Heterogeneous Fenton system has been widely used in water treatment because of its effective degradability in a wide range of pH. A two-step hydrothermal method for the synthesis of Fe
3
O
4
/reduced ...graphene oxide (RGO) aerogel was designed as an efficient and recyclable heterogeneous Fenton catalyst for degradation of methylene blue (MB). Firstly, the Fe
3
O
4
colloidal solution was synthesized by hydrothermal progress. Secondly, graphene oxide hydrogels were formed by the self-assembling and reduced to graphene during the hydrothermal reaction. Meanwhile, zero-dimensional Fe
3
O
4
nanoparticles were anchored onto the graphene oxide through the colloidal coagulation effect. The obtained samples were characterized by XRD, SEM, TEM, BET, Zeta, XPS, Raman, TG, and VSM. Adsorption isotherm and kinetics of MB onto Fe
3
O
4
/RGO composites revealed that the maximum adsorption capacity was 163.83 mg/g, and the adsorption process confirmed to the pseudo-second-order model. The determinants of heterogeneous Fenton system including oxidant concentration, initial pH, and reaction mechanism were investigated. The studies indicated that MB degradation efficiencies increased with the initial pH increasing (pH 3–10), showing a complete degradation in alkaline condition within 60 min. It is due to that catalytic reaction mainly occurs on the solid–liquid interface, as pH values increase, the electrostatic attraction between the cationic MB molecules and the surface of Fe
3
O
4
/RGO increases, the enhancement of adsorptivity is helpful to improve catalytic activity. The catalyst can be easily recovered by an applied magnetic field and exhibited excellent stability after five degradation cycles.
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•A novel resource utilization of the calcium-based semi-dry flue gas desulfurization ash.•A low cost and efficient treatment technology for the vanadium industrial wastewater using a ...semi-dry FGD ash.•The resource utilization methods of the by-product gypsum and heavy metal precipitation from this technology are submitted.•The new technology achieves the objective of “waste control by waste”.
A novel resource utilization of the calcium-based semi-dry flue gas desulfurization ash is investigated. In the present study, the semi-dry desulfurization ash is used as a reductant for chromium and vanadium removal by chemical reduction precipitation, the byproduct gypsum and chromium-contained sludge are obtained. Besides, the effects of main operational parameters (reaction pH, desulfurization ash dosage and reaction time) on the heavy metal removal are investigated, and the main reaction mechanism for this treatment technology is also proposed. Under the optimal conditions, the residual concentrations of Cr(VI), total Cr and V are 0.163mg/L, 0.395mg/L and 0.155mg/L, respectively. Additionally, byproduct gypsum and chromium-contained sludge are characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and thermogravimetry differential scanning calorimetry (TG-DSC), respectively. Finally, the resource utilization methods of the byproduct gypsum and chromium-contained sludge from this technology are also submitted. The byproduct gypsum can be utilized to produce hemihydrate calcium sulfate whisker, and the roasted heavy metal precipitation can be used as a primary chromium raw material (Cr2O3 content is about 83%).
The poor understanding of HONO sources in the daytime highlights the importance of the heterogeneous photochemical reaction of NO2 with aerosol or soil surfaces. The conversion of NO2 to HONO on ...humic acid (HA) under simulated sunlight was investigated using a flow tube reactor at ambient pressure. The uptake coefficient (γ) of NO2 linearly increased with irradiation intensity and HA mass in the range of 0–2.0 μg/cm2, while it decreased with the NO2 concentration. The HONO yield was found to be independent of irradiation intensity, HA mass, and NO2 concentration. The temperature (278–308 K) had little influence on both γ and HONO yield. Additionally, γ increased continuously with relative humidity (RH, 7–70%), and a maximum HONO yield was observed at 40% RH. The heterogeneous photochemical reaction of NO2 with HA was explained by the Langmuir–Hinshelwood mechanism.
Borax and boric acid are important primary products in China's boron industry. Their characteristic production technology has been adapted to the low ore grade. To analyze the environmental impacts ...of different borax and boric acid production processes and to promote cleaner production of boron industry, the life cycle assessment method of cradle-to-gate was applied in this study. GaBi4.4 software was used in the assessment and the environmental impacts were classified according to the CML2001 method. To show the degree of consumption of mineral resources and energy respectively, the abiotic depletion potential was divided into the mineral resources depletion potential and fossil energy depletion potential. A comparison between the mineral processing and entire system studied shows that energy consumption is important in life cycle environmental impacts. Boron production industries should refrain from using coal as their main heat source and try to use clean energy. A comparison between the borax production processes shows that the boron-rich slag is the cleanest material and that blast furnace gas can be used to reduce environmental impacts further in slow cooling link. A comparison between the boric acid production processes shows that flotation (I) is the cleanest process with the material of szaibelyite. Ludwigite should be processed after dressing to reduce the environmental impacts. Boron concentrate can be used to produce borax or boric acid as an alternative to szaibelyite but feasible production processes are still the focus of future research.
The influence of the TiO2 particle size on the enhanced Raman spectroscopy properties was systematically investigated on the nanometer-size scale. We report on the enhanced Raman spectrum of ...4-mercaptobenzoic acid adsorbed on TiO2 nanoparticles. The results presented in this study highlight the major findings that the intensities of both the molecular lines and the phonon modes of TiO2 are strongly size-dependent. The TiO2 crystallite size estimated using the Scherrer equation varied from 6.8 to 14.2 nm; as a function of crystal size, a large increase in intensity is observed, with a maximum near 10.9 nm and a subsequent decline at larger sizes. Moreover, we have investigated quantum confinement effects between TiO2 and the adsorbed molecules and attribute this to a charge-transfer resonance, which is responsible for the Raman enhancement.
