Presence Of NH Research Articles

Nitrogen and magnesium Co-doped biochar for phosphate adsorption

In this paper, nitrogen-doped (ND) and nitrogen-magnesium co-doped (NMD) chars were synthesized by different combinations of pyrolysis-activation steps of anaerobically digested fiber (ADF), wheat straw (WS), and Douglas fir wood (DFW) to adsorb phosphate from aqueous solutions. Five different series of char were produced through different methods: (1) biomass pyrolyzed under N2, (2) biomass pyrolyzed under N2 followed by activation with ammonia, (3) biomass pyrolyzed and char activated both in the presence of NH3, (4) biomass impregnated with MgCl2 pyrolyzed under N2, and (5) biomass impregnated with MgCl2 pyrolyzed under NH3. Proximate analysis, elemental composition, gas physisorption, inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) techniques were used to characterize the resulting chars. All the chars derived from ADF (independent of the procedure used) showed the best phosphate adsorption capacity, likely due to their higher ash content. Pyrolysis of ADF under NH3 resulted in char with phosphate adsorption capacity of 95 mg/g (254% higher than char produced under N2). Results from kinetic study show almost all phosphate adsorption by ND-ADF (one step) char occurred within 2 h. Richie nth-order model fits well the sorption process indicating that phosphate adsorption on the surface of the ND-ADF (one step) char was mediated by multiple mechanisms. Equilibrium data were fitted to different adsorption isotherms and the Langmuir-Freundlich and Redlich Peterson adsorption models provided the best fit. We hypothesized that the presence of Ca and Mg in the ADF enhanced N fixation and leads to higher phosphate adsorption. Therefore, we studied the effect of MgCl2 impregnation on DFW and WS pyrolyzed and activated under NH3. Our hypothesis was confirmed, and DFW and WS chars doped with Mg and N showed phosphate adsorption of 216 and 122 mg/g, respectively (37- and 24-fold increase compared with chars produced only under N2).

Unraveling the nature of sulfur poisoning on Cu/SSZ-13 as a selective reduction catalyst

In order to investigate sulfate poisoning of Cu/SSZ-13 catalysts used for NOx removal by selective catalytic reduction with ammonia (NH3-SCR), they were exposed to SO2 at different temperatures in the presence and absence of NH3. Standard physicochemical characterization and density functional theory calculations were performed to probe the nature of the sulfate species formed on the catalyst and the corresponding effects. The results showed that sulfate poisoning has little effect on the chabazite structure of the catalyst, but the sulfate species formed blocks the Cu/SSZ-13 pores. For sulfation with pure SO2, copper bisulfate forms and its content increases with sulfation temperature. However, in the presence of NH3, the major sulfate formed is ammonium bisulfate (~80%). Moreover, the total sulfate contents are lower for higher sulfation temperatures because of difficulties in ammonium bisulfate formation. Regardless of the kind of sulfate species formed, the poisoning leads to lower availability of active sites, causing inferior NOx conversion. Importantly, as copper bisulfate and ammonium bisulfate on Z-Cu(OH)+ are interconvertible, our study reveals that using NH3 to promote the transformation from copper bisulfate to ammonium bisulfate is a viable method to improve the recovery effect of sulfated Cu/SSZ-13.

Hydrazine Formation via Coupling of a Nickel(III)–NH2 Radical

AbstractM(NHx) intermediates involved in N−N bond formation are central to ammonia oxidation (AO) catalysis, an enabling technology to ultimately exploit ammonia (NH3) as an alternative fuel source. While homocoupling of a terminal amide species (M‐NH2) to form hydrazine (N2H4) has been proposed, well‐defined examples are without precedent. Herein, we discuss the generation and electronic structure of a NiIII‐NH2 species that undergoes bimolecular coupling to generate a NiII2(N2H4) complex. This hydrazine adduct can be further oxidized to a structurally unusual Ni2(N2H2) species; this releases N2 in the presence of NH3, thus establishing a synthetic cycle for Ni‐mediated AO. Distribution of the redox load for H2N‐NH2 formation via NH2 coupling between two metal centers presents an attractive strategy for AO catalysis using Earth‐abundant, late first‐row metals.

Hydrazine Formation via Coupling of a Nickel(III)-NH2 Radical.

