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Amine hybrid silsesquioxane aerogel (AHSA) was synthesized through a single-step sol–gel process followed by supercritical drying. CO 2 adsorption performances of highly porous AHSA in 1% CO 2 were investigated. 50 °C is preferred to perform the CO 2 capture of AHSA to achieve a CO 2 adsorption capacity of 3.04 mmol/g (dry) or 3.84 mmol/g (humid) under given conditions. A rise in adsorption gas flow rate from 300 to 700 ml/min results in the decrease of CO 2 adsorption capacity from 3.04 to 2.42 mmol/g. The CO 2 adsorption rate is mainly affected by the gas flow rate, while the effect of temperature can be ignored. Different with the adsorption performance, the CO 2 desorption kinetics of AHSA is mainly affected by the temperature, the effect of gas flow rate is indifferent. Water favors the CO 2 capture capability of AHSA, however, it is bad for the CO 2 adsorption and desorption kinetics. The CO 2 adsorption capacities of AHSA in 1% CO 2 are much higher than those of other amine based porous adsorbents obtained with a 1% or even higher CO 2 gas mixture. Also, AHSA has very short adsorption half time (22–55 s) and low desorption temperature of 80 °C, much lower than those of other amine-based adsorbents. The resulting adsorbent is dynamic and possesses excellent regenerability for low-concentration CO 2 capture. [ABSTRACT FROM AUTHOR]

This paper proposes a process for reducing the content of copper and zinc in polluted soils and a combined photocatalytic-physical process for the treatment of the soil washing effluents. For this purpose, real soil samples were taken from the “Land of Fires”, a region in Southern Italy which is known for its high incidence of cancer mortality. Ethylenediamine- N,N ′-disuccinic acid (EDDS) was used to extract the heavy metals from the contaminated soil. The soil washing effluents were treated through a sequence of photocatalytic and adsorption processes to lower the concentration values of metals (Cu, Zn, Fe and Mn) below the limits of national legislation for discharge in municipal sewers and to remove the EDDS from the soil washing solutions. Ecotoxicological tests, using different living organisms ( Daphnia magna , Vibrio fischeri , Pseudokirchneriella subcapitata and Lepidium sativum ), were performed on the soil washing effluents before and after the treatments to assess the effects of the proposed combined process on the ecotoxicity of the soil washing solutions. [ABSTRACT FROM AUTHOR]

Calcium alginate cohered beads of copper hexacyanoferrate (CuHCF), and iron hexacyanoferrate (FeHCF), were prepared and studied for their competence in the environmental Cs decontamination. The influence of temperature and solution pH, parameters which are crucial for effective decontamination are studied in detail. Kinetic study performed at varying temperatures showed that adsorption of Cs onto CuHCF is faster than on FeHCF, the difference observed mainly due to the difference in the adsorption capacities of the materials. Additionally, an important environmental issue, which is often omitted, the possibility of release of the ferrocyanide ion into the effluent solution, is discussed in detail. The concentration of total cyanide in the effluent solution passed through FeHCF is comparatively very high beyond pH 4. In contrary, it is lower than in CuHCF passed solution at pH below 4. Based on these results, FeHCF is a good option in highly acidic solutions, and for weakly acidic to slightly alkaline pH, CuHCF is effective. [ABSTRACT FROM AUTHOR]

Hierarchical three-dimensional (3D) porous structures are of great significance for their versatile applications in diverse fields. Herein, uniform Ca 4 B 10 O 19 ·7H 2 O microspheres were successfully fabricated via a facile hydrothermal method, followed by a thermal conversion (700 °C, 2.0 h) without any additives, leading to the 3D hierarchical porous calcium metaborate (Ca(BO 2 ) 2 ) microspheres with well-preserved spherical morphology and high crystallinity. When employed as adsorbents, the adsorption isotherms of Pb 2+ and Cd 2+ onto porous Ca(BO 2 ) 2 microspheres were well fitted with the Langmuir adsorption model, giving rise to the maximum adsorption capacities for Pb 2+ and Cd 2+ as 140.2 and 110.6 mg g −1 , respectively. When utilized as catalyst support, the good dispersion and smaller size of metallic Pd nanoparticles (NPs) as well as more and stronger acid sites on the catalyst resulted in the 1.05 wt% Pd/Ca(BO 2 ) 2 catalyst, by using which the conversion of benzyl alcohol and selectivity to benzaldehyde with O 2 as oxidant reached 94.3% and 96.0%, respectively. The resultant supported catalyst also exhibited satisfactory high conversion and especially excellent selectivity during 10 cycles of catalysis, revealing the as-prepared porous Ca(BO 2 ) 2 microspheres as superior catalyst carrier. The present hierarchical porous Ca(BO 2 ) 2 microspheres afforded promising and competitive candidates for water treatment and heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Recently, a diffusive intraparticle dynamic model has been published by the authors and applied for describing few systems in order to check its validity. The aim of the present paper is to improve its validity in describing different kind of systems. At this purpose, adsorption data have been taken from literature, in which different adsorbate/adsorbent systems have been considered. In every case, the surface diffusivity of the pollutant ( D S ) has been fitted on the experimental data. The obtained parameters fall within reasonable ranges and a good fitting has been obtained for each case, demonstrating the generality of the adopted model. [ABSTRACT FROM AUTHOR]

