Phosphine Adsorption Research Articles

Phosphine Sorption on Paddy Rice: Effects on Fumigation and Grain Quality Parameters.

During storage, infestation by insect pests occurs, causing quantitative and qualitative losses in grains, which requires the control of these insects with phosphine gas. Rice husk has a high phosphine adsorption capacity, influencing the gas concentration during fumigation and potentially leading to inefficient fumigation. Additionally, the high sorption of rice husk results in a higher residue of phosphine in the grain. Therefore, the objective of this study was to evaluate the phosphine sorption and phosphine residue in rice husk, paddy rice, and brown rice, as well as the industrial quality (head rice yield, rehydration capacity, cooking time, colorimetric profile) of brown and white rice during storage. To achieve this, fumigation of paddy rice, brown rice, and rice husks with 3.0 g·m-3 of phosphine was carried out for 240 h (recommended duration in the industry). A high sorption rate was observed in the rice husk (94.77%), paddy rice (97.61%), and, lastly, brown rice (35.17%). Due to the high sorption rate, only brown rice maintained a concentration above the recommended level for effective pest control (400 ppm for 120 h). Higher phosphine residues than permitted were observed in the rice husk (0.25 ppm). Lower rice head yields were observed in non-fumigated rice samples when analyzing the brown rice samples (66.21% for paddy rice and 65.01% for brown rice). A greater rehydration capacity was observed in fumigated samples at the beginning of storage when analyzing the brown rice samples (1.21 for paddy rice, 1.23 for brown rice), reducing the cooking time (24.00 for paddy rice, 23.80 for brown rice). More studies should be carried out to evaluate the effectiveness of fumigation on paddy rice, considering the high sorption rate of the paddy.

Theoretical investigation of gas sensing properties of a monolayer gallenene: First-principles insight

Two dimensional (2D) materials exhibit potential to be used in thin film electronic devices. In present paper, we explore 2D polymorphs of α-Ga by performing ab−initio calculations based on density functional theory. Phonon calculations show that Ga100 and Ga010 planes are dynamically stable at 6% and 2% bi-axial tensile strain. The ab-initio molecular dynamics calculations show that while Ga100 plane retain structural stability in a free standing state for temperature up to 500 K, Ga010 plane shows structure distortion which further increases with increase in temperature. We find total energy of Ga010 plane is smaller (−1.09 eV/f.u.) than Ga100 plane, indicating that Ga010 plane is energetically more stable. We next follow the adsorption of toxic gas molecule over Ga010 plane, referred as gallenene sheet. The negative adsorption energy shows that adsorption of phosgene (CCl2O), hydrogen cyanide (HCN), phosphine (PH3), and hydrogen selenide (H2Se) gas molecule over gallenene sheet is feasible. We find that (CCl2O) H2Se gas (weakly) strongly interact with gallenene with adsorption energy of (−0.39 eV) −0.52 eV. Bader charge calculation shows transfer of electronic charge between adsorbed gas molecule and gallenene sheet, which further confirmed by plot of electron localization function (ELF). The recovery time of desorption for CCl2O (PH3) gas comes 3.90×10−6 s (2.85×10−4 s) due to greater (smaller) out of plane distance of 2.93 Å (2.75 Å). The current–voltage (I–V) characteristic shows small deviation due to lower concentration of gases over gallenene, which further confirmed by transmission spectra. We hope that our theoretical predictions will help experimentalists to synthesize gallenene based gas sensors.

Sorption Kinetics and Equilibrium Isotherms of Phosphine Gas into Wheat Kernels

Highlights The pseudo-first order kinetic model fits well with the experimental data of sorbed phosphine versus time. Sorption isotherm curves were developed using Langmuir, Freundlich, and Redlich-Peterson models. Phosphine adsorption capacity of wheat kernels increased with increase in applied concentration (400-2400 ppm). Abstract. Phosphine (PH3) is the most used fumigant in the U.S. due to its low price, ease of use, and wide accessibility. With the growing concerns of phosphine-resistant insect pests, the sustainability of PH3 as an effective fumigant has been put at risk. Sorption equilibrium data is critical for improving the accuracy of modeling studies for phosphine-wheat fumigation systems and would clarify the PH3 uptake and sorption capacity of wheat. The objectives of this study were to determine the effect of initial concentration (from 400 to 2400 ppm) on the equilibrium concentration for PH3 in wheat kernels and on cumulative and daily PH3 sorption through time. Kinetic data showed the sorption process was time-dependent and occurred in two phases: an initial faster adsorption phase, followed by a phase with a slower sorption rate as the grain and PH3 reached equilibrium. Pseudo-first and pseudo-second order models were fit to PH3 concentrations versus time experimental data. The pseudo-first order model provided better equilibrium estimates and was used for the sorption isotherm analysis. Langmuir, Freundlich, and Redlich-Peterson sorption isotherm models were fit to the plot of equilibrium headspace gas concentration versus sorbed PH3 quantity. All three models had low standard errors of prediction (0.46-0.47). These PH3 sorption kinetics and values of total sorbed quantity at equilibrium are valuable for modeling the rate and maximum quantity of PH3 uptake in wheat. Keywords: Fumigation, Kinetics, Phosphine, Sorption Isotherm, Wheat.