M(NHx ) intermediates involved in N-N bond formation are central to ammonia oxidation (AO) catalysis, an enabling technology to ultimately exploit ammonia (NH3 ) as an alternative fuel source. While homocoupling of a terminal amide species (M-NH2 ) to form hydrazine (N2 H4 ) has been proposed, well-defined examples are without precedent. Herein, we discuss the generation and electronic structure of a NiIII -NH2 species that undergoes bimolecular coupling to generate a NiII 2 (N2 H4 ) complex. This hydrazine adduct can be further oxidized to a structurally unusual Ni2 (N2 H2 ) species; this releases N2 in the presence of NH3 , thus establishing a synthetic cycle for Ni-mediated AO. Distribution of the redox load for H2 N-NH2 formation via NH2 coupling between two metal centers presents an attractive strategy for AO catalysis using Earth-abundant, late first-row metals.

Insight into carbohydrate polymers (chitosan and 2- hydroxyethyl methacrylate/methyl methacrylate) intercalated bentonite-based nanocomposites as multifunctional and environmental adsorbents for methyl parathion pesticide

Two-hybrid products of bentonite intercalated carbohydrate polymers (chitosan (BE.P.CH) and 2- hydroxyethyl methacrylate/methyl methacrylate copolymer (BE/P.HEMA/MMA)) were synthesized as enhanced adsorbents for methyl parathion pesticide (MPP). The intercalation processes induced the affinity and the capacity of bentonite achieving the best value at pH 8. The maximum MPP adsorption capacities of BE (287.3 mg/g), BE/P.CH (634.5 mg/g), and BE/P.HEMA-MMA (868.5 mg/g) obtained after 300 min, 240 min, and 360 min, respectively. The kinetic properties of BE follow the Pseudo-second order behavior (R2 = 0.93) while BE/P.CH and BE/P.HEMA-MMA are of Pseudo-First order behavior (R2 > 0.92). Based on the equilibrium studies, the three products are of Freundlich isotherm behavior (R2 > 0.9) and the uptake is of multilayer forms on heterogeneous surfaces. The Gaussian energies (>8 KJ/mol), Gibbs free energies (>20 to <40 KJ/mol), and enthalpies (>40 to <80 KJ/mol) give an indication about adsorption mechanism involved chemical and physical reactions. The thermodynamics of MPP uptake reactions by the three products are of endothermic and spontaneous behaviors. The MPP uptake in the presence of NH+4, PO4−3, Mn+2, and Pb+2 competitive ions reflects enhancement in the affinity of BE after the integration between it and the selected polymers.

Direct contribution of ammonia to &amp;lt;i&amp;gt;α&amp;lt;/i&amp;gt;-pinene secondary organic aerosol formation

Abstract. Ammonia (NH3), a gaseous compound ubiquitously present in the atmosphere, is involved in the formation of secondary organic aerosol (SOA), but the exact mechanism is still not well known. This study presents the results of SOA experiments from the photooxidation of α-pinene in the presence of NH3 in the reaction chamber. SOA was formed in in nucleation experiments and in seeded experiments with ammonium sulfate particles as seeds. The chemical composition and time series of compounds in the gas and particle phase were characterized by an online high-resolution time-of-flight proton-transfer-reaction mass spectrometer (HR-ToF-PTRMS) and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), respectively. Our results show that the mass concentration of ammonium (NH4+) was still rising even after the mass concentration of the organic component started to decrease due to aerosol wall deposition and evaporation, implying the continuous new formation of particle-phase ammonium in the process. Stoichiometric neutralization analysis of aerosol indicates that organic acids have a central role in the formation of particle-phase ammonium. Our measurements show a good correlation between the gas-phase organic mono- and dicarboxylic acids formed in the photooxidation of α-pinene and the ammonium in the particle phase, thus highlighting the contribution of gas-phase organic acids to the ammonium formation. The work shows that the gas-phase organic acids contribute to the SOA formation by forming organic ammonium salts through acid–base reaction. The changes in aerosol mass, particle size and chemical composition resulting from the NH3–SOA interaction can potentially alter the aerosol direct and indirect forcing and therefore alter its impact on climate change.