The adsorption of dioxin–modeling compounds on activated carbon has been investigated in this manuscript. A series of benzene compounds with different numbers and types of substituent groups were chosen as the dioxin–modeling compounds, and the gas adsorption behaviors were evaluated using a fixed-bed reactor. The adsorption results showed that the methyl, chlorine and phenolic substituent groups on a benzene ring can greatly promote gas adsorption, especially the phenolic group, the addition of which increased the adsorption capacity to more than 1.5 times that of benzene. The adsorbed AC samples were detected by TPD-MS with the combines between adsorbate and adsorbent analyzed, the methyl and chlorine groups enhanced the attraction between the gaseous compounds and AC, while the phenolic group reduced the combine force due to its oxidation on AC. The effect of an increasing number of chlorine substituents on the adsorption of gases and the combine forces were investigated. On average, the capacity of gas adsorption doubled and the desorption temperature increased by 20 K with one chlorine substituent on a benzene ring. The attachment of chlorine substituent groups to the AC lactone and quinone groups has been verified again, and the increasing chloric substituent groups consumed more oxygen groups. According to the linear relationships between gas properties and adsorption behaviors, the actual dioxin adsorption capacity has been inferred to be 600 mg/g or greater, showing that dioxin is much more easily adsorbed on AC than the conventional organic gases. [ABSTRACT FROM AUTHOR]

A continuous-flow adsorption/desorption process for the recovery of phenolic compounds (PCs) from olive mill wastewaters (OMWs) was developed in a 0.53 m packed column, using a previously selected resin (Amberlite XAD16) and an actual OMW. The main goals of the study were (i) to evaluate the PC adsorption/desorption performances of XAD16 by means of adsorption isotherms and adsorption/desorption breakthrough tests, and (ii) to develop a reliable model of the process. A combination of centrifugation and microfiltration resulted necessary to attain a high suspended solid removal (98.5%) and thus avoid clogging of the packed bed. The quality of two packing procedures was evaluated by means of frontal analysis tests. XAD16 performed well in terms of both adsorption yield at 20% breakthrough (87–88%) and PC/COD selectivity (PC/COD adsorption constant = 7–9). The desorption solvent (acidified ethanol) was effectively regenerated by vacuum distillation. The adsorption breakthrough curves were successfully simulated with a 1-D convection/dispersion model with mass-transfer ( R 2 = 0.95–0.99; k L a = 0.8–2.5 · 10 −3 1/s), whereas an equilibrium adsorption model with dispersion failed to predict the experimental data. In the perspective of a process scale-up, the simulation of the best-performing operational condition was used to evaluate the process performances for different column lengths (0.5–10 m). A precise and automated HPLC method for total PC measurement was developed and compared to the traditional Folin–Ciocalteu methodology. Further research is needed to optimize the desorption step, to scale up the process and to evaluate the long-term resin performances. [ABSTRACT FROM AUTHOR]

The objective of this research is to reveal the mechanism of effective and inexpensive sorbent MnCl 2 for elemental mercury (Hg 0 ) removal from the flue gas. The adsorption behavior of Hg 0 on MnCl 2 (1 1 0) surface was investigated theoretically using Density Functional Theory. The geometry optimization and adsorption energy of Hg 0 on MnCl 2 surface were calculated by generalized gradient approximation with Perdew−Burke−Ernzerh functional (GGA/PBE) and DNP basis. Results showed that Hg 0 adsorption on MnCl 2 (1 1 0) surface is chemisorption with adsorption energy of −156.620 kJ/mol. According to Hirshfeld charge analysis, Hg 0 has active interaction with Cl atoms (Cl-12, Cl-32, Cl-44) and Mn-40 atom on MnCl 2 (1 1 0) surface. The partial density of states (PDOS) analysis further reveals that p- and d-orbitals of Cl atoms strongly hybridize with s- and d-orbitals of Hg atom. The d-orbital of Mn-40 also has essential interaction with Hg atom. Both of them contribute to the stable adsorption system of Hg 0 –MnCl 2 . The equilibrium constant decreases with the increase of temperature, which coincides with data for exothermic adsorption system. For the first time, this study investigated the mechanism of Hg 0 adsorption on metal chloride surface using DFT method. It provides a significance theoretical support for metal chloride application in Hg 0 adsorption and removal. The results obtained in this research are in good agreement with previous experiment. This method can be used to reveal Hg 0 capture mechanism in some complex systems. [ABSTRACT FROM AUTHOR]

