Capturing Cu2+ and recycling spent Cu-adsorbents as catalyst for eliminating Rhodamine B: reactivity and mechanism.

The thorny problem of adsorption is the disposing of spent adsorbent. In this manuscript, the exhaust adsorbent of efficient capture Cu(II) over ZSM-5 that supported zero-valent iron (nZVI) was reused as a catalyst for eliminating Rhodamine B (RhB). Batch experiments were used to evaluate the removal performance of Cu2+ and RhB. The results demonstrated that the Cu2+ adsorption process obeyed pseudo-second-order kinetics, and the adsorption performance was dependent on solution pH. The maximum adsorption capacity at the optimal pH 4.0 was 375.9 mg/g; equilibrium was reached rapidly within 35 min. From XPS, the reduction-oxidation between Fe0 and Cu2+ was occurred in the adsorption process, and Fe2+, Fe3+, and Cu0 was formed. In the recycling experiments, RhB was removed by the spent Cu adsorbent, with the removal performance being dependent on the initial Cu concentration, in the order of 5 mg/L > 20 mg/L > 0 mg/L > 100 mg/L > 500 mg/L. RhB removal also improved with increasing H2O2 concentration. More than 99.9% of the RhB was degraded within 8 min using 1.75 mM H2O2, which was a large improvement over the previously used catalyst. The hydroxyl radical was found to be the main free radical responsible for RhB degradation.

Enhanced Free-Radical Generation on MoS2 /Pt by Light and Water Vapor Co-Activation for Selective CO Detection with High Sensitivity.

Semiconductor-based gas sensors hold great promise for effective carbon monoxide (CO) detection. However, boosting sensor response and selectivity remains a key priority in moist conditions. In this study, a composite material, Pt quantum dots decorated MoS2 nanosheets (MoS2 /Pt), is developed as a highly sensitive material for CO detection when facilitated with visible light. The MoS2 /Pt sensor shows a significantly improved response (87.4%) with impressive response/recovery kinetics (20 s/17 s), long-term stability (60 days), and good selectivity to CO at high humidity (≈60%). It is confirmed both experimentally and theoretically that the MoS2 /Pt surface lowers the activation energy to convert CO to CO2 via the free radicals induced by the synergy of photochemical effects and water vapor. As a result, the MoS2 /Pt surface promotes both CO response and selectivity, providing fundamental clues to improve room-temperature semiconductor-based sensors for gas detection under extreme conditions.

Extraction of alumina from high-alumina fly ash by ammonium sulfate: roasting kinetics and mechanism.

The recycling of aluminum is commonly an important step to achieve the high value-added utilization of fly ash, which is a kind of solid waste generated from coal-fired power plants. In this study, high-alumina fly ash was efficiently activated by ammonium sulfate method and the alumina was efficiently extracted. The effects of roasting temperature, roasting time, and ammonium sulfate/high-alumina fly ash mass ratio on the leaching rate of alumina were fully analyzed, and the roasting kinetics and reaction mechanism in the roasting process were discussed. The experimental results showed that the leaching rate of alumina in the roasted material achieved 93.57% with the roasting temperature of 673 K, the roasting time of 60 min, and the mass ratio of ammonium sulfate to high-alumina fly ash of 6 : 1. The roasting kinetics showed that the reaction between high-alumina fly ash and ammonium sulfate was controlled by internal diffusion, the apparent activation energy was 37.40 kJ mol-1, which accorded with the reaction kinetic equation 1 - 2x/3 - (1 - x)2/3 = 2.9546 exp[-37 400/(RT)]t. The reaction mechanism showed that the aluminum and structural damage mullite in the high-alumina fly ash reacted with molten ammonium sulfate to form (NH4)3Al(SO4)3 and NH4Al(SO4)2. Finally, (NH4)3Al(SO4)3 was transformed into NH4Al(SO4)2 with the increase of temperature.

The nature of K-induced 2H and 1T'-MoS2 species and their phase transition behavior for the synthesis of methanethiol (CH3SH).

