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The detection of the identities and concentrations of sulfur hexafluoride, SF 6 , decomposition products is important for evaluating the conditions of SF 6 -gas-insulated equipment. This study is a preliminary test of the use of cassiterite (110) for detecting SF 6 and SF 6 decomposition gases, including HF, H 2 S, SO 2 , SOF 2 , SO 2 F 2 , CF 4 , CO, and CO 2 . First-principles calculations were adopted to investigate the adsorption mechanism of SF 6 decomposition gases on a cassiterite (110) surface, using adsorption energy, geometrical structure, frontier molecular orbitals, electron density, density of states, potential energy, and work functions. We found that the adsorption of H 2 S made a noticeable change in the electronic properties of the (110) surface. The adsorption of SO 2 strongly influenced the charge distribution of the cassiterite (110) surface and made the greatest decrease in the work function of the nine gas molecules tested. Conversely, changes in the cassiterite's electronic properties induced by other gases, especially SF 6 , were slight. Therefore, cassiterite could be a promising candidate for highly selective and sensitive sensors to detect H 2 S and SO 2 in SF 6 decomposition gases. [ABSTRACT FROM AUTHOR]

Highlights: [•] Prediction accuracy of adsorption models on both adsorbents has been compared over a wide pressure and temperature range. [•] Isosteric heat of hydrogen adsorption on both adsorbents has been determined by adsorption isosteres on absolute amounts. [•] A stronger interaction has been found between hydrogen molecules and the graphene layers. [ABSTRACT FROM AUTHOR]

To address the most significant environmental challenges, the quest for high-performance gas sensing materials is crucial. Among numerous two-dimensional materials, this study investigates the gas-sensitive capabilities of monolayer As, Sb, and Bi materials. To compare the gas detection abilities of these three materials, we employ first-principles calculations to comprehensively study the adsorption behavior of NO and NO2 gas molecules on the material surfaces. The results indicate that monolayer Bi material exhibits reasonable adsorption distances, substantial adsorption energies, and significant charge transfer for both NO and NO2 gases. Therefore, among the materials studied, it demonstrates the best gas detection capability. Furthermore, monolayer As and Sb materials exhibit remarkably high capacities for adsorbing NO and NO2 gas molecules, firmly interacting with the gas molecules. Gas adsorption induces changes in the material's work function, suggesting the potential application of these two materials as catalysts. [ABSTRACT FROM AUTHOR]

Predicting and designing highly gas‐sensitive semiconductors is crucial for solving growing environmental problems. Herein, four lateral heterostructures (LHSs), As6/Sb6 AC‐/ZZ‐LHSs and Sb6/Bi6 AC‐/ZZ‐LHSs, are constructed. The adsorption of NO molecule on these LHSs is investigated using first‐principle calculations. The results indicate that the adsorption of NO molecule on As6/Sb6 LHS with armchair (AC) interface is physisorption, whereas NO molecule is chemically adsorbed on As6/Sb6 LHS with zigzag (ZZ) interface and Sb6/Bi6 AC‐/ZZ‐LHSs, with strong adsorption energy and large charge transfer. All LHSs act as charge donors for the NO molecule. Meanwhile, the adsorption of NO molecule causes a significant change in the electronic properties of As6/Sb6 ZZ‐LHS and Sb6/Bi6 AC‐/ZZ‐LHSs, which shows that these LHSs have great potential for application in NO gas sensors. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculation was used to study the potential applications of pure and metal-doped C 24 N 24 fullerene as highly sensitive and selective gas sensors. It is found that gases commonly existing in the air, including NO 2 , CO, NO, NH 3 , N 2 and CO 2 , are weakly adsorbed on pure C 24 N 24. The adsorption strength is increased when they are adsorbed on the metal-doped (Co-, Cr-, Cu-, K-, Li-, Fe-, Ni-, Pd-, Ti-, Mn-, Na-, Zn-, V-) C 24 N 24. The pure and metal-doped C 24 N 24 have a specific response to certain gas according to adsorption energy, charge transfer, band gap and the density of states analyses. Among various metal-doped C 24 N 24 , the adsorption energies of NO 2 on K- and Na-doped C 24 N 24 are apparently lager than those of other gas molecules, which fall between the suitable range of strong physical adsorption and weak chemical adsorption. Upon NO 2 adsorption, the band gap changes of K- and Na-doped C 24 N 24 which corelate with its conductivity reach −12.75% and −26.67%, respectively. In accordance with the band gap changes, the density of states changes and charge transfer for NO 2 adsorption on K- and Na-doped C 24 N 24 are most obvious. Sensor performance analysis further shows K- and Na-doped C 24 N 24 are highly selective in NO 2 detection. The recycle time of Na–C 24 N 24 under ambient condition is also in the suitable range (1.80 s). This study concludes the potential application of the Na-doped C 24 N 24 as high-performance NO 2 sensor. [ABSTRACT FROM AUTHOR]

