Adsorption Of Hydrogen Cyanide Research Articles

Quality Improvement of Kesambi-Seed Oil using Free Fatty Acids and Hydrogen Cyanide Adsorption

Kesambi-seed (Schleichera oleosa) is an Indonesian potential feedstock to produce vegetable oil for energy resources and oleochemicals. Crude Kesambi-seed oil (KSO) contains 8.43% free fatty acids (FFA) and 128 ppm hydrogen cyanide (HCN), which exceeds the Indonesian National Standard (SNI) for refined oil. Purification process is needed for crude KSO to be high quality vegetable oil. This study aimed to improve the quality of KSO by reducing the FFA and HCN contents using adsorption. The adsorption equilibrium is also determined to obtain the equilibrium constants. The purification process was developed in 2 steps, i.e., degumming and adsorption. Degumming was developed using 2.5% v/v H3PO4 to separate phospholipids/phosphatides in the crude oil, while adsorption using activated carbon was introduced to reduce the FFA and HCN contents. Kesambi-seed oil purification using activated carbon adsorption could be used as one-step refining for bleaching and reducing FFA and HCN. More adsorbent is needed to reach the FFA standard for the shorter adsorption time. Adsorption using 10% activated carbon for 24 hours reduced hydrogen cyanide up to 36 mg/kg oil, lightened the oil color, and achieved the highest yield (74.62%). Meanwhile, the activated carbon concentration of 40% w/w for 96 hours obtained 0.16% FFA. All three parameters have fulfilled the Indonesian National Standard for refined vegetable oil. Furthermore, the Freundlich model best fits equilibrium adsorption of FFA in the KSO.

An ab-initio investigation of transition metal-doped graphene quantum dots for the adsorption of hazardous CO2, H2S, HCN, and CNCl molecules

The quantum confinement and size effects make graphene quantum dots (GQDs) remarkable candidates for sensing applications. Gas molecules can easily be adsorbed on GQDs because of their large specific areas and exposed edges. This computational work concerns the adsorption performance of pristine and transition metal [chromium (Cr) or nickel (Ni)]-doped coronene GQD to hazardous gases carbon dioxide (CO2), hydrogen sulfide (H2S), hydrogen cyanide (HCN), and cyanogen chloride (CNCl), along with structural properties such as bond length and angle, electronic properties including molecular orbital analysis, natural bond orbital and Mulliken charge analysis, spectroscopic properties of infrared and ultraviolet spectra, quantum theory of atoms in molecules with non-covalent interaction analysis, and sensing properties of recovery time, work function, and sensing response. As pristine GQDs show poor gas adsorption, doping with Cr and Ni enhance performance. The results of Cr-doped coronene GQD indicate that the gas molecules have strong interaction with GQDs as the computed adsorption energies are highly negative (−3.56, −3.81, −4.02, and −4.81 eV). Since the computed recovery times are extremely long, the Cr-doped GQDs can be used as removers of CO2, H2S, HCN, and CNCl gas molecules from specific environments. In the case of Ni-doped GQDs, only the interaction with CNCl yields chemisorption, with adsorption energy of −0.83 eV. However, the short recovery time (9.36 ms–93.6 s) indicates its potential candidature as a CNCl sensor.

Enhancing catalytic hydrolysis activity of ZnNiAl hydrotalcite-like compounds-derived oxides using rare earth metals

Efficient catalysts are highly desirable for the simultaneous removal of hydrogen cyanide (HCN) and carbonyl sulfide (COS) to meet the increasingly stringent emission standards and achieve cleaner production. In this study, ZnNiAl hydrotalcite-like compounds (HTLCs)-derived oxides doped with a series of rare earth metals, such as cerium (Ce), gadolinium (Gd), and yttrium (Y), were synthesized and used for the simultaneous hydrolysis of HCN and COS. The results demonstrated that the chemical state and electronic structure of ZiNiAl were changed by Ce doping because of the incorporation of Ce into the nickel oxide (NiO) network. Thus, abundant active species for the adsorption and dissociation of HCN and COS, including chemically adsorbed oxygen and strong basic sites, were produced by Ce doping. Meanwhile, the well-developed mesoporous structure provided accessibility to the active sites. As a result, Ce doping significantly enhanced the catalytic performance of ZnNiAl. Furthermore, the mechanisms of HCN and COS hydrolysis over Ce-ZnNiAl and their deactivation were proposed. This study provides a novel route for efficiently eliminating HCN and COS in diverse industrial processes.

Adsorption of HCN on cosmic silicates: a periodic quantum mechanical study.

