Search

Abstract In this paper, the adsorption and degradation mechanism of metronidazole on TiO 2 (101) and (001) surfaces was elucidated at DFT level. The adsorption stability of metronidazole on the surface of anatase was studied under the condition of vacuum and neutral aqueous solvent respectively, and the most stable adsorption configuration was optimized theoretically. It was found that metronidazole could be adsorbed on the surface of TiO 2 under both conditions. The hydrogen bond generated by the adsorption process can enhance the stability of the adsorption structure. The surface adsorption made the C N bond length of metronidazole longer, which could facilitate the reaction of open-loop degradation. The mechanism of ring-opening degradation of metronidazole on two surfaces of TiO 2 was also studied. It was found that the activation energy of the degradation reaction of metronidazole on the crystal plane of TiO 2 was decreased under the condition of water solvent, which indicated that the solvent condition could promote the degradation of metronidazole. The utilization efficiency of different crystal planes of TiO 2 in the visible light and predicted the photocatalysis were achieved. The study found that TiO 2 (101) crystal plane catalytic degradation of metronidazole has high visible light utilization rate, explaining the experimental results. Graphical abstract Schematic diagram of catalytic ring-opening reaction of metronidazole on TiO 2 surface: when the reactant is attacked by OH radical on the surface of the catalyst, the N(1) C(2) bond breaks and the hydroxyl H atom on C(2) is transferred to N(3). Unlabelled Image Highlights • The most stable adsorption configuration of metronidazole on the surface of TiO 2 was optimized. • The degradation of metronidazole on the TiO 2 (101) surface is easy to occur. • The ring-opening reaction contains two steps: N-C bond breaking and proton transfer on the imidazole ring. [ABSTRACT FROM AUTHOR]

[Display omitted] • The two-dimensional Ti 3 C 2 was modified with sodium ligninsulfonate. • The resultant Ti 3 C 2 -SL was used for adsorptive removal of DOX. • The adsorption capacity of Ti 3 C 2 -SL is obvious higher than Ti 3 C 2. • The Ti 3 C 2 -SL shows acceptable recyclability. MXene is a newly emerged two-dimensional material that has been extensively explored for different applications, including as adsorbents for adsorptive removal of environmental pollutants. However, the lack of active adsorption sites will inevitably impede their adsorption performance and surface functionalization is generally required. In this work, a novel MXene-based adsorbent (named as Ti 3 C 2 -SL) was fabricated by a simple substitution reaction using hexachlorocyclotriphosphazene (HCCP) as the linkage to conjugate amino groups terminated Ti 3 C 2 and sodium ligninsulfonate. Ti 3 C 2 -SL was examined as adsorbent for adsorption of doxorubicin hydrochloride (DOX) and many experiments were performed to evaluate different parameters on the adsorption behaviors. These experimental data were fitted and related parameters were calculated to study the adsorption kinetics and thermodynamics. Results demonstrated that DOX can be rapidly adsorbed by Ti 3 C 2 -SL and the adsorption capacity reached a relatively high value within 2 min. The maximum adsorption capacity after equilibrium is up to 190.78 mg g−1, which is about four folds as compared with that of Ti 3 C 2. The adsorption process is a spontaneous endothermic process and dominated by physical adsorption. All the above results suggested that Ti 3 C 2 -SL is promising for adsorptive removal environmental pollutants. [ABSTRACT FROM AUTHOR]

Silica-gel adsorbents PAMAM- n .0SSASG ( n = 1–4) with dendrimer-like polyamidoamine (PAMAM) and 5-sulfosalicylic acid as functional groups were prepared and characterized with FTIR, SEM, TG, elemental analysis and porous structure analysis. Micro-column enrichment and measurement of Pb 2+ with graphite furnace atomic absorption spectroscopy (GFAAS) was studied with PAMAM- n .0SSASG ( n = 1–4) as adsorbent. It was emphasized to investigate the relationship between dynamic adsorption/desorption rates, adsorption capacities, and grafting percentage of PAMAM onto silica-gel surface. Experiments showed that the generation increase of grafted PAMAM changed the pore diameter distribution of adsorbent and obviously improved adsorption/desorption property for Pb 2+ . Adsorption capacity of PAMAM- n .0SSASG ( n = 1–4) was 14.04, 17.43, 20.07 and 25.05 mg g −1 for Pb 2+ respectively. An enrichment factor of 200 was obtained with PAMAM-4.0SSASG as adsorbent and with 2000 mL Pb 2+ solution (1.0 ng mL −1 ). The priority of adsorption property of PAMAM-4.0SSASG was explained by steric hindrance effect of PAMAM on adsorption/desorption, and selective adsorption of 5-sulfosalicylic acid with Pb 2+ . With PAMAM-4.0SSASG as adsorbent, GFAAS method for analysis of Pb 2+ combined with micro-column enrichment was proposed and applied to the determination of Pb 2+ of standard reference sample and sea water sample. [ABSTRACT FROM AUTHOR]

A facile approach is demonstrated to synthesize a series of magnetite/graphene nanocomposites by solvothermal method, which can be easily collected after removal of pollutants without secondary pollution of graphene powders. Raman and FT-IR analyses show that the reduction of the mixing vapor of ammonia and hydrazine at different reaction periods generates the discrepancy of oxidation degree for reduced graphene oxide (rGO), which can be kept after the solvothermal synthesis of Fe 3 O 4 /rGO nanocomposites. Batch adsorption experiments indicate that the nanocomposite with maximum oxidation degree of rGO presents the largest magnetization of 35.4 emu g −1 and adsorption capacity of 59.2 mg g −1 for Cu 2+ , while the one with minimum oxidation degree exhibits the strongest adsorption of 39.0 mg g −1 for methylene blue accompanied with appropriate magnetization of 9.0 emu g −1 , and only 23% of initial capacity was lost after seven recycling use. The adsorption kinetics of the both composites follows the pseudo-second-order model, suggestive of physical and chemical interactions between the pollutants and adsorbent. The results suggest that the oxidation degree of the rGO substrate can apparently influence both the structure and the adsorbing behavior of Fe 3 O 4 /rGO nanocomposites, which allows the control over the adsorbent performance according to the pollutant of interest. [ABSTRACT FROM AUTHOR]

Abstracts Understanding the interaction mechanisms of hydrogen sulfide (H 2 S) with graphene is important in developing graphene-based sensors for gas detection and removal. In this study, the effects of doped Fe atom on interaction of H 2 S with graphene were investigated by density functional theory calculations. Analyses of adsorption energy, electron density difference, and density of states indicated that the doped Fe atom can significantly improve the interaction of H 2 S gas molecules with graphene, as well as Pt-doped graphene. The location of the sulfur atom is important in the interactions between H 2 S and Fe-doped graphene. The influence of the Fe S distance can be very weak within a certain distance, as simulated in this study. [ABSTRACT FROM AUTHOR]

Highlights: [•] Favorable adsorption configurations of H2S, HS on Mo(100) were characterized. [•] All possible dissociation pathways of H2S dehydrogenation were distinguished and mapped. [•] Decomposition of H2S on Mo(100) is facile. [•] The difference of reaction barrier during the second dehydrogenation with and without hydrogen co-adsorption is minor. [ABSTRACT FROM AUTHOR]

Highlights: [•] Adsorptive geometry and energy on perfect and defective surface have been calculated. [•] The electronic structure has been analyzed by CDD and DOS. [•] Adsorption rate has been deduced employing a model of grand canonical ensemble. [•] The transition temperate of nuclide from adsorption to desorption has been obtained. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Ti-doped graphene exhibited selective gas adsorption. [•] The order of interactions between these molecules and the Ti-doped graphene sheet was as follows: HCHO>SO2 >NO>CO. [•] The N-doped graphene do not own the selectivity ability. [Copyright &y& Elsevier]

