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• Iron oxide doped carbon nitride was synthesized. • Doped photocatalyst was proven better than pure carbon nitride. • Photon concentrator was fabricated by 3D printing. • Dicamba was degraded by photocatalyst/H2O2 exposure under visible light. We have synthesized iron oxide doped carbon nitride with 0.5 to 2 wt.% iron oxide and characterized by XPS, TGA, FTIR, SEM, photoluminescence spectroscopy and photoelectrochemical measurements. A herbicide, dicamba was employed as model organic pollutant for degradation in presence with the catalyst and hydrogen peroxide. A 3D printed photon concentrator with two chips on board (COB) LEDs with visible light spectra and two complex parabolic mirror surfaces was used as photo-reactor. The findings revealed that both photocurrent and degradation of dicamba were functions of light intensity and concentrator geometry. The rapid degradation of dicamba can be attributed to the holistic and individual actions of structural components of the photocatalyst. Four distinct phenomena, including photocatalytic activity of carbon nitride, quenching of electron/hole pairs and generation of additional reactive hydroxyl radicals by hydrogen peroxide, Fenton and photo-Fenton activity of iron oxide component of carbon nitride in presence of hydrogen peroxide and photocatalytic activity of iron oxide alone in conjuncture with carbon nitride can contribute to the overall photocatalytic activity of the system. Liquid Chromatography-Mass spectrometry (LCMS) analysis of the degradation products showed loss of chlorine from the aromatic ring and evidence of free radical addition reactions in the course of photocatalysis. [ABSTRACT FROM AUTHOR]

Magnetisation of carbonaceous adsorbent using iron oxide (Fe x O y ) has potential to decrease the recovery cost of spent adsorbent because it could be separated magnetically. However, formation of various phases of Fe x O y and iron hydroxide (Fe x (OH) y ) during synthesis particularly the non-magnetic phases are difficult to control and could significantly reduce the magnetic saturation of the adsorbent. Hence, formation of the most magnetic Fe x O y , Fe 3 O 4, on biochar via oxidative hydrolysis of FeCl 2 under alkaline media was performed to synthesise magnetic adsorbent using pine sawdust biochar (magnetic pine sawdust biochar: MPSB). The Fe 3 O 4 nanoparticles on the surface of biochar contributed to high saturation magnetisation of MPSB, 47.8 A m 2 /kg, enabling it to be separated from aqueous solution using a magnet. MPSB were examined physically and chemically using various techniques. Sorbent-stability, parametric, kinetics, isotherm, thermodynamic and sorbent-regeneration studies were performed to comprehend the potential of MPSB as adsorbent to remove an emerging contaminant, sulfamethoxazole (SMX) from aqueous solution. Results showed that MPSB was stable within solution pH 4–9. Adsorption of SMX onto MPSB was favourable at low pH, fast and best described by Redlich-Peterson model. Adsorption was exothermic with physisorption possibly due to hydrophobic interaction and spent adsorbent could be regenerated by organic solvents. [ABSTRACT FROM AUTHOR]

Molybdenum (Mo) is a naturally-occurring trace element in drinking water. Most commonly, molybdate anions (MoO 4 2-) are in well water and breast milk. In addition, it is used in medical image testing. Recently, the EPA classified Mo as a potential contaminant, as exposure can lead to health effects such as gout, hyperuricemia, and even lung cancer. We have assessed the sorptive removal of aqueous molybdate using Douglas fir biochar (DFBC) and a hybrid DFBC/Fe 3 O 4 composite containing chemically-coprecipitated iron oxide (Fe 3 O 4). Adsorption was studied at various: pH values, equilibrium times (5 min-24 h), initial Mo concentrations (2.5–1000 mg/L), and temperatures (5, 25, and 40 °C) using batch sorption and fixed-bed column equilibrium methods. Langmuir capacities for DFBC and DFBC/Fe 3 O 4 (at pH 3, 2 hrs equilibrium) were within 459.3–487.9 mg/g and 288–572 mg/g, respectively. These adsorbents and their Mo-laden counterparts were characterized by elemental analysis, BET, PZC, SEM, TEM, EDS, XRD, and XPS. MoO 4 2- adsorption on DFBC is thought to be governed primarily via electrostatic attraction. Adsorption by DFBC/Fe 3 O 4 is primarily governed by chemisorption onto magnetite surface hydroxyl groups, while electrostatics prevail in the DFBC-exposed phase. Stoichiometric precipitation of iron molybdates triggered by iron dissolution was also considered. The data suggest that DFBC and DFBC/Fe 3 O 4 are promising candidates for molybdate sorption. [Display omitted] • Douglas fir biochar and its iron oxide analogue removed ∼500 mg/g aqueous molybdate. • Adsorption from anion mixtures and complex natural water was robust. • Fixed-bed column capacity for iron oxide/biochar was ∼19 mg/g. • Uptake was governed by chemisorption, hydrogen bonding and preciptiation. [ABSTRACT FROM AUTHOR]

