nature of the coke deposited on the catalysts, as well as on the physical-chemical properties (B
TL;DR: Eucalyptus wood was used to produce activated carbon by chemical activation with H 3 PO 4 as an adsorbent for adsorption of CO 2 in order to improve CO 2 capture.
TL;DR: In this article, the performance of chitosan/hydroxyapatite (Cs/HAp) composite nanofiber membrane prepared by electrospinning process for the removal of lead, cobalt and nickel ions from aqueous solution was investigated.
Abstract: The performance of chitosan/hydroxyapatite (Cs/HAp) composite nanofiber membrane prepared by electrospinning process for the removal of lead, cobalt and nickel ions from aqueous solution was investigated. The prepared nanofiber membranes were characterized by FTIR, SEM and BET analysis. A response surface methodology based on Box–Behnken Design (BBD) was used to predict the average diameter of electrospun nanofibers. In optimum conditions (voltage of 18.90 kV, tip-collector distance of 15.60 cm and flow rate of 0.43 ml/h), the minimum experimental fiber diameter was obtained 198 nm which was in good agreement with the predicted value by the BBD analysis (200.6 nm). Then, the adsorption experiments were carried out to investigate the effect of different adsorption parameters, such as contact time, initial concentration and temperature in a batch system. The kinetic and equilibrium data were well described by pseudo-second-order and Langmuir models, respectively. Thermodynamic parameters were evaluated to obtain the nature of adsorption process onto the Cs/HAp composite nanofibers. The obtained results of reusability of nanofiber membrane after five sorption–desorption cycles offer promising potential in industrial activities.
TL;DR: A new mesoporous MOF, Zn4O(bpdc)(btctb)(4/3) (DUT-32), containing linear ditopic and tritopic linkers was synthesised, adding this compound to the top ten porous materials with the highest BET surface area.
TL;DR: In this article, the influence of different dopants on the physicochemical properties and catalytic behavior of nano-Au/CeO2 catalyst for CO oxidation was investigated, where various metal ions were incorporated into the ceria lattice by a facile coprecipitation approach using ultra-high dilute aqueous solutions.
Abstract: The present investigation was undertaken to know the influence of different dopants on the physicochemical properties and catalytic behavior of nano-Au/CeO2 catalyst for CO oxidation. Accordingly, various metal ions namely, Fe3+, La3+ and Zr4+ were incorporated into the ceria lattice by a facile coprecipitation approach using ultra-high dilute aqueous solutions. An anion adsorption method was used to prepare the Au/doped-CeO2 catalysts in the absence of any base, reducing and protective agents. The physicochemical characterization was performed by XRD, BET surface area, ICP-AES, TG-DTA, FT-IR, TEM, UV–vis DRS, Raman, XPS and TPD techniques. Doped CeO2 exhibited smaller crystallite size, higher BET surface area and larger amount of oxygen vacancies than the pure CeO2. These remarkable properties showed a beneficial effect toward gold particle size as confirmed by XRD and TEM studies. XPS results revealed that Au is present in the metallic state and Ce in both +3 and +4 oxidation states. Incorporation of Zr into the Au/CeO2 resulted in high CO oxidation activity attributed to the presence of more Ce3+ ions and oxygen vacancies. In contrast, the La-incorporation caused an opposite effect due to the presence of carbonate species on the surface of Au/CeO2–La2O3 catalyst, which blocked the active sites essential for CO oxidation. It was shown that accumulation of carbonate species strongly depends on the acid–base properties of the supports. The catalytic performance of Au catalysts is highly dependent on the nature of the support.
TL;DR: In this paper, a simple in situ soft chemical synthesis of nanoscale copper(II) oxide, together with its characterization and a study of the adsorption and desorption behaviors of Pb(II), was conducted.
Abstract: The present work deals with a simple in situ soft chemical synthesis of nanoscale copper(II) oxide, together with its characterization and a study of the adsorption and desorption behaviors of Pb(II) on nanoscale CuO. The nanoparticles are characterized by XRD, FESEM, TEM and BET surface area analyses. Electron microscopy clearly reveals a rod-like morphology of rhombohedral CuO, with an average diameter of ∼5 nm and a length extending up to 50 nm. BET shows the average surface area of the nanorods to be ∼52.57 m2 g−1. In an adsorption study, the influence of operational conditions, such as the contact time, the initial concentration of Pb(II), the initial pH of the solution and the temperature, on the adsorption of Pb(II) has also been examined. Studies also reveal that the uptake of Pb(II) onto CuO is a fast process; >70% of the uptake occurred within the first 10 min of contact time and uptake reached >92% within 60 min. The maximum sorption capacity of Pb(II) is 3.31 mg g−1 at 298 K. The +ve ΔS° value and the +ve ΔH° value of 37.77 kJ mol−1 indicate the endothermic nature of the adsorption process, whereas a decrease of Gibbs free energy (ΔG°) with increasing temperature indicates the spontaneous nature of the adsorption process. The adsorbent can be up to 84.1% regenerated using dilute acid and shows potential for the removal of lead from contaminated water.