Dissociation paths of H 2 O dissociation on PuH 2 (1 1 0) surface. [Display omitted] • The adsorption of H 2 O molecule on the surface of PuH 2 (1 1 0) basically presents chemical adsorption. • The adsorption direction of H 2 O molecule parallel to the PuH 2 (1 1 0) surface preferentially on the top of Pu atom. • The vibration frequencies results of the adsorbed H 2 O molecule show a red shift phenomenon in the absorbed H 2 O molecule. • The climbing-image nudged elastic band (CI-NEB) results show the dissociation of H 2 O on the surface of PuH 2 (1 1 0) is a hydroxylation process with dissociation energy barrier 0.406eV, forming hydroxide of plutonium on the surface. The reaction between water and plutonium hydride plays a significant role in the oxidation and corrosion rate of plutonium materials. The adsorption and dissociation of water molecule on PuH 2 (1 1 0) surface have been studied by first-principles GGA + U method. To search the more favorable adsorption sites and adsorption types of H 2 O in terms of energy, the adsorption energies of H 2 O on different active sites were compared. The results reveal that the adsorption of H 2 O molecule on the surface of PuH 2 (1 1 0) basically presents chemical adsorption, while the adsorption direction of H 2 O molecule parallel to the PuH 2 (1 1 0) surface appears to be preferentially adsorbed on the top of Pu atom. We analyze the vibrational frequencies of H 2 O molecule adsorbed on the surface. It is found that there is a red shift phenomenon under the action of surface atoms. Two possible dissociation pathways of H 2 O molecule on PuH 2 (1 1 0) surface were studied by the climbing-image nudged elastic band (CI-NEB) method. The calculation result shows that the more favorable dissociation energy barrier is about 0.406 eV. This indicates that the dissociation of H 2 O molecule on the surface of PuH 2 (1 1 0) is favorable, even at room temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • NH 3 , PH 3 , AsH 3 adsorptions on rare earth metal doped graphenes are investigated. • Rare earth metal leads to enhanced chemisorption towards NH 3 and weakened adsorption towards AsH 3. • Considering the sensor response and recovery time, CeG is the best candidate for NH 3 detection. To explore new sensor materials towards hazardous gases NH 3 , PH 3 , and AsH 3 , their adsorptions on pristine graphene and rare earth metal (REM = La, Ce, Nd, Pm, Sm, Eu and Gd) doped graphenes were studied by using density functional theory calculations. The adsorption energies show that pristine graphene exhibits weak physisorption towards the NH 3 , PH 3 , and AsH 3 gas molecules. Almost no changes appear on the geometrical structures, charge populations and DOSs of pristine graphene. However, the rare earth metal element modifications lead to enhanced chemisorption towards NH 3 and weakened adsorption towards AsH 3 , accompanied with significant electron redistribution and orbital hybridization. The electrical conductivity of the graphenic substrate is also increased, leading to higher sensor response towards NH 3. Facile sensitivity and recovery time reveals Ce doped graphene is an ideal candidate for room temperature monitoring of NH 3. [ABSTRACT FROM AUTHOR]

In this study, we present the adsorption behavior of NO, NO2 and H2O on trivalent rare-earth ion-exchanged ZSM-5 (RE-ZSM-5; RE=La, Ce, Nd, Sm, Gd and Dy) using density functional theory. The results show that Ce-ZSM-5 is more effective for the activation of NOx than La-ZSM-5 and Nd-ZSM-5, which is in good agreement with experimental results. The present investigation also suggests that Dy-ZSM-5 has a considerable ability for the activation of NO2 as compared to Sm-ZSM-5 and Gd-ZSM-5. Furthermore, the Ce-, Nd- and Dy-analogues posses a quite stronger affinity for NOx and that the low affinity of H2O indicate the poisoning resistance ability of these catalysts. In addition, the relationship between the adsorption energy of NO and the contribution of NO-2πg1 molecular orbital was also investigated in the NO/RE-ZSM-5 adsorption complex. [Copyright &y& Elsevier]

• NH 3 , PH 3 and AsH 3 adsorptions on Be-Sr doped graphenes are investigated. • Mg doped graphene (MgG) exhibits the strongest adsorption capability. • Sensor response and recovery time are evaluated. • MgG is the best candidate for PH 3 or AsH 3 detection. • SrG is an ideal candidate for selectively sensitive NH 3 detection of PH 3 and AsH 3. To bring more safety assurance to human's life, effectively monitoring and suppressing NH 3 , PH 3 , and AsH 3 gases is highly demanded. In this study, NH 3 , PH 3 and AsH 3 adsorptions on intrinsic and alkaline earth metal- (AEM = Be, Mg, Ca, and Sr) doped graphenes are theoretically investigated. Adsorption energies analysis reveals that NH 3 , PH 3 and AsH 3 molecules are weakly adsorbed on intrinsic graphene, and lead to negligible changes in the electronic properties. The IIA element doped graphenes exhibit enhanced chemisorption towards NH 3 , PH 3 and AsH 3 molecules, due to the strong chemical reactivity of Be, Mg, Ca and Sr. Significant increase is observed in adsorption energies, charge transfers and orbital hybridizations of these adsystems. The sensitivity response and recovery time reveal that Mg doped graphene seems available for monitoring PH 3 and AsH 3. Sr doped graphene could be an ideal candidate for selectively sensitive NH 3 detection under the mixed atmosphere of NH 3 , PH 3 and AsH 3 gases with appropriate recovery time. This study could facilitate the applications of AEM doped graphenes in the fields of NH 3 , PH 3 and AsH 3 detection. [ABSTRACT FROM AUTHOR]

We selected representative carbon substrates (MnN 4 -Gra and MnN 4 -C60) to study the thermodynamics of toxic gas molecule adsorption processes. Gas molecules are physically adsorbed on MnN 4 -Gra and MnN 4 -C60, which are easily desorbed spontaneously at low temperatures, so only chemisorbed toxic gas molecules are studied here. With the results of the vibrational frequency analysis of the DFT calculation, reveal that ΔG ads (T) increases with increasing T, when ΔG ads (T) changes from negative to positive at Td, where Td is defined as the desorption temperature. According to the second law of thermodynamics, the adsorption of gas molecules on the MnN 4 -Gra or MnN 4 -C60 surface will spontaneously occur when T is below Td. The Td of gas molecules adsorbed on MnN 4 -Gra (or MnN 4 -C60) increased in the order of SO 2 (210 K) < NH 3 (450 K) < CO(770 K) < NO 2 (980 K) [SO 2 (310 K) < H 2 S(400 K) < N 2 O(510 K) < CO/NH 3 (690 K)]. • The most stable adsorption configuration of the molecule on MnN 4 -CS can be determined by molecular electrostatic potential and adsorption energy. • The adsorption properties of MnN 4 -CS are mainly affected by doped atoms, curvature and size of the substrate. • MnN 4 -Gra, MnN 4 -GNR and MnN 4 -GNS are preliminarily determined as suitable for ORR catalysts. MnN 4 -Gra, MnN 4 -GNR, MnN 4 -CNT are suitable as catalysts for CO oxidation. • We subsequently determined the normal operating temperature of the gas sensor by Gibbs free energy and molecular dynamics. Toxic gases destroy the ecological environment and endanger human health, which enlightened the researchers in development of new materials and technologies that effectively collect and capture toxic gases, and convert to harmless gases with the aid of catalyst. Density functional theory (DFT) calculations are performed to evaluate the changes in adsorption energy, charge transfer, sensitivity and Gibbs free energy for MnN 4 -decorated graphene (MnN 4 -Gra), graphene nanoribbons (MnN 4 -GNR), graphene nanosheets (MnN 4 -GNS), carbon nanotubes (MnN 4 -CNT) and C60 fullerenes (MnN 4 -C60) after adsorbing gas molecules, including NO, NO 2 , CO, SO 2 , NH 3 , H 2 S, N 2 O, O 2 , H 2 O and CO 2. The most stable adsorption configuration of the molecule on MnN 4 -CS can be determined by molecular electrostatic potential and adsorption energy. The adsorption properties of MnN 4 -CS are mainly affected by doped atoms, curvature and size of the substrate. Among five tested materials, MnN 4 -C60 has good adsorption energy for toxic gases and is suitable for collecting and trapping gases. MnN 4 -Gra, MnN 4 -GNR and MnN 4 -GNS are evaluated as catalysts for oxygen reduction reaction (ORR), MnN 4 -Gra, MnN 4 -GNR, MnN 4 -CNT are suitable as catalysts for CO oxidation. Also the normal operating temperatures of gas sensors were determined by Gibbs free energy and molecular dynamics (MD). This investigation provides valuable information for designing high-performance gas sensors. [ABSTRACT FROM AUTHOR]