Nitroaromatic compounds are substantial hazard to the environment and to the supply of clean drinking water. We report here the successful reduction of nitroaromatic compounds by use of iron oxide coated electrodes, and demonstrate that single sheet iron oxides formed from layered iron(II)-iron(III) hydroxides have unusual electrocatalytic reactivity. Electrodes were produced by coating of single sheet iron oxides on indium tin oxide electrodes. A reduction current density of 10 to 30 μA cm −2 was observed in stirred aqueous solution at pH 7 with concentrations of 25 to 400 μM of the nitroaromatic compound at a potential of −0.7 V vs. SHE. Fast mass transfer favors the initial reduction of the nitroaromatic compound which is well explained by a diffusion layer model. Reduction was found to comprise two consecutive reactions: a fast four-electron first-order reduction of the nitro-group to the hydroxylamine-intermediate (rate constant = 0.28 h −1 ) followed by a slower two-electron zero-order reduction resulting in the final amino product (rate constant = 6.9 μM h −1 ). The zero-order of the latter reduction was attributed to saturation of the electrode surface with hydroxylamine-intermediates which have a more negative half-wave potential than the parent compound. For reduction of nitroaromatic compounds, the SSI electrode is found superior to metal electrodes due to low cost and high stability, and superior to carbon-based electrodes in terms of high coulombic efficiency and low over potential. [ABSTRACT FROM AUTHOR]

A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared and used in the Catalytic Wet Air Oxidation (CWAO) of 2-chlorophenol (2-CP). The catalysts were characterized in terms of elemental composition, surface area, pHPZC, XRD and SEM. The performances of the FeSC catalyst in the CWAO of 2-CP was assessed in a batch reactor operated at 120°C under 0.9MPa oxygen partial pressure. Complete decomposition of 2-CP was achieved within 5h and 90% Total Organic Carbon (TOC) was removed after 24h of reaction. Quite a straight correlation was observed between the 2-CP conversion, the amount of iron leached in solution and the pH of the reaction mixture at a given reaction time, indicating a strong predominance of the homogeneous catalysis contribution. The iron leaching could be efficiently prevented when the pH of the solution was maintained at values higher than 4.5, while the catalytic activity was only slightly reduced. Upon four successive batch CWAO experiments, using the same FeSC catalyst recovered by filtration after pH adjustment, only a very minor catalyst deactivation was observed. Finally, based on all the identified intermediates, a simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst. [ABSTRACT FROM AUTHOR]

Abstract: Nano-sized Fe(II, III) oxides with various Fe(II)/Fe(III) ratios were characterized and tested as catalysts for the oxidative degradation of phenol via Fenton-like reactions at neutral pH. Under conditions typically applied for wet peroxide oxidation, Fe(II) in magnetite is oxidized to Fe(III), successively converting the mineral into maghemite. The residual Fe(II) content in the catalyst core is of only minor benefit for the catalytic activity in phenol oxidation, i.e. magnetite is not superior to maghemite. Achievable reaction rates for phenol degradation appeared to be rather low, e.g. phenol half-life of about 12h when 3gL−1 magnetite and 5gL−1 H2O2 were applied. Preceding surface-reduction of maghemite by NaBH4, leading to an over-stoichiometric Fe(II) content compared to magnetite, only enhanced the non-productive decomposition of H2O2 rather than the rate of phenol degradation. Reaction rates were shown to be relatively insensitive to catalyst concentration in the range of 1–10gL−1, probably resulting from a scavenging of reactive species by the catalyst surface, whereby particle agglomeration seems to play a key role. Degradation experiments with various structurally distinct compounds were carried out, indicating a similar selectivity of the heterogeneous Fenton-like system to that known for oxidation with imple-para> [Copyright &y& Elsevier]

