High Brunauer Emmett Teller Surface Area Research Articles

Preparation of core-shell structured CaCO3 microspheres as rapid and recyclable adsorbent for anionic dyes.

Core–shell structured CaCO3 microspheres (MSs) were prepared by a facile, one-pot method at room temperature. The adsorbent dosage and adsorption time of the obtained CaCO3 MSs were investigated. The results suggest that these CaCO3 MSs can rapidly and efficiently remove 99–100% of anionic dyes within the first 2 min. The obtained CaCO3 MSs have a high Brunauer–Emmett–Teller surface area (211.77 m2 g−1). In addition, the maximum adsorption capacity of the obtained CaCO3 MSs towards Congo red was 99.6 mg g−1. We also found that the core–shell structured CaCO3 MSs have a high recycling capability for removing dyes from water. Our results demonstrate that the prepared core–shell structured CaCO3 MSs can be used as an ideal, rapid, efficient and recyclable adsorbent to remove dyes from aqueous solution.

Ex Cathedra Immobilization of 8-Hydroxyquinoline to Inorganic Carriers via a New Silane Coupling Reagent for Extractive Sample Cleanup of Iron(III)

By the use of a new silane coupling reagent, dimethyldichlorosilane (DMDCS), effective and instantaneous immobilization of 8-hydroxyquinoline (HQ) on an inorganic carrier (silica gel, SG) has been carried out for the facile synthesis of an extractor material (composition: {Si(OSi)p=4(H2O)x=0.16}n=11[−Si(CH3)2–NH–C6H4–N═N–HQ]z=4·25H2O; molar mass: 4010.3 g/mol). The material (thermal stability: ≤100 °C; chemical stability: ≤8 M HNO3) possesses a high Brunauer–Emmett–Teller surface area (BET-SAFe(III): 1170 m2·g–1), an appreciable preconcentration factor (PFFe(III): 145.1), and high breakthrough capacity (BTCFe(III): column exchange capacity, 269 μmol·g–l; Langmuir Q0, 278.6 μmol·g–1) for Fe(III). Along with these discernible analytical qualities, a high level of reusability (<800 cycles @ 95% recovery) reflects the material warranty. Fe(III), present as [Fe(OH)(H2O)5]2+ at the recommended pH (1.90 ± 0.15), binds at the highest occupied molecular orbital (HOMO) of the sorbent (η = 7.69 eV) through hard–soft binding with an appreciable binding energy (−14.2 eV). The breakthrough capacity (BTC: 269–278.6 μmol·g–1) was found to be the product of the amount of extractor HOMO (280 μmol·g–1) and the degree of polymerization of the adsorbed metal ion, x (i.e., BTC = [amount of HOMOextractor (μmol·g–1)] × x for monomeric (x = 1) and polymeric (x > 1) species). The findings reveal substantial improvement of Weetall–Hill immobilization of chelating ligands on inorganic carriers.

Highly efficient simultaneous adsorption and biodegradation of a highly-concentrated anionic dye by a high-surface-area carbon-based biocomposite

Mesoporous high-surface-area activated carbon (MHSA-AC), which has a honeycomb structure, was produced from coconut shells by simultaneous chemical and physical activation and used for the rapid adsorption of an anionic dye, namely acid orange 10 (AO10), from water. Owing to its porosity and high Brunauer–Emmett–Teller surface area (2283.91 m2g−1), MHSA-AC is a highly efficient adsorbent. It also has good biocompatibility and is a good immobilization carrier; the grooves on the MHSA-AC surface facilitate immobilization. Here, a new, highly efficient, and environmentally friendly simultaneous adsorption and biodegradation (SAB) process was developed. Highly concentrated AO10 (6000 mg L-1, 20 mL) was removed with an efficiency of 100% (pH = 7, 35 °C) by SAB using cells immobilized on MHSA-AC (500 mg). The immobilized cells were used directly, without pretreatment; the SAB process is therefore simple and has good potential for application in the treatment of dyes in industrial wastewater.