Alternating therapeutic plasma exchange with double plasma molecular adsorption system can rapidly remove bilirubin and ammonia and supplement the essential substance from the blood, which could be used as an effective treatment for fulminant hepatic failure. [ABSTRACT FROM AUTHOR]

The gasification of lignite with a moisture content of 5–10% was carried out by GSP pulverized coal gasification process(GSPPCP). An air separation unit was set up to make use of oxygen and nitrogen during lignite drying process. This was a potential approach to utilize the mixture of oxygen and moisture in lignite as a feedstock for gasification agent. In this paper, the physico-chemical properties of several lignites from Xilingol dehydrated under different atmospheres were characterized by the thermogravimetry mass spectrometry analyzer (TG-MS), fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM), to investigate the impact of drying atmosphere, heating rate and particle size on drying rate, gas evolutions and drying kinetics. FWO and Vyazovkin methods were applied elaborating the drying kinetics and mechanism. The moisture in lignite decreased with the rise of drying temperature, but the dehydration rate was did not change much under different heating rate at initial stage. The distribution of energy consumption during water evaporation and water migration was determined by the fitted DTG curve. Moisture re-adsorption was greater for large particles, which correlated to the content of oxygen-containing functional groups. The combustion activation energy of nitrogen-dried lignite was larger than that of oxygen-dried lignite. [ABSTRACT FROM AUTHOR]

Iron has been proved effective for hydrogen adsorption due to its high binding energy with hydrogen molecules. Here a series of iron-doped interconnected ordered mesoporous carbons (Fe/OMCs) with controllable doping level (zero to 9.11%) and large surface area were successfully prepared by adjusting the initial additive mass of ferric nitrate. The mesoporous carbon materials were characterized by means of nitrogen adsorption, pore size distribution, low-angle X-ray diffractometer, energy dispersive X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectra (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses. The results show that the Fe/OMCs possess well-ordered mesostructured, intrinsic 3D network structure, and large surface area from 921 to 1378 m 2 g −1 . The low-angle XRD diffraction peaks of the Fe/OMC samples shifted slightly toward high angles, indicating the introduced Fe on the OMC prevents framework shrinkage during the calcination. The controllable iron particles with size of 20–40 nm partially embedded on the 3D network structure showed different state of iron particles, namely zero iron (α-Fe), magnetite (Fe 3 O 4 ) and hematite (α-Fe 2 O 3 ), and part of them kept naked in the pore, providing more available iron actives for hydrogen adsorption. Based on the unique structure, adsorption data of hydrogen on the OMC were collected to independently investigate the iron doping effect on the Fe/carbon composite surface interactions. The results indicate that hydrogen adsorption capacity is greatly enhanced with the iron content, and the sample Fe/OMC-9 with 9.11% iron content exhibits the highest hydrogen adsorption capacity of 1.10 wt%, 59% higher than the non-doped OMC. The high hydrogen adsorption is attributed to OMC's 3D porous network structure with well-dispersed iron nanoparticles partially exposed in the pore. [ABSTRACT FROM AUTHOR]

Fe 3 O 4 @SiO 2 -Chitosan/GO (MSCG) nanocomposite was investigated by various techniques (SEM, TEM, XRD, VSM, FT-IR, XPS) for the removal of tetracycline (TC). Effects of pH, zeta potential and initial contaminant concentration were studied in detail. Four background cations (Na + , K + , Ca 2+ and Mg 2+ ) with a concentration of 0.01 M showed little influence on the TC adsorption at the studied pH range while the divalent heavy metal cation Cu(II) could significantly enhance the adsorption. The results indicated that the highest adsorption capacity of TC were 183.47 mmol/kg and 67.57 mmol/kg on MSCG with and without Cu(II), respectively. According to mechanism investigation for the adsorption of TC by pH impact study and XPS analysis, besides electrostatic interaction and π–π interactions, the Cu(II) also acts as a bridge between TC and MSCG, which significantly improve the adsorption of TC. This study provided valuable guidance and effective method for the removal of TC from aquatic environments. [ABSTRACT FROM AUTHOR]

Abstract: In this study, 5-aminosalicylic acid was successfully grafted onto the poly(glycidyl methacrylate) (PGMA) macromolecular chains of PGMA/SiO2 to obtain a novel adsorbent designated as ASA–PGMA/SiO2. The adsorption properties of ASA–PGMA/SiO2 for heavy metal ions were studied through batch and column methods. The experimental results showed that ASA–PGMA/SiO2 possesses strong chelating adsorption ability for heavy metal ions, and its adsorption capacity for Cu2+, Cd2+, Zn2+, and Pb2+ reaches 0.42, 0.40, 0.35, and 0.31mmolg−1, respectively. In addition, pH has a great influence on the adsorption capacity in the studied pH range. The adsorption isotherm data greatly obey the Langmuir and Freundlich model. The desorption of metal ions from ASA–PGMA/SiO2 is effective using 0.1moll−1 of hydrochloric acid solution as eluent. Consecutive adsorption–desorption experiments showed that ASA–PGMA/SiO2 could be reused almost without any loss in the adsorption capacity. [Copyright &y& Elsevier]