The one-step reaction approach from syngas with hydrogen sulfide (CO/H2/H2S) over potassium (K) promoted Molybdenum disulfide (MoS2) materials can provide alternatives for the synthesis of methanethiol (CH3SH). However, the direct confirmation and determination of the real active nature of K-induced 2H and 1T'-MoS2 for this reaction and the corresponding phase transformation behavior and origin of K-induced 2H-MoS2 from/to 1T'-MoS2 remains unclear. Herein, we proved at the atomic level the precise position of K over 1T'-MoS2 and 2H-MoS2 species using the technique of HAADF-STEM. A relationship between K-induced 1T' and 2H-MoS2 phases and the catalytic property to synthesize CH3SH was established, and K-intercalated 1T'-MoS2 phase was confirmed to have excellent catalytic performances. Moreover, the behavior, origin, and influencing factors of phase transformation of 2H-MoS2 from/to 1T'-MoS2 in the existence of K were well proved.

Degradation of phenol by photocatalysis using TiO2/montmorillonite composites under UV light.

Composites of titanium (IV) oxide combined with montmorillonite (MMT) with various TiO2/MMT were prepared for photocatalysis application. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance UV-visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). The main influential factors such as the TiO2/MMT dose, calcined temperature, and pH value of the solution were studied. The main intermediates of phenol degradation were determined by high performance liquid chromatography (HPLC). The results showed that the average size of TiO2 nanoparticles was decreased from 22.51 to 10.66 nm through the immobilization on MMT. The components in the interlayer domain were replaced by titanium pillars, and the pillaring reaction proceeded in the interlayer domain, the basic skeleton of MMT was unchanged, and TiO2 was dispersed on the surface of the MMT. When the initial concentration of phenol is 10 mg/L, the phenol solution pH is 6, and the UV light irradiation time is 240 min; the phenol degradation rate of 30%TiO2/MMT composite is 89.8%, which is better than MMT (11.5%) and pure TiO2 (58.8%). It shows that TiO2 loaded on MMT improves its photocatalytic activity. The phenol reaction process detected by HPLC showed that it had undergone through hydroquinone and benzoquinone, and finally converted into maleic acid and carbon dioxide and small molecules. The possible photocatalysis mechanism is presented.

Silencing oncogene cell division cycle associated 5 induces apoptosis and G1 phase arrest of non-small cell lung cancer cells via p53-p21 signaling pathway.

BACKGROUNDS: As a regulator of cell cycle, cell division cycle-associated 5 (CDCA5) is involved in the progression of various malignant tumors. However, the potential relationship between CDCA5 and lung cancer has not been reported. METHODS: In our study, we analyzed the expression of CDCA5 in a variety of malignant tumors, performed Kaplan-Meier survival analysis of lung adenocarcinoma (LUAD), explored the potential relationship between CDCA5 expression and clinicopathological characteristics, assessed the predictive capability of at different stages of clinicopathological characteristics, revealed the enriched functions and signaling pathways among LUAD paitents with high CDCA5 expression, and investigated the correlation between PD-1, PD-L1, and CDCA5 through bioinformatics analyses. Subsequently, we performed quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) and western blotting (WB) to demonstrate that CDCA5 mediates the p53-p21 pathway and regulates the cell cycle. RESULT: CDCA5 is probably involved in the occurrence and development of NSCLC, and function as a reliable biomarker for predicting the survival outcomes of patients with early stage of patients with LUAD. Furthermore, CDCA5 may be a promising indicator of immunotherapy efficacy. In addition, silencing the expression of CDCA5 significantly increased the proportion of apoptotic NSCLC cells, and caused NSCLC cells to be arrested in the G1 phase. CONSLUSION: In conclusion, CDCA5 regulated the cell cycle of NSCLC cells by mediating the p53-p21 signaling pathway, participating in the development and progression of NSCLC patients.