Hydrogen cyanide (HCN) represents a small but widely distributed fraction of the interstellar molecules, and it has been observed in all the environments characterizing the formation of a new planetary system. HCN can polymerize to form biomolecules, including adenine (H5C5N5), and it has drawn attention as a possible precursor of several building blocks of life due to the presence of its polymerization products in meteorites, comets and other asteroidal bodies. To elucidate the potential catalytic role that cosmic silicates have played in these processes, we have investigated, at DFT-PBE level inclusive of a posteriori dispersion correction, the energetic and spectroscopic features of the adsorption of HCN molecules on the most relevant crystalline surfaces of the mineral forsterite (Mg2SiO4), a common silicate constituent of the interstellar core grains and planetary rocky bodies. The results reveal that HCN adsorbs both in molecular and dissociative ways, within a wide range of adsorption energies (-29.4 to -466.4 kJ mol-1). Thermodynamic and kinetic results show that dissociative adsorption is dominant already at low temperatures, a fact particularly relevant at the protoplanetary conditions (i.e., the latest stages in the star system formation process). The simulated spectroscopic features of the studied adducts show a wide range of different degrees of perturbation of C-H and CN bonds. This finding agrees with previous experimental works, and our results confirm that a complex chemistry is observed when this astrochemically-relevant molecule interacts with Mg2SiO4, which may be associated with a considerable potential reactivity towards the formation of relevant prebiotic compounds.

A theoretical study of HCN adsorption and width effect on co-doped armchair graphene nanoribbon

Hydrogen cyanide (HCN) is one of the hazardous gas and requires sensitive detection material. In the present work stable structures, adsorption analysis, charge transfer and electronic properties of defective, pristine, Phosphorus doped, Boron doped and Boron Phosphorus co-doped ArGNRs are studied using first principles calculations combined with Density functional theory (DFT). In two models of ArGNRs with N = 6 and N = 8 atoms along width, it is observed that pristine ArGNR is not a good sensing material for HCN molecule however, on introducing defects and dopants its sensitivity drastically increases and results in chemisorption for all models of ArGNRs. Different doping site optimizations for all models of ArGNR are observed which reveal that defective, Phosphorous doped, Boron-Phosphorus co-doped ArGNR with width N = 6 shows higher negative value of adsorption energy with adsorption energy values are −5.81 eV, −1.27 eV and −1.06 eV. Band nature predicts that for BP-ArGNR with N = 6 shows large reduction as compared to co-doped system of N = 8 model system. A remarkable charge transfer occurs between the HCN molecule and BP-ArGNR as proved by the electronic charge densities. DOS analysis predicts that the defective, phosphorus doped and boron-phosphorus co-doped ArGNRs are good sensing materials with intense peaks after adsorption of cyanide molecule as compared to pristine ArGNR for N = 6 model system. This implies that defective, Phosphorus and B, P co-doped ArGNR with N = 6 has high sensitivity to cyanide molecule as compared to N = 8 model system. Results of our simulated work are not only helpful to evaluate sensing mechanism but also provide a potential sensor material detection of HCN.

Adsorption of HCN on pristine and Al/Si/P decorated C18 nanocluster: A first principles study

Hydrogen cyanide (HCN) is a poisonous compound that is likely to be found in a gaseous form due to its high volatility. Therefore, its tracing is necessary. Here, we have studied adsorption properties of C18 nanocluster towards HCN molecule. Pristine C18 towards HCN yields negligible adsorption energy and large adsorption distance. For enhancement of interaction between HCN and C18, we have decorated Al, Si, P atoms on C18 nanocluster. After the decoration, we found that C18Al nanocluster is most suitable candidate for HCN sensor due to optimal adsorption energy (-0.61 eV), adsorption distance (2.11 Å), and recovery time (17.7 ms).

Understanding the effect of CaO on HCN conversion and NOx formation during the circulating fluidized combustion process using DFT calculations

Hydrogen cyanide (HCN) is an important intermediate during the conversion of fuel nitrogen to NOx. The mechanism of HCN oxidation to NO, N2, and N2O on the CaO (100) surface model was investigated using density functional theory calculations to elucidate the effect of in-furnace SOx removal on HCN oxidation in circulating fluidized bed boilers. HCN adsorption on the CaO (100) surface releases as high as 1.396 eV and the HC bond is strongly activated. The CaO (100) surface could catalyze the oxidation of CN radical to NCO with the energy barrier decreasing from 1.560 eV for the homogeneous case to 0.766 eV on the CaO (100) surface. The succeeding oxidation of NCO by O2 forming NO is catalyzed by the CaO (100) surface with the energy barrier decreasing from 0.349 eV (homogeneous process) to 0.026 eV on the CaO (100) surface, while the reaction between NCO and NO forming either NO or N2 is prohibited in comparison with corresponding homogeneous routes. The rate constants of these reactions under fluidized bed combustion temperature range are provided, and the calculation results lead to the conclusion that CaO (100) surface catalyzes the HCN conversion and improves the NO selectivity during HCN oxidation in the HCN/O2/NO atmosphere, which could well explain previous experimental observations. Kinetic parameters of HCN oxidation on the CaO (100) surface are provided in the Arrhenius form for future kinetic model development.

