This work focused on determining the physico-chemical characteristics (pH, carbon and nitrogen) and trace metal elements (TMEs) content (As, Sb, Cd, Hg, Ni, Pb, Cr, Zn) of soils in the Brazzaville city. Soil samples w...This work focused on determining the physico-chemical characteristics (pH, carbon and nitrogen) and trace metal elements (TMEs) content (As, Sb, Cd, Hg, Ni, Pb, Cr, Zn) of soils in the Brazzaville city. Soil samples were taken from a depth of 0 to 20 cm using a hand auger on both banks of five tributaries of the Congo River (Djoué, Mfilou, Mfoa, Tsiémé, Djiri) that flow through the city of Brazzaville. 90 sampling points were defined, with 3 points 250 m apart on the banks and located, for each river, at three sites: upstream, midstream and downstream. Finally, 15 composite samples representative of the study area were taken. The average pH values of the water varied between 6.5 and 7.5. These pH values show that the soils studied are neutral. Total carbon content varied between 0.7% (Djiri) and 1.6% (Djoué). Total nitrogen content ranged from 0.08% (Djiri) to 0.12% (Djoué). TMEs contents varied from 0.5 to 1.8 mg/kg for Sb, from 0.5 to 2.5 mg/kg for As, from 0.1 to 0.18 mg/kg for Cd, from 4.2 to 11.3 mg/kg for Cr, from 0.07 to 0.27 mg/kg for Hg, from 0.7 to 2.4 mg/kg for Ni, from 0 to 158 mg/kg for Pb and from 16 to 105 mg/kg for Zn. The lowest TMEs levels were observed in the soils of the Djiri river, while the highest levels were observed in the soils of the Djoué and Tsiémé rivers. The ANOVA and Bonferroni test did not show significant differences in the means of the parameters measured (p > 0.05). The TMEs levels were below the accepted standards (NF U44-041), with the exception of Pb, which had high levels downstream of the Djoué. According to the pollution index values calculated using soil TME content, the soils on the banks of the Djoué river are considered polluted, while those on the banks of the Tsiémé river are moderately polluted, those on the banks of the Mfoa and Mfilou rivers are slightly polluted, and the soils on the banks of Djiri river are unpolluted.展开更多
The conversion of forest land to other types of land cover is one of the major issues in the global fight against climate change. Understanding the direct and indirect factors of these conversions from local studies i...The conversion of forest land to other types of land cover is one of the major issues in the global fight against climate change. Understanding the direct and indirect factors of these conversions from local studies in the tropics is essential to project the future impact of human activities on the preservation of tropical forests in general and the forests of the Republic of Congo in particular. This study, conducted in five localities with different socioeconomic contexts in the Republic of Congo, aims to analyze the variability of drivers of deforestation and forest degradation linked to urbanization in the Congo Basin. Using a series of land cover maps from the years 1986, 2003 and 2019 for the cities of Ouesso, Pokola, Ngombe, Impfondo and Dongou, as well as field data and socio-economic information collected from local and central administrations, a unique model has been developed to understand the explanatory patterns of forest loss. Deforestation around urban centers is mainly due to urban agriculture due to population growth, as well as the spatial expansion of cities, which have a major impact on the stability and integrity of forests. Shifting agriculture is the main direct cause of deforestation and forest degradation, representing 48% of the total sample, followed by the collection of wood fuel (22%), the collection of construction wood (19%), illegal logging (6%) and urban expansion (5%). Forecasts indicate that forest loss around major cities will increase by 487, 20 ha to 5266, 73 ha by 2050 compared to the base year of 2019. This study highlights the need for a new system of land management and poverty alleviation of local populations to ensure the stability of the Congo Basin tropical forests around large and small African cities.展开更多
Groundwater,surface water and tap water contamination by PTEs(Potentially Toxic Elements)was assessed in Kipushi town and Lupoto locality of Kipushi administrative territory in the Upper-Katanga province,Democratic Re...Groundwater,surface water and tap water contamination by PTEs(Potentially Toxic Elements)was assessed in Kipushi town and Lupoto locality of Kipushi administrative territory in the Upper-Katanga province,Democratic Republic of Congo.A total of fifty four water samples including thirty two samples from drilled water wells,ten samples from spade-sunk water wells,six samples from supplied tap water,four samples from a mine effluent and two samples from a river were collected from both localities in November and December 2017 and in January,February and March 2018.Then the samples were analyzed for their PTE contents by ICP-SF-MS(Inductively Coupled Plasma-Sector Field Mass Spectrometry).Twenty PTEs including aluminum,arsenic,barium,bismuth,cadmium,cesium,chromium,cobalt,copper,iron,lead,manganese,molybdenum,nickel,strontium,thallium,tungsten,uranium,vanadium and zinc were detected at various concentrations in each one of the samples.Many samples had concentrations and mean concentrations of PTE,such as arsenic,aluminum,cadmium,iron,lead,manganese and zinc,higher than the respective acceptable limits set for drinking water by the EU(European Union),the USEPA(United States Environmental Protection Agency),and the WHO(World Health Organization)standards.Most PTEs being deleterious to human health even at very low concentrations,people who use the groundwater,surface water and tap water to meet their water needs in both localities are at risk.展开更多