Nanoarchitectonics of Ni/CeO2 Catalysts: The Effect of Pretreatment on the Low-Temperature Steam Reforming of Glycerol.

CeO2 nanosphere-supported nickel catalysts were prepared by the wetness impregnation method and employed for hydrogen production from glycerol steam reforming. The dried catalyst precursors were either reduced by H2 after thermal calcination or reduced by H2 directly without calcination. The catalysts that were reduced by H2 without calcination achieved a 95% glycerol conversion at a reaction temperature of only 475 °C, and the catalytic stability was up to 35 h. However, the reaction temperature required of catalysts reduced by H2 with calcination was 500 °C, and the catalysts was rapidly inactivated after 25 h of reaction. A series of physicochemical characterization revealed that direct H2 reduction without calcination enhanced the concentration of oxygen vacancies. Thus, the nickel dispersion was improved, the nickel nanoparticle size was reduced, and the reduction of nickel was increased. Moreover, the high concentration of oxygen vacancy not only contributed to the increase of H2 yield, but also effectively reduced the amount of carbon deposition. The increased active nickel surface area and oxygen vacancies synergistically resulted in the superior catalytic performance for the catalyst that was directly reduced by H2 without calcination. The simple, direct hydrogen reduction method remarkably boosts catalytic performance. This strategy can be extended to other supports with redox properties and applied to heterogeneous catalytic reactions involving resistance to sintering and carbon deposition.

Study of the Metal-Support Interaction and Electronic Effect Induced by Calcination Temperature Regulation and Their Effect on the Catalytic Performance of Glycerol Steam Reforming for Hydrogen Production.

Steam reforming of glycerol to produce hydrogen is considered to be the very promising strategy to generate clean and renewable energy. The incipient-wetness impregnation method was used to load Ni on the reducible carrier TiO2 (P25). In the process of catalyst preparation, the interaction and electronic effect between metal Ni and support TiO2 were adjusted by changing the calcination temperature, and then the activity and hydrogen production of glycerol steam reforming reaction (GSR) was explored. A series of modern characterizations including XRD, UV-vis DRS, BET, XPS, NH3-TPD, H2-TPR, TG, and Raman have been applied to systematically characterize the catalysts. The characterization results showed that the calcination temperature can contribute to varying degrees of influences on the acidity and basicity of the Ni/TiO2 catalyst, the specific surface area, together with the interaction force between Ni and the support. When the Ni/TiO2 catalyst was calcined at 600 °C, the Ni species can be produced in the form of granular NiTiO3 spinel. Consequently, due to the moderate metal-support interaction and electronic activity formed between the Ni species and the reducible support TiO2 in the NiO/Ti-600C catalyst, the granular NiTiO3 spinel can be reduced to a smaller Ni0 at a lower temperature, and thus to exhibit the best catalytic performance.

MXene/WS2 hybrids for visible-light-activated NO2 sensing at room temperature.

Optoelectronic gas sensors based on two-dimensional (2D) materials are touted as potential candidates for NO2 sensing at room temperature. However, most of the developed optoelectronic sensors to date are confined to the ultraviolet region with unsatisfactory performance. Herein, a room-temperature visible-light-activated optoelectronic NO2 sensor based on 2D/2D T3C2Tx/WS2 nanocomposites is presented. The T3C2Tx/WS2-based gas sensor exhibited fast response/recovery rate, full reversibility, long stability, good selectivity, and low detection limit (10 ppb). In addition to the efficient interfacial charge separation provided by 2D/2D heterostructures, the improvement of optoelectronic NO2 sensing performance was attributed to the visible-light-activation effects. This study provides a promising method to fabricate room-temperature high-performance gas sensors based on 2D nanomaterials.

Flowing-Air-Induced Transformation to Promote the Dispersion of the CrOx Catalyst for Propane Dehydrogenation.