First-principles study on the adsorption of hydrogen cyanide on the metal-doped (8, 0) boron nitride nanotubes

In this paper, the adsorption of Hydrogen cyanide (HCN) molecules on metal-doped boron nitride nanotube (BNNT) is studied by using density functional theory (DFT) method. Our calculations indicate that the adsorption energy corresponding to this structure increases greatly. In addition, metal doping changes the charge distribution of the BNNT, which results in various hybrid orbitals. The frontier orbital function distribution of this configuration also changes from being uniformly distributed in the tube to being substantially concentrated around the metal atoms and HCN molecules. The results of this series of studies provide new possibilities for HCN sensor research.

Density functional theory evaluation of pristine and BN-doped biphenylene nanosheets to detect HCN.

Hydrogen cyanide (HCN) adsorption on pristine and B-N doped biphenylene nanosheets was investigated by means of density functional theory calculations. According to biphenylene geometry, all distinct possible B-N substitutions were designed. Adsorption energy and electronic structure at the level of M062X/6-31g (d,p) theory were computed for all possible geometries. Our results reveal that pristine biphenylene nanosheet is not a suitable candidate for HCN detection. Also, for B-N doping, the sensitivity of the nanosheet depends on the B-N doped configuration. One of these derivative structures shows higher sensitivity to HCN adsorption due to the greater change in electronic properties. Moreover, atoms in molecules and natural bond orbital analysis were performed to obtain more in-depth knowledge about the adsorption mechanism. The range of energy for interaction between HCN and the nanosheets belongs to physical adsorption.

Exploring adsorption mechanism of hydrogen cyanide and cyanogen chloride molecules on arsenene nanoribbon from first-principles

The SIESTA package is employed in examining the electronic and adsorption features of the toxic asphyxiants hydrogen cyanide (HCN) and cyanogen chloride (NCCl) on armchair arsenene (As-arm) nanoribbon. Based on the generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) level of theory, we explored the adsorption of HCN and NCCl on As-arm nanoribbon. The significant parameters necessary to validate the electronic and stable nature of As-arm nanoribbon are computed with the help of formation energy and energy gap change. The density of states (DOS) spectrum and the energy band structure are figured-out for both isolated and asphyxiants adsorbed As-arm nanoribbon, which affirms the transfer of electrons taking place between As-arm nanoribbon and the asphyxiants. Also, surface assimilating properties like Bader charge transfer, average energy gap variation, and adsorption energy are calculated for the asphyxiants adsorbed As-arm nanoribbon. Moreover, the comparison is made between the electron density of isolated and asphyxiants adsorbed As-arm nanoribbon to enunciate the utilization of As-arm nanoribbon as a chemisensor for detecting the asphyxiants HCN and NCCl molecules.

Adsorption of HCN from Pyrolysis of Tobacco Leaves with Na<i>2</i>CO<i>3</i>, NaHCO<i>3</i>, and Proline

Hydrogen cyanide (HCN) was produced by flameless combustion of dried tobacco leaves for investigating the adsorption on Na2CO3, NaHCO3 and proline (HNC4H7COOH). The concentration of HCN could be produced steadily at 0.73 mg/dm3. For the given 245 cm3 of smoke with the flow rate of 17.5 cm3/s, the efficiency of adsorption of HCN was improved to 80% by the addition of the optimal amounts of Na2CO3, NaHCO3 and proline (HNC4H7COOH), which were 10, 20, and 30 mg respectively. In the circumstances, the breakthrough concentration was reduced to 0.15 - 0.20 mg/dm3.

Assessment of DFT Calculations and Molecular Dynamics Simulation on the Application of Zinc Oxide Nanotube as Hydrogen Cyanide Gas Sensor

In this study, to providing the valuable insights into the develop a novel gas sensor for the detection of hydrogen cyanide (HCN), we have employed the molecular dynamics simulation in order to examine the adsorption of carbon monoxide (CO), nitrous oxide (N2O), nitrogen (N2) and HCN gas molecules on the surface of zinc oxide nanotube (ZnONT). More tendencies of the HCN molecules for the adsorption on the nanotube surface contrary to the other considered gases in the simulation study indicate that ZnONT can be a suitable sensor for the HCN gas molecule. Moreover, the detailed studies about the effect of the HCN adsorption on the electronic properties of ZnONT are performed by the density functional theory (DFT) calculation. The negative values of the adsorption energies (Eads) and the small transferred charge from ZnONT to the gas molecule indicate that the adsorption of the HCN gas on the surface of the nanotube is weak. The atom in molecules (AIM) analysis reveals the partially covalent nature of the intermolecular interaction between HCN gas molecule and the nanotube.