CO2 adsorption isotherms on KOH, H3PO4 and FeCl3.6H2O Impregnated palm shell kernel activated carbon

Commercial sorbents available are expensive as a result of using high cost and non-renewable materials as precursors. It is imperative to select cheap, viable and sustainable carbon source for production of adsorbents for subsequent use in adsorption applications. Palm kernel shell char was obtained by carbonisation process at 730 °C ± 20 °C for 2 h with 10 °C/min heating rate under inert gas flow. The bio-char obtained was further grinded and sieved to 0.5 to 0.85 mm, then treated and synthesised separately each sample by KOH, H3PO4 and FeCl3.6H2O solution with ratio 1 : 1 weight ratio and followed by microwave treatment technique. Samples treated with chemicals used were named as PKS-POT (Palm Kernel Shell with Potassium Hydroxide ), PKS- PAP (Palm Kernel Shell with Phosphoric acid) and PKS-FER(Palm Kernel Shell with Ferric chloride hexahydrate). CO2 gas was used during the adsorption and desorption study. Samples were characterised by Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM) and Fourier transform infraredspectroscopy (FTIR). PKS-POT showed highest BET surface area (208.7037 m2/g) and pore volume (0.06580 cm3/g). PKS-POT’s SEM result also confirms large surface area, pores and more compact of the shell structure which related to high adsorption capacity compared to PKS-PAP and PKS-FER. CO2 PKS-POT, PKS-PAP and PKS-FER adsorption capacities were 2.19, 0.62 and 1.25 mmol/g and no CO2 gas left for the end desorption phase. From the study concluded that sustainable palm kernel shell material was successfully achieved to obtain the high surface area, high porosity and high adsorption sorbent capacity.

Microstructural characterization of spray-dried NiO-8YSZ particles as plasma sprayable anode materials for metal-supported solid oxide fuel cell

The plasma spray method is widely used to produce NiO-8YSZ (composed of nickel oxide (NiO) and 8mol% yttria-stabilized zirconia) anode layers in metal-supported solid oxide fuel cell (SOFC). Flowability control of microsized particles is important for achieving consistent performance of the SOFC anode layer. When microsized particles are fabricated via spray drying and sintering, the most significant factors that influence flowability are their sizes, distribution, and surface conditions. Thus, the aim of this study is to analyze the fabrication conditions for microsized NiO-8YSZ cermet particles made from a nanoscale, sinterable NiO-8YSZ dispersion solution by using an appropriate spray-drying and sintering process. The characteristics of the as-sprayed and sintered NiO-8YSZ composite particles (such as size, distribution, roughness, and nanostructure) were analyzed via field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS), particle size distribution (PSD), Brunauer–Emmett–Teller (BET) surface area, and atomic force microscopy (AFM). The as-sprayed microsized NiO-8YSZ particles became smaller and more uniformly distributed as the rotational speed used for spray drying increased. As a result of sintering, the extent of shrinkage of as-sprayed microsized NiO-8YSZ particles generated at high RPMs was lower than that of particles formed at low RPMs. No significant difference was observed in the distribution of the nanosized NiO and 8YSZ particles at different rotational speeds. Furthermore, the highest BET surface areas were observed for particles generated at 8000 RPM before sintering at 13.74m2/g. After sintering, the highest BET surface area was 0.94m2/g for particles generated at 16,000 RPM. Differences in nanostructure and surface roughness between as-sprayed and sintered microsized NiO-8YSZ particles were identified via AFM. This study is expected to provide important fundamental information useful for optimizing SOFC efficiency by promoting flowability control during the production of SOFC anodes via plasma spraying.

Microwave-Assisted Solution Combustion Synthesis of Spinel-Type Mixed Oxides for Esterification Reaction

Environmentally benign production of biodiesel using heterogeneous catalysts is an important issue that requires the preparation of catalysts with high activity and reusability by a simple procedure. In this study, pure alumina and zinc oxide- and copper oxide-modified alumina were tested for the esterification of oleic acid to its methyl ester. The microwave-assisted solution combustion (MSC) method was used to prepare the catalyst samples that were characterized by X-ray diffraction (XRD), Fourier transform infra-red (FTIR), Brunauer–Emmett–Teller (BET) surface area measurement, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The spinel-type zinc aluminate was successfully synthesized, but CuO-modified alumina particles were clearly observed. Whereas in the alumina, much lower activity was observed than the doped alumina, zinc aluminate showed higher activity than copper oxide-alumina due to its smaller particle size, higher BET surface area, larger average pore size, and higher acidity. Finally, after the reaction conditions for the conversion of oleic acid were optimized for the case of spinel ZnAl2O4 as nanocatalyst, a yield of higher than 94% was obtained at 180°C, 9 methanol/oleic acid molar ratio, 3 wt% of catalyst for 6 h. Furthermore, the catalyst deactivation was not observed after four reaction cycles at the optimal reaction conditions, indicating the feasibility of the proposed method for the preparation of industrial catalysts.

