Effect of CO2 on the Desulfurization of Sintering Flue Gas with Hydrated Lime

The effect of carbon dioxide (CO₂) on the desulfurization of sintering flue gas with hydrate (Ca(OH)₂) as an absorbent was investigated, and the formation of calcium carbonate (CaCO₃) and its effect on the desulfurization was discussed. The competitive relationship between carbon dioxide (CO₂) and sulfur dioxide (SO₂) with the deacidification agent in sintering flue gas is discussed thermodynamically, showing that sulfates are more likely to be generated under high oxygen potential conditions and that SO₂ reacts more preferentially than CO₂ under a thermodynamic standard state. The amount of produced CaCO₃ increases under the condition that the CO₂ concentration is absolutely dominant to SO₂ in the sintering flue gas atmosphere. The effect of temperature, humidity and CO₂ concentration on the desulfurization of Ca(OH)₂ are discussed experimentally. The increasing temperature is not conducive to desulfurization, and the humidity can promote desulfurization, while excessive humidity could inhibit desulfurization. The suitable relative humidity is 20%. In situ generated calcium carbonate has a certain desulfurization effect, but the desulfurization effect is not as good as Ca(OH)₂. However, a large proportion of CaCO₃ was produced in the desulfurization ash under the condition that CO₂ concentration was absolutely dominant to SO₂ in the sintering flue gas atmosphere.

Development of a wide-range soft sensor for predicting wastewater BOD5 using an eXtreme gradient boosting (XGBoost) machine

In wastewater monitoring, detecting extremely high pollutant concentrations is necessary to properly calibrate the treatment process. However, existing hardware sensors have a limited linear range which may fail to measure extremely high levels of pollutants; and likewise, the conventional "soft" model sensors are not suitable for the highly-skewed data distributions either. This study developed a new soft sensor by using eXtreme Gradient Boosting (XGBoost) machine learning to 'measure' the wastewater organics (in terms of 5-day biochemical oxygen demand (BOD5)). The soft sensor was tested on influent and effluent BOD5 of two different wastewater treatment plants to validate the results. The model results showed that XGBoost can detect these extreme values better than conventional soft sensors. This new soft sensor can function using a sparse input matrix via XGBoost's sparsity awareness algorithm - which can address the limitation of the conventional soft sensor with the fallibility of supporting hardware sensors even.

Experimental and computational approaches to study the chlorination mechanism of pentlandite with ammonium chloride

Pentlandite (Fe_4.5Ni_4.5S₈) is the primary source for the metallurgical production of nickel worldwide, however it usually coexists with copper sulfide in nature. To develop an efficient and green process for the separation and extraction of valuable metals from the nickel sulfide concentrate, herein we conducted experimental studies and density functional theory (DFT) calculations to elucidate the chlorination mechanism of pentlandite using ammonium chloride (NH₄Cl). First, low-temperature chlorination roasting experiments with NH₄Cl were performed in which pentlandite was successfully converted into the corresponding metal chlorides (FeCl₂ and NiCl₂). Then, the chlorination product was analyzed via energy dispersive spectrometry to reveal the elemental distribution at the cross-section. Results reveal that Fe atoms in pentlandite underwent preferential chlorination to form a chloride layer, whereas Ni atoms remained at the center of the grain. Furthermore, density functional theory calculations were performed to investigate the chlorination mechanism of pentlandite by exploring two possible pathways, involving the adsorption of oxygen (O₂), ammonium chloride (NH₄Cl) and chlorine (Cl₂) on both the (001) and (010) surfaces of pentlandite. Considering that the chlorination of pentlandite was achieved in air atmosphere, we first consider the direct chlorination of pentlandite by NH₄Cl in the presence of oxygen. Dissociative oxygen adsorption was found to promote the chlorination process by providing oxygen sites for the dissociation of HCl, which is decomposed from NH₄Cl, eventually leading to the formation of H₂O and FeCl₂ species. Alternatively, the reaction between pentlandite and Cl₂ was proved to be feasible thermodynamically.

The chlorination mechanism of pentlandite with NH₄Cl has been proposed. The chlorination of pentlandite can be achieved by two pathways, where O₂ plays a crucial role in promoting the chlorination process.

Suppressing photoinduced charge recombination at the BiVO4||NiOOH junction by sandwiching an oxygen vacancy layer for efficient photoelectrochemical water oxidation

Nickel oxyhydroxide (NiOOH) is regarded as one of the promising cocatalysts to enhance the catalytic performance of photoanodes but suffers from serious interfacial charge-carrier recombination at the photoanode||NiOOH interface. In this work, surface-engineered BiVO₄ photoanodes are fabricated by sandwiching an oxygen vacancy (O_vac) interlayer between BiVO₄ and NiOOH. The surface O_vac interlayer is introduced on BiVO₄ by a chemical reduction treatment using a mild reducing agent, sodium hypophosphite. The induced O_vac can alleviate the interfacial charge-carrier recombination at the BiVO4||NiOOH junction, resulting in efficient charge separation and transfer efficiencies, while an outer NiOOH layer is coated to prevent the O_vac layer from degradation. As a result, the as-prepared NiOOH-P-BiVO₄ photoanode exhibits a high photocurrent density of 3.2 mA cm^-2 at 1.23 V vs. RHE under the irradiation of 100 mW/cm² AM 1.5G simulated sunlight, in comparison to those of bare BiVO₄, P-BiVO_4, and NiOOH-BiVO₄ photoanodes (1.1, 2.1 and 2.3 mA cm^-2, respectively). In addition to the superior photoactivity, the 5-h amperometric measurements illustrate improved stability of the surface-engineered NiOOH-P-BiVO₄ photoanode. Our work showcases the feasibility of combining cocatalysts with O_vac, for improved photoactivity and stability of photoelectrodes.