A new approach is proposed for pre-concentrating emerging pollutants, taking nalidixic acid as representative. The approach consists of performing successive adsorption–desorption cycles in order to remove the pollutant from the main stream, generating a new stream with higher pollutant concentration during the adsorbent regeneration. For accomplishing these scopes (efficient removal and capability for pre-concentrate), adsorbents presenting both high adsorption capacity and regeneration easiness are needed. In this work, the performance of three different adsorbents is studied: activated carbon (GF-40), multi-walled carbon nanotubes (MWCNTs) and high surface area graphite (HSAG-500). Adsorption experiments were performed at 25 °C, whereas two different desorption temperatures (35 and 40 °C) were chosen in order to evaluate the ability of the materials for concentrating the NAL. The adsorption breakthrough curves were modeled considering different models: Bed Depth Service Time (BDST), Thomas and Yoon-Nelson. Although activated carbon largely presents the highest adsorption capacity, it is difficult to regenerate needing long regeneration times, leading to very dilute regeneration solutions. By contrast, MWCNTs present lower adsorption capacity, but they are more easily regenerated leading to higher NAL concentrations. [ABSTRACT FROM AUTHOR]

Organo-montmorillonites (OMts) modified by cationic surfactant (hexadecyltrimethylammonium bromide, C16) and zwitterionic surfactant (hexadecyldimethyl (3-sulphonatopropyl) ammonium, Z16) were used to remove phenol and Cu(II) from aqueous solution. The OMts were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), Fourier-transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), and C, H, and N elemental analyses. Besides the independent adsorption of single contaminants, simultaneous and sequential adsorption of phenol and Cu(II) onto OMts were also investigated. The organic carbon contents of the two OMts were similar but the basal spacing of Z16 modified montmorillonite (Z16-Mt) was larger than that of C16 modified montmorillonite (C16-Mt) indicating a higher packing density of surfactant and hydrophobicity in C16-Mt with a slight higher adsorption capacity toward phenol. On the other hand, C16-Mt showed much lower capacity in adsorbing Cu(II) as compared with raw montmorillonite. On the contrary, the adsorption capacity of Z16-Mt toward Cu(II) was comparable with that of raw montmorillonite. The equilibrium data of phenol and Cu(II) were fitted satisfactorily with Linear and Langmuir models, respectively. In the sequential adsorption system, the adsorption of one contaminant was not affected by the other pre-adsorbed one; desorption of pre-adsorbed contaminant was also investigated. For both two contaminants, one did not affect the adsorption of the other one onto Z16-Mt and C16-Mt in the simultaneous system. Z16-Mt could rapidly and efficiently remove both phenol and Cu(II) simultaneously. The adsorption kinetics followed the Pseudo-second order model. The results of this work might provide novel information for developing new effective adsorbents toward organic contaminants and heavy metals. [ABSTRACT FROM AUTHOR]

We employ a previously developed model of a high surface area activated carbon, based on a random packing of small fragments of a carbon sheet, functionalized with hydroxyl surface groups, to explore adsorption of water and multicomponent mixtures under conditions representing typical carbon capture processes. Adsorption of water is initialized and proceeds through the growth of clusters around the surface groups, in a process predominantly governed by hydrogen bond interactions. In contrast, energetically favorable locations for carbon dioxide molecules are different from that for water, with the main contribution coming from the Lennard-Jones interactions with the extended surfaces of the fragments. This explains why over a broad range of conditions small amounts of water do not have any substantial impact on adsorption of carbon dioxide and other species in activated carbons. From the studies of various carbon capture processes, the model material shows promising properties for pre-combustion capture due to large capacity at high pressures and other favorable characteristics. [ABSTRACT FROM AUTHOR]

We investigated the effect of local curvature on the adsorption of oxygen on single-walled carbon nanotubes based on density functional theory calculations with van der Waals corrections. The results showed that as the curvature increases, the interaction of the nanotubes with oxygen increases as well. An oxygen atom was strongly chemisorbed on the bridge site of the nanotubes accompanied by a significant transfer of charge from the surface to the oxygen atom. Larger curvature enhanced both the adsorption energy and charge transfer due to the greater strain on the carbon atoms that led to a better interaction with oxygen. The oxygen molecule was physisorbed on the nanotubes with the interaction arising mostly from the long-range van der Waals interactions. The adsorption energy was also enhanced by greater curvature. The results were compared with the flat graphene sheet to confirm the effects of surface curvature. [ABSTRACT FROM AUTHOR]