Adsorption capacity of methyl blue onto the ammonium-functionalized hollow polymer particles (HPP-DETA) increased remarkably from 407 to 1341 mg g−1 as their cross-linking degree decreased from 26% to 3%. • Ammonium-functionalized hollow polymer particles (HPP-DETA) with varying degree of crosslinking are synthesized. • Highly enhanced adsorption property is achieved on weakly cross-linked HPP-DETA. • Adsorption capacity of a -MB reached up to 1025 mg g−1 in 15 min. • q max increased dramatically from 407 to 1341 mg g−1. • Removal efficiency of a -MB is >98% after 5 adsorption/desorption process. Adsorption is one of the most effective techniques for dye removal from wastewater, and advanced adsorbents with fast adsorption rate and remarkable adsorption capacity are highly desired. To attain this goal, we specially designed and synthesized a series of diethylenetriamine-modified hollow polymer particles (HPP-DETA) with varying degree of cross-linking, which exhibited highly enhanced dye-adsorption performance for selective removal of negatively charged dyes (methyl blue, as a model dye). Even though the density of ammonium groups remained almost unchanged, the sorption rate and capacity of HPP-DETAs can be significantly enhanced as their cross-linking degree decreased, which is strikingly different from conventional porous adsorbents. The adsorption isotherms are well described by Langmuir isotherm model and the calculated maximum adsorption capacity increased dramatically from 407 to 1341 mg g−1 as their cross-linking degree decreased from 26% to 3%. Most importantly, the weakly cross-linked HPP-DETA shows excellent reusability after regeneration, and the removal efficiency of methyl blue was higher than 98% after five successive adsorption-desorption process. In view of its highly enhanced adsorption rate, remarkable adsorption capacity and excellent recyclability, the weakly cross-linked HPP-DETA exhibits significant potentials as advanced adsorbents for dye removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel MgO-modified palygorskite/biochar composite was successful synthesis. • The maximum adsorption capacity of MNBC is 441.1 mg/g for Cd2+. • The mechanisms are precipitation, complexation, ion exchange, and Cd–π interaction. • Nucleophilic Cd tends to transfer electrons to the electrophilic O atom of MgO. The treatment of Cd2+ pollution in water has been a hot topic of research, while the studies for the preparation and application of biochar composites to treat Cd2+ and the corresponding micro-mechanisms were still lacking. In this study, a novel MgO-modified palygorskite/biochar derived from rice straw composite (MPBC) was synthesized to remove Cd2+ in the aqueous solution. Batch experiments were conducted to evaluate the adsorption ability for Cd2+ on MPBC. The results showed that the maximum adsorption capacity of MPBC was 441.1 mg/g, which was 4.6 times higher than that of the original biochar (BC). Adsorption mechanisms were clarified combine systematic characterization and density functional theory (DFT) calculations. Precipitation, complexation, ion exchange, and Cd-π interaction were the main adsorption mechanisms, and the contribution of the ion exchange, compared with 12.08% of BC, increased to 37.82%. The O atom of the MgO group performed negative electrostatic potentials as an electrophilic active site. The nucleophilic Cd tends to transfer electrons to the electrophilic O atom of the MgO group. Furthermore, the density of state (PDOS) identified that hybrid overlap occurred between MgO and Cd, and a new chemical bond was formed in the adsorption process. Overall, this work offers a new approach to removing aqueous Cd2+ and uses biowaste to create a sustainable environment. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • An innovative design for anionic imprinted polymers by electrostatic attraction. • Phosphate imprinted polymer (IIP) have better adsorption performance than NIP. • IIP shown predominant adsorption performance in selectivity and specificity to phosphate. • Phosphate speciation and IIP surface potential has effect on phosphate capture. • Imprinted cavities were verified form by dual interaction of N+–O− and N H hydrogen bonded. Abstract It is therefore difficult to develop anionic imprinted polymers due to its intrinsic properties of anionic templates, which have much smaller charge size ratio, species diversity, and irregular geometry than cationic templates. Moreover, its synthesis is not suitable for traditional apolar media. Hence, well-defined recognition cavities formed by coordination are almost impossible for anion imprinted polymers. Synthesized anion imprinted polymers (IIP) by electrostatic attraction of positive and negative charges to enhance the stability of anion and functional monomer in the pre-polymerization process were proposed. Speciation of phosphate and surface potential at different pH on IIP have effect on phosphate capture were investigated. The resultant IIP has a high 78.88 mg g−1 at 35 °C while non-anion imprinted polymers (NIP) has only 33.35 mg g−1 adsorption capacity. In coexist experiments, all the selectivity coefficients (α) of IIP are greater than 1.8, and selectivity would rise with anion concentration increased. All these shows IIP possessed outstanding selectivity and specificity to phosphate. Adsorption energy E , and ΔH0 of IIP are 14.26 kJ mol−1 and 36.32 kJ mol−1, respectively. It indicated that phosphate adsorbed to IIP is ion exchange reaction. It is further verified by FTIR and XPS that recognition sites of anion imprinted polymers are N+ of AMD and P–O− in H 2 PO 4 −. They moved to imprinted cavities and form N+–O−, N H hydrogen bonded, which also contribute to adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • The optimum pore size for the adsorption separation of CH 4 /C 2 H 4 /C 3 H 8 was obtained. • The porous carbon with excellent adsorption and separation properties was prepared. • The vital role of pore size on light hydrocarbons adsorption separation is proved. • Provide a rational guiding strategy for the preparation of porous carbon. The efficient adsorption and separation of light hydrocarbons is considered to be the vital processes in petrochemicals. Therefore, it is important to design and develop efficient adsorbents. Herein, we investigated the detailed mechanistic effects of the pore size of porous carbon on the adsorption and separation performance of three light hydrocarbons based on GCMC simulations. The optimum pore size range for their adsorption and separation was determined. Accordingly, bamboo fibres-based porous carbons (BPCs) with tunable pore size distribution were prepared using bamboo fibres mixed with different ratios of KOH. The results display that C 3 H 8 (0.7–1.6 nm) exhibits the wider optimal pore size range for adsorption compared to CH 4 (0.7–0.8 nm) and C 2 H 4 (0.7–1.2 nm). Meanwhile, the selectivity of C 3 H 8 /CH 4 (C 3 H 8 /C 2 H 4) depends primarily on the 1.0–1.6 nm (1.2–1.6 nm) pore size. Furthermore, BPCs with these optimal pore sizes exhibited excellent adsorption performance for CH 4 (2.07 mmol/g), C 2 H 4 (6.29 mmol/g) and C 3 H 8 (12.23 mmol/g). Among them, BPC-4 possessed the greatest selective separation for C 3 H 8 /CH 4 (11.1) and C 3 H 8 /C 2 H 4 (2.3). This study achieved effective adsorption separation of light hydrocarbons, which would further guide the design direction regarding the pore size of light hydrocarbon adsorbents and provide new ideas for preparation of porous carbon materials. [ABSTRACT FROM AUTHOR]