Differences in oxidation-reduction kinetics and mobility of Cu species in fresh and SO2-poisoned Cu-SSZ-13 catalysts

Fresh and SO2-poisoned Cu-SSZ-13 selective catalytic reduction (SCR) catalysts were studied using near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) in the presence of NH3, O2, and NO, as well as by in situ X-ray absorption spectroscopy (XAS) using H2, He, and CO. In contrast to the fresh catalyst, inhibited reduction of Cu-species and the absence of Cu-metal nanoparticles was found in the SO2-poisoned catalyst during heating/cooling in H2 and CO. High structural disorder and differences in the formation of Cu-carbonyl species were seen for the SO2-poisoned catalyst compared to the fresh catalyst. Suppressed oxidation-reduction and low mobility of Cu-species during exposure to NH3-SCR-related gases were observed in the SO2-poisoned catalyst, unlike in the fresh catalyst. These observations help explain catalyst deactivation during the standard NH3-SCR reaction. The formation of Cu-metal nanoparticles in the fresh catalyst revealed another possible deactivation pathway for the SCR-catalyst in combined LNT-SCR systems during fuel-rich periods.

Genetics and regulation of nitrogen fixation in Paenibacillus brasilensis PB24

Biological nitrogen fixation (BNF), performed by diazotrophic prokaryotes, is responsible for reducing dinitrogen (N2) present in the biosphere into biologically available forms of nitrogen. Paenibacillus brasilensis PB24 is a diazotrophic Gram-positive bacterium and is considered ecologically and industrially important because it is able to produce antimicrobial substances and 2,3-butanediol. However, the genetics and regulation of its nitrogen fixing (nif) genes have never been assessed so far. Therefore, the present study aimed to (i) identify the structural and regulatory genes related to BNF in the PB24 genome, (ii) perform comparative genomics analysis of the nif operon among different Paenibacillus species and (iii) study the expression of these genes in the presence and absence of NH4. Strain PB24 showed a nif operon composed of nine genes (nifBHDKENXhesAV), with a conserved synteny (with small variations) among the Paenibacillus species evaluated. BNF regulatory genes, glnK and amtB (encoding GlnK signal transduction protein and AmtB transmembrane protein, respectively) and glnR and glnA genes (encoding the transcription factor GlnR and glutamine synthetase) were found in the PB24 genome. Primers were designed for qPCR amplification of the nitrogenase structural (nifH, nifD and nifK) and regulatory (glnA and amtB) BNF genes. The structural gene expression in PB24 was up- and downregulated in the absence and presence of NH4, respectively. The gene expression levels indicated a GlnR-mediated repression of genes associated with ammonium import (amtBglnK) and BNF (nif genes). Additionally, the regulatory mechanism of GlnR in P. brasilensis PB24 differed from the other Paenibacillus evaluated, considering the different distribution of binding sites recognized by GlnR.

Hydrogen production from thermal decomposition of ammonia-contaminated acid gas using a detailed reaction mechanism

The increase in the production of acid gas consisting of H2S, CO2, and associated impurities such as ammonia and hydrocarbons from oil and gas plants and gasification facilities has stimulated the interest in the development of alternative means of acid gas utilization to produce hydrogen and sulfur, simultaneously. The present literature lacks a detailed reaction mechanism that can reliably predict the thermal destruction of NH3 and its blend with H2S and CO2 to facilitate process optimization and commercialization. In this paper, a detailed mechanism of NH3 pyrolysis is developed and is merged with the reactions of NH3 oxidation and H2S/CO2 thermal decomposition from our previous works. The mechanism is validated successfully using different sets of experimental data on the pyrolysis and oxidation of NH3, H2S, and CO2. The proposed mechanism predicts the experimental data on NH3 pyrolysis remarkably better than the existing mechanisms in the literature. The mechanism is used to investigate the effects of NH3 concentration (0–20%) and reactor temperature (1000–1800 K) on the thermal decomposition of H2S and CO2. A synergistic effect is observed in the simultaneous decomposition of NH3 and CO2, i.e., NH3 conversion is improved in the presence of CO2 and the decomposition CO2 to CO is enhanced in the presence of NH3. The presence of H2S suppressed NH3 conversion, while the conversion of H2S remained unchanged with increasing NH3 concentration at temperature below 1400 K due to the low conversion of NH3 (up to 18%). At temperature above 1400 K, NH3 conversion increased rapidly and it triggered a decrease in H2S conversion as well as the yields of H2 and S2. The major reactions involved in the decomposition of H2S, CO2, and NH3 and the production of major products such as H2, S2, and CO are identified. The detailed reaction mechanism can facilitate the design and optimization of acid gas thermal decomposition to produce hydrogen and sulfur, simultaneously.