• Stone-Wales defects can upgrade the SO 2 -sensing performance of arsenene. • It is highly appreciated because point defects especially Stone-Wales defect generate much easier on arsenene than other common 2D material. • Most of gas sensor based on 2D material have a slow recovery. • The external electric field can greatly adjust the SO 2 -sensing performance on arsenene with Stone-Wales defects. • This makes it possible to substantially accelerate the recovery of the arsenene with Stone-Wales defects. • Both biaxial strain and external electric field can further enhance the SO 2 -sensing performance of arsenene with Stone-Wales defects. Reported here is a first-principle study of the adsorption of four SF 6 decomposition products on pristine arsenene and arsenene with Stone-Wales defects (SW). The results revealed that pristine arsenene exhibited high sensitivity and selectivity to SO 2 , and Stone-Wales defects enhanced the SO 2 -sensing performance. The presence of ambient O 2 , H 2 O, and SF 6 only slightly affected the adsorption on both pristine and SW arsenene. We also investigated the effect of biaxial strain and an external electric field on the SO 2 detection of SW arsenene. The SO 2 adsorption strength on SW arsenene was drastically enhanced or weakened, depending on the direction of the electric field, which is desirable for realizing the ultra-sensitive adsorption and desorption of SO 2. [ABSTRACT FROM AUTHOR]

• High selectivity and sensitivity of GeP monolayer to nitrogen oxides. • The variation of work function change can be used to distinguish NO 2 and NO. • Compressive strain improve sensitivity of GeP to NO 2 without raising recovery time. • Applied negative electric field can greatly enhance response of GeP monolayer to NO 2. The sensing properties of GeP monolayer to small gas molecule (CO, CO 2 , O 2 , H 2 O, NH 3 , NO and NO 2) have been investigated by performing first-principle calculations. Based on calculated adsorption distance, adsorption energy and charge transfer, we find that GeP monolayer is the most sensitive to NO 2 and NO molecules, and all gas molecules act as acceptors to gain electrons from GeP monolayer. The adsorption energy of NO 2 is smaller than that of NO molecule, which implies that NO 2 is more easily desorbed from GeP. And different work function changes also indicate the possibility to identify NO 2 and NO in an oxygen-free environment. Moreover, we apply uniaxial and biaxial strains to GeP monolayer and find that a small biaxial compressive strain can effectively enhance the sensitivity of work function type sensor based GeP to NO 2 molecule without increasing recovery time. We also discuss the effect of external vertical electric field on the adsorption performance of NO 2 molecule. The negative electric field can significantly increase the adsorption strength, charge transfer and work function change of NO 2 -GeP system. Our results indicate that GeP monolayer is a potential candidate for NO 2 gas sensor. [ABSTRACT FROM AUTHOR]

In order to take insight into the gas sensing performance of single ultrathin WO 3 nanowire, we performed first principles calculation to investigate the gas adsorption properties and used non-equilibrium Green function (NEGF) to investigate the electron transport properties of WO 3 nanowires with gas adsorption. Our investigation indicated that the WO 3 nanowires with/without oxygen vacancies are both sensitive to H 2 S due to the large adsorption energies and distinct charge transfer. Besides, we found that the WO 3 nanowire with O a type oxygen vacancies is highly selective to SO 2. We supposed that the high chemical activity and the small molecular volume of H 2 S and SO 2 are the main reasons of the selectivity. Finally, the negative differential resistance (NDR) effect of single ultrathin WO 3 nanowire and the gate voltage were proposed to benefit the application of WO 3 nanowires gas sensors. We also supposed two ways to take advantage of the NDR effect of single ultrathin WO 3 nanowire in gas sensing applications. It should be noted that this is the first theoretical investigation of WO 3 nanowires gas sensors considering the electron transport properties. Our work highlighted the possibility to use the single ultrathin WO 3 nanowire as superior gas sensors for SO 2 and H 2 S. Image 1 • The single ultrathin WO 3 nanowire without oxygen vacancies was sensitive to H 2 S. • The single ultrathin WO 3 nanowire with oxygen vacancies was sensitive to SO 2. • High chemical activity and small molecular volume are main reasons of selectivity. • Negative differential resistance effect will benefit gas sensing application. [ABSTRACT FROM AUTHOR]