The adsorption of sodium dimethyl dithiocarbamate (SDD) and butyl xanthate (BX) on sphalerite (1 1 0) surface in the absence and presence of water molecules was simulated using density functional theory (DFT). The results indicated that both the SDD and BX can chemically adsorb on the sphalerite surface in the absence of water molecules. However, the presence of water molecules on sphalerite surface significantly increases the adsorption energy of SDD and BX, which is detrimental to SDD and BX attachment on sphalerite surface. Particularly, the presence of water molecules changes the adsorption of BX on sphalerite surface from chemisorption to physical absorption, but the adsorption of SDD on sphalerite surface is still very strong like that of chemisorption. The results of DOS comparison analysis, electron density and Mulliken population analysis also confirmed the adsorption of SDD on sphalerite surface is more easy and stable than that of BX adsorption. [ABSTRACT FROM AUTHOR]

The copper activation and potassium butyl xanthate (PBX) adsorption on sphalerite and marmatite surfaces were comparatively investigated using in situ local electrochemical impedance spectroscopy (LEIS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and surface adsorption tests. Comparing the LEIS and surface adsorption results, it was found that the activation time is a key factor influencing the copper activation and PBX adsorption on marmatite surface, but it has a negligible influence on sphalerite. For a short activation time within 10 min, the Fe impurity in marmatite shows an adverse influence on the speed of Cu adsorption and ion exchange as well as on the subsequent PBX adsorption. For a long activation time of 30 min, the LEIS, ToF-SIMS and surface adsorption results suggested that the Fe impurity in marmatite enhances the copper adsorption, whereas such enhanced copper adsorption of marmatite cannot result in corresponding enhancing of PBX adsorption. DFT result showed that the Fe impurity in marmatite has harmful influence on the PBX interaction with the Cu-activated surface by increasing the interaction energy. ToF-SIMS result further indicated that the Cu distribution in the outermost surface of marmatite is less than that of the sphalerite, which also results in the less PBX adsorption for the marmatite. [ABSTRACT FROM AUTHOR]

We present a theoretical investigation of the reaction mechanism of TiCl 4 dissociation on pyrolytic carbon surface and discuss the influence of H atom on adsorption and dissociation behaviors of TiCl 4 by using density functional theory. The adsorption behaviors of TiCl x (x = 4-0) and the interactions between pre-adsorbed H atom and TiCl x are studied by calculating adsorption energies E ads and interaction energies H Ti , respectively. The pre-adsorbed H atom significantly facilitates the adsorption of TiCl x on pyrolytic carbon surface. Specially, TiCl 3 adsorption on pyrolytic carbon surface converts from an endothermic process into an exothermic process due to the present of pre-adsorbed H atom. The calculation results of H Ti show that the interactions between pre-adsorbed H atom and TiCl x are attractive. The dissociation of TiCl 4 on pre-adsorbed H pyrolytic carbon surface is an exothermic process, and TiCl 4 → TiCl 3 is the limited step. The dissociation barriers of each step are less than 1.5 eV except for TiCl → Ti, which does not need to overcome any barriers, that is to say, once TiCl is adsorbed on pre-adsorbed H surface the reaction of TiCl → Ti spontaneously occurs. It thus can be concluded that the dissociation of TiCl 4 on pyrolytic carbon surface is a favorable process as long as H 2 molecular have decomposed into atomic H and adsorbed on pyrolytic carbon surface, and the intermediate species (TiCl 3 , TiCl 2 and TiCl) play an important role on the titanium CVD deposition. We also study the adsorption behavior of H atom and the dissociation behavior of H 2 molecular on pyrolytic carbon surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • ATT heterocyclic surfactant could adsorb on chalcopyrite interface and make it hydrophilic. • ATT can selectively and strongly depress chalcopyrite and has no obvious negative effect on molybdenite. • A four-coordination structure was formed through S-Cu and N -Cu bonds confirmed by XPS and DFT. • Water could strengthen the adsorption of ATT on chalcopyrite interface via DFTB+ method. Flotation is an interfacial chemical reaction in essence. The selective adsorption of flotation reagents on mineral surfaces leads to the transition of hydrophilicity/hydrophobicity of mineral particles, and then to regulate the floatability differences between various minerals. 5-amino-1,3,4-thiadiazole-2-thiol (ATT) is a heterocyclic ring compound, which can chelate copper ions easily and usually used as a copper corrosion inhibitor. Based on those good chelating properties with copper ions, this paper attempted to apply ATT as a chalcopyrite depressant in the flotation separation of Cu/Mo ores. The adsorption mechanism of ATT on chalcopyrite surface was explored by means of UV–vis, FTIR, contact angle and XPS analysis, and it revealed the possibility of ATT using as a selective chalcopyrite depressant in the flotation separation of Cu/Mo ores by micro-flotation tests. Finally, the adsorption morphology of ATT depressant on chalcopyrite surface was unveiled by DFT method from a microscopic level. Through these FTIR and XPS analysis, combined with DFT simulation results, it was inferred that ATT was mainly chemically adsorbed on chalcopyrite surface by S Cu and N Cu bonds. These studies confirmed that ATT was very likely to be an excellent chalcopyrite depressant in Cu/Mo flotation separation. [ABSTRACT FROM AUTHOR]

[Display omitted] • 2D Vs-Co@MoS 2 and 1D Rh@MoS 2 useful in adsorbing phenol were constructed successfully. • The stable phenol adsorption (η 6) relies the introduce of Co and Vs on MoS 2 surface. • Large number of active sites were the most attractive feather of Vs-Co@MoS 2. • Unique pocket-like configuration of HO-Mo-Rh 1 -Mo-OH caused high selectivity for phenol. As MoS 2 is a useful catalyst for phenol hydrodeoxidation, it is important to develop MoS 2 based catalysts. However, identifying active site remains challenging. In the present study, two monatomic catalysts, namely, Vs-Co@MoS 2 and Rh@MoS 2 , were prepared and on which the adsorption sites of phenol were investigated via density functional theory (DFT). By systemically comparing the adsorption configuration, adsorption energy and adsorption distance, we found that the most stable configuration of phenol on 2D Vs-Co@MoS 2 monatomic catalyst was from η6 adsorption mode (horizontal adsorption; adsorption energy, −1.51 eV; adsorption distance, 1.7 Å), and the adsorption site was the Co-Vs interface that formed by an isolated Co atom and its adjacent S vacancy (Vs) site. The density of state (DOS) analysis indicated the adsorption active sites originated from defect states and orbital hybridization distribution near Fermi level. As for 1D Rh@MoS 2 , the adsorption site was coming from the isolated Rh 1 atom, whose selectivity towards phenol was strengthened by the steric confinement effect of the unique pocket-like structure (Ho-Mo-Rh 1 -Mo-OH). It was hoped that this study would provide important ideas for exploring the hydrodeoxygenation mechanism of phenol compounds. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fe3O4@SiO2-IIP is prepared by surface imprinting technique with a sol–gel process. [•] Adsorption equilibrium of Pb(II) on Fe3O4@SiO2-IIP is reached within 10min. [•] Fe3O4@SiO2-IIP shows high adsorption capacity and good selectivity for Pb(II). [•] Fe3O4@SiO2-IIP shows high chemical stability and performs well after five runs. [•] Fe3O4@SiO2-IIP shows an excellent performance in Pb(II) removal from river water. [ABSTRACT FROM AUTHOR]