Abstract: Surface modification of TiO2 with Fe2O3 clusters was made through chemisorption of ferric phthalocyaninetetracarboxylate onto TiO2, followed by sintering in air to remove organic moiety. Solid characterization with electron paramagnetic resonance spectroscopy and other techniques showed that ferric oxides were highly dispersed on TiO2 as a noncrystallized cluster, while TiO2 phases remained unchanged. For phenol degradation in aerated aqueous suspension, only the sample containing less than 0.3at.% Fe was more active than bare TiO2 under UV light, whereas no activity was found under visible light. As anatase thermally transferred into rutile, the Fe-containing catalyst became less active than bare TiO2, mainly ascribed to the increased size of Fe2O3 clusters. In the presence of H2O2, all Fe-containing catalysts were more active than bare TiO2. Moreover, similar trend in activity among different catalysts was also observed with the formation of hydroxyl radicals, and with the generation of photocurrent measured under N2 with Fe/TiO2 electrode. Present work clearly shows that only Fe2O3 clusters in a small size and at low coverage on TiO2 are beneficial to the photocatalytic reaction, while excess iron oxide is detrimental. Possible mechanism is discussed in the text. [Copyright &y& Elsevier]

Abstract: The photocatalytic activity of a brick grain-supported iron oxide (denoted as B1) was tested for its activity to degrade Reactive Black 5 (RB5) in the presence of oxalic acid. B1 was obtained as a solid waste from a wastewater treatment plant, and characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD) and N2 adsorption/desorption isotherm analyses. The decolorization experiments were performed in a fluidized bed reactor with aeration under UV-A irradiation (λ =365nm). The effects of various factors such as solution pH, concentration of oxalic acid and dissolved oxygen on the decolorization of RB5 were evaluated considering the contributions of adsorption and photo-catalytic degradation. The role of dissolved iron in the removal of RB5 and the stability of B1 were also examined. In addition, the removal of TOC during the photo-catalytic reaction was monitored. [Copyright &y& Elsevier]

Abstract: The municipal sewage sludge was modified with iron oxide employed in metal ions removal. The surface modification method was proposed and the effect of parameters in the preparation was studied. The iron oxide coated sludge had higher surface area, pore volume and iron content, compared to uncoated sludge. The suitable conditions for removal of Cu(II), Cd(II), Ni(II) and Pb(II) ions from solutions were investigated using batch method. The suitable pH value in the extraction was 7 for adsorption of Cd(II) and Ni(II), 6 for Cu(II) and 5 for Pb(II) ions. The presence of NaNO3, Ca(NO3)2 and Na2SO4 in metal solution in the concentration of 0.01M and 0.50M could reduce the removal efficiency. The adsorption isotherms for the adsorption of the metal ions were defined by Langmuir relation. The maximum adsorption capacity of the iron oxide coated sludge for Cu(II), Cd(II), Ni(II) and Pb(II) was 17.3, 14.7, 7.8 and 42.4mgg−1, respectively. The adsorption kinetics for every metal ions followed pseudo-second order model. The metal removal from wastewater by iron oxide coated sludge was also demonstrated. [Copyright &y& Elsevier]

Abstract: Iron oxide nanoadsorbents are cost-effective adsorbents that provide high adsorption capacity, rapid adsorption rate and simple separation and regeneration. In this study, Fe3O4 nanoadsorbents have been employed for the removal of Pb(II) ions from aqueous solutions by a batch-adsorption technique. The effects of contact time, initial concentration of Pb(II) ions, temperature, solution pH and coexisting ions on the amount of Pb(II) adsorbed have been investigated. Pb(II) adsorption was fast, and equilibrium was achieved within 30min. The amount of Pb(II) adsorbed increased as temperature increased, suggesting an endothermic adsorption. The optimal pH value for Pb(II) adsorption was around 5.5. Furthermore, the addition of coexisting cations such as Ca2+, Ni2+, Co2+, and Cd2+ has no remarkable influence on Pb(II) removal efficiency. The adsorption equilibrium data fitted very well to Langmuir and Freundlich adsorption isotherm models. The thermodynamics of Pb(II) adsorption onto the Fe3O4 nanoadsorbents indicated that the adsorption was spontaneous, endothermic and physical in nature. The desorption and regeneration studies have proven that Fe3O4 nanoadsorbents can be employed repeatedly without impacting its adsorption capacity. [ABSTRACT FROM AUTHOR]