Dye wastewater poses a significant threat to aquatic organisms due to its high toxicity.Reducing or eliminating the dye waste from the water is necessary for a healthy and sustainable aquaculture.This study investigat...Dye wastewater poses a significant threat to aquatic organisms due to its high toxicity.Reducing or eliminating the dye waste from the water is necessary for a healthy and sustainable aquaculture.This study investigated the adsorption properties of Congo red dye on Mytilus edulis shell powders prepared by calcination at 500℃,700℃,and 900℃.The modified shell powder products were analyzed by SEM(scanning eletron microscopy)and FTIR(fourier transform infrared spectroscopy)for the morphology and structural characterization.The effects of different calcination temperatures,reaction times,reaction temperatures,and initial concentration of Congo red on the adsorption properties were investigated.The adsorption kinetics and isothermal adsorption models were also established.The results revealed that the shell powder calcinated at 900℃showed the best adsorption capacity on Congo red from aqueous solution.The adsorption reaction reached equilibrium after 150 min and followed by the pseudo-second-order kinetic model.At 25℃,96.2%of the Congo red in the solution could be removed,and the adsorption capacity could reach at least 1015 mg g^(–1).The adsorption isotherm is fit with the Freundlich model,indicating a multiphase adsorption process.These results are helpful for cleaning and treating printing and dyeing effluents as well as high-value utilization of shell waste resources.展开更多
Porous materials are excellent adsorbents for the removal of organic dyes from sewage and play a significant role in environmental restoration.Herein,two ferrocene(Fc)-based covalent organic frameworks(Fc-COFs),namely...Porous materials are excellent adsorbents for the removal of organic dyes from sewage and play a significant role in environmental restoration.Herein,two ferrocene(Fc)-based covalent organic frameworks(Fc-COFs),namely FcTF-COF and FcBD-COF,are successfully synthesized for the first time through a solvothermal method,and the obtained Fc-COFs powders are used to adsorb Congo red(CR)from water.The results show that both FcTF-COF and FcBD-COF have superb adsorption performance towards CR with ultrahigh adsorption capability of 1672.2 mg g−1 and 1983.7 mg g−1 at pH=4.0,respectively,outperforming the majority of the reported solid porous adsorbents.The maximum adsorption of both Fc-COFs agrees with the Sips adsorption isothermal model,indicating that their adsorption was dominated by heterogeneous adsorption.The Coulombic interactions,hydrogen bonding,π-πinteractions and ion-dipolar interactions should all contribute to their ultrahigh CR adsorption capability and high-pH resistance performance regardless of the pH in the range of 4-9.In addition,after five cycles,both COFs still remain their exceptional high CR adsorption capabilities.This study offers a prospective organic porous adsorbent with promising applications for organic dye removal in sewage processing.展开更多
A BiOI/BiOBr S-scheme heterojunction photocatalyst was synthesized using a solvothermal method,and its ability to degrade Congo red was thoroughly investigated.The photocatalytic performance of the BiOI/BiOBr heteroju...A BiOI/BiOBr S-scheme heterojunction photocatalyst was synthesized using a solvothermal method,and its ability to degrade Congo red was thoroughly investigated.The photocatalytic performance of the BiOI/BiOBr heterojunction was compared with that of pure BiOBr and BiOI.The structural,morphological,optical,and electrical properties of the samples were characterized using X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),UV-vis diffuse reflectance spectroscopy(UV-vis DRS),and zeta potential analysis.The degradation rate of Congo red was determined by spectrophotometry,revealing that the BiOI/BiOBr S-scheme heterojunction exhibited excellent photocatalytic performance,achieving a degradation rate of 96.8%for a 50 mg/L Congo red solution within 75 minutes.This rate was significantly higher than those achieved by pure BiOBr(77.2%)and BiOI(83.1%).Theoretical calculations indicate that the S-scheme heterojunction effectively facilitates the separation of photogenerated charge carriers while preserving the strong redox ability of the composite.These characteristics are identified as the key factors underlying the superior photocatalytic degradation efficiency of the BiOI/BiOBr S-scheme heterostructure.展开更多