TL;DR: Porous anatase TiO2 has shown moderate porosity with a BET surface area of 220 m2 g−1 attributed to the highly porous structure of the MIL-125(Ti) precursor.
Abstract: Porous anatase TiO2 has been prepared, for the first time, through the calcination of a metal–organic framework (MOF) precursor under an air atmosphere at 380 °C. The resulting TiO2 has shown moderate porosity with a BET surface area of 220 m2 g−1 attributed to the highly porous structure of the MIL-125(Ti) precursor. The porous anatase TiO2 was examined as a lithium-ion battery anode, exhibiting high capacity retention and good rate capability. The porous structure of anatase TiO2 enforces Li+ diffusion and helps to buffer the volumetric variation. It has shown reversible capacities of 166, 106 and 71 mA h g−1 at 1 C, 5 C and 10 C charge/discharge rates, respectively, after 500 cycles.
TL;DR: A series of activated carbons (ACs) were prepared from Eucalyptus camaldulensis wood by chemical activation with H3PO4, ZnCl2 at different impregnation ratios as well as by pyrolysis, followed by activation with KOH as mentioned in this paper.
Abstract: A series of activated carbons (ACs) were prepared from Eucalyptus camaldulensis wood by chemical activation with H3PO4, ZnCl2 at different impregnation ratios as well as by pyrolysis, followed by activation with KOH. The porosity characteristics of these ACs were determined by N2 adsorption isotherms. Through varying the H3PO4/biomass ratio from 1.5 to 2.5, the prepared ACs displayed BET surface areas in the range of 1875–2117 m2/g with micropores content of 69–97%. For the ZnCl2 activated series, BET surface areas varying from 1274.8 to 2107.9 m2/g with micropores content of 93–100% were obtained from impregnation ratios of 0.75–2.0. The AC obtained by KOH had the largest BET surface area of 2594 m2/g and the high micropore content of 98%. In addition, the FTIR and SEM analyses conducted for characterizing the ACs and the CO2 adsorption onto all series of the eucalyptus wood based ACs at pressures ranging from 0 to 16 bar using a volumetric method were investigated. Also the effect of temperature (15–75 °C) on the amount of CO2 adsorbed by the ACs that was prepared with H3PO4, KOH and ZnCl2 was studied. The CO2 adsorption capacity on the AC prepared with KOH was up to 4.10 mmol/g at 1 bar and 303 K, having an increase of about 63% in comparison with the commercial AC.
TL;DR: In this article, the effects of steam activation on the pore structure evolution and surface chemistry of activated carbon (AC) obtained from bamboo waste were investigated, and the results revealed the presence of a large number of basic groups on the surface of the pyrolyzed char and AC.
TL;DR: The catalytic B-M activity of soluble, substitution-inert, and acidic Cr(NO3)3·9H2O supports the Brønsted-acid effect of the MIL materials.
Abstract: Porous chromium(III) 2-nitro-, 2-amino-, and nonfunctionalized terephthalate (MIL-101Cr) metal organic frameworks are heterogeneous catalysts for diacetal formation from benzaldehyde and methanol (B–M reaction) as well as other aldehydes and alcohols. MIL-101Cr-NO2 obtained by direct reaction between CrO3 and 2-nitro-terephthalate showed the highest activity with 99% conversion in the B–M reaction in 90 min and turnover numbers of 114. The activity decreased in the order MIL-101Cr-NO2 > MIL-101Cr > MIL-101Cr-NH2. Within different samples of nonfunctionalized MIL-101Cr the activity increased with surface area. Methanol gas sorption of the different MIL materials correlates with the BET surface area and pore volume but not with the diacetalization activity. Benzaldehyde adsorption from heptane showed no significant difference for the different MILs. Gas sorption studies of CD3CN to probe for a higher Lewis acidity in MIL-101Cr-NO2 remained inconclusive. A high B–M catalytic activity of wet MIL-101Cr-NO2 exc...
TL;DR: This noble metal free method provides a simple pathway for effective multiple H(+)/e(-) CO2 photoreduction in TiO2 for chemisorption, activation and photocatalytic CO2 reduction.
TL;DR: In this paper, a novel adsorbent based on electrospun polyvinyl alcohol (PVA)/NaX nanozeolite nanocomposite nanofibers was prepared using electrospinning process and its application for the removal of Ni2 and Cd2+ ions from aqueous solutions was investigated.
TL;DR: In this article, a non-precious metal catalyst (NPMC) with nano-porous structure and high BET surface area, was prepared by pyrolyzing the polyaniline on carbon nanospheres using ferric chloride both as an oxidant and iron source.