Enhanced Atomic Precision Fabrication by Adsorption of Phosphine into Engineered Dangling Bonds on H-Si Using STM and DFT.

The doping of Si using the scanning probe hydrogen depassivation lithography technique has been shown to enable placing and positioning small numbers of P atoms with nanometer accuracy. Several groups have now used this capability to build devices that exhibit desired quantum behavior determined by their atomistic details. What remains elusive, however, is the ability to control the precise number of atoms placed at a chosen site with 100% yield, thereby limiting the complexity and degree of perfection achievable. As an important step toward precise control of dopant number, we explore the adsorption of the P precursor molecule, phosphine, into atomically perfect dangling bond patches of intentionally varied size consisting of three adjacent Si dimers along a dimer row, two adjacent dimers, and one single dimer. Using low temperature scanning tunneling microscopy, we identify the adsorption products by generating and comparing to a catalog of simulated images, explore atomic manipulation after adsorption in select cases, and follow up with incorporation of P into the substrate. For one-dimer patches, we demonstrate that manipulation of the adsorbed species leads to single P incorporation in 12 out of 12 attempts. Based on the observations made in this study, we propose this one-dimer patch method as a robust approach that can be used to fabricate devices where it is ensured that each site of interest has exactly one P atom.

Characterization of Metal Oxide-modified Walnut-shell Activated Carbon and Its Application for Phosphine Adsorption: Equilibrium, Regeneration, and Mechanism Studies

We prepared a kind of metal oxide-modified walnut-shell activated carbon (MWAC) by KOH chemical activation method and used for PH3 adsorption removal. Meanwhile, the PH3 adsorption equilibrium was investigated experimentally and fitted by the Toth equation, and the isosteric heat of PH3 adsorption was calculated by the Clausius-Clapeyron Equation. The exhausted MWAC was regenerated by water washing and air drying. Moreover, the properties of five different samples were characterized by N2 adsorption isotherm, SEM/EDS, XPS, and FTIR. The results showed that the maximum PH3 equilibrium adsorption capacity was 595.56 mg/g. The MWAC had an energetically heterogeneous surface due to values of isosteric heat of adsorption ranging from 43 to 90 kJ/mol. The regeneration method provided an effective way for both adsorption species recycling and exhausted carbon regeneration. The high removal efficiency and big equilibrium adsorption capacity for PH3 adsorption on the MWAC were related to its large surface area and high oxidation activity in PH3 adsorption-oxidation to H3PO4 and P2O5. Furthermore, a possible PH3 adsorption mechanism was proposed.

Adsorption of Phosphine on a BN Nanosurface

Electrical sensitivity of a Boron Nitride Nano Sheet (BNNS) to phosphine (PH3) molecule is studied using Density Functional Theory (DFT) calculations at the B3LYP/6-31G(d) level of theory. The adsorption energy (Ead) of phosphine on the surface of the pristine Nanosheet is about -678.96×1019eV. Pristine BNNS is a suitable adsorbent for phosphine and can be used in separation processes or adsorption of phosphine toxic gas from environmental systems. Consequently, BNNS is doped by Al atom and results show that the adsorption energy range is about - 28882.18×1019 to -52097.61×1019eV which means an increase in adsorption energy. Moreover, the HOMO/LUMO energy gap (Eg) reduces significantly. This reduction shows that the doped BNNS in the presence of phosphine is a suitable semiconductor and generates an electrical signal. Therefore, it can be used potentially as phosphine toxic gas detection sensors in environmental systems.