Revealing the different performance of Li4SiO4 and Ca2SiO4 for CO2 adsorption by density functional theory

To reveal the difference between Li₄SiO₄ and Ca₂SiO₄ in CO₂ adsorption performance, the CO₂ adsorption on Li₄SiO₄ (010) and Ca₂SiO₄ (100) surfaces was investigated using density functional theory (DFT) calculations. The results indicate that the bent configuration of the adsorbed CO₂ molecule parallel to the surface is the most thermodynamically favorable for both Li₄SiO₄ and Ca₂SiO₄ surfaces. The Li₄SiO₄ (010) surface has greater CO₂ adsorption energy (E_ads = −2.97 eV) than the Ca₂SiO₄ (100) surface (E_ads = −0.31 eV). A stronger covalent bond between the C atom of adsorbed CO₂ and an O_S atom on the Li₄SiO₄ (010) surface is formed, accompanied by more charge transfer from the surface to CO₂. Moreover, the Mulliken charge of O_S atoms on the Li₄SiO₄ (010) surface is more negative, and its p-band center is closer to the E_f, indicating O_S atoms on Li₄SiO₄ (010) are more active and prone to suffering electrophilic attack compared with the Ca₂SiO₄ (100) surface.

The Li₄SiO₄ (010) exhibits greater adsorption towards CO₂ than the Ca₂SiO₄ (100) with a stronger covalent bond and more charge transfer between the surface and CO₂.

Surface hydroxyl groups: the key to a CrOx/TiO2 catalyst for efficient catalytic oxidation of 2,2′-hydrazine diisobutyronitrile

Surface hydroxyl groups could contribute to the formation of Cr–O–Ti bonds on the surface of the CrOx/TiO2 catalyst, which thus promote the oxidation of 2,2′-hydrazobis-isobutyronitrile.

Wafer-Scale Synthesis of WS2 Films with In Situ Controllable p-Type Doping by Atomic Layer Deposition

Wafer-scale synthesis of p-type TMD films is critical for its commercialization in next-generation electro/optoelectronics. In this work, wafer-scale intrinsic n-type WS₂ films and in situ Nb-doped p-type WS₂ films were synthesized through atomic layer deposition (ALD) on 8-inch α-Al₂O₃/Si wafers, 2-inch sapphire, and 1 cm² GaN substrate pieces. The Nb doping concentration was precisely controlled by altering cycle number of Nb precursor and activated by postannealing. WS₂ n-FETs and Nb-doped p-FETs with different Nb concentrations have been fabricated using CMOS-compatible processes. X-ray photoelectron spectroscopy, Raman spectroscopy, and Hall measurements confirmed the effective substitutional doping with Nb. The on/off ratio and electron mobility of WS₂ n-FET are as high as 10⁵ and 6.85 cm² V⁻¹ s⁻¹, respectively. In WS₂ p-FET with 15-cycle Nb doping, the on/off ratio and hole mobility are 10 and 0.016 cm² V⁻¹ s⁻¹, respectively. The p-n structure based on n- and p- type WS₂ films was proved with a 10⁴ rectifying ratio. The realization of controllable in situ Nb-doped WS₂ films paved a way for fabricating wafer-scale complementary WS₂ FETs.

Elucidating the promotion of Na2CO3 in CO2 capture by Li4SiO4

Although Li₄SiO₄-based sorbents are candidates for CO₂ capture at high temperatures, it is still necessary to improve their kinetic activation for adsorption and desorption. Carbonate doping to Li₄SiO₄ is considered as one of the effective means to improve CO₂ capture by Li₄SiO₄. In this study, Li₄SiO₄ was synthesized using Li₂CO₃ and SiO₂ at 900 °C, and mixed with different amounts of Na₂CO₃ as CO₂ sorbents. The effects of Na₂CO₃ on the absorption and desorption were characterized using thermal analyses in an atmosphere of 80 vol% CO₂-20 vol% N₂. In situ Raman and XRD were used for the characterization of the structural transformations and phase evolution during the CO₂ capture. The activation energy of both chemisorption and diffusion in adsorption dropped significantly. The additive Na₂CO₃ can react with CO₂ and produce the pyrocarbonate, which is favorable for CO₂ capture of Li₄SiO₄ and CO₂ diffusion. The doped Na₂CO₃ served two functions: producing the intermediate product and forming the melt with the product Li₂CO₃ to accelerate CO₂ transport. The Na₂CO₃-doped Li₄SiO₄ exhibits stable cyclic durability with conversions of 75% in 20 adsorption-desorption cycles.

Daratumumab for Refractory IgD Multiple Myeloma with Lung Cancer and Persistent Thrombocytopenia: a Case Report

BACKGROUND

Immunoglobulin D multiple myeloma (IgD-MM) is a rare but aggressive disease. The safety and effectiveness of anti-CD38 monoclonal antibody (daratumumab) have not been known in either IgD-MM or MM complicated with secondary neoplasm.

METHODS

A fragile IgD-MM patient had an aggressively relapsed disease concurrent with lung cancer and severe thrombocytopenia, which led to a dilemma for management. After a failure of ixazomib-based chemotherapy, a salvage therapy with daratumumab unexpectedly induced complete remission and platelet recovery, and the patient successfully proceeded to lung cancer surgery.

CONCLUSIONS

Our case indicates daratumumab is both safe and effective for refractory IgD-MM with severe complications.