Abstract: A non-precious metal catalyst (NPMC), with nano-porous structure and high BET surface area, is prepared by pyrolyzing the polyaniline on carbon nanospheres using ferric chloride both as an oxidant and iron source. Electrochemical test results show that the catalyst has a high activity and much better stability than that of commercial Pt/C in acid medium.
TL;DR: Results indicated that OMCN treated at 800°C with largest BET surface area and highest amounts of pyrindinic N showed improved electrocatalytic activity for H2O2, nitrobenzene, and NADH in neutral solution.
TL;DR: The removal of Cu(II) ions from industrial effluent indicated that the fresh swine manure biochar pyrolyzed at 400 °C can be considered as an effective adsorbent.
Abstract: The purpose of this study was to investigate adsorption characteristic of swine manure biochars pyrolyzed at 400 °C and 700 °C for the removal of Cu(II) ions from aqueous solutions. The biochars were characterized using BET surface area, Fourier transform infrared spectroscopy (FTIR), zeta potential, scanning electron microscopy/energy dispersive spectrometer (SEM-EDS), and X-ray diffraction (XRD). The adsorption of Cu(II) ions by batch method was carried out and the optimum conditions were investigated. The adsorption processes of these biochars are well described by a pseudo-second-order kinetic model, and the adsorption isotherm closely fitted the Sips model. Thermodynamic analysis suggested that the adsorption was endothermic. The maximum Cu(II) adsorption capacities of biochars derived from fresh and composted swine manure at 400 °C were 17.71 and 21.94 mg g(-1), respectively, which were higher than those at 700 °C. XRD patterns indicated that the silicate and phosphate particles within the biochars served as adsorption sites for Cu(II). The removal of Cu(II) ions from industrial effluent indicated that the fresh swine manure biochar pyrolyzed at 400 °C can be considered as an effective adsorbent.
TL;DR: In this paper, a prepared zeolite 13X was characterized by X-ray powder diffraction, N 2 -adsorption-desorption measurements, and scanning electron microscopy.
TL;DR: In this paper, both pure and Y-doped SnO 2 hollow nanofibers with porous structures were fabricated via electrospinning technique and calcination procedure, and they were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy.
Abstract: Pure and Y-doped SnO 2 hollow nanofibers with porous structures were fabricated via electrospinning technique and calcination procedure. The porous SnO 2 hollow nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and X-ray photoelectron spectroscopy (XPS). Acetone sensing properties of the hollow nanofibers were also investigated. The surface morphology of pure SnO 2 and Y-doped SnO 2 possessed a hollow nanostructure with rough porous surface after being annealed at 600 °C, and the diameters of the nanofibers were in the range of 154–200 nm. The BET surface area measurement further indicated that the surface textural was mesoporous, and the pore size was calculated above 24 nm by Barret–Joyner–Halenda (BJH). Gas sensing properties revealed that Y-doped SnO 2 hollow nanofibers exhibited a much higher response to acetone vapor than pure SnO 2 hollow nanofibers at 300 °C. Y-doped SnO 2 hollow nanofibers exhibited good stability and excellent selectivity, which were ascribed to the 1D hollow nanostructure and the effect of Y doping. The formation mechanism and the acetone sensing mechanism of SnO 2 hollow nanofibers were also discussed.
TL;DR: This scalable fabrication method supplies a low-cost, high-efficiency metal-free oxygen reduction electrocatalyst and also suggests an economic and sustainable route from biomass-based molecules to value-added nanocarbon materials.
Abstract: Graphene-like nitrogen-doped carbon nanosheets (NCN) have become a fascinating carbon-based material for advanced energy storage and conversion devices, but its easy, cheap, and environmentally friendly synthesis is still a grand challenge. Herein we directly synthesized porous NCN material via the facile pyrolysis of chitosan and urea without the requirement of any catalyst or post-treatment. As-prepared material exhibits a very large BET surface area of ∼1510 m2 g–1 and a high ratio of graphitic/pyridinic nitrogen structure (2.69 at. % graphitic N and 1.20 at. % pyridinic N). Moreover, compared to a commercial Pt/C catalyst, NCN displays excellent electrocatalytic activity, better long-term stability, and methanol tolerance ability toward the oxygen reduction reaction, indicating a promising metal-free alternative to Pt-based cathode catalysts in alkaline fuel cells. This scalable fabrication method supplies a low-cost, high-efficiency metal-free oxygen reduction electrocatalyst and also suggests an eco...
TL;DR: In this article, a composite containing silver nanoparticles and colemanite ore waste (COW) was synthesized and tested in adsorption and photocatalysis to remove Reactive Yellow 86 (RY86) and Reactive Red 2 (RR2) from aqueous solution in single and binary dye systems.