First-Principle Study of Phosphine Adsorption on Si(001)-2 × 1–Cl

This paper presents a DFT study for phosphine adsorption on a Si(001)-2$\times$1 surface covered by a chlorine monolayer, including adsorption on local defects, i.e. mono- and bivacancies in the adsorbate layer (Cl, Cl$_2$), and combined vacancies with removed silicon atoms (SiCl, SiCl$_2$). Activation barriers were found for the adsorbing PH$_3$ to dissociate into PH$_2$+H and PH+H$_2$ fragments; it was also established that phosphine dissociation on combined vacancies is possible at room temperature. If there is a silicon vacancy on the surface, phosphorus settles in the Si(001) lattice as PH (if the vacancy is SiCl) or as PH$_2$ (if the vacancy is SiCl$_2$). This paper suggests a method to plant a separate phosphorus atom into the silicon surface layer with atomic precision, using phosphine adsorption on defects specially created on a Si(001)-2$\times$1-Cl surface with an STM tip.

Ab Initio Screening of Metal Catecholates for Adsorption of Toxic Pnictogen Hydride Gases

Density functional theory was used to study interactions between phosphine and 17 functional groups, revealing that only the functional groups containing metal ions bind phosphine strongly. This led to a detailed examination of the adsorption of the pnictogen hydride gases ammonia, phosphine, and arsine on 33 metal catecholates in order to examine periodic trends in the binding strength for these adsorbates. Phosphine and arsine adsorption is primarily driven by donation of electron density from the adsorbate molecule to the metal atom, while ammonia binding involves both electron donation and a significant Coulomb attraction between the negatively charged N atom and the positive metal atom. This Coulomb effect results in notably different binding behavior for ammonia than for phosphine and arsine, which are quite similar to each other. Generally, for metals on the left side of the periodic table, the Coulomb effect dominates in ammonia adsorption, and metals on the right side of the periodic table have l...

Detection of Ammonia and Phosphine Gas using Heterojunction Biomolecular Chain with Multilayer GaAs Nanopore Electrode

This paper presents Density Functional Theory and Non-Equilibrium Green’s Function based First Principles calculations to explore the sensing property of Adenine and Thymine based hetero-junction chins for Ammonia and Phosphine gas molecules. This modeling and simulation technique plays an important and crucial role in the fast growing semiconductor based nanotechnology field. The hetero-junction chain has been passed through the multi layer GaAs nanopore electrodes. It has been found that Current-Voltage characteristics of the bio-molecular chain highly depend during the foreign gas molecules adsorption. This Current-Voltage sensitivity has been raised upto 40 and 9.3 times with the presence of single Ammonia and Phosphine molecules respectively under the ultra low bias voltage application. Adsorption of single molecule Ammonia and Phosphine increases the conductivity of the heterogeneous bio-molecular chain at room temperature. The quantum ballistic transmission through the direct band gap semi-conductor material GaAs nanopore increases during the Ammonia and Phosphine gas adsorption by the heterogeneous chain. In this paper we attempt to present the molecular model sensor with circuit elements. The attractive potential of conductivity modulation suggests this heterogeneous bio-molecular chain as an application in future generation bio-sensor technology.

Phosphine Gas Adsorption in a Series of Metal-Organic Frameworks.

For the first time, phosphine adsorption has been evaluated in a series of metal-organic frameworks (MOFs). Open-metal coordination sites were found to significantly enhance the ability of MOFs to adsorb highly toxic phosphine gas, with the identity of the open-metal site also modulating the amount of gas adsorbed. The MOFs studied outperform activated carbon, a commonly used material to capture phosphine.

Purification of yellow phosphorus tail gas for the removal of PH3 on the spot with flower-shaped CuO/AC

The morphology of CuO adsorbent plays an important role in phosphine adsorption for purifying yellow phosphorus tail gas.

Preparation and Phosphine Adsorption of Activated Carbon Prepared from Walnut Shells by KOH Chemical Activation

Walnut-shell activated carbons (WSACs) with high surface area and predominant micropore development were prepared by KOH chemical activation. The effects of carbonization temperature, activation temperature, and ratio of KOH to chars on the pore development of WSACs and PH3 adsorption performance of the modified walnut-shell activated carbons (MWSACs) were studied. Criteria for determining the optimum preparation conditions were pore development of WSACs and PH3 breakthrough adsorption capacity of MWSAC adsorbents. The result shows that the optimum preparation conditions are a carbonization temperature of 700°C, an activation temperature of 700°C, and a mass ratio of 3. The BET surface area and the micropore volume of the optimal WASC are 1636m2/g and 0.641cm3/g, respectively. The micropore volume percentage of WSAC plays an important role in PH3 adsorption when there is a slight difference in BET surface areas. High-surface-area WSACs with predominant micropores are suitable for PH3 adsorption removal. The MWSAC adsorbent owns the biggest PH3 breakthrough adsorption capacity (284.12mg/g) due to the biggest specific surface area, total pore volume, and micropore volume percentage. The MWSAC adsorbent will be a potential adsorbent for PH3 adsorption removal from yellow phosphorus tail gas.

