Irradiated Ammonia Research Articles

Microwave irradiated ammonia nitrogen removal from anaerobically digested liquid dairy manure: A response surface methodology and artificial neural network-based optimization and modeling

Anaerobic digestion (AD) is a commonly adopted technology to treat liquid dairy manure. However, an increase in ammonia nitrogen (NH3-N) concentrations in anaerobically digested liquid dairy manure (DLDM) has been observed due to the conversion of organic nitrogen to NH3-N during AD. The removal and recovery of NH3-N from DLDM has therefore gained increased attention among researchers to ensure environmental sustainability along with making better uses of manure N fertilizer values. In this study, 150 mL of DLDM was treated under different operating conditions using a modified domestic microwave and the key operational parameters viz. pH, irradiation time (min), and microwave power output (W) were optimized and modeled via response surface methodology (RSM) and RSM-artificial neural network (ANN). The role of operational parameters on the performance of the treatment process was first evaluated using RSM. Afterward, the RSM was combined with ANN to predict the NH3-N removal from DLDM. Although all the operational parameters at a linear level along with the interactive effect of irradiation time, microwave power output, and pH at a quadratic level significantly influenced NH3-N removal from the waste stream (p < 0.001). The results also revealed that pH acted as the primary factor affecting NH3-N removal during the microwave irradiated treatment process. Under the optimal conditions (pH: 10.8, irradiation time: 4.1 min, and microwave power output: 625 W), the NH3-N removal efficiency of 86.71 ± 1.85% was observed and found to be in line with the computational values from both the RSM and RSM-ANN models, while the recovery efficiency was found to be 77.98 ± 3.71%. Furthermore, a statistical comparison between the models demonstrated the RSM-ANN model has a greater prediction capability than the RSM model. The high NH3-N removal efficiency obtained under the optimal conditions indicates the effectiveness of the process and will further encourage the application of microwave irradiation to treat DLDM in pilot and full-scale processes.

Detection of the Elusive Triazane Molecule (N3H5) in the Gas Phase

AbstractThe front cover artwork is provided by the groups of Prof. R. I. Kaiser (University of Hawaii) and Prof. A. H.‐H. Chang (National Dong Hwa University). The image shows a triazane molcule as it sublimes from irradiated ammonia ices along with its ion profile after photoionization; ammonia has been detected on Kuiper Belt Objects with Pluto being the most prominent member (courtesy NASA). Read the full text of the article at 10.1002/cphc.201500560

Indirect detection of nitrogen spins in ammonia target at superlow temperatures

The COMPASS polarized target at CERN operates with irradiated ammonia (NH3) as a material having a reasonable content of polarizable nucleons and the highest resistance against radiation damages. We study the magnetic structure of ammonia polarized by the Dynamic Nuclear Polarization (DNP) method at 0.2K and 2.5T. In this material, electron spins, induced by ionizing radiation, couple proton and nitrogen nuclear spins by indirect J-interactions. This coupling and the dipole–dipole interactions between nuclear spins produce an asymmetry in the proton NMR line shape depending on the value of nitrogen polarization. We consider the asymmetry as an indirect imaging of the actual nitrogen spectra, useful for research developments and, in practice, for monitoring of nitrogen polarization in the long target, instead of a complicated analysis of NMR nitrogen spectra.

The irradiation of ammonia ice studied by near edge x-ray absorption spectroscopy

A vapor-deposited NH(3) ice film irradiated at 20 K with 150 eV photons has been studied with near-edge x-ray absorption fine structure (NEXAFS) spectroscopy at the nitrogen K-edge. Irradiation leads to the formation of high amounts (12%) of molecular nitrogen N(2), whose concentration as a function of the absorbed energy has been quantified to 0.13 molecule/eV. The stability of N(2) in solid NH(3) has been also studied, showing that N(2) continuously desorbs between 20 and 95 K from the irradiated ammonia ice film. Weak concentrations (<1%) of other photoproducts are also detected. Our NEXAFS simulations show that these features own to NH(2), N(2)H(2), and N(3)(-).