[Display omitted] • Structure and core level spectra of CoSi 2 -like to Co-rich silicides are discussed. • 200 ML Co on Si(1 1 1) forms a closed metallic Co thin film in contrast to 100 ML. • Thermostable CoSi 2 and Co-Si(1 1 1) ring clusters do not bind CO at RT. • CO adsorption at RT only occurs on Co-rich silicides and metallic Co. We report on the structure and reactivity of the Co-Si polycrystalline surfaces that form at room temperature (RT). Scanning tunneling microscopy (STM) was used to examine the surface morphology while X-ray photoelectron spectroscopy (XPS) was used to detect the chemical states of cobalt and silicon as a function of cobalt coverage. Moreover, XPS measurements after exposing the Co-Si(1 1 1) samples to CO gas provide information about CO adsorption and dissociation. When <5 ML Co is deposited on Si(1 1 1) at RT, most Co atoms diffuse into Si lattice and no CO adsorption is found at RT. This shows that coordination of Co to Si suppresses CO adsorption. Neither Co-induced Si(1 1 1)-ring cluster nor CoSi 2 crystalline film adsorb CO at RT. In contrast, CO adsorption was found at RT for cobalt doses >5 ML, an indication that Co-rich silicides and metallic Co present. The CO adsorption capacity increases with cobalt dose up to 30 ML after which it levels off, an indication that metallic cobalt sites are dominantly exposed on the surface. Furthermore, a closed metal film is formed for 200 ML dose. Some dissociation of CO was observed during heating of the CO-covered samples for Co doses ≥30 ML. [ABSTRACT FROM AUTHOR]

[Display omitted] • Adsorption of fatty acid potassium salts on diamond-like carbon substrates was studied based on structural and energetics analyses. • Effect of alkyl chain lengths and adsorptive conditions on molecular adsorption was studied. • The input energy during the energy-assisted adsorption plays an important role in the conversion from uneven adsorption to uniform adsorption of adsorbed molecules. • The Coulomb interactions play a dominant role in determining the adsorption behavior and structural properties of FAMS molecules on DLC substrates. Organic monolayers on solid substrates have received considerable attention due to their excellent versatilities in many fields. In this paper, molecular dynamics (MD) simulations were performed to study the adsorption of fatty acid potassium salts (FAPS) on diamond-like carbon (DLC) substrates. The results indicated that adsorbed molecules tend to aggregate on DLC surfaces due to the intense attractions between FAPS molecules. In order to obtain evenly distributed molecular films, the external energy input is needed to facilitate molecular adsorption and overcome the potential barriers. Also, the effects of alkyl chain lengths on molecular adsorption were investigated. A positive correlation was observed between the alkyl length and the adsorptive energy exerted by DLC substrates. Furthermore, the Coulomb interaction between adsorbed molecules is the most powerful interaction within the MD system. Affected by the Coulomb interactions, adsorbed molecules would undergo severe deformation. And a net-like structure composed of polar ends is formed in molecular films. The hollow area within the network is full of alkyl chains of molecules. It can be concluded that the powerful Coulomb interactions between adsorbed molecules play a dominant role in determining the adsorption behavior and structural properties of potassium salts on DLC substrates. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fluorescent dye (NP) was synthesized for visualising adsorption behavior of SDS. • SDS was preferentially adsorbed on the α-Mg phase via physicochemical adsorption. • Mg-SDS precipitation results in brighter fluorescence adsorption on the local sites. • The corrosion inhibition mechanism was proposed by experimental and theoretical. Corrosion inhibitors, have the characteristics of environmental friendly and high efficient, are widely used to inhibit the corrosion of alloys; however, their corrosion inhibition mechanism and adsorption behavior is still unclear. Herein, a cationic dye (1,8-naphthalenimide, NP) is synthesized for fluorescent visualisation of the sodium dodecyl sulfate (SDS) adsorption behavior on the α-Mg and β-Li phases. In-situ observation showed that obvious fluorescence adsorption preferentially appeared on the α-Mg phase via physicochemical adsorption. Moreover, stronger fluorescence intensity was observed on the local corrosion sites due to the precipitation of Mg-SDS complex. Micro-scale in situ observation under electrochemical control is applied to explain the inhibition mechanism from the perspective of corrosion kinetics. The inhibition efficiency is evidently improved (>90%) after the addition of SDS, and the optimum value reaches 95.1% at the SDS concentration of 0.04 M. Surface characterizations are conducted to validate the adsorption behaviour of SDS on the Mg alloy surface. The inhibition mechanism of SDS is proposed by experimental and theoretical calculations. This work advances the development and application of specific fluorescence tracking to elucidate the adsorption behaviour of corrosion inhibitors at the micro-level and provides a new idea for the development of efficient corrosion inhibitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cd2+ can be fast qualitatively/quantitatively detect and adsorbed to be removed. • Tetracycline can be effectively degraded to be removed by visible light irradiation. • The above two performances can be simultaneously achieved by using TiO 2 /DAT. • TiO 2 /DAT is highly potential to treat complex pollution thanks to its trifunction. Waste water is difficult to treat, mainly because of the co-existence of organic and inorganic contaminants, attracting much attention. Herein, a novel nanohybrid of TiO 2 /dicarboxylate 1,5-diphenyl-3-thiocarbazone(III) (denoted as TiO 2 /DAT) was facilely synthesized. TiO 2 /DAT was used to treat the waste water with the co-existence of tetracycline (TC) and Cd2+. The results indicated that TiO 2 /DAT can qualitatively/quantitatively detect Cd2+ via colorimetry, and the Cd2+ adsorption can boost the TC degradation by TiO 2 /DAT. It was found that the co-existence of TC does not affect the detection and adsorption of Cd2+. Furthermore, whether Cd2+ being adsorbed in advance or co-existent with TC, the TC degradation manners over TiO 2 /DAT were similar. A reasonable deduction for these phenomena is that Cd2+ was adsorbed by TiO 2 /DAT before TC, which was confirmed by density functional theory (DFT) calculations. So TC and Cd2+ will not compete the surface active sites of TiO 2 /DAT when treated simultaneously by TiO 2 /DAT, and that is why TiO 2 /DAT can effectively treat TC and Cd2+ co-existent waste water. Upon TiO 2 /DAT, the treating strategies of detection, adsorption and degradation are combined into one functional material. This one stone three birds strategy can simplify the treating process of complex pollution systems, exhibiting highly promising in practical applications. [ABSTRACT FROM AUTHOR]