The present study was aimed at investigating the effect of Na2O and B2O3 addition on the viscosity and electrical conductivity of slag which was used for mineral wool production. Industrial slag ...samples of the CaO–Al2O3–MgO–SiO2 system were used to modify its composition with different Na2O and B2O3 addition content and soaked at a certain temperature range (1400–1500°C). Raman spectrum was used to represent the structure of the slag system. Results showed that the Na2O addition modified process had a larger effect on the two parameters (macro aspect) and the relative fraction of the structural units (micro aspect) compared with the results of B2O3 addition.
The photocatalytic degradation of methylene blue（MB） over Fe-doped CaTiO3 under UV-visible light was investigated. The as-prepared samples were characterized using X-ray diffraction（XRD）, scanning ...electron microscope（SEM） equipped with an energy dispersive spectrometer（EDS） system, Fourier transform infrared spectra（FT-IR）, and UV-visible diffuse reflectance spectroscopy（DRS）. The results show that the doping with Fe significantly promoted the light absorption ability of CaTiO3 in the visible light region. The Fe-doped CaTiO3 exhibited higher photocatalytic activity than CaTiO3 for the degradation of MB.However, the photocatalytic activity of the Fe-doped CaTiO3 was greatly influenced by the calcination temperature during the preparation process. The Fe-doped CaTiO3 prepared at500°C exhibited the best photocatalytic activity, with degradation of almost 100% MB（10 ppm）under UV-visible light for 180 min.
The photochemical conversion of NO2 to HONO on humic acids (HA) in the presence of benzophenone (BP) was investigated using a flow tube reactor coupled to a NOx analyzer at ambient pressure. BP ...significantly enhanced the reduction of NO2 to HONO on HA under simulated sunlight, as shown by the increase of NO2 uptake coefficient (γ) and HONO yield with the mass ratio of BP to HA. The γ and HONO yield on the mixtures of HA and BP obviously depended on the environmental conditions. Both γ and HONO yield increased with the increase of irradiation intensity and temperature, whereas they decreased with pH. The γ exhibited a negative dependence on the NO2 concentration, which had slight influences on the HONO yield. There were maximum values for the γ and HONO yield at relative humidity (RH) of 22%. Finally, atmospheric implications about the photochemical reaction of NO2 and HA in the presence of photosensitive species were discussed.
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•BP significantly enhanced the photochemical conversion of NO2 to HONO on HA.•The γ and HONO yield were found to be dependent on the mass ratio of BP to HA.•The γ and HONO yield were measured under various environmental conditions.•Implications of the photochemical reaction of NO2 on HA and BP were discussed.
Benzophenone significantly enhanced the photochemical conversion of NO2 to HONO on humic acids, leading to an increase in NO2 uptake coefficient and HONO yield.
The effect of TiO
2
on the crushing strength for high-Cr V-Ti magnetite pellets was studied in this paper. On one hand, the crushing strength obviously decreased with the increasing TiO
2
contents. ...On the other hand, the crushing strength had an obvious increase after grinding treatment for the high-Cr V-Ti magnetite and titanium concentrate. It is found that the crushing strength has great relations with the mineral phase and microstructure. The effect of TiO
2
on the smelting mechanism for high-Cr V-Ti magnetite pellets was also studied in this paper. With the increasing TiO
2
contents in the range of 2.47 to 12.14 pct, the softening start temperature and softening temperature gradually increased, and the softening zone gradually narrowed down; the melting start temperature and the dripping temperature increased, and the melting–dripping temperature zone also increased. The permeability index increased with the increasing TiO
2
contents as a whole. In the process of slag–iron’s dripping and separating, it is proposed that amounts of Cr and V moving to the melted iron are obviously more than those moving to the slag, while amount of Ti moving to slag is much greater than that moving to the melted iron. It is demonstrated that Ti(C,N) generates increasingly with the increasing TiO
2
contents and accumulates as especial regular rigid granules on the surface of coke. The size of melted iron decreased with the increasing TiO
2
contents, and this is in accordance with the present investigations that the dripping difficulty increased with the increasing TiO
2
contents.
Excellent thermal neutron absorption performance of boron expands the potential use of boron rich slag to prepare epoxy resin matrix nuclear shielding composites. However, shielding attenuation ...behaviors and mechanism of the composites against gamma rays are unclear. Based on the radiation protection theory, Phy-X/PSD, XCOM, and 60Co gamma ray source were integrated to obtain the shielding parameters of boron rich slag/epoxy resin composites at 0.015–15 MeV, which include mass attenuation coefficient (μt), linear attenuation coefficient (μ), half value thickness layer (HVL), electron density (Neff), effective atomic number (Zeff), exposure buildup factor (EBF) and exposure absorption buildup factor (EABF).μt, μ, HVL, Neff, Zeff, EBF and EABF are 0.02–7 cm2/g, 0.04–17 cm−1, 0.045–20 cm, 5–14, 3 × 1023–8 × 1023 electron/g, 0–2000, and 0–3500. Shielding performance is BS4, BS3, BS3, BS1 in descending order, but worse than ordinary concrete. μ and HVL of BS1-BS4 for 60Co gamma ray is 0.095–0.110 cm−1 and 6.3–7.2 cm. Shielding mechanism is main interactions for attenuation gamma ray by BS1-BS4 are elements with higher content or higher atomic number via Photoelectric Absorption at low energy range, and elements with higher content via Compton Scattering and Pair Production in Nuclear Field at middle and higher energy range.
•Shielding parameters of boron rich slag/epoxy composites were obtained.•Shielding performance is BS4, BS3, BS3, BS1 in descending order.•μ and HVL for 60Co gamma ray is 0.095–0.110 cm−1 and 6.3–7.2 cm, respectively.•Shielding mechanism of boron rich slag/epoxy resin composites was uncovered.
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