The synthesis of heteroleptic cyanometallate aminopyridine complexes and an investigation into their structural properties with various spectroscopic methods

In this study, three new transition metal(II) complexes consisting of zinc(II), mercury(II) atoms, cyanide group (CN), 3-aminopyridine (3AP) and 4-aminopyridine (4AP) ligand molecules were successfully synthesized in a single crystal form. The formulas of these newly synthesized heteroleptic cyanometalate aminopyridines complexes are given as [Zn(II)(3AP)2(CN)2], [Zn(II)(4AP)2(CN)2] and [Hg(II)(4AP)2(CN)2]. The crystal structures of these heteroleptic cyanometalate complexes were characterized by spectral analysis including single crystal X-ray diffraction techniques, FT-IR, and thermal analysis. The FT-IR and single crystal XRD spectra of these complexes were recorded in the 3750–250 cm−1 wavenumber range and in the region of about 3–29°, respectively. In addition, the thermal analysis curves of these complexes were recorded in the temperature range of 40–850 ℃ using TG, DTG, and DSC methods. The structural properties of these complexes are explained with reference to the changes in their characteristic peaks belonging to 3AP, 4AP ligand molecules and cyanide group in their FT-IR spectra. The most important feature of these new complexes is the presence of NH···N interactions between the H atom of the NH2 group of the 3AP and 4AP ligand molecules and the nitrogen atom of the CN group. These interactions play the most important role in the realization of the three-dimensional structure of the new heteroleptic cyanometalate complexes in crystal form. According to the spectral data of the newly obtained heteroleptic cyanometalate complexes, the complex with 3AP has the orthorhombic crystal system and the space group Pca21, whereas the other two heteroleptic cyanometalate complexes with 4AP have in the monoclinic crystal system and the C2/c space group. The asymmetric unit of [Zn(II)(3AP)2(CN)2] comprises one Zn(II) ion, two cyano groups, and two 3AP ligand molecules; the asymmetric unit of [Zn(II)(4AP)2(CN)2] comprises one Zn(II) ion, one cyano group and one 4AP ligand molecule. Similarly, the asymmetric unit of [Hg(II)(4AP)2(CN)2] comprises one Hg(II) ion, one cyano group and one 4AP ligand molecule.

Co-hydroprocessing of straight-run gasoil – Rapeseed oil mixture over stacked bed Mo/Al2O3 + NiMo/Al2O3-SAPO-11 catalysts

Co-hydroprocessing of straight-run gasoil (SRGO) – rapeseed oil (RSO) mixture over stacked bed sulfide catalytic system (Mo/Al2O3 + NiMo/Al2O3-SAPO-11) was investigated at temperature 350–380 °C, pressure 4.0–7.0 MPa, H2/feed – 1000 Nm3/m3 and liquid hour space velocity 1.0–1.5 h−1. Mo/Al2O3 catalyst was used in the first layer to provide selective conversion of RSO preferably through “direct hydrodeoxygenation” route, excluding COx formation. The influence of temperature and pressure on the product quality and on the conversion of n-octadecane (n-C18H38) produced in hydrodeoxygenation of RSO were studied. The co-processing of 30%RSO/70%SRGO mixture at 350 °C, 5.0 MPa, 1000 Nm3/m3 and 1.5 h−1 gives the product with the acceptable density, sulfur and aromatics contents, but increased cloud point (-1°C). It was shown that a temperature increase from 350 °C to 380 °C resulted in a decrease of cloud point for 12° due to higher n-C18H38 conversion at 380 °C. On the contrary, a pressure increase from 4.0 to 7.0 MPa led to a decrease of n-C18H38 conversion over sulfide Mo/Al2O3 + NiMo/Al2O3-SAPO-11 catalysts. This observation could be explained by higher concentration of NH3 and H2S, by-products of SRGO hydrotreatment, in liquid phase at higher pressure. To prove this hypothesis the effects of NH3 and H2S were investigated on co-processing of 30 wt% RSO in hydrotreated SRGO. It was found that the presence of NH3 was the main reason of inhibiting effect on hydrocracking/ hydroisomerization reactions in co-processing of RSO-SRGO mixtures.