Adsorption behavior of thiadiazole derivatives, 2,5-bis(ethyldisulfanyl)-1,3,4-thiadiazole (DTA), dimercapto-1,3,4-thiadiazole (DMDT) as anticorrosion additives at copper oxide surface were studied by first-principles calculations, weight loss, electrochemical and surface characterization techniques. The adsorption energies calculated by density functional theory (DFT) were less than 0.3 eV, DTA and DMDT physically adsorbed on the copper surface and cannot replace the oxygen atom at the top site of the Cu O slab models. The predicted physically interaction of the corrosion inhibitor on the copper surface, which was basically consistent with the results of XPS analysis and surface microtopography. It was shown that in the presence of DTA and DMDT adsorbed on copper surface depress the reaction rate of anodic dissolution and cathodic hydrogen evolution and obey Langmuir isotherm. Surface findings indicated the inhibitor film formed at copper surface can block corrosion and improve hydrophobicity. Unlabelled Image • Adsorption behavior of DTA and DMDT as anticorrosion additives at Cu-O surface was studied by DFT and experimental. • DTA and DMDT cannot replace the oxygen atom at the top site of the Cu O slab models. • Inhibitor film formed at copper-oxide surface can block corrosion and improve hydrophobicity. [ABSTRACT FROM AUTHOR]

Abstract Understanding the method of inducing magnetism and the source of magnetism in two-dimensional (2D) materials is essential for the development of spintronic devices. Here, we present a spin-polarized first-principles study on the electronic and magnetic properties of a ZnO monolayer with adsorbed noble metals NM (NM = Pd, Pt, Ag, Au, Cu). The results demonstrate that the most preferable adsorption sites for all the considered noble metals NM (NM = Pd, Pt, Ag, Au, Cu) are located on top of the O atoms (T O). Furthermore, both Pd and Pt adsorbed on the ZnO monolayer remain nonmagnetic. Interestingly, sufficient Ag, Au, and Cu adsorbates can induce magnetic properties, and the magnetic moments mainly originate from the adsorbates. Moreover, as the distance between the two atoms of the same element (Ag, Au, or Cu) increases, the ZnO monolayer undergoes FM-AFM transitions, which expand the utilization of ZnO monolayers in nanoelectronics and spintronics. These results may pave the way for future experiments based on 2D noble metal-adsorbed ZnO materials, which can serve as potential materials in nanoelectronics and spintronics. Graphical abstract Unlabelled Image Highlights • The most stable adsorption sites are the same for NM atoms (NM = Pd, Pt, Ag, Au, Cu). • The covalent chemical bonding character between NM adatom and ZnO monolayer is found. • The magnetic properties of Ag, Au, and Cu adsorbed systems mainly originate from the adsorbates. • The electronic and magnetic properties of ZnO monolayer can be effectively modulated by NM adsorption. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The ultrahigh stiffness, good conductivity and excellent Li migration capability of C 3 N. • The adsorption and diffusion mechanisms of Li in pristine and defect-containing C 3 N. • The trap effect in defect-containing C 3 N. Abstract Two-dimensional single-layer C 3 N has attracted extensive attentions currently owing to its excellent mechanical and electronic properties. In this work, as a potential anode material in lithium-ion battery, the pristine and defect-containing C 3 N are systematically studied base on first-principles calculations. The results show pristine C 3 N might has great potential in the application of lithium-ion batteries due to its excellent stiffness (Young's modulus is 364.33 N m−1), high storage capacity (1071.56 mA h g−1), good electronic conductivity (bandgap is 0.39 eV), and lithium migration capability (energy barrier is 0.27 eV). We further investigate the adsorption and diffusion mechanisms of lithium ion in C 3 N with and without vacancy defect and find out as an anode material, it is vital to control defects of C 3 N to improve the performance of lithium ion batteries. These studies could deepen the understanding of perfect and defect-containing two-dimensional materials and provide a guidance for the application of CN-based material in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Highlights: • Clarify the effect of vacancy on H 2 S dissociation and H atom diffusion on Fe(1 0 0) surfaces. • Demonstrate the effects of adjacent vacant atom on H atom diffusion. • Reveal the minimum energy-diffusion path of the H atom from the Fe(1 0 0) surfaces into the bulk Fe. Abstract Vacancy defects on an iron surface have a great influence on the occurrence of hydrogen embrittlement. The adsorption/dissociation mechanism of H 2 S and the diffusion behavior of H atoms were calculated by first-principles spin-polarization density functional theory (DFT) on defect-free and vacancy-defective Fe(1 0 0) surfaces. The results show that the maximum dissociation energy barriers of H 2 S on the Fe(1 0 0) surface of defect-free and first-layer vacancy-defective Fe are 0.35 and 0.17 eV, respectively, indicating that the reactivity of the vacancy-defective Fe(1 0 0) surface is moderately increased. The existence of vacancy defects changes the preferential H atom diffusion entrance to the subsurface and shortens the diffusion path. For H diffusion in bulk Fe(1 0 0), it is found that H atoms diffuse via a tortuous path from one tetrahedral-site to a neighboring tetrahedral-site rather than diffusing through a linear trajectory. Moreover, the previously suggested path via the octahedral site is excluded due to its higher barrier and the rank of the saddle point. Diffusion barriers computed for H atom penetration from the surface into the inner-layers are approximately 0.54 eV (except for second-layer vacancy defects), which are all greater than the activation energy for dissociation of H 2 S on the Fe(1 0 0) surfaces. This suggests that H diffusion is more probable than H 2 S dissociation as the rate-limiting step for hydrogen permeation into the bulk Fe(1 0 0). [ABSTRACT FROM AUTHOR]

[Display omitted] • The introduced copper can weaken Mn-O bond and produce more surface lattice oxygen. • Cu 1 Mn 5 O x showed excellent activity over a wide temperature range (50–275 °C). • In situ tests revealed species involved in adsorption and activation of styrene. • The degradation of benzoic acid is the rate-limiting step of styrene oxidation. Copper-manganese composite oxides have been extensively researched for the catalytic oxidation of volatile organic compounds (VOCs), but there is little understanding of the adsorption and activation of VOCs over these compounds. In this work, a series of amorphous Cu-Mn binary oxides with varying Cu/Mn ratios were prepared to explore their catalytic performance and the species involved in the adsorption and activation of styrene (C 8 H 8). It was found that Cu 1 Mn 5 O x demonstrated better catalytic activity among the four samples, better stability and water resistance due to the presence of more structural flaws, weaker Mn-O bonds and more surface lattice oxygen species. In situ designed experiments showed that the adsorbed oxygen species, O 2 , lattice oxygen, and copper species all played roles in the adsorption and activation of C 8 H 8 at low temperatures. The degradation route for C 8 H 8 was revealed by in situ DRIFTS, and benzoic acid decomposition was identified as the rate-limiting step of C 8 H 8 degradation. This work provides a novel technique for regulating the synergistic adsorption and catalytic ability of amorphous bimetallic oxides to remove VOCs. [ABSTRACT FROM AUTHOR]

Vanadium dioxide (VO 2 ) has attracted great attention, with scientific and technological advances over the past few decades due to its reversible metal-insulator transition at 340 K. However, the high phase transition temperature ( T c ) of VO 2 limits its practical applications. Our first-principles calculations show that VO 2 (1 1 0) surfaces with adsorbed noble metals (Ag, Au, Pt) exhibit a lower work function compared with the clean surface and further induces a lower T c due to charge transfer from the noble metals to the VO 2 (1 1 0) surface. However, the work functions of the VO 2 (1 1 0) surfaces after the incorporation of noble metals are higher than that of the clean surface. In addition, the results of formation energies of various configurations show that the VO 2 (1 1 0) surface with the adsorption and incorporation of Ag is energetically more favorable than those with Au and Pt. Therefore, it may be concluded that the adsorption and incorporation of noble metals can not only tailor the work function of VO 2 , in turn realizing the rational tuning of T c of VO 2 , but also stabilize the structures of VO 2 thin films. These results provide guidance for further exploration of VO 2 -based optical switching devices and smart windows. [ABSTRACT FROM AUTHOR]