Highly dispersed chromium (Cr)-based catalysts are promising candidates for the catalytic dehydrogenation of propane (DHP). However, the easier aggregation of Cr species into crystalline Cr2O3 at the high-temperature calcination and reaction process is a big challenge, which severely restricts the improvement of activity and stability of the DHP reaction. Herein, a flowing-air-induced transformation method was first proposed, and the catalytic performance of the prepared Cr/MCM-41 catalysts was found to be significantly improved compared to that of the Cr-based catalyst prepared by the traditional calcination method, even better than that of most of the reported Cr-based catalysts and some noble metal-based catalysts. X-ray absorption spectroscopy and in situ Raman spectroscopy as well as other characterization techniques demonstrated that the in situ calcination in flowing air could not only effectively restrain the conversion of Cr(VI) into Cr(III) but also largely improve the dispersion of Cr species. Furthermore, DHP activity is found to have a positive correlation with the amount of monomeric Cr(VI) species, which is proved to be the precursor of active coordinatively unsaturated Cr sites. Our proposed flowing-air-induced transformation method provides a general strategy for preparing the highly dispersed Cr-based catalysts and other metal oxide materials with varied valence and exhibits potential application prospects in industry.

The identification of active chromium species to enhance catalytic behaviors of alumina-based catalysts for sulfur-containing VOC abatement.

As to the treatment of sulfur containing VOCs (examples are compounds of CH3SH and C2H5SH), finding a catalyst with high performance is necessary. In this work, Cr(x)-Al2O3 (x = 1.0, 2.5, 5.0, 7.5 and 10 wt%) catalysts were synthesized, and their behaviors toward CH3SH and C2H5SH abatement were investigated. The results indicated that Cr(7.5)-Al2O3 exhibited higher activity than other samples and the reported catalysts, on which CH3SH could be almost completely converted at 375 °C, while the temperature for the reported catalysts was above 450 °C. Moreover, there was no obvious deactivation during 30 h on stream over Cr(7.5)-Al2O3, while only about 10 h was found on the reported CeO2 and HZSM-5 catalysts. The improvement in the catalytic performance could be explained by the important role of the Cr6+ species, while the state of Cr3+ was suggested to be ineffective in the degradation process. The identification of the active Cr sites was proved by the characterization measurements, and the control experiments by using mechanical mixtures of CrO3 or Cr2O3 with Al2O3 as well as the comparison studies between spent Al2O3 and spent Cr(7.5)-Al2O3 catalysts.

Facile synthesis of amino-functional large-size mesoporous silica sphere and its application for Pb2+ removal.

Amino-functional large-size mesoporous silica spheres (LMS-AP) were successfully synthesized through a one-step method with (3-aminopropyl) triethoxysilane (APTES) addition during the pseudomorphic transformation process. LMS-AP were characterized using thermogravimetry-differential thermal analysis, Nitrogen adsorption-desorption measurement, infrared spectroscopy, and X-ray photoelectron spectroscopy. The study found that -NH2 was grafted into LMS, and the LMS-AP had a better thermal stability than other samples. The Pb2+ removal properties of LMS-AP were investigated using the static and dynamic experiments in simulated and real wastewater solutions. The kinetic and equilibrium experiments indicated that the adsorption process of LMS-AP fitted the Langmuir adsorption model and the pseudo-second-order kinetics model (R2 > 0.98), respectively. The maximum Qe (mg/g) was about 100 mg/g in the static adsorption condition. The adsorption mechanism of removal of Pb2+ was also investigated. In fix bed column experiments, LMS-AP exhibited excellent Pb2+ adsorption ability for simulated wastewater, with the maximum qe (mg/g) of 48.7 mg/g for particle size under 1-3 mm. Meanwhile in actual industrial wastewater treatment process, LMS-AP had a better Pb2+, Zn2+ and Cr (VI) removal efficiency of 80% and As (V) of 30-40% removal efficiency at initial pH 4, suggesting selective adsorption property for different heavy metal ions.

Recycling Spent Cr Adsorbents as Catalyst for Eliminating Methylmercaptan.