FIRST PRINCIPLES STUDY OF HCN ADSORPTION ON GRAPHENE DOPED WITH 5D TRANSITION METAL

Hydrogen cyanide (HCN) adsorption on graphene doped with 5d transition metal (TM) is investigated by the first principles based on density functional theory. It is observed that Hg atom cannot be doped into graphene due to saturated valence electron configurations of 5d106s2. Three kinds of HCN adsorption configurations are investigated, in which H, C and N in HCN are close to the adsorption site, respectively. The most stable adsorption configuration is obtained by total energy optimization. HCN adsorption can be studied by adsorption energy and electron density difference. HCN can only be physisorbed on Ir, Pt and Au-doped graphenes, while chemisorption is observed for Lu, Hf, Ta, W, Re and Os-doped graphenes. The band structure is calculated by B3LYP and Generalized gradient approximation (GGA) functionals. It is observed from B3LYP method that the conductivity of Lu, Hf, Re and Os-doped graphenes does not obviously change before and after HCN adsorption. Ta and W-doped graphenes change from semiconductor to metal after adsorption of HCN molecule. The results indicate that Ta and W-doped graphenes may be a promising sensor for detecting HCN. This study provides a useful basis for understanding of a wide variety of physical properties on graphene.

First-principles study of terpyrrole as a potential hydrogen cyanide sensor: DFT calculations.

The sensitivity of terpyrrole (TPy; used as a polypyrrole model) to toxic hydrogen cyanide (HCN) adsorption was studied by using DFT to perform geometry optimization and to calculate the adsorption energy of HCN on TPy as well as orbital properties. The interaction of terpyrrole with HCN was studied for different relative orientations of the molecules. The adsorption energy, charge analysis, and the density of states were used to evaluate the ability of TPy to sense HCN in these different relative orientations. The adsorption energy was calculated to be -3.9 and -3.1 kcal mol(-1) for two possible relative orientations. Frontier molecular orbitals and energies indicated that some hybridization occurs during the adsorption of HCN on TPy when the molecules have appropriate relative orientations, resulting in an increase in conductivity. Considering the changes in the HOMO-LUMO energy gap that were calculated to occur during HCN adsorption, it is clear that TPy is sensitive to HCN adsorption, suggesting that TPy has the potential to act as an HCN sensor. Graphical abstract HCN adsorption on TPy.

Novel activated carbon fiber cloth filter with functionalized silica nanoparticles for adsorption of toxic industrial chemicals

Toxic industrial chemicals (TICs) are used for various civilian and military operations but can be hazardous to humans. There is interest in developing filters that can remove a wide range of airborne TICs (e.g., basic, acidic, organophosphate, and aromatic compounds) to reduce exposure in the work place and from terrorist attacks. A regenerable TIC air filter is particularly desirable because it removes the need for costly filter disposal and replacement. This study evaluates commercially available activated carbon fiber cloth (ACFC) and ACFC that has been modified with functionalized nanoparticles for their abilities to adsorb select TICs and for the regenerability of the adsorbents. The unmodified and modified ACFC samples were tested here for their ability to adsorb anhydrous ammonia (NH3), hydrogen cyanide (HCN), and dimethyl methylphosphonate (DMMP) in dry and humid gas streams as representative basic, acidic, and organophosphate compounds, respectively. The unmodified ACFC was not an effective adsorbent for NH3 (i.e., 2 and 3.1 mg NH3/g ACFC at 1000 ppmv NH3 in dry and humid air respectively) or HCN (no detectable adsorption), but successfully adsorbed 840 mg DMMP/g ACFC at 100 ppmv DMMP. The modified ACFC showed significant improvements for NH3 and HCN adsorption in dried air (i.e., 19.5 mg NH3/g ACFC at 1000 ppmv NH3 and 4.7 mg HCN/g ACFC at 150 ppmv HCN, respectively) and in humid air (i.e., 41.4 mg NH3/g ACFC at 1000 ppmv NH3 and 1.6 mg HCN/g ACFC at 50 ppmv HCN, respectively) when compared to the unmodified sample. The modified ACFC also showed 2–5 % degradation of its initial dry mass after regeneration and then showed no detectable degradation. The modified ACFC also had similar electrical resistance to that of unmodified ACFC (i.e., within 1 %), indicating that it can be regenerated using electrothermal heating.