An Effective Mitigation for Phosphine Present in Ammunition Container Assemblies and in Munitions Containing Red Phosphorus

AbstractA major issue associated with munitions containing red phosphorus is that, during storage, red phosphorus can react, in the presence of moisture and air, to form a mixture of corrosive phosphorus acids and the toxic gas phosphine. This has raised serious concerns relating to the health and safety of personnel handling these munitions. This paper details the studies undertaken to assess the suitability of a chemically impregnated activated carbon cloth (phosphine getter material – PGM) for the static adsorption of phosphine evolved from munitions containing red phosphorus and its effective mitigation of phosphine present in both ammunition container assemblies and within the main body of munitions of this type. Laboratory assessment of PGM was undertaken along with real‐life ammunition container assembly trials covering several munitions containing red phosphorus and accelerated ageing trials using modified countermeasure cartridges. Reaction products formed from the reaction of phosphine with chemical impregnates were studied using scanning electron microscopy (SEM) and energy dispersive X‐ray analysis (EDX). Aqueous extraction of the phosphine reacted PGM confirmed the presence of the acidic species orthophosphoric acid (H3PO4) and phosphorus acid (H3PO3).

Analysis of Adsorption Mechanism of Anti-Balling Additive for Drilling Engineering on Metal Surface

Due to the repeated cracking caused by the adsorption of cuttings on the surface of drilling bits and BHA during drilling operation, the rate of penetration (ROP) could reduce remarkably. The anti-balling additive for drilling fluids (ABA) could eliminate the adsorption effect of cuttings, and increase ROP significantly. In this paper, the mechanism of eliminating the adsorption effect of cuttings was investigated in details. The results indicate that ABA can form multilayer chemical and physical adsorption on the surface of drill bits and BHA in the form of oriented adsorption of organic phosphine, which is of great importance to the design of drilling fluid system and field operation to raise ROP.

Surface-driven, one-step chemical vapor deposition of γ-Al4Cu9 complex metallic alloy film

The present paper is a paradigm for the one-step formation of complex intermetallic coatings by chemical vapor deposition. It genuinely addresses the challenge of depositing an intermetallic coating with comparable contents of Cu and Al. Depending on processing conditions, a pure γ-Al4Cu9 and multi-phase Al-Cu films are grown with wetting properties of the former being similar to its bulk counterpart. The deposition process and its parametric investigation are detailed. Two metalorganic precursors are used taking into account their transport and chemical properties, and deposition temperature ranges. On line and ex situ characterizations enlighten the competition which occurs at the growing surface between molecular fragments, and which limits growth rates. Notably, introducing a partial pressure of hydrogen gas during deposition reduces Al growth rate from dimethylethylamine alane (DMEAA), by displacing the hydrogen desorption equilibrium. This Al partial growth rate decrease is not sufficient to achieve a Cu/Al atomic ratio that is high enough for the formation of intermetallics with close Al and Cu compositions. A fivefold increase of the flux of the gaseous copper(I) cyclopentadienyl triethylphosphine CpCuPEt3, whereas the DMEAA flux remains constant, results in the targeted Al/Cu atomic ratio equal to 44/56. Nevertheless, the global growth rate is rendered extremely low by the deposition inhibition caused by a massive phosphine adsorption (-PEt3). Despite these limitations, the results pave the way towards the conformal coating of complex surface geometries by such intermetallic compounds.

Preparation of Activated Carbons from Tobacco Stems by Potassium Hydroxide Activation and Phosphine Adsorption

Activated carbon preparation from tobacco stems by KOH activation at different activation temperatures and KOH/char mass ratios were investigated in this study. The effects of preparation parameters on activated carbon pore structure, morphometrics, microcrystallinities, and surface functional groups were characterized by N2 adsorption, SEM, XRD, and FTIR technologies, respectively. The optimum preparation condition of activated carbon was activation temperature of 850°C, and KOH/char mass ratio of 2. Under this condition, the BET surface area of 2215 m2/g, and the pore volume of 1.343 cm3/g can be obtained. Prepared activated carbon showed clearly honeycomb holes, and a predominated amorphous structure. With increase of activation temperature and KOH/char mass ratio, decrease of surface oxygen functional group, and aromatization of the carbon structure was found. The activated carbon was subject to PH3 purification, and the maximum PH3 adsorption capacity of 253 mg/g can be realized based on well prepared KOH-AC with modification of 2.5% Cu. It seems that the activated carbon produced from chemical activation of tobacco stem would be an effective and alternative adsorbent for PH3 adsorption because of its high surface area, adsorption capacity, and low cost.