Waste adsorbents generated from treating Cr(VI)-containing wastewater are hazardous materials and generally landfilled or treated by acid or base desorption, with concomitant high cost and toxic effects. The present work shows that these Cr adsorbents can be reused as highly efficient catalysts for treating sulfur-containing VOCs (CH3SH), not only avoiding the economic and environmental impact from the conventional approaches, but also achieving the efficient treatment of sulfur-containing waste gas. Importantly, these reused Cr adsorbents exhibit enhanced activity and stability compared with the catalysts reported elsewhere, indicating a new avenue of green chemistry. The highly toxic adsorbed Cr(VI) species are reduced to a Cr2O3 crystalline phase by calcination and finally immobilized as a Cr2S3 solid phase while converting and eliminating CH3SH. Still, the presence of Cr(VI) species on the reused Cr adsorbent provides enough reactive sites for reaction, but high concentration of Cr(VI) species causes serious accumulation of coke deposit on the catalyst, leading to fast deactivation of the catalyst.

Investigation of the reaction pathway for synthesizing methyl mercaptan (CH3SH) from H2S-containing syngas over K-Mo-type materials.

The reaction pathway for synthesizing methyl mercaptan (CH3SH) using H2S-containing syngas (CO/H2S/H2) as the reactant gas over SBA-15 supported K-Mo-based catalysts prepared by different impregnation sequences was investigated. The issue of the route to produce CH3SH from CO/H2S/H2 has been debated for a long time. In light of designed kinetic experiments together with thermodynamics analyses, the corresponding reaction pathways in synthesizing CH3SH over K-Mo/SBA-15 were proposed. In the reaction system of CO/H2S/H2, COS was demonstrated to be generated firstly via the reaction between CO and H2S, and then CH3SH was formed via two reaction pathways, which were both the hydrogenation of COS and CS2. The resulting CH3SH was in a state of equilibrium of generation and decomposition. Decomposition of CH3SH was found to occur via two reaction pathways; one was that CH3SH first transformed into two intermediates, CH3SCH3 and CH3SSCH3, which were then further decomposed into CH4 and H2S; another was the direct decomposition of CH3SH into C, H2S and H2. Moreover, the catalyst (K-Mo/SBA-15) prepared with co-impregnation exhibits higher catalytic activities than the catalysts (K/Mo/SBA-15 and Mo/K/SBA-15) prepared by the sequence of impregnation. Based on characterization of the oxidized, sulfided and spent catalysts via N2 adsorption-desorption isotherms, XRD, Raman, XPS and TPR, it was found that two K-containing species, K2Mo2O7 and K2MoO4, were oxide precursors, which were then converted into main K-containing MoS2 species. The CO conversion was closely related to the amount of edge reactive sulfur species that formed the sulfur vacancies over MoS2 phases.

Investigating the Heavy Metal Adsorption of Mesoporous Silica Materials Prepared by Microwave Synthesis.

Mesoporous silica materials (MSMs) of the MCM-41 type were rapidly synthesized by microwave heating using silica fume as silica source and evaluated as adsorbents for the removal of Cu2+, Pb2+, and Cd2+ from aqueous solutions. The effects of microwave heating times on the pore structure of the resulting MSMs were investigated as well as the effects of different acids which were employed to adjust the solution pH during the synthesis. The obtained MCM-41 samples were characterized by nitrogen adsorption-desorption analyses, X-ray powder diffraction, and transmission electron microscopy. The results indicated that microwave heating method can significantly reduce the synthesis time of MCM-41 to 40 min. The MCM-41 prepared using citric acid (c-MCM-41(40)) possessed more ordered hexagonal mesostructure, higher pore volume, and pore diameter. We also explored the ability of c-MCM-41(40) for removing heavy metal ions (Cu2+, Pb2+, and Cd2+) from aqueous solution and evaluated the influence of pH on its adsorption capacity. In addition, the adsorption isotherms were fitted by Langmuir and Freundlich models, and the adsorption kinetics were assessed using pseudo-first-order and pseudo-second-order models. The intraparticle diffusion model was studied to understand the adsorption process and mechanism. The results confirmed that the as-synthesized adsorbent could efficiently remove the heavy metal ions from aqueous solution at pH range of 5-7. The adsorption isotherms obeyed the Langmuir model, and the maximum adsorption capacities of the adsorbent for Cu2+, Pb2+, and Cd2+ were 36.3, 58.5, and 32.3 mg/g, respectively. The kinetic data were well fitted to the pseudo-second-order model, and the results of intraparticle diffusion model showed complex chemical reaction might be involved during adsorption process.