The adsorption and dissociation of H 2 S on Rh(100) surface have been investigated using self-consistent periodic density functional theory. The adsorption mechanisms on Rh(100) surface of H 2 S, HS, H and S were examined. It is found that H 2 S is weakly adsorbed on bridge, top and hollow sites with their adsorption energies of −0.98, −0.86 and −0.82 eV, respectively. In contrast to H 2 S, HS is strongly chemisorbed on Rh(100) surface at hollow, top and bridge site with the adsorption energies of −4.33, −4.31 and −3.85 eV, whereas S and H preferred to be absorbed at hollow site. By using climbing nudged elastic band method (CI-NEB), we found the four most feasible paths for H 2 S dissociation on Rh(100), with energy barriers of 0.19 eV, 0.25 eV, 44 meV and 98 meV, respectively. The energy barrier to break the S-H bond of HS with H co-adsorption or without H co-adsorption was almost the same low. This study reveals that H 2 S decomposition on Rh(100) surface is a facile process both kinetically and thermodynamically. [ABSTRACT FROM AUTHOR]

[Display omitted] • Using CMC alone was unable to achieve Cu-As separation. • Ca2+ selectively enhanced the depressive effect of CMC towards arsenopyrite. • The hydroxyl calcium ions selectively adhered on arsenopyrite surface. • Hydroxyl calcium ions further enhanced CMC adsorption through its bridging effect. The rejection of arsenopyrite during chalcopyrite flotation is crucial to prevent the arsenic pollution to the ecosystem. Herein, surface modification by calcium ions coupled with the carboxymethyl cellulose (CMC) were successfully used to achieve Cu-As separation. Flotation results confirmed that the depressive effect of CMC alone towards arsenopyrite was unsatisfactory, but it was greatly enhanced in the presence of calcium ions (Ca2+), thus the As content in copper concentrate was lowered significantly. Mechanism research indicated that the wettability of arsenopyrite caused from CMC was strongly enhanced by the pretreatment with Ca2+, while that of chalcopyrite increased slightly. Reagent adsorption and FTIR spectra measurements further illustrated the adsorption of CMC on arsenopyrite was facilized by Ca2+, but that on chalcopyrite remained very weak. More detailed adsorption mechanisms uncovered by XPS and DFT calculations demonstrated that the Fe, As and S atoms of arsenopyrite were unactive and thus unable support the chemisorption of CMC. Nevertheless, hydroxyl calcium ions adhered on the surface of arsenopyrite after interaction with Ca2+. Furthermore, the electrophilic strength of the adhered hydroxyl calcium ions was stronger than that of pristine arsenopyrite surface, ultimately, CMC chemisorbed on arsenopyrite surface through the bridging effect of adhered hydroxyl calcium ions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Activity and K-resistance of FZCT/TNT catalyst are enhanced by H 2 SO 4 pretreatment. • H 2 SO 4 pretreatment obviously enhances the surface acidity of FZCT/TNT catalyst. • Adsorption strength of NO x on KFZCT/TNT catalyst is weakened by H 2 SO 4 pretreatment. • H 2 SO 4 pretreatment changes the L-H mechanism of FZCT/TNT catalyst to E-R mechanism. CeTiO x catalyst has attracted extensive attention for its superior activity and N 2 selectivity for NH 3 -SCR reaction. However, it still suffers a lot from the deactivation by alkali metals. Thus, it is vital to develop some novel alkali-resistant CeTiO x catalysts for application. In this work, we loaded FeZrCeTiO x component on TiO 2 nanotube (TNT) support to obtain FeZrCeTiO x /TNT (FZCT/TNT) catalyst, and then simply pretreated it with H 2 SO 4 to obtain H 2 SO 4 -pretreated FeZrCeTiO x /TNT (SFZCT/TNT) catalyst. Besides, the effects of H 2 SO 4 pretreatment on catalytic performance, alkali-resistance as well as physicochemical properties of FZCT/TNT catalyst are comprehensively analyzed. The results manifest that excellent catalytic performance and alkali-resistance (mainly in 350–500 °C) are both achieved by simple H 2 SO 4 pretreatment with only small amounts of active components. This can be mainly attributed to the enhanced acid sites (especially B acid), the prompted adsorption and activation of NH 3 species and the inhibited too strong adsorption strength of NO x species. [ABSTRACT FROM AUTHOR]

In this paper, a simple and versatile approach for the fabrication of a polyethyleneimine (PEI)-functionalized nanofibrous membrane utilizing polydopamine (PDA) as a mediator is proposed. The morphology and structure of the PDA-coated and PEI-grafted nanofibrous membranes were confirmed using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Due to a large specific surface area and long fibrous morphology, the synthesized membranes were used as novel adsorbents for copper ion (Cu 2+ ) removal from aqueous solutions. The adsorption of Cu 2+ was investigated on the synthesized membranes regarding the membrane dosages, initial solution pH values, initial solution concentrations, contact times and temperatures. In addition, the adsorption equilibrium data of PEI-grafted membranes were well fitted with the Langmuir adsorption isotherm, and a maximum adsorption capacity value of 33.59 mg g −1 was determined (while it was 21.94 mg g −1 for the PDA-coated membranes). The thermodynamic parameters indicated that Cu 2+ absorption was a spontaneous and exothermic adsorption process. In addition, XPS peak differentiation imitating analysis permitted the proposal of a copper-amine coordination adsorption mechanism that can be used to explain changes in the adsorption properties compared to PDA coating nanofibrous membranes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Doped Sm activate surface adsorbed oxygen and increase the acid content. • The bidentate nitrates adsorbed on Sm 0.2 MnTiSnO y participate in the NH 3 -SCR reaction. • Sm 0.2 MnTiSnO y follows Langmuir-Hinshelwood (L-H) mechanism. NO x is one of the main sources of air pollution, and the abatement of NO x emission has aroused increasing attention. The NH 3 -SCR technology is mature and widely used for controlling NO x emissions from fixed sources. In this work, Sm x MnTiSnO y was synthesized by a mixed solvothermal synthesis. The NH 3 -SCR performance of Sm x MnTiSnO y was tested and the H 2 O and SO 2 resistance of Sm 0 MnTiSnO y , Sm 0.1 MnTiSnO y , and Sm 0.2 MnTiSnO y catalysts (5 %H 2 O, 25 ppm SO 2) were tested at 250 °C. The physicochemical properties of Sm x MnTiSnO y were studied by XRD, FESEM, TEM, BET, XPS, H 2 -TPR, NH 3 -TPD and In-situ DRIFTS. The experimental results reveal that Sm 0.2 MnTiSnO y has a better low-temperature NH 3 -SCR performance and splendid H 2 O and SO 2 durability. Moreover, appropriate Sm doping increases the specific area and enhances the acidity of the catalyst's surface. The In-situ DRIFTS results suggest that the adsorption and activation of NH 3 are of primary importance in the NH 3 -SCR reaction. Besides, a large number of weak acid sites on Sm 0.2 MnTiSnO y are conducive to adsorb and activate NH 3 and good redox ability facilitates the activation of bidentate nitrate, respectively. Meanwhile, Sm doping could transfer electrons from the Sm species to the Mn species, which inhibits the formation of Mn sulfate. [ABSTRACT FROM AUTHOR]