An agricultural by-product, peanut husk, was modified by a cationic surfactant hexadecylpyridinium bromide (CPB) and used as adsorbent to remove light green dye (LG, anionic dye) from aqueous solution in a fixed-bed column. Adsorption capacity of LG was significantly increased after CPB modification. The experiments were conducted to investigate the effects of bed depth, flow rate, and LG concentration on breakthrough curves. The adsorption quantity is up to 60.5 mg g − 1 from experiments. The breakthrough curves were predicted by the Thomas model and Yan model using nonlinear regressive analysis. The results showed that the Yan model was more suitable for the description of breakthrough curves. The LG-loaded adsorbent can be regenerated and reused using sodium hydroxide solution. [ABSTRACT FROM AUTHOR]

The dye adsorption by chitosan is considered an alternative and eco-friendly technology, however, when chitosan structure is chemically modified it can result in a more suitable adsorbent. In this work, cyanoguanidine-crosslinked chitosan (CC-chitosan) was prepared and characterized, and it was applied for the adsorption of Food Blue 2 and Food Yellow 4 in the aqueous binary system. The equilibrium curves showed adequate to fit the extended Langmuir model at different temperatures. The equilibrium results showed that the more suitable conditions for the food dye adsorption in a binary system were at 288 K, and the maximum adsorption capacities were around 595–680 mg g − 1 . Avrami model was the most appropriate to fit the kinetic behavior, and desorption was possible for two cycles. On the basis of FT-IR spectrums, it was shown that cyanoguanidine was successfully inserted on the chitosan polymeric chains. CC-chitosan was an efficient adsorbent in removing dyes from aqueous binary systems. [ABSTRACT FROM AUTHOR]

The present manuscript deals with the synthesis and application of NiO nanoparticles for the removal of Co(II) ions from synthetic wastewater. NiO nanoparticles were synthesized at 500 °C calcination temperature. Synthesized nanoparticles were characterized by XRD, TEM, SEM and FTIR. TEM revealed the formation of nanosized particles. Central composite design (CCD) of the response surface methodology (RSM) was employed to optimize the important adsorption parameters viz. Co(II) concentration, pH of Co(II) solution and adsorbent dosage. Co(II) adsorption followed pseudo second order kinetic model. Thermodynamic study confirmed the feasibility of Co(II) adsorption and also revealed the exothermic nature of adsorption. Various two and three parameter isotherms were studied and the best fit isotherm was determined by the standard deviation and chi square test. Redlich–Peterson isotherm was found to be the most suitable isotherm for Co(II) adsorption. Langmuir adsorption capacity of nanoparticles was determined to be 149.51 mgg -1 . NiO nanoparticles were found to be efficient in Co(II) adsorption in the presence of anions like Cl − and PO 4 3 − while the presence of SO 4 2 − , NO 3 − NO 3 − and CO 3 2 − decreased their removal efficiency. Significant removal of Co(II) ions was observed in the presence of other cations. [ABSTRACT FROM AUTHOR]

A novel biomagnetic composite (MnFe 2 O 4 /PW) was synthesized and used for the removal of Congo red (CR) from aqueous solutions. Adsorption of CR on the composite adsorbent was studied as a function of time (5–300 min), initial CR concentration (100–200 mg/L), composite dose (0.05–0.1 g), pH (6–10), and temperature (25–55 °C). The properties of the biomagnetic composite were measured by BET, SEM, SEM–EDX, FTIR, XRD, and VSM techniques. The kinetics and isotherm studies were carried out under optimum removal conditions of CR by MnFe 2 O 4 /PW. The kinetics and equilibrium data fitted to the pseudo-first-order kinetics and Langmuir isotherm models. Using CR as model pollutant, the prepared composite adsorbent showed good adsorption capacity of 86.96 mg/g. Thermodynamic analysis showed that the adsorption was favorable, spontaneous and endothermic. The adsorbent could be regenerated using 50% of ethanol–water solution, remaining 87.36% of its original capacity after the first regeneration cycle and reaching 65.68% of the original capacity after the fifth cycle. This study shows that the synthesized biomagnetic composite could be utilized as an efficient and magnetically separable adsorbent for the dye removal applications. [ABSTRACT FROM AUTHOR]

The effects of different operating parameters such as initial pH, initial Pb(II) ion concentration, adsorbent dosages, and contact time are studied to optimize the conditions for maximum batch adsorptive removal of Pb(II) ions from aqueous solution using six different low cost natural bio-sorbents. Applicability of artificial neural network (ANN) analysis is investigated for the removal of Pb(II). Three standard training algorithms (Backpropagation, Levenberg–Marquardt and Scaled Conjugate Gradient) along with four different standard transfer functions in a hidden layer with a linear transfer function in the output layer are used for the analysis. Statistical analysis show that the ANN model with a BP algorithm, using transfer function 1 and 25 processing elements in a single hidden layer gives best predictability of the percentage removal of Pb(II) ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