Cocatalyst‐Free Hybrid Ionic Liquid (IL)‐Based Porous Materials for Efficient Synthesis of Cyclic Carbonates through a Cooperative Activation Pathway

Cocatalyst-free ionic liquid (IL)-based porous polymers (Px -Vy -OHz R) functionalized with an intermolecular hydroxyl group were prepared by means of radical copolymerization of 1-butyl-3-vinylimidazolium bromide, (4-vinylphenyl)methanol (VBzOH), and divinylbenzene (DVB) under solvothermal conditions. As the ratio of 4-vinylphenylmethanol in the initial mixture increased, the content of the hydroxyl groups in the polymer increased from 3.35 to 5.35 mmol g-1 and the Brunauer-Emmett-Teller (BET) surface area of the polymer decreased sharply from 365 to 2.5 m2 g-1 . In the carbonation of CO2 and epoxides, the turnover frequency (TOF) of Px -Vy -OHz R increased gradually from 25 to 67 h-1 as the OH ratio increased irrespective of the sharp decrease in BET surface area, which suggests the existence of a cooperative activation effect between OH and ILs. To obtain a high OH content while still maintaining a high BET surface area, hybrid porous materials (SBA-[Vx OHy ]R-n) were prepared by means of copolymerization of 1-ethyl-3-vinylimidazolium bromide and 4-vinylphenylmethanol in the mesopores of SBA-15. SBA-[Vx OHy ]R-n was more active than its polymer counterpart (TOF: 188 versus 71 h-1 ) in the cycloaddition of CO2 with propyl oxide owing to the combined effect of the high BET surface area and the high OH content. The hybridization of mesoporous materials with polymers represents an efficient strategy for the preparation of high-performance solid catalysts for chemical transformations.

A novel methoxy-decorated metal–organic framework exhibiting high acetylene and carbon dioxide storage capacities

A methoxy-decorated novel metal–organic framework (MOF), Cu2(DTPD) (ZJU-12, H4DTPD = 5,5′-(2,6-dimethoxynaphthalene-1,5-diyl)diisophthalic acid) with optimized pore space and open metal sites, was solvothermally synthesized and structurally characterized. The activated ZJU-12a displays a moderately high BET (Brunauer–Emmett–Teller) surface area of 2316 m2 g−1. Due to the pore size of the crystal being consistent with the molecular size and kinetic diameters of C2H2 and CO2, ZJU-12a exhibits a high C2H2 storage capacity of 244 cm3 g−1 and CO2 capture capacity of 134 cm3 g−1 at room temperature.

Adsorption Properties of C2H4 and C3H6 on 11 Adsorbents

Adsorption isotherms of pure C2H4 and C3H6 were measured on 11 adsorbents and at pressures up to 0.8 MPa using a volumetric method. The Brunauer–Emmett–Teller (BET) surface area of the adsorbents had a significant effect on adsorption capacities of both C2H4 and C3H6. The metal organic framework MIL-101 had the highest BET surface area and the highest adsorption capacity. For zeolite molecular sieves 5A, the C2H4 adsorption capacity was higher than that of C3H6, which is opposite to the results for most adsorbents. The isosteric heats of C3H6 on AC-1, 5A, MIL-101, ZIF-8, and SG-1 were higher than those of C2H4. The C3H6/C2H4 separation selectivities were calculated using the ideal solution theory, and the activated carbon AC-1 had the highest separation selectivity of 8.8.

Nanocrystalline mesoporous zeolite X with a considerable external surface area prepared via an ordered precursor: a potential adsorbent

A nanocrystal zeolite X with intracrystalline mesopores has been successfully prepared by using organofunctionalised mesoporous silica in hydrothermal system. The as-prepared zeolitic material persist the inherent framework structure of FAU zeolite, and present a crystallographic morphology of stacked three-dimensional intergrowths made up of rectangular nanocrystals. The intracrystalline mesopores are formed via a bond-blocking principle with hydrophobic carbon chains of organosilane inhibiting the growth of zeolite units and crystals in the channels of mesoporous silica during hydrothermal synthesis. The results showed that the zeolitic material has a considerable external surface area (247 m2g−1)and mesopore volume (0.44 cm3g−1), maintaining high Brunauer–Emmett–Teller surface area (991 m2g−1) and large total pore volume (0.71 cm3g−1), and clearly stating a larger adsorption capacity for p-xylene at relative higher pressure.