Role of impurity components and pollutant removal processes in catalytic oxidation of o-xylene from simulated coal-fired flue gas

Volatile organic compounds (VOCs) emitted from coal-fired flue gas of thermal power plants have reached unprecedented levels due to lack of understanding of reaction mechanisms under industrial settings. Herein, inhibition mechanisms for catalytic oxidation of o-xylene in simulated coal-fired flue gas are elucidated with in-situ and ex-situ spectroscopic techniques considering the presence of impurity components (NO, NH3, SO2, H2O). MnCe oxide catalysts prepared at Mn: Ce mass ratios of 6:4 are demonstrated to promote 87% o-xylene oxidation at 250 °C under gas hourly space velocities of 60,000 h−1. Reaction intermediates on the catalyst surface are revealed to be o-benzoquinones, benzoates, and formate and they were stably formed under O2/N2 atmospheres. When either NO or NH3 was introduced into the simulated flue gas, the formed species shifted toward formate in minutes, which indicated that changes in catalyst surface chemistry are directly related to impurity components. Presence of NH3 in the simulated flue gas inhibited o-xylene oxidation by reducing Mn and lowering Brønsted acidity of the catalyst. Impurity components associated with pollutant removal processes (Hg0 oxidation and selective catalytic reduction of NO) lowered o-xylene removal efficiency. Presence of o-xylene in the flue gas had little effect on the efficiency of pollutant removal processes. Layered catalytic beds located downstream from Hg0/NO pollutant removal processes are proposed to lower VOC emissions from coal-fired flue gases of thermal power plants in industrial settings.

Effect of selected ammonia escape inhibitors on carbon dioxide capture and utilization via calcium carbonate precipitation

Abstract Carbon dioxide was used to precipitate CaCO3 with CaCl2 solution in the presence of NH3 as a CO2 absorption promoter. Compounds that were previously indicated as inhibitors of ammonia escape during CO2 absorption were also added to the reaction mixture. Inorganic salts, i.e. ZnCl2, CuCl2, CoCl2, and organic substances, i.e. glycerol, ethylene glycol and triethanolamine were tested inhibitors in this work. A model post-distillation liquid from the Solvay process was used as the reaction mixture, while the gas stream fed into the system had a composition corresponding to the exhausted gases produced by the fossil fuels combustion. The purpose of this research was to investigate the efficiency of CO2 sequestration and the consumption of calcium ions during precipitation in the carbonation processes and determine the characteristics of produced CaCO3 particles. Of the tested additives, glycerol turned out to be the most effective, because its presence resulted in increased calcium ion consumption and CO2 sequestration compared to the control process. 90.5 % CO2 sequestration and 88.1 % Ca2+ consumption were obtained. The CaCO3 particles obtained in the presence of all tested organic inhibitors were in the form of vaterite and were characterized by a significantly larger specific surface area and larger pore volume.

First principles characterization of defect-free and vacancy-defected monolayer PtSe2 gas sensors

In this paper, we investigate the gas sensing properties of pristine and vacancy-defected monolayer PtSe2 in the presence of NH3, NO2, NO, O2, and CO gas molecules. The current-voltage (I–V) characteristics as well as dielectric functions are calculated before and after gas adsorption using a non-equilibrium Green’s function (NEGF) formalism. The first-principles calculations reveal that the bandgap of PtSe2 decreases in the presence of NO, NO2, and O2 which lowers required bias voltages to drive the current, while presence of NH3 and CO gas molecules has no considerable effect on the bandgap and I–V characteristic of the sensor. Furthermore, adsorption of NO and NO2 on PtSe2 monolayer leads to the negative differential resistance in corresponding I–V characteristic. Adsorption of O2 on the sensor, especially on the pristine monolayer, increases the conductivity of sensor. From the optical properties point of view, NO2 and NO gas molecules induce new peaks at different energies in the optical absorption spectrum of the pristine and defective sensors, while O2 only modulates the absorption spectrum of the defect-free structure. At the presence of CO, the main energy peak of the spectrum shifts, whereas the presence of NH3 does not modulate the optical absorption spectrum considerably.