BACKGROUND Thyroid cancer incidence is rising globally,including the Democratic Republic of Congo(DRC).Despite its increasing incidence,limited data exist on physicians’knowledge of thyroid cancer management in the D...BACKGROUND Thyroid cancer incidence is rising globally,including the Democratic Republic of Congo(DRC).Despite its increasing incidence,limited data exist on physicians’knowledge of thyroid cancer management in the DRC.AIM To evaluate the knowledge levels of Congolese physicians regarding the diagnosis and treatment of thyroid nodules and cancers,and to identify existing gaps and areas for improvement.METHODS A descriptive cross-sectional study was conducted from June to August 2024,involving 369 physicians practicing in healthcare facilities across Kinshasa,DRC.Participants were selected using a multi-stage sampling method.Data were collected via a structured questionnaire covering thyroid cancer epidemiology,diagnostic methods,treatment approaches,and prognosis.Data were analyzed using SPSS version 25,employing descriptive and inferential statistics,with a P value≤0.05 being considered as statistically significant.RESULTS Overall response rate was 96.1%.Of all participants,68%were female and 32%were male physicians.General practitioners constituted 84.8%of respondents,with an average age of 34 years.While 53.7%demonstrated adequate knowledge of hypothyroidism management post-thyroidectomy and 61.2%identified the approach for hypoparathyroidism,only 5.1%recognized the need for radiotherapy in metastatic thyroid cancer cases.Awareness of anaplastic thyroid cancer treatment was limited(6.5%),and 90.2%of physicians were unfamiliar with the surgical complications.Moderate understanding was noted in diagnostic protocols,with 44.2%correctly identifying repeat fine-needle aspiration timing in Bethesda I cases.Knowledge of molecular genetics,recurrence risks,and metastasis patterns was remarkably low.CONCLUSION This study highlights significant knowledge gaps among Congolese physicians regarding thyroid cancer management,especially about advanced treatment modalities and molecular genetics.Targeted educational programs and improved access to diagnostic tools are critical to bridging these deficits.Addressing these gaps can enhance the quality of thyroid cancer care and align clinical practices in the DRC with global standards.展开更多
Pure TiO_(2)and copper-modified titania(Cu/TiO_(2))nanoparticles were synthesized through sol gel combined with the pyrolysis method for the removal of Congo red(CR)in wastewater treatment.Surface morphology and struc...Pure TiO_(2)and copper-modified titania(Cu/TiO_(2))nanoparticles were synthesized through sol gel combined with the pyrolysis method for the removal of Congo red(CR)in wastewater treatment.Surface morphology and structural evaluation utilized XRD,TEM,Raman,FTIR and BET techniques.Cu/TiO_(2)showed rich defects and a higher specific surface area than that of TiO_(2).The 1Cu/TiO_(2)(molar ratio Cu/TiO_(2)of 1/100)showed the best performance to adsorption of CR solution at different reaction conditions(contact duration,CR concentration,adsorbent dose,temperature,and initial pH).Adsorption kinetics and equilibrium isotherms were well-described with a pseudo-second-order kinetics and Freundlich model,respectively.The negative ΔG indicates stable adsorption of CR on the Cu/TiO_(2)surface.The adsorption efficiency only decreases by 6%after 5 cycles of adsorption regeneration.The successful synthesis of Cu/TiO_(2)offers a new possibility to address the problems related to CR dye from aqueous solutions.展开更多
Dear Editor,Crimean–Congo hemorrhagic fever(CCHF),caused by the CCHF virus(CCHFV),is a severe tick-borne illness with a wide geographical distribution,posing a significant threat with case fatality rates ranging from...Dear Editor,Crimean–Congo hemorrhagic fever(CCHF),caused by the CCHF virus(CCHFV),is a severe tick-borne illness with a wide geographical distribution,posing a significant threat with case fatality rates ranging from 5%to 70%(Hawman and Feldmann,2023).Due to the lack of approved vaccines and therapeutics,the World Health Organization(WHO)has listed CCHF as one of the priority diseases(Semper et al.,2024).CCHF initially presents as a nonspecific febrile illness,characterized by fever,malaise,myalgia,and nausea,which can rapidly progress to hemorrhagic disease.The hemorrhagic stage is particularly pronounced in severe cases,with rapid progression to disseminated intravascular coagulation(DIC),overt bleeding,kidney or liver failure,and shock(Frank et al.,2024).Up to date,there is an absence of a suitable animal model that can accurately mimic the coagulopathy and bleeding associated with CCHFV infection.Consequently,our understanding of the pathogenic mechanisms underlying these conditions remains limited(Rodriguez et al.,2022).展开更多
Metal-organic frameworks(MOFs) provide great prospective in the photodegradation of pollutants. Nevertheless, the poor separation and recovery hamper their pilot-or industrial-scare applications because of their micro...Metal-organic frameworks(MOFs) provide great prospective in the photodegradation of pollutants. Nevertheless, the poor separation and recovery hamper their pilot-or industrial-scare applications because of their microcrystalline features. Herein, this challenge can be tackled by integrating Cu-MOFs into an alginate substrate to offer environmentally friendly, sustainable, facile separation, and high-performance MOF-based hydrogel photocatalysis platforms. The CuⅡ-MOF 1 and CuⅠ-MOF 2 were initially synthesized through a direct diffusion and single-crystal to single-crystal(SCSC) transformation method, respectively,and after the immobilization into alginate, more effective pollutant decontamination was achieved via the synergistic effect of the adsorption feature of hydrogel and in situ photodegradation of