Study on Drilling Fluid Technology of Eliminating Bit Balling by Changing Wettability

Using triethanolamine, vegetable fatty acid, alkyl polyoxyethylene alkyl ether sulfuric acid ester and dimethyl sulfate as raw materials, a new kind of anti-balling additive for drilling engineering (WORB) was synthesized. The wetting property and anti-balling performance of WORB were investigated according to the experiments of wettability, surface tension and absorption effect. The results indicate that the adsorption of WORB on the surface of the cuttings is monolayer adsorption, which can avoid repeated cutting caused by the agglomeration of cuttings. WORB can alter the wettability of rock surface and the inner pores of the rock to reduce the surface tension of the rocks. Moreover, WORB can form multilayer chemical and physical adsorption on the surface of drill bits and BHA in the form of oriented adsorption of organic phosphine.

Effect of Preparation Conditions on the Property Cu/AC Adsorbents for Phosphine Adsorption

Copper-based activated carbon adsorbents (Cu/AC) were prepared and used to investigate the effects of various copper precursors, impregnation solution concentration, and calcination temperature on phosphine (PH3) adsorption removal from yellow phosphorus tail gas. N2 adsorption isotherm and X-ray Diffraction (XRD) were used for characterizing the Cu/AC adsorbents. It can be seen that the Cu(N)/AC adsorbent prepared from the Cu(NO3)2 precursor has higher PH3 breakthrough adsorption capacity than other three adsorbent because the surface copper status of it is mainly CuO. Fresh activated carbon requires an optimal impregnation solution concentration (0.05 mol/L) to reach this optimal PH3 breakthrough adsorption capacity (78.62 mg/g). The result shows that the surface chemical characteristics (Cu content) of activated carbon is more important than the physical ones (specific surface or pore volume) for the PH3 adsorption performance. When the calcination temperature is 350°C, the Cu(N)/AC adsorbent has the biggest PH3 breakthrough adsorbed amount of 112.38 mg/g. The present study confirmed that the Cu/AC adsorbents would be one of the candidates for PH3 adsorption removal from yellow phosphorus tail gas.

Phosphorus atomic layer doping of germanium by the stacking of multipleδ layers

In this paper we demonstrate the fabrication of multiple, narrow, and closely spacedδ-doped P layers in Ge. The P profiles are obtained by repeated phosphine adsorption ontoatomically flat Ge(001) surfaces and subsequent thermal incorporation of P intothe lattice. A dual-temperature epitaxial Ge overgrowth separates the layers,minimizing dopant redistribution and guaranteeing an atomically flat starting surfacefor each doping cycle. This technique allows P atomic layer doping in Ge andcan be scaled up to an arbitrary number of doped layers maintaining atomiclevel control of the interface. Low sheet resistivities (280 ) and high carrier densities (2 × 1014 cm − 2, corresponding to 7.4 × 1019 cm − 3) are demonstrated at 4.2 K.

Kinetics and thermodynamics of the phosphine adsorption on the modified activated carbon

The kinetics and the thermodynamics of phosphine (PH3) adsorption on the modified activated carbon have been explained for the adsorption process of PH3. This study investigated the kinetic and thermodynamic properties of PH3 adsorption on the activated carbon impregnated with 5% HCl solution. The thermodynamic properties including PH3 adsorption isotherm and adsorption heat were separately investigated at 20°C, 70°C, 90°C. The results showed that the Freundlich-type isotherm equation described the isotherms well. The adsorption capacity increased with increasing temperature between 20°C and 70°C. Between 70°C and 90°C, the adsorption capacity decreased obviously with increasing temperature. The adsorption capacity reached the maximum at 70°C. By analyzing the results of the kinetics and the thermodynamics, we found that the adsorption of PH3 was dominated by physical adsorption at the lower temperature (20°C). Then with increasing temperature, chemical adsorption gradually dominated in the adsorption process. The adsorption capacity decreased at above 70°C is due to the exothermic effects in the process of adsorption.