A novel and facile method to rapidly synthesize Ce0.8Zr0.2O2 nanoparticles for CO preferential oxidation in H2-rich stream.

A novel urea grind combustion (UGC) route was reported in this paper to rapidly prepare the ceria-zirconia nanoparticles (Ce0.8Zr0.2O2). For comparison, the conventional surfactant-assisted (SA) and sol-gel (SG) methods were also employed to prepare Ce0.8Zr0.2O2 nanoparticles. CO preferential oxidation in H2-rich stream (CO-PROX) was chosen as probe reaction to investigate the catalytic performance of these Ce0.8Zr0.2O2 catalysts prepared with different methods to highlight the superiority of UGC. It was found that Ce0.8Zr0.2O2-UGC showed the better reducibility and oxygen mobility than the Ce0.8Zr0.2O2 prepared by SA and SG, because the UGC route favored the more incorporation of zirconia into CeO2, leading to more serious distortion of the structure, and more defective sites in the Ce0.8Zr0.2O2. As a result, Ce0.8Zr0.2O2-UGC exhibited the higher CO conversion, better O2 selectivity, and excellent catalytic stability without any deactivation during 72-h reaction on stream. More importantly, the UGC method, as compared to the relatively complex and time-consuming SA and SG method, is simple, facile, low-cost, time-saving (within 30 minutes) and scalable, thereby, might be very promising for the application in many fields.

The optimization of As(V) removal over mesoporous alumina by using response surface methodology and adsorption mechanism.

The Box-Behnken Design of the response surface methodology was employed to optimize four most important adsorption parameters (initial arsenic concentration, pH, adsorption temperature and time) and to investigate the interactive effects of these variables on arsenic(V) adsorption capacity of mesoporous alumina (MA). According to analysis of variance (ANOVA) and response surface analyses, the experiment data were excellent fitted to the quadratic model, and the interactive influence of initial concentration and pH on As(V) adsorption capacity was highly significant. The predicted maximum adsorption capacity was about 39.06 mg/g, and the corresponding optimal parameters of adsorption process were listed as below: time 720 min, temperature 52.8 °C, initial pH 3.9 and initial concentration 130 mg/L. Based on the results of arsenate species definition, FT-IR and pH change, As(V) adsorption mechanisms were proposed as follows: (1) at pH 2.0, H3AsO4 and H2AsO4(-) were adsorbed via hydrogen bond and electrostatic interaction, respectively; (2) at pH 6.6, arsenic species (H2AsO4(-) and HAsO4(2-)) were removed via adsorption and ion exchange, (3) at pH 10.0, HAsO4(2-) was adsorbed by MA via ion exchange together with adsorption, while AsO4(3-) was removed by ion exchange.

[AHP application to study of weighted coefficient on multicriteria optimization of extraction technology about Chinese traditional compound drugs].

OBJECTIVE: Establishing a subjective and objective method to conform the weighted coefficient in multicriteria optimization of the extraction technology about Chinese traditional compound drugs. METHOD: This article used analytic hierarchy process (AHP) to conform the weighted coefficient. RESULT: Consistency checking result (CR < 0.1) indicated that the weighted coefficient is reasonable and efficient. CONCLUSION: AHP method is simple and of high accuracy. This method improved on the scientific and accuracy of multicriteria optimization of the extraction technology about Chinese traditional compound drugs.