Abstract: Adsorption of cationic pesticides in soils is generally attributed to mineral clays and organic matter components. However, iron oxides may also contribute to such adsorption or affect it by associating with other components. Using goethite and humic acid as models for iron oxides and organic matter respectively, we studied the adsorption of the cationic pesticide paraquat on goethite and humic acid-coated goethite. At pH 4.0 the adsorption on goethite was not significant, and at pH 10.0, although the surface of the oxide was negatively charged, much less pesticide was adsorbed than on mineral clays. At this pH the adsorption of paraquat decreased as the ionic strength increased, and application of the charge distribution multisite complexation model (CD-MUSIC model) enabled interpretation of the results. At pH 4, the adsorption of paraquat on the humic acid-coated goethite was similar to the adsorption on mineral clays, but was considerably less than the adsorption on humic acid in solution. The lower adsorption on solid organic matter is attributed to a decrease in the number of “active” binding sites on the humic acid as a result of the binding to iron oxide. [Copyright &y& Elsevier]

Abstract: The main objective of this work was to study the effectiveness of iron oxide-coated pumice and volcanic slag particles in removing disinfection by-product (DBP) precursors from a raw drinking water source with high specific UV absorbance (SUVA254) value. Iron oxide coating of particles significantly increased dissolved organic carbon (DOC) uptakes and decreased DBP formation after chlorination compared to uncoated particles. pH values close to neutral levels during adsorption and chlorination provided DOC, trihalomethane and haloacetic acid reductions around 60–75% employing 6g/L coated particle dosage. Higher degree of DOC and DBP reductions (>85%) were obtained with increasing particle dose. The uptake of bromide by iron oxide surfaces was negligible and increasing bromide concentrations (up to 550μg/L) did not negatively impact the DOC uptake. However, due to competition between natural organic matter (NOM) and bicarbonate for the iron oxide surfaces, increasing bicarbonate alkalinity levels reduced DOC uptakes. Overall, the results indicated that the iron oxide-coated pumice/slag particles are effective adsorbents to remove NOM and control DBP formation in waters with relatively high DOC and SUVA254 levels. However, they may not be effective for waters with alkalinity levels above 250mg CaCO3/L. [Copyright &y& Elsevier]

The catalytic efficiency of iron (II, III) oxide to promote Fenton-like reaction was examined by employing Rhodamine B (RhB) as a model compound at neutral pH. Two types of iron (II, III) oxides were used as heterogeneous catalysts and characterized by XRD, Mössbauer spectroscopy, BET surface area, particle size and chemical analyses. The adsorption to the catalyst changed significantly with the pH value and the sorption isotherm was fitted using the Langmuir model for both solids. Both sorption and FTIR results indicated that surface complexation reaction may take place in the system. The variation of oxidation efficiency against H2O2 dosage and amount of exposed surface area per unit volume was evaluated and correlated with the adsorption behavior in the absence of oxidant. The occurrence of optimum amount of H2O2 or of exposed surface area for the effective degradation of RhB could be explained by the scavenging effect of hydroxyl radical by H2O2 or by iron oxide surface. Sorption and decolourization rate of RhB as well as H2O2 decomposition rate were found to be dependent on the surface characteristics of iron oxide. The kinetic oxidation experiments showed that structural FeII content strongly affects the reactivity towards H2O2 decomposition and therefore RhB decolourization. The site density and sorption ability of RhB on surface may also influence the oxidation performance in iron oxide/H2O2 system. The iron (II, III) oxide catalysts exhibited low iron leaching, good structural stability and no loss of performance in second reaction cycle. The sorption on the surface of iron oxide with catalytic oxidation using hydrogen peroxide would be an effective oxidation process for the contaminants. [Copyright &y& Elsevier]

