Dose Of Iron Ions Research Articles

Biogas production in the methane fermentation of excess sludge oxidized with Fenton’s reagent

The advanced oxidation processes (AOPs) play an important role in the degradation of hardly decomposable organic pollutants. AOPs methods rely on the production of highly reactive hydroxyl OH• radicals. The aim of the conducted research was to intensify biogas production in the methane fermentation process of excess sludge subjected to the process of deep oxidation with Fenton's reagent. In the process of oxidation of sewage sludge with the Fenton reagent, doses of iron ions in the range 0.02–0.14 g Fe2+/g TS (total solids) were used Hydrogen peroxide was measured in the proportions 1: 1–1:10 in relation to the mass of iron ions. The basic substrate of the study was excess sludge. In the case of excess sludge oxidation with the use of Fenton's reagent, the most favorable process conditions were considered to be the dose of iron ions 0.08 g Fe2+/g d.m. and a Fe2+: H2O2 ratio of 1:5. As a result of subjecting the excess sludge to disintegration with the Fenton reagent in the above-mentioned dose, with respect to the fermentation process of unprocessed sludge, about two-fold increase in the digestion degree of excess sludge and about 35% increase of the biogas yield was obtained.

Epitaxial growth of silicon on silicon implanted with iron ions and optical properties of resulting structures

The method of ultrahigh-vacuum low-temperature (T = 850°C) purification of silicon single crystals having the (100) and (111) orientation and implanted with low-energy (E = 40 keV) iron ions with various doses (Φ = 1015−1.8×1017 cm−2) and subjected to pulsed ion treatment (PIT) in a silicon atom flow has been tested successfully. The formation of semiconducting iron disilicide (β-FeSi2) near the surface after PIT is confirmed for a Si(100) sample implanted with the highest dose of iron ions. The possibility of obtaining atomically smooth and reconstructed silicon surfaces is demonstrated. Smooth epitaxial silicon films with a roughness on the order of 1 nm and a thickness of up to 1.7 μm are grown on samples with an implantation dose of up to 1016 cm−2. Optical properties of the samples before and after the growth of silicon layers are studied; the results indicate high quality of the grown layers and the absence of iron disilicide on their surface.

Influence of the Implantation Dose and of the Annealing Duration on the Raman Spectra of Ion‐Beam Synthesized β‐FeSi2 Layers

AbstractSummary: The samples under investigation are prepared by ion‐beam synthesis, followed by rapid thermal annealing. Fe ions with two different doses, each of them with two different energies, are implanted into Si substrates. The two step implantation with the iron doses used ensure the formation of unburied polycrystalline continuous β‐FeSi2 layers with a thickness of about 50 nm in the case of the lowest implantation dose, and of about 100 nm in the case of the higher one. We observed the same Raman modes, which are predicted theoretically and detected experimentally by other authors as well. The influence of the Fe ion dose and of the annealing time on the Raman spectra behavior is characterized.Raman spectra of a sample obtained by implantation with 5 × 1016 cm−2 dose of iron ions, and annealed at 900 °C for 60 s.imageRaman spectra of a sample obtained by implantation with 5 × 1016 cm−2 dose of iron ions, and annealed at 900 °C for 60 s.

Photoluminescence and structural defects in silicon layers implanted by iron ions

The photoluminescence spectra of silicon samples implanted by 56Fe+ ions [energy, 170 keV; dose, 1×1016, (2–4)×1017 cm−2] and annealed at temperatures of 800, 900, and 1000°C are measured. The structure of the samples at each stage of treatment is investigated using transmission electron microscopy (TEM). It is found that the phase formation and morphology of crystalline iron disilicide precipitates depend on the dose of iron ions and the annealing temperature. A comparison of the dependences of the intensity and spectral distribution of the photoluminescence on the measurement temperature, annealing temperature, and morphology of the FeSi2 phase revealed the dislocation nature of photoluminescence.

Thermal redistribution of iron implanted in Czochralski silicon

Different doses of iron ions were implanted in Czochralski grown single-crystal silicon samples and subsequently annealed at 1000 °C for 2 h in a dry nitrogen atmosphere. The behavior of the implanted iron and of oxygen already present in the material was monitored. It was found that the existence of the remaining structural disorder after the annealing treatment plays a dominant role in iron and oxygen segregation into the disordered region. This confirms the theory which predicts that the structural disorder and related strain fields are dominant mechanisms for gettering of metallic ions.