Abstract: H2O inhibits the SCR performance of the Ce-Cu-Ti (CCT) oxide catalyst at low temperatures, while it promotes SCR performance at high temperatures above 300°C. A combination of experiments and DFT calculations was applied to study this phenomenon. NH3 adsorption profiles showed that the presence of H2O would greatly decrease the NH3 adsorption amount, especially the weakly adsorbed NH3 part. The DFT calculations of H2O and NH3 adsorption on the CCT catalyst showed that the presence of H2O would compete with NH3 to be adsorbed on the catalyst. NH3 oxidation experiments indicated that NH3 oxidation at high temperatures decreases with the addition of 10% H2O. The DFT calculation also indicated that H2O would inhibit NH3 oxidation. The inhibition effect of H2O at low temperatures could be attributed to the competing adsorption of H2O with NH3. The promotional effect of H2O at high temperatures was due to the inhibition of NH3 oxidation. [Copyright &y& Elsevier]

Abstract: The morphology of a chromium-free conversion coating for AZ91D magnesium alloy was observed with an Atomic Force Microscopy. The results showed the uniform conversion coating has a relatively smooth appearance with shallow valleys. The EDX results indicated that the compositions of the coating were mainly compounds of Mg, Al, Mn, P, Ca and O. The XRD result showed that the coating contained amorphous materials and a small quantity of crystalline compound. The pitting product of the coating in NaCl water solution mainly composed of Mg, Cl, Mn, P, Ca and O. The corrosion behavior of the samples in NaCl solution was also studied by electrochemical impedance spectroscopy (EIS), which was characterized by one capacitive loop and one inductive loop. Based upon study on both a mathematical model for Faradic admittance of coating in NaCl solution and EIS, it could be considered that the inductive loop was caused by the adsorption of Cl anion and the appearance of pitting corrosion. A degradation mechanism of the coating in NaCl solution is set forth: dissolution velocity of the Cl− adsorption regions of the coating is higher than those non-adsorption regions, for Cl− anions are selective adsorption at some regions of coating surface. When the adsorption regions of coating layer are penetrated by dissolution, the pitting comes into being. The degradation mechanism of conversion coating and the mathematical model are consistent with the EIS results, polarization measurement results and coating''s corrosion test results. [Copyright &y& Elsevier]

[Display omitted] • XG depressed dolomite powerfully but barely influenced the flotation of apatite. • XG was tended to adsorb on dolomite due to much more dense Ca sites exposed. • XG was chelated strongly through COOH or OH groups with Ca sites on dolomite. • The pre-adsorption of XG hindered the adsorption of NaOL on dolomite. • XG could remarkably improve the removal efficiency of dolomite from apatite. In this work, xanthan gum (XG) was exploited as a novel dolomite depressant in the flotation separation of apatite from dolomite in sodium oleate system. The flotation performances and adsorption mechanism of XG towards apatite and dolomite were studied through flotation tests, adsorption capacity measurements, micro-heat tests, atoms density calculations and surface characterizations. Flotation results revealed that XG exhibited strong depression effect on dolomite but barely influenced the flotation of apatite. The results of zeta potential, infrared spectroscopy analysis, adsorption capacity measurements and micro-heat tests proved that XG trended to adsorb on dolomite other than apatite, which hindered the adsorption of NaOL on dolomite and rendered the surface hydrophilic. Atom density calculations indicated that the preferential adsorption of XG on dolomite was due to much more dense and active Ca sites on dolomite surface than that of apatite. XPS results suggested that XG was strongly adsorbed on dolomite surface by means of chelation between COOH or OH groups within XG and Ca sites on dolomite, while it was weakly adsorbed on apatite by hydrogen bonding between OH groups within XG and F atoms on apatite surface. [ABSTRACT FROM AUTHOR]

• Adsorption energy can be tuned for C 6 H 6 and C 7 H 8 on Pd and Pt mediated ZnO monolayer. • Band gaps and apparent charge transfer could be realized by Pd or Pt mediated. • Pd- and Pt-ZnO exhibit a higher sensitivity and selectivity to C 6 H 6 and C 7 H 8. • Pd- and Pt-ZnO monolayer serve a potential application as C 6 H 6 and C 7 H 8 sensors. ZnO monolayers, as typical two-dimensional materials, have attracted considerable interests for gas-sensing applications due to their ultralarge theoretical specific surface area and unique electronic properties. Here, using first-principles calculations, the adsorption behaviors of C 6 H 6 and C 7 H 8 molecules on pristine and metal (Pd, Pt)-mediated ZnO monolayers including the adsorption energy, charge transfer, band structure, and recovery time, are systematically investigated. The results show that C 6 H 6 and C 7 H 8 molecules on pristine and metal (Pd, Pt)-mediated ZnO monolayers are energetically favorable. The adsorption energies for C 6 H 6 and C 7 H 8 molecules on the metal-adsorbed (Pd, Pt) ZnO monolayer range from −2.631 eV to −1.986 eV, while the adsorption energies range from −1.023 eV to −0.785 eV for C 6 H 6 and C 7 H 8 molecules on the metal-doped (Pd, Pt) ZnO monolayer, indicating that metal (Pd, Pt) mediation can greatly enhance the adsorption ability of the ZnO monolayer to C 6 H 6 and C 7 H 8 molecules. Moreover, the band gaps of C 6 H 6 and C 7 H 8 molecules on the ZnO monolayer could be greatly modulated by metal (Pd, Pt) doping. More importantly, the moderate adsorption energies and short recovery time suggest that metal-doped (Pd, Pt) ZnO monolayers are the promising C 6 H 6 and C 7 H 8 sensors with high selectivity and sensitivity, and good reversibility. The current results provide insight into the adsorption behavior of metal-mediated ZnO monolayers upon C 6 H 6 and C 7 H 8 molecules, which could promote the further application of ZnO-based materials in the gas-sensing field. [ABSTRACT FROM AUTHOR]

• ZrOx/porous carbon nanocomposites with tunable specific surface area and pore volume was prepared. • The regulatory mechanism of the specific surface area and pore volume was revealed. • The specific surface area of the nanocomposites reached to 468.9 m2 g−1. • The nanocomposites exhibited a high adsorption performance for the removal of carbamazepine. • The main adsorption interaction is the π-π electron donor-acceptor interaction. Nanoarchitecture design of metal oxides/porous carbon nanocomposites from metal-organic frameworks is attracting considerable attention. Herein, UiO-66 was used as precursor and template to fabricate zirconia/porous carbon nanocomposites with tunable specific surface area and pore volume by a two-step calcination. The results showed that the tetragonal ZrO 2 nanoparticles in carbon matrix gradually grow up and transform into monoclinic ZrO 2 and ZrO as well as escape from the porous carbon nanocubes resulting in the increase of their specific surface area and pore volume with the increase of calcination temperature. The as-prepared nanocomposites at 1200 °C (ZPCNCs-12) exhibited a high specific surface area up to 468.9 m2 g−1, and excellent adsorption performance with high adsorption capacity (190 mg g−1), fast adsorption equilibrium (60 min) and recyclability for the removal of carbamazepine from water in a wide pH range of 2–12. FTIR spectra suggested that the adsorption of carbamazepine on ZPCNCs-12 was physical, and XPS results further confirmed that the adsorption was mainly dominated by the π-π electron donor-acceptor interaction between carbamazepine molecule and carbon nanocubes. It indicates that the two-step calcination of metal-organic frameworks is an effective approach to fabricate highly efficient sorbent for the removal of organic pollutants from water. [ABSTRACT FROM AUTHOR]