A solid polarized target for high-luminosity experiments

We have built a polarized proton and deuteron target for experiments using intense high-energy electron beams. This system exploits dynamical nuclear polarization of irradiated ammonia in a 5 T magnetic field at temperatures near 1 K. We describe the various features and the performance of the target.

EPR-spectra analysis of irradiated ammonia under ħω/kT&gt;1 conditions

The spectroscopic investigation results of the electron spin subsystem in irradiated deutero-ammoniaND3 obtained on the low-temperature magnetic EPR-spectrometer with the resonant cell as a short-focus open resonator under ħω/kT>1 conditions have been carried out. The temperature dependences of g-factor anysotropy and asymmetry parameters of the EPR-line shape of\(\dot ND_2 \) radical are analyzed. The reasons of the anomalous change of the experimental spectra near the temperatureT=1K are discussed.

Observation of a 96% proton polarization in irradiated ammonia.

Using dynamic nuclear polarization we obtained proton spin-polarization values of +(95\ifmmode\pm\else\textpm\fi{}5)% and -(97\ifmmode\pm\else\textpm\fi{}5)% in radiation-doped frozen ammonia. Moreover, the polarization reached 90% in about 25 min. These results were obtained using our new 1-K high cooling power $^{4}\mathrm{He}$ evaporation refrigerator operating in a 5-T magnetic field with 140-GHz microwaves. This unexpectedly large and rapid polarization coupled with about 1 W of cooling power should allow significant improvements in high-energy spin-physics experiments and may have some physics interest in itself.

The polarisation of 14N and 15N nuclei in polarised proton targets using irradiated ammonia

The steady state and transient behaviour of the nitrogen polarisation in dynamically polarised irradiated ammonia has been experimentally investigated. It is concluded from the results obtained with both 14N and 15N that these nuclei are in spin temperature equilibrium with the protons under the conditions normally existing in polarised targets and hence the nitrogen polarisation may be calculated from the measured proton polarisation.

Irradiated ammonia (NH 3) as target material for polarized proton targets

Dynamic proton polarization measurements in irradiated NH 3 were performed at 1 K and 0.5 K in a magnetic field of 2.5 T. The paramagnetic radicals in the frozen ammonia beads were created by irradiation with 20 MeV electrons from the injection linac of the Bonn 2.5 GeV electron synchrotron. During the irradiation the ammonia beads were cooled in liquid argon at about 90 K. Electron paramagnetic resonance measurements identified the created radicals as NH 2. Samples of NH 3 yielded a maximum proton polarization of 35% at 1 K and 66% at a temperature of 0.5 K. They exhibited short polarization build-up times of 2 min at 1 K and 9 min at 0.5 K. The radiation resistance of the polarization of NH 3 is better than that of butanol. The radiation damage can be repaired by annealing.

Dynamic nuclear polarization in irradiated ammonia below 0.5 K

We have reached +90.5% and −93.6% dynamic proton polarization in solid NH 3 using paramagnetic radicals created by proton irradiation of 40 Mrad total dose. The dynamic polarization experiments were performed at 25 kG field in a dilution refrigerator. These results may indicate a breakthrough in the development of better polarized target materials for high-energy physics experiments.

An Ionization Chamber Study of Electron and Ion Decay in Irradiated Ammonia

Ionization chambers with plane parallel and coaxial electrodes have been used to study the ion and electron concentrations in ammonia subjected to 120 kvp X-ray pulses of 17 and 30 ms duration. Differences in the numbers of positive and negative ions collected on the application of pulses of high voltage imply that free diffusion of electrons to the cell walls occurs in the early part of the X-ray pulse until it is inhibited by the positive ion space charge. Thereafter, positive and negative ions decay at equal rates.The rate constant for the neutralization reaction[Formula: see text]at 1200 Torr of ammonia and 297°K was calculated to be 4.2 ± 1.0 × 10−5 cm3 ion−1 s−1. However, unless extensive precautions are taken to remove electron-attaching impurities reactions between NH4+•nNH3 ions and impurity negative ions are dominant. The results are discussed and compared to other work on electron–ion neutralization reactions.