The role of adsorption in the photocatalytic decomposition of Orange II on carbon-modified TiO2

Carbon-modified TiO2 was successfully prepared via simple heat treatment of TiO2 in alcohol vapors (1-butanol and 2-butanol) at a constant temperature (500°C). The prepared samples were characterized by means of X-ray diffraction (XRD) and Fourier transform infrared diffuse reflectance spectroscopy (FTIR/DRS). Brunauer-Emmett-Teller (BET) adsorption and zeta potential analyses were also conducted. The Freundlich adsorption model fitted both carbon-modified and original TiO2, which provide a heterogeneous surface for the adsorption of Orange II. The carbon-modified TiO2 was used as a photocatalyst to remove Orange II from aqueous solution by combined processes of adsorption and photocatalytic decomposition. The adsorption performance of the carbon-modified TiO2 was higher than that of the unmodified TiO2. Carbon adsorption approached synchronicity with oxidation, leading to the higher activity. This enhanced adsorption capacity may be a promising factor for the photocatalytic removal of Orange II onto carbon-modified TiO2. The prepared Carbon-modified TiO2 samples had higher BET surface area than unmodified TiO2 (44, 54.48 and 49.72m2/g for TiO2, C1B-TiO2 and C2B-TiO2, respectively) and exhibited higher hydrophobicity and a positively charged surface, which were favorable for adsorption of Orange II. High adsorption of dye on the porous structure of C-TiO2 enhanced its photocatalytic decomposition under visible light.

Synthesis of Titanium Dioxide Nanoparticles Using a Double-Slit Curved Wall-Jet Burner

ABSTRACTA novel double-slit curved wall-jet (DS-CWJ) burner was proposed and utilized for flame synthesis. This burner was comprised of double curved wall-jet nozzles with coaxial slits; the inner slit was for the delivery of titanium tetraisopropoxide (TTIP) precursor while the outer one was to supply premixed fuel/air mixture of ethylene (C2H4) or propane (C3H8). This configuration enabled rapid mixing between the precursor and reactants along the curved surface and inside the recirculation zone of the burner. Particle growth of titanium dioxide (TiO2) nanoparticles and their phases was investigated with varying equivalence ratio and Reynolds number. Flow field and flame structure were measured using particle image velocimetry (PIV) and OH planar laser-induced fluorescence (PLIF) techniques, respectively. The nanoparticles were characterized using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and nitrogen adsorption Brunauer–Emmett–Teller (BET) for surface area analysis. The flow field consisted of a wall-jet region leading to a recirculation zone, an interaction jet region, followed by a merged-jet region. The DS-CWJ burner revealed appreciable mixing characteristics between the precursor and combustion gases near the nozzle regions, with a slight increase in the axial velocity due to the precursor injection. The precursor supply had a negligible effect on the flame structure. The burner produced a reasonably uniform size (13–18 nm) nanoparticles with a high BET surface area (>100 m2/g). The phase of TiO2 nanoparticles was mainly dependent on the equivalence ratio and fuel type, which impact flame height, heat release rate, and high temperature residence time of the precursor vapor. For ethylene flames, the anatase content increased with the equivalence ratio, whereas it decreased in the case of propane flames. The synthesized TiO2 nanoparticles exhibited high crystallinity and the anatase phase was dominant at high equivalence ratios (ϕ > 1.6) for C2H4, and at low equivalence ratios (ϕ < 1.3) for the C3H8 flame.

One-pot synthesis of triptycene-based porous organic frameworks with tailored micropore environments for highly efficient and selective amine adsorption

Triptycene-based porous organic frameworks (POFs) with high BET (Brunauer–Emmett–Teller) surface areas and tailored micropore environments were prepared using a facile external knitting strategy. The functionalized POFs exhibited very high aliphatic amine vapor uptakes of up to 5 times their own weight and more than 30 times selectivity for aliphatic amines over n-hexane; thus, they provide new opportunities for environment-related applications. Triptycene-based porous organic frameworks (POFs) with high BET (Brunauer–Emmett–Teller) surface and tailored micropore environments were prepared through a facile external knitting strategy. The functionalized POFs exhibited very high aliphatic amine vapor uptakes of up to 5 times of their own weight, and more than 30 times selectivity for aliphatic amines over n-hexane, and thus they open up new opportunities for environment-related applications.