Magnetic carbon nanomaterials have been widely adopted as adsorbents in water treatment, but the low adsorption capacities largely limit their practical applications. In this study, magnetic graphene sponge (Fe 3 O 4 -GS) was prepared by lyophilization for the adsorption of dye pollutant. The incorporation of Fe 3 O 4 enabled the magnetic separation of Fe 3 O 4 -GS after the adsorption of methylene blue (MB). The adsorption capacity of Fe 3 O 4 -GS for MB was 526 mg/g, much higher than those of the magnetic carbon nanoadsorbents in the literature. The adsorption kinetics of MB on Fe 3 O 4 -GS was moderately fast, which could be analyzed by the pseudo-second-order model and intraparticle diffusion model. The thermodynamics study revealed that the adsorption was driven by the increased randomness on the interface. The pH and ionic strength had meaningful influences on the adsorption capacity of Fe 3 O 4 -GS. The facile regeneration of Fe 3 O 4 -GS would definitely reduce its operating cost. The implications to the environmental applications of magnetic carbon nanoadsorbents are discussed. [ABSTRACT FROM AUTHOR]

TiO 2 and TiO 2 –V 2 O 5 nanocrystals were prepared by coupling sol–gel and solvothermal methods, followed by heat-treatment at 400 °C, after which the mean nanocrystal size was about 5 nm. The materials were characterized by X-ray diffraction, transmission electron microscopy and solid state nuclear magnetic resonance spectroscopy. It was shown that while the TiO 2 phase was always anatase even after heat-treatment at 500 °C, the presence of the vanadium oxide species enhanced the surface re-configuration of the Ti ions. Hence the coordination environment of surface Ti atoms was drastically changed, by formation of further bonds and imposition of a given local geometry. The final hypothesis was that in pure titania surface rearrangement occurs, leading to the new NMR signal, but this modification was favored in the TiO 2 –V 2 O 5 sample, where the Ti surface atoms were forced into the final configurations by the bonding with V atoms through oxygen. The materials heat-treated at 400 °C were used to process chemoresistive sensors, which were tested to hydrogen, CO and NO 2 , as examples of gases with peculiar sensing mechanisms. The results evidenced that the surface deposition of V 2 O 5 onto the anatase TiO 2 nanocrystals was effective in modifying the adsorption properties of the anatase nanocrystals. [ABSTRACT FROM AUTHOR]

The adsorption and decomposition reaction mechanisms of H 2 S on Mo 2 C(001) has been systematically studied using self-consistent periodic density functional theory. Results show that the molecular of H 2 S is adsorbed either on the Mo top site or bridge site. Mulliken population analysis and density of states for H 2 S/Mo-terminated Mo 2 C(001) adsorption system are examined to confirm the adsorption mechanism of H 2 S with the Mo 2 C(001) surface, which can involve the donation of charge from the “s lone pair electrons” that are LUMO orbitals into the surface and the back donation of electrons from the surface into the HOMO orbital. The optimal pathway for the dissociation of H 2 S on the Mo 2 C(001) surface can be H 2 S top → SH fcc + H fcc → S fcc + H fcc + H fcc . The first step is the rate-determining step because it has the smallest rate constant among the possible reactions pathways. [ABSTRACT FROM AUTHOR]

The electronic properties, structural stability and nitric oxide (NO) adsorption characteristics on pristine, Al and P substituted silicene nanosheet are studied using density functional theory with B3LYP/LanL2DZ basis set. The structural stability of silicene nanostructure is discussed in terms of formation energy. The formation energy, dipole moment, point symmetry, ionization potential and electron affinity of silicene nanosheet are reported. The adsorption characteristics of NO on silicene nanosheet are explored in terms of adsorption energy, energy gap and Mulliken charge transfer. The favorable adsorption site of NO on silicene nanosheet is identified and reported. From the observations, it is inferred that the adsorption characteristics of NO are prominent on pristine and P substituted silicene nanosheet. [ABSTRACT FROM AUTHOR]

The structural and electronic properties of platinum atom adsorbed on periodic graphene nanobuds (PGNBs) have been investigated and compared with graphene by means of density functional theory (DFT) calculations. Our result based on the generalized gradient approximation has been validated by the state-of-the-art B3LYP level of theory for Pt adsorption on the graphene surface. We demonstrate that the bridge site over the C–C bond center intervening between two hexagonal rings of type I PGNB and the hollow site over the nonagonal ring center of type II PGNB serve as the most thermodynamically favorable states amongst several considering starting configurations. The binding energies of about −3.34 and −3.78 eV were obtained for I PGNB and II PGNB, respectively, within the BSSE corrections, which are more stronger than the Pt binding energy of −2.12 eV for a pure graphene. The electronic structures for the most favorite configurations of Pt atom adsorbed on the systems of interest, in terms of the Mulliken population, the electronic density of states (DOS), and the projected density of states (PDOS) analysis have been discussed. The stability of the Pt–PGNBs and Pt–graphene complexes was confirmed within ab initio molecular dynamics simulation carrying out at ambient temperature. We also indicate that oxygen binding energies at the most energetically favorable configurations on the Pt–PGNB I and Pt–PGNB II complexes are weaker than the O 2 binding energy on a Pt–graphene complex. The very desirable Pt binding energy obtained accompanied by high specific surface area (because of fastened C 60 molecules) and relatively weaker O 2 binding energy of PGNBs compared with the pristine graphene lead to experimentally apprehend these novel hybrid nanostructured materials as a superior media for Pt adsorption. Our study recommends possible avenues for intensification the stability and electro-catalytic activity of platinum atoms on PGNB surfaces through hybrid engineering. [ABSTRACT FROM AUTHOR]

In the current study, the sand collected from a specific location called Ruba Al-Khali in Saudi Arabia has been identified and efficiently used for the removal of dye contaminate through adsorption process. It was found that the crystalline SiO (including quartz and cristobalite SiO) is the major component in the micrometer-sized sand adsorbent with lava-like rough surface. Batch adsorption experiments were investigated and discussed by using Rhodamine B (RhB) as the model toxic contaminant. The adsorption of RhB with the exothermic nature is considered to be more favorably by the pseudo-second-order model. The corresponding adsorption capacity at room temperature is examined at around 2.94 mg g by Langmuir fitting. Furthermore, the effects of empty bed contact time, initial concentration, and the pH value of RhB solution on the breakthrough point in the column adsorption process were investigated. [ABSTRACT FROM AUTHOR]

It was developed the technology of manufacturing planar betavoltaic converter based on silicon, providing a higher rate of conversion of ionizing radiation into electrical energy by reducing reverse currents. The active region of silicon p-i-n structure is 1 cm2, which is irradiated by the of radionuclide 63Ni with the activity 2,7 mCi/cm2. The results of experimental studies of C-V samples are presented. The values of the open-circuit voltage (Vsc) 0.111 V are presented and short circuit current density (Jsc) 27 nA/cm2. The maximum density of output power (Pmax) was 1.52 nW/cm2. [ABSTRACT FROM AUTHOR]

In this study we investigate the efficacy of iron gettering as a function of electrically inactive phosphorus in the emitter in combination with low temperature annealing steps. To achieve different amounts of electrically inactive phosphorus in the emitter a highly doped PSG produced emitter with a large plateau depth of electrical active phosphorus is etched back stepwise by a wet-chemical procedure. Therewith we achieve a gradual reduction in electrically inactive phosphorus with small changes in electrically active phosphorus (ΔR sh < 4 Ω/sq). After this step, the wafers with different emitters have been annealed at 700 °C for 30 min and the content of Fe i in the bulk has been measured using QSS-PC. The results show, (i) that for higher amounts of electrically inactive phosphorusa stronger iron gettering effect can be observed and (ii) that an additional annealing step leads to a significant change of Fe i . This means, (i) that anelectricallyinactive phosphorus concentration dependence for iron gettering is observed and (ii) additional annealing steps, below the usual diffusion temperature of phosphorus, can be used to reduce interstitial iron in highly contaminated wafers further. [ABSTRACT FROM AUTHOR]

In this work we describe a technique, namely Saw Damage Gettering (SDG),which improves the lifetime of highly contaminated multi-crystal silicon wafers. The wafers to which it is applied are from the top and bottom of ingots, the so called “red zones” of ingots. Such wafers are currently discarded before processing due to high impurity levels which result in low efficiency cells. SDG entails an extra annealing step before the saw damage is removed by etching. The effect of the anneal is to dissolve metallic precipitates present in the material after casting. On subsequent cooling precipitates are preferentially nucleated in the high defect density regions associated with saw damage at the surfaces of the wafer so leaving the concentration of impurities in the bulk of the material significantly reduced. The anneal conditions, typically ∼850 o C for ∼20 minutes, are chosen so that the majority of metal precipitates dissolve. The cooling step, taking ∼ 30 minutes, is such that the impurities have sufficient opportunity to diffuse from the center of the wafer to the damaged regions at the edges. This processing is found to improve carrier lifetimes by up to a factor of 4. This enhancement may be sufficient to enable red-zone wafers to be processed in the same manner as other, higher quality, mc-Si wafers without sacrificing cell efficiency. SDG is expected to be cost effective and easily incorporated into current cell processing procedures. [ABSTRACT FROM AUTHOR]

In this study we investigate the efficacy of iron gettering as a function of electrically inactive phosphorus in the emitter in combination with low temperature annealing steps. To achieve different amounts of electrically inactive phosphorus in the emitter a highly doped PSG produced emitter with a large plateau depth of electrical active phosphorus is etched back stepwise by a wet-chemical procedure. Therewith we achieve a gradual reduction in electrically inactive phosphorus with small changes in electrically active phosphorus (ΔRsh < 4 Ω/sq). After this step, the wafers with different emitters have been annealed at 700°C for 30 min and the content of Fei in the bulk has been measured using QSS-PC. The results show, (i) that for higher amounts of electrically inactive phosphorus a stronger iron gettering effect can be observed and (ii) that an additional annealing step leads to a significant change of Fei. This means, (i) that an electrically inactive phosphorus concentration dependence for iron gettering is observed and (ii) additional annealing steps, below the usual diffusion temperature of phosphorus, can be used to reduce interstitial iron in highly contaminated wafers further. [ABSTRACT FROM AUTHOR]

Consecutive absorption/desorption cycles of the ZrCo–H2 system were studied to simulate the real International Thermonuclear Experimental Reactor (ITER) hydrogen getter system. A ZrCo getter was used in this paper instead of the depleted uranium (DU) getter material, which has been recently considered as the hydrogen getter in ITER. In a cyclic pressure-composition isotherm (PCI) measurement, the high-pressure Sievert apparatus seems impractical to describe the equilibrium state of the ZrCo–H2 system in detail, especially for the desorption stage. This high-pressure PCI apparatus, however, shows cause and effect well, from the previous getter state to the following state in presenting hydriding/dehydriding performance. In case of the ZrCo–H2 system or in case of the DU–H2 system having multiple getter bed battery, a similar affection by previous getter status might be related and a similar aspect could be shown to consider further ITER design; for example, a need for control logic from PCI measurements using a high-pressure Sievert apparatus. [ABSTRACT FROM PUBLISHER]

The article focuses on a study of metallothermic reduction in sintering's early stage due to gettering. Topics include use of internal getter effect to promote sintering, internal oxidation by addition of metal carriers contained with manganese and transfer of oxygen to stable formers of oxides due to iron oxides' reduction on surface. Also it mentions formation of methane by hydrogen's reaction with added carbon and base-powder oxides' metallothermic reduction by gaseous intermediate products.

Three-dimensional distribution of oxygen atoms at small-angle tilt boundaries (SATBs) in Czochralski-grown p-type silicon ingots was investigated by atom probe tomography combined with transmission electron microscopy. Oxygen gettering along edge dislocations composing SATBs, post crystal growth, was observed. The gettering ability of SATBs would depend both on the dislocation strain and on the dislocation density. Oxygen atoms would agglomerate in the atomic sites under the tensile hydrostatic stress larger than about 2.0GPa induced by the dislocations. It was suggested that the density of the atomic sites, depending on the tilt angle of SATBs, determined the gettering ability of SATBs. [ABSTRACT FROM AUTHOR]

This paper reports a novel and inherently simple fabrication process, so-called advanced MEMS (aMEMS) process, that is developed for high-yield and reliable manufacturing of wafer-level hermetic encapsulated MEMS devices. The process enables lead transfer using vertical feedthroughs formed on an Silicon-On-Insulator (SOI) wafer without requiring any complex via-refill or trench-refill processes. It requires only seven masks to fabricate the hermetically capped sensors with an experimentally verified process yield of above 80%. Hermetic encapsulation is achieved by Au–Si eutectic bonding at 400 °C, and the pressure inside the encapsulated cavity has been characterized to be as low as 1 mTorr with successfully activated thin-film getters. The pressure inside the encapsulated cavity can also be adjusted in the range of 1 mTorr-5 Torr by various combinations of outgassing and gettering options in order to satisfy the requirements of different applications. The package pressure is being monitored for the selected chips and is observed to be stable below 10 mTorr since their fabrication about 10 months ago. The shear strengths of several packages are measured to be as high as 30 MPa with average shear strength of 22 MPa, indicating a mechanically strong bonding. The robustness of the packages is tested by thermal cycling between 100 °C and 25 °C, and absolutely no degradation is observed in the hermeticity and the package pressure. The package pressure is also verified to remain unchanged after storing the packages at a high storage temperature of 150 °C for 24 h. Furthermore, the packaged chips are observed to withstand a high temperature shock test performed at 300 °C for 5 min, at the end of which the characteristics of the encapsulated sensor indicates that the package still remains hermetic (no detectable leaks) and also the package pressure remains constant at $\sim 20$ mTorr. [2014-0338] [ABSTRACT FROM AUTHOR]

The polyelectrolyte adsorption on colloid particles is often used for stabilization or flocculation of water suspensions. The aim of this work is to study the adsorption of carboxymethyl cellulose (CMC) on alumina ( γ -Al 2 O 3 ) colloid particles. The particles and polymer are chosen because of the capability of the metal-oxide ampholyte surface and the weak polyelectrolytes to alter their charge by pH. The measurements are done at pH 6.0 where the CMC carboxylic gropes are almost fully dissociated and the alumina surface is positively charged. The high linear charge density of the polyelectrolyte chain provides Na + counterions condensation on the COO − groups. The main employed method is the electric light scattering based on particle orientation in sinusoidal electric field. The electric polarizability and the relaxation time after field switching off (both depending on the particle charge and size) are used as criteria for polymer adsorption and particle aggregation. Micro-electrophoresis is applied as additional techniques indicating the sign and density of the surface charge. The results obtained give the conditions (time dependence, particle and polymer concentrations) where the CMC adsorption is complete and the suspension is stable. [ABSTRACT FROM AUTHOR]

Impurities and defects are of significant interest in multicrystalline silicon, due to the detrimental effect they can have on carrier lifetimes and electrical properties. In view of that, it is important to incorporate certain processing steps to decrease the recombination activities. In this study, a novel experiment was applied as a beneficial approach to improve the electronic quality of low-resistivity mc-Si substrates via a two-step process. Initially, the first step involves gettering multicrystalline substrates using sacrificial porous silicon layer on both sides, which was introduced as a simple sequence for efficient extrinsic gettering schemes. The gettering experiment was performed at 600–900 °C, and optimum results were obtained at 900 °C. Then, the second step involves coating the front surface of gettered mc-Si at 900 °C with vanadium oxide that serves as an excellent antireflection layer and leads to improve furthermore the electrical properties. Significant improvements were obtained after the deposition of vanadium oxide antireflection coating, in view of the fact that gettered mc-Si substrate at 900 °C provides the highest minority carrier lifetime and the lowest effective surface recombination velocity. An overall increase of the electrical properties was obtained after the described two-step process. The conversion efficiency increases from 6% (reference) and reached 13.7%. [ABSTRACT FROM AUTHOR]

Activated carbons are widely applicable in industrial adsorption processes. However, characterization of their surface properties is problematic due to the number of different source materials and variations in production processes. Here, a model of the carbon surface derived that is based on the knowledge of fundamental molecular interactions on carbon surfaces. Adsorption isotherms of selected probe molecules are measured on different activated carbons and discussed how the model can be applied in the characterization of the surface properties of activated carbons. [ABSTRACT FROM AUTHOR]

A simple and highly selective chromatographic separation method named high temperature size exclusion–liquid adsorption chromatography (SEC–LAC) was developed for the separation of the parent isotactic polypropylene (iPP) homopolymer from either segmented or random ethylene-propylene copolymers (EPCs). The compositions of the adsorption promoting and desorption promoting solvents were carefully optimized, so that an intermediate elution mode between total liquid adsorption (LAC) and liquid chromatography at critical conditions (LCCC) of iPP was established. At the same time selectivity in the separation of PPs of different tacticity was not altered. This was encouraging and showed that this approach should be applicable across samples of different stereoregularity. The main advantage of the SEC–LAC method over LAC methods is the completely independent first step SEC analysis of the iPP homopolymers and the subsequent LAC analysis of all other olefin homopolymers and copolymers over a wide range of chemical compositions. Therefore, SEC–LAC combination can overcome the major drawbacks in LAC such as loss of separation selectivity depending on the molar masses of iPP homopolymers. In this way, the present study clearly proves that this separation protocol can discriminate the molar mass heterogeneity of iPP homopolymers present in complex EP copolymer systems without using multidimensional analytical approaches such as high temperature two-dimensional liquid chromatography (HT-2D LC). FTIR measurements were performed to obtain structural information on the separated components for the proper understanding of the separation mechanism. In conclusion, this study clearly shows that SEC–LAC coupled to FTIR is a powerful analytical method that is ideal for quantifying small amounts of iPP homopolymer contaminations in propylene/α-olefin copolymers and other multicomponent polyolefin blends. [ABSTRACT FROM AUTHOR]

This paper investigates the adsorption behaviour of sulfate on calcium-silicate-hydrate (C-S-H) gel, which is significantly related to cement hydration and delayed ettringite formation. Aqueous sulfate solution from cement paste and prepared calcium-silicate-hydrate samples are used to take other ions and cement hydration into account. The effects of gypsum content, temperature and alkalinity on dissolution and adsorption behaviours of sulfate in cement paste are studied. The results show that higher gypsum content leads to more sulfate ions adsorbed on samples. Sulfate adsorption on calcium-silicate-hydrate samples increases with temperature elevation, which is in agreement with both Divet's and Škapa's results, which used relatively simple calcium-silicate-hydrate-sulfates systems. Higher alkalinity is unfavourable for sulfate ions adsorbed on calcium-silicate-hydrate samples. An alternative opinion was given by Divet and Randriambololona whose result is complex and not representative owing to the adsorption behaviour of sodium ions being neglected. [ABSTRACT FROM AUTHOR]