Low‐T CO Oxidation over Cu−CHA Catalysts in Presence of NH3: Probing the Mobility of CuII Ions and the Role of Multinuclear CuII Species

The Cover Feature portrays two CuII ions as trapeze artists swinging inside a CHA zeolite cage until they join hands to form a single complex. In their Communication, reporting CO titration experiments over preoxidized Cu-CHA catalysts, R. Villamaina et al. provide evidence that NH3 ligands, like trapezes, mobilize initially isolated CuII ions to form the dimeric complexes with removable oxygen needed for CO oxidation. This is confirmed by transient kinetic analysis, which shows that the rate of CuII reduction is 2nd order in the ZCuIIOH species. These findings may be relevant for elucidation of the reduction half cycle in the redox mechanism of the Standard NH3-SCR reaction over Cu-CHA systems. More information can be found in the Communication by R. Villamaina et al.

Laser-engraved ammonia sensor integrating a natural deep eutectic solvent

Ammonia is a naturally-occurring gas, present throughout the atmosphere at sub-ppb concentrations. As result of various processes, significantly higher concentrations can be found in the areas surrounding industrial and agricultural operations. In such cases, the presence of NH3 in air is not only associated with a very pungent odor but can also affect the environment, animals, plants, and humans. Aiming to provide a simple platform to monitor NH3 in air, a paper-derived gas sensor, integrating a natural deep eutectic solvent (NADES) was developed. The herein described paper-derived ammonia gas sensor was fabricated using direct laser scribing, to form a carbon-based interdigitated array. Characterization and optimization (using chemometrics) were performed to develop a material with the lowest possible resistivity. A unique feature of the proposed sensor is that it integrates a natural deep eutectic solvent formed with lactic acid:glucose:water (LGH). This NADES conveys selectivity toward ammonia (over methanol, ethanol, 1-propanol, and water) and greatly enhances the sensitivity of the sensor (over the plain carbon array). The resistance of the sensor was dependent on the NH3 concentration in the 0.11–40.6% range and rendered an estimated limit of detection of 0.33%. Although the sensitivity of the sensor is lower than that of others based on metallic oxides, the herein described approach represents a low-cost, portable, and simple way to address the need of emerging markets such as the NH3-based fuel industry or waste treatment where most of the current sensors would be saturated.

Electrosynthesis of glycine from bio-derivable oxalic acid

Electrochemical hydrogenation of non-fossil resources to produce value added chemicals has great potential to contribute to realization of sustainable material supply. We previously demonstrated that TiO2 catalyzed electrochemical reduction of biomass-derivable α-keto acid in the presence of NH3 or NH2OH affords amino acids. In this work, we focused on oxalic acid, which is producible by chemical degradation of agro wastes, as a starting material for the electrosynthesis of an amino acid. We examined the electrocatalytic properties of various materials, including Cu, Pt, Ti foils, calcined Al, Co, Mo, Nb, Ni, Ti, V, W, Zr foils, and some TiO2 catalysts, by conducting linear sweep voltammetry (LSV) measurements, and found that Mo and Ti foil calcined at 450 °C show favorable catalytic features for the one-step glycine electrosynthesis from oxalic acid and NH2OH. Electrochemical reduction of oxalic acid at an applied potential of − 0.7 V using calcined Ti foil resulted in formation of glycine and glyoxylic acid oxime, i.e., intermediate of the glycine formation, with moderate Faradaic efficiency of 28 and 28%, respectively.

Effect of iron minerals during coaling on the transformation of NO in the presence of NH3: Take pyrite as an example

Pyrite, a naturally occurring mineral, can be found extensively in coal. The change in the pyrite structure that occurs during coaling process, the ability of the pyrite-derived α-Fe2O3 to convert NO in the presence of NH3 before catalyst bed and the kinetic study were investigated in this work. The pyrite-derived α-Fe2O3 was obtained by calcining at 500, 600, 700, 800 °C and was characterized by the X-ray diffraction (XRD), N2 physisorption, the X-ray photoelectron spectrometer (XPS), the scanning electron microscope (SEM), UV–visible near-infrared spectroscopy (UV–vis DRS), the temperature-programmed desorption of ammonia (NH3-TPD) and the in situ diffuse reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS). The results indicated that the α-Fe2O3 derived from natural pyrite exhibited an affirmative effect on NO conversion in the presence of NH3 at reaction temperatures of 200–450 °C, particularly at 350 °C, the pyrite-derived α-Fe2O3 displayed the best efficiency for the NO conversion. In addition, the formed sulfate derived from the oxidation of pyrite enhanced the NO conversion at the temperature of 300–450 °C, while hinder the NO conversion at 200–275 °C. The in-situ DRIFTS and kinetic studies demonstrated that both the Eley-Rideal and Langmuir-Hinshelwood mechanism contributed to the selective catalytic reduction (SCR) of NO when the reaction temperature was over 200 °C, while selective catalytic oxidization (CO) happened over 300 °C. This study favored the understanding of the NO behavior in flue gas pipeline after sprawling NH3 and the mechanism of NO conversion before the catalyst bed.