Adsorption of HCN onto sodium montmorillonite dependent on the pH as a component to chemical evolution

AbstractThe aim of this work is to study the behaviour of hydrogen cyanide (HCN) adsorbed onto mineral surfaces (sodium montmorillonite, a clay mineral) in different pH environments as a possible prebiotic process for complexation of organics. Our experimental results show that specific sites on the surface of the clay increased the concentration of HCN molecules dependent on the pH values. Moreover, this adsorption can occur through physical and chemical interactions enhanced by the channel structure of the sodium montmorillonite. The three-dimensional channelling structure of the clay accumulates the organics, hindering the releasing (desorption) of the organic molecules. A molecular model developed here also confirms the role of the pH as a regulating factor in the adsorption of HCN onto the inorganic surfaces and the possibility for further reactions forming more complex molecules, as an abiotic mechanism important in prebiotic chemical evolution processes.

Metal loaded zeolite adsorbents for hydrogen cyanide removal

Metal (Cu, Co, or Zn) loaded ZSM-5 and Y zeolite adsorbents were prepared for the adsorption of hydrogen cyanide (HCN) toxic gas. The results showed that the HCN breakthrough capacity was enhanced significantly when zeolites were loaded with Cu. The physical and chemical properties of the adsorbents that influence the HCN adsorption capacity were analyzed. The maximal HCN breakthrough capacities were about the same for both zeolites at 2.2 mol of HCN/mol of Cu. The Cu2p XPS spectra showed that the possible species present were Cu2O and CuO. The Nls XPS data and FT-IR spectra indicated that CN− would be formed in the presence of Cu+/Cu2+ and oxygen gas, and the reaction product could be adsorbed onto Cu/ZSM-5 zeolite more easily than HCN.

A molecular simulation approach to the study of adsorption of hydrogen cyanide and methyl ethyl ketone in silicalite, mordenite and zeolite beta structures

In the present research study the primary aim is to understand and characterize the physical adsorption of polar molecules such as hydrogen cyanide (HCN) and methyl ethyl ketone (MEK), in silicalite-1, mordenite, and zeolite beta structures through detailed Monte-Carlo simulation studies. The sorption capacity and affinity of the different zeolites is compared by simulating single component isotherms for different Si/Al ratios at 298 K. It was found that the number of the Na+ cations has an important effect on adsorption characteristics at lower pressures. In particular, within the range of [Na+] studied, the adsorption capacity of these zeolites was found to be independent of the [Na+], except in the case of zeolite beta. Furthermore, the MEK sorption capacity of zeolite beta was found to be the highest, followed by silicalite and mordenite respectively. The HCN sorption capacity of silicalite was shown to be greater than mordenite due to the presence of the 10-membered ring channels of silicalite.

Infrared Spectroscopic Study of the Adsorption of HCN by γ-Al2O3: Competition with Triethylenediamine for Adsorption Sites

The adsorption and vibrational properties of chemisorbed HCN on Lewis acid sites, Lewis base sites, and Brønsted Al−OH acid sites on a partially hydroxylated γ-Al2O3 surface have been obtained by a combination of FTIR and density functional theory studies. The vibrational modes from the molecular and dissociative adsorption of HCN were assigned by using deuterium and 13C-labeled D13CN molecules at 170 K. In addition, η2(C, N)−HCN bonding is also found from the ν(CN) vibrational spectra. Good correlation of the calculated vibrational frequencies for the adsorbed species with experimental data is found. The effect of triethylenediamine (TEDA) (also called 1, 4-diazabicyclo [2.2.2]octane, DABCO) on the adsorption of hydrogen cyanide (HCN) on the high area γ-Al2O3 surface has been investigated using transmission FTIR spectroscopy. During HCN adsorption on TEDA-functionalized surfaces, there is no spectral change or emerging feature in either the TEDA or HCN spectral regions, indicating that no direct interaction occurs between these two molecules. Instead, we found that TEDA competes with HCN for the active sites on γ-Al2O3. The observed ν(C⋮N) mode on a TEDA-precovered surface is due to the HCN adsorption on Lewis base sites (Al−O−Al) which are less affected by TEDA preadsorption.

Hydrogen cyanide adsorption on the palladium(111) surface: surface temperature and coverage dependence

Etude de l'adsorption, de la dissociation et de la recombinaison de HCN sur une surface de Pd(111), entre 87 et 1000 K