Catalytic oxidations of PCDD/Fs (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans) with ozone on the transition metal oxides (iron oxide or manganese oxide) at the temperature range of 120–180°C were investigated. These two catalysts were prepared by precipitation methods. Iron oxide has a higher surface area (330m2/g) than manganese oxide (53m2/g). In the absence of ozone, the removal efficiencies of PCDD/Fs achieved with iron oxide or manganese oxide were between 83% and 85%, while the destruction efficiencies were only between 20% and 25% at 180°C. It indicates that adsorption was the main removal mechanism of PCDD/Fs over these two catalysts. On the other hand, ozone addition greatly enhanced the catalytic activity of iron oxide or manganese oxide catalysts on the oxidation of gaseous PCDD/Fs. At 180°C, the destruction efficiencies of gaseous PCDD/Fs achieved with iron oxide or manganese oxide with 100ppm O3 exceeded 90%. It indicates that catalytic ozonation achieved with iron oxide or manganese oxide is effective in decomposing PCDD/Fs and the application of ozone lowers the reaction temperature of PCDD/F oxidation below 200°C. Furthermore, the synergistic effect of iron oxide and ozone is superior to that of manganese oxide due to the fact that the surface of iron oxide has more hydroxyl groups, which easily form hydrogen bonds with ozone and decompose to form atomic oxygen for the further reaction with dioxin molecules. [Copyright &y& Elsevier]

Abstract: The adsorption features of activated carbon and the oxidation properties of iron oxides were combined in a composite to produce new materials for atrazine removal from aqueous medium. Activated carbon/iron oxide composites were prepared at 1/1 and 5/1 mass ratios and characterized with powder X-ray diffractometry (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and nitrogen adsorption measurements. The adsorption and oxidation processes were evaluated in batch experiments, in order to monitor the atrazine removal capacity of these composites. The main iron oxide actually present in the composites was goethite (α-FeOOH). Impregnation with iron oxide reduced the surface area by its deposition in the activated carbon pores. However, a higher iron concentration promoted a higher oxidation rate, indicating that the efficiency of the oxidation reaction is related with the iron content and not with the pre-concentration of the contaminant on the carbon surface through adsorption process. [Copyright &y& Elsevier]

To better understand the photodegradation of polycyclic aromatic hydrocarbons (PAH) in solid phase in natural environment, laboratory experiments were conducted to study the influencing factors, kinetics and intermediate compound of pyrene photodegradation by iron oxides. The results showed that the pyrene photodegradation rate followed the order of α-FeOOH>α-Fe2O3 >γ-Fe2O3 >γ-FeOOH at the same reaction conditions. Lower dosage of α-FeOOH and higher light intensity increased the photodegradation rate of pyrene. Iron oxides and oxalic acid can set up a photo-Fenton-like system without additional H2O2 in solid phase to enhance the photodegradation of pyrene under UV irradiation. All reaction followed the first-order reaction kinetics. The half-life (t 1/2) of pyrene in the system showed the higher efficiencies of using iron oxide as photocatalyst to degrade pyrene. Intermediate compound pyreno was found during photodegradation reactions by gas chromatography–mass spectrometry (GC–MS). The photodegradation efficiency for PAHs in this photo-Fenton-like system was also confirmed by using the contaminated soil samples. This work provides some useful information to understand the remediation of PAHs contaminated soils by photochemical techniques under practical condition. [Copyright &y& Elsevier]

Abstract: Poly-l-cysteine (PLCys n ) (n =20) was immobilized onto the surface of commercially available magnetic γ-Fe2O3 nanoparticles, and its use as a selective heavy metal chelator was demonstrated. Magnetic nanoparticles are an ideal support because they have a large surface area and can easily be retrieved from an aqueous solution. PLCys n functionalization was confirmed using FTIR and the quantitative Ellman''s test. Metal binding capacities for As(III), Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II) were determined at pH 7.0 and compared to adsorption capacities for unfunctionalized γ-Fe2O3 nanoparticles. The effect of pH on the PLCys n functionalized nanoparticles was also investigated. For all of the metals examined, binding capacities (μmol metal/g support) were more than an order of magnitude higher than those obtained for PLCys n on traditional supports. For As(III), Cu(II), Ni(II) and Zn(II), the binding capacities were also higher than the metal adsorption capacities of the unfunctionalized particles. Metal uptake was determined to be rapid (<2.5min) and metal recoveries of >50% were obtained for all of the metals except As(III). PLCys n , which has a general metal selectivity towards soft metals acids, was chosen to demonstrate the proof of concept. Greater metal selectivity may be achievable through the use of combinatorial peptide library screening or by using peptide fragments based on known metal binding proteins. [Copyright &y& Elsevier]