Direct preparation of green and renewable aerogel materials from crude bagasse

Lignocellulosic biomass aerogels with relatively high Brunauer–Emmett–Teller (BET) surface area and pore volume were prepared directly from bagasse solutions in the present study. Bagasse was dissolved in DMSO/LiCl, treated with cyclic freezing-thawing processes, and regenerated with water. The resulted bagasse hydrogels were solvent-exchanged to t-butanol and subjected to freeze-drying to obtain the lignocellulosic aerogels. The structure of the aerogels was studied with FTIR, nitrogen absorption, SEM, and XRD. The results showed that the aerogels had sheet-like skeletons interconnected with one another to form three-dimensional networks. The highest BET surface area and total pore volume of the aerogels were 185 m2/g and 0.46 cm3/g, respectively. By adjusting the concentration of bagasse solution in DMSO/LiCl, the structure of the aerogels could be controlled to some extent.

Photocatalytic Degradation of Methylene Blue by Nanosized Visible Light Active Nitrogen and Iron Codoped Titania: Characterization and Feasibility Investigation

AbstractSurface modification of titanium dioxide, TiO2, by codoping with nitrogen and iron to get the photocatalyst active under ordinary visible light was investigated for the photocatalytic degradation of methylene blue. The sol-gel method was used in preparing the modified titanium dioxide. Titanium tetraisopropoxide (TTIP), ammonium nitrate and ferric nitrate were used as precursors with the dopant concentration of 1% and calcination temperature at 600°C. The prepared photocatalyst samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area, ultraviolet (UV)–visible diffusive reflectance spectra (DRS), and X-ray photoelectron spectroscopy (XPS) in order to study their physical properties. The results from XRD confirmed that all prepared photocatalyst were of the anatase phase whereby the codoping photocatalyst perfectly fitted with the standards and also found with high BET surface area. The analysis of band gap energy from UV-vi...

Biodiesel production via transesterification of palm oil by using CaO–CeO2 mixed oxide catalysts

Solid base CaO–CeO2 mixed oxide catalysts have been synthesized via wet impregnation method and characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, temperature-programmed desorption of CO2 (TPD-CO2) and scanning electron microscopy (SEM). The catalytic activity was determined by transesterification of palm oil. Optimum biodiesel yield, 95%, was achieved by 50Ca–Ce catalyst under the reaction conditions of 5wt.% of catalyst, methanol to oil molar ratio of 12:1, reaction temperature of 65°C and reaction time of 4h. The high catalytic activity (95%) of 50Ca–Ce catalyst may be due to strong basicity and high BET surface area, which indicate more number of active sites on the catalyst surface for transesterification process. Besides, 50Ca–Ce catalyst showed better reusability than the bulk CaO where it can be reused up to 6 times without a significant loss of catalytic activity (>80%). The lixiviation of CaO active phase was greatly reduced with the presence of strong synergic interaction between CaO and CeO2. Deactivation of the catalyst was mainly due to the leaching of CaO active phase into the methanolic solution and pore-filling by fatty acid or glycerol.

Synthesis and characterization of Cu2O–modified Bi2O3 nanospheres with enhanced visible light photocatalytic activity

In this work, a series of Cu2O–modified Bi2O3 nanospheres with perfect visible-light catalytic activity were successfully synthesized via the two-step method. The obtained products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area, UV–visible diffuse reflectance spectroscopy (UV–vis DRS), and X-ray photoelectron spectroscopy (XPS). In the catalysts of Cu2O–modified Bi2O3 nanospheres, Cu2O was dispersed on the surface of Bi2O3 nanospheres. All of Cu2O–modified Bi2O3 nanospheres showed uniformly nanospheres with the size of 80–150nm, and exhibited enhanced photocatalytic activity in the degradation of Rhodamine B. The higher BET surface area, the band gap narrowing, and the interfacial charge transfer effect were considered to cause the excellent photocatalysis of Cu2O loading Bi2O3 samples. Furthermore, the possible photocatalysis mechanism was proposed.