The effects of humidity and ammonia on the chemical composition of secondary aerosols from toluene/NOx photo-oxidation

The secondary aerosol formation mechanism in the presence of ammonia (NH3), is poorly understood, especially under high relative humidity (RH) conditions. In this study, a total of seven experiments were conducted from toluene/NOx photo-oxidation in the presence/absence of NH3 under dry (~7% RH) and wet (>60% RH) conditions in a ~3 m3 smog chamber. A series of instruments including gas analysers, scanning mobility particle sizer (SMPS), aerosol mass spectrometry (HR-ToF-AMS) etc. were applied to measure the NOx and O3 concentrations, the mass concentration and chemical composition of secondary aerosol. It was found that NH3 could enhance the mass loading of secondary aerosol, especially under wet condition. However, the presence of NH3 or increasing RH did not have a significant influence on SOA yield. The organic aerosol mass spectrum from AMS showed that the most abundant fragment was at m/z = 44, which was mainly from the fragmentation of carboxylic acids. Compared to the absence of NH3, the fraction of fragment at m/z = 44 and O:C was higher in the presence of NH3, regardless of dry or wet conditions. The highest O:C value of 0.71–0.75 was observed in the presence of NH3 under wet condition, suggesting there could be a synergetic effect between the high RH and the presence of NH3, which jointly contributed to the photochemical aging process of SOA. The N:C increased in the presence of NH3 under both dry and wet conditions, which might be attributed to the carboxylates and organic nitrates formed from the reaction between NH3 and carboxylic acids. The results implied that SOA modelling should consider the role of NH3 and water vapour, which might fill the gap of O:C between laboratory studies and field measurements.

Synthesis of cisplatin encapsulated Zinc oxide nanoparticles and their application as a carrier in targeted drug delivery

Cisplatin is a frequently used anticancer drug that has been developed as the first platinum-based anticancer drug. The cis configuration enables the coordination complex to be covalently binding to one or two DNA strands and thus cross-linking the DNA strands, causing the cells to die in a programmed manner. Cisplatin is administered as an IV infusion in saline solution for medication of solid malignity. Anticancer drugs usually have a variety of side effects, but an encapsulation of the drug in a suitable host material minimizes the side effects while improving the efficacy of the drug due to its slow release only at the target. The aim of this research is to develop a simple, but effective mechanism for the preparation of porous zinc oxide nanoparticles (PZnO NPs) using the forced hydrolysis method reaction of zinc acetate dihydrate with deionized water in diethylene glycol (DEG) media. This synthesized PZnO NPs were then characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX), Fourier Transform Infrared Spectroscopy (FT-IR), Particle Size Analysis and Powder X-Ray Diffraction (PXRD). The encapsulation of cisplatin within the porous zinc oxide nanoparticles was confirmed by X-ray Fluorescence (XRF), SEM, EDX, and FT-IR studies. Our results show that the synthesized nanoparticles have the hexagonal wurtzite structure as confirmed by PXRD. The average particle size as determined by light scattering is 52.4 ± 0.1 nm SEM images show porous spherical morphology with aggregated particles. XRF data of the cisplatin encapsulated product show a Pt: Cl ratio of 1:2 showing cisplatin encapsulation without any fragmentation or other chemical change. The presence of NH3 in the encapsulated product is also apparent from FT-IR data. The encapsulation of the anti-cancer drug cisplatin to PZnO NPs and its pH dependence on the release of the drug from PZnO NPs was studied by measuring the amount of Pt released as a function of the time which was done using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) at λmax 265.94 nm. The encapsulation efficiency of Cisplatin into PZnO NPs was found to be 50.52%. The percentage of Cisplatin released from PZnO NPs during the first 7 hours was < 6.30% in the acetate/phosphate buffer at pH 4.0, 5.0, 6.0, 7.0 and 8.0. The maximum release of 8.64% was observed at pH = 6.0 after 24 hours.