Abstract: The abatement of ferulic acid (FA), a polyphenolic constituent of olive mill wastewater, is studied in the pH range 5.0–7.0 by using hydrogen peroxide and an amorphous iron oxide as catalyst. The effect of pH, catalyst load, hydrogen peroxide and substrate starting concentrations is assessed during the investigation. A suitable reaction scheme is developed and used to build a mathematical model which satisfactorily describes the system''s behavior. Kinetic constants for the proposed scheme as well as the total active site concentration of the catalyst in the studied pH range are estimated. The occurrence of internal mass-transfer limitation for the adopted granulometric fraction of the catalyst is demonstrated. [Copyright &y& Elsevier]

Silica gel is widely used in research laboratories, especially for the purification of organic compounds. Consequently, waste silica gel is generated in increasing amounts. In this work, waste silica was modified by coating its surface with iron oxide aiming to obtain an effective adsorbent for metal removal from wastewater. In the preparation of the adsorbent, the optimal pretreatment temperature and iron concentration were investigated. The coated waste silica was characterized for BET surface area, pore size, specific pore volume and iron content. Iron oxide-coated waste silica was tested for the adsorption of Pb(II), Cu(II), Cd(II) and Ni(II) from solutions in a batch system. The effect of contact time, pH and salt concentration on metal adsorption was investigated. It was found that the adsorption of metals occurred rapidly and reached equilibrium within 30min. The pH suitable for metal adsorption was between 6 and 7 and leaching of iron from the coating was observed only at pH 3 or lower. The presence of salt reduced the adsorption efficiency of the adsorbent. The adsorption behavior followed both Langmuir and Freundlich isotherms (25°C). Finally, the efficacy of the adsorbents was investigated using aqueous lab waste where removal efficiencies ranging from 62 to 89% were achieved when the initial metal concentrations ranged from 13 to 42mgL−1. [Copyright &y& Elsevier]

Abstract: To understand the photodegradation of azo dyes in natural aquatic environment, a novel photo-Fenton-like system, the heterogeneous iron oxide–oxalate complex system was set up with the existence of iron oxides and oxalate. Five iron oxides, including γ-FeOOH, IO-250, IO-320, IO-420 and IO-520, were prepared and their adsorption capacity was investigated in the dark. The results showed that the saturated adsorption amount (Γ max) was ranked the order of IO-250>IO-320>γ-FeOOH>IO-420>IO-520 and the adsorption equilibrium constant (K a) followed the order of IO-250>IO-520>γ-FeOOH>IO-420>IO-320. The effect of initial pH value, the initial concentrations of oxalate and orange I on the photodegradation of orange I were also investigated in different iron oxide–oxalate systems. The results showed that the photodegradation of orange I under UVA irradiation could be enhanced greatly in the presence of oxalate. And the optimal oxalate concentrations () for γ-FeOOH, IO-250, IO-320, IO-420 and IO-520 were 1.8, 1.6, 3.5, 3.0 and 0.8mM, respectively. The photodegradation of orange I in the presence of optimal was ranked as the order of γ-FeOOH>IO-250>IO-320>IO-420>IO-520. The optimal range of initial pH was at about 3–4. The first-order kinetic constant for the degradation of orange I decreased with the increase in the initial concentration of orange I. Furthermore, the variation of pH, the concentrations of Fe3+ and Fe2+ during the photoreaction were also strongly dependent on the and iron oxides. [Copyright &y& Elsevier]

Samples of various iron oxides suspended above ethylene oxide in an adiabatic calorimeter exhibit exothermic activity at temperatures as low as room temperature. A γ-Fe2O3 sample was found to show the highest reactivity with ethylene oxide. Ethylene oxide in combination with most of the iron oxide fines tested displayed exothermic activity below 100 °C. Self-heat rates near 2000 °C/min were observed for the γ-Fe2O3 fines while rates in excess of 100 °C/min were found for other fines (α-Fe2O3 and hydrated α-Fe2O3). In two cases (α-Fe3O4 and α-Fe2O3), pressurization rates above 1000 psi/min took place. No reactivity was observed for ethylene oxide with the FeO. Thermal inertia effects in commercial operation, such as heat uptake by the equipment to which fines are attached, are presumed to be a factor in limiting the occurrence of related exotherms in ethylene oxide manufacturing facilities. [Copyright &y& Elsevier]