Characterization of bio-oils and bio-chars obtained from the catalytic pyrolysis of alkali lignin with metal chlorides

The pyrolysis experiments were carried out in a fixed bed reactor at a reaction temperature of 873K and gas residence time of 1.0s. The physicochemical properties of bio-oils and bio-chars obtained from alkali lignin pyrolysis with and without KCl, CaCl2, and FeCl3 additives were studied. The compositions of bio-oils were examined using gas chromatography–mass spectrometry (GC–MS). Characterizations of bio-chars were performed using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area and scanning electron microscopy (SEM) techniques. Adding KCl caused a sharp decrease in bio-oil yield while an increase in bio-char yield was found as a result. The addition of CaCl2 and FeCl3 significantly increased the yield of bio-oil and phenol content while inhibited the formation of char residues. The bio-char generated after FeCl3 addition has a much high BET surface area. This result indicates that the addition of FeCl3 in alkali lignin significantly improves the quality of both bio-oil and bio-char, which is beneficial to the usage of bio-oil for chemical materials and bio-char for activated carbon species.

Ethyl Cellulose and Cetrimonium Bromide Assisted Synthesis of Mesoporous, Hexagon Shaped ZnO Nanodisks with Exposed ±{0001} Polar Facets for Enhanced Photovoltaic Performance in Quantum Dot Sensitized Solar Cells.

Hexagon shaped mesoporous zinc oxide nanodisks (ZnO NDs) with exposed ±{0001} polar facets have been synthesized by using ethyl cellulose (EC) and cetrimonium bromide (CTAB) as the capping and structure directing agents. We have characterized ZnO NDs using analytical techniques, such as powder X-ray diffraction (PXRD), diffuse reflectance UV-visible (UV-vis) spectroscopy, photoluminescence (PL) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) surface area analysis and proposed a plausible mechanism for the formation of ZnO NDs. EC molecules form a colloidal solution in a 1-butanol:water (3:1) solvent system having a negative zeta potential (ζ ≈ -32 mV) value which can inhibit CTAB assisted c-axis growth of ZnO crystal and encourage the formation of ZnO NDs. In the control reactions carried out in presence of only CTAB and only EC, formation of hexagonal ZnO nanorods (NRs) and ZnO nanosheets (NSs) composed of numerous ZnO nanoparticles are observed, respectively. Photovoltaic properties of ZnO NDs as compared to ZnO NRs, ZnO NSs, and conventional ZnO nanoparticles (NPs) are investigated by co-sensitizing with CdS/CdSe quantum dots (QDs). An ∼35% increase in power conversion efficiency (PCE, η) is observed in ZnO NDs (η ≈ 4.86%) as compared to ZnO NPs (η ≈ 3.14%) while the values of PCE for ZnO NR and ZnO NS based devices are found to be ∼2.52% and ∼1.64%, respectively. Enhanced photovoltaic performance of the ZnO NDs based solar cell is attributed to an efficient charge separation and collection, boosted by the exposed ±(0001) facets apart from the single crystalline nature, better light-scattering effects, and high BET surface area for sensitizer particle adsorption. Electrochemical impedance spectroscopy (EIS) analysis further reveals that the charge recombination resistance and photoinduced electron lifetime are substantially higher in the ZnO ND based device than in ZnO NR, ZnO NP, and ZnO NS based devices, which demonstrates a slower electron-hole (e(-)-h(+)) recombination rate and faster charge migration through the single crystalline ZnO NDs.

Study of Mercury Adsorption by Low-Cost Sorbents Using Kinetic Modeling

In order to make further progress in the field of reducing mercury emissions to the atmosphere, it is necessary to develop efficient and economically viable technologies. Low-cost solid sorbents are a candidate technology for mercury capture. However, kinetic models are required to predict the adsorption mechanism and to optimize the design of the process. In this study, several low-cost materials (biomass chars) were evaluated for the removal of gas-phase elemental mercury and kinetic studies were performed to investigate the mechanism of mercury adsorption. These kinetic studies were also used to predict the behavior of a fixed-bed column. The models applied were pseudo-first-order and pseudo-second-order equations, Fick’s intraparticle diffusion model, and the Yoon–Nelson model. The chars obtained from the gasification of plastic-paper waste demonstrated the best behavior for mercury capture because of their high Brunauer–Emmett–Teller surface area, large total pore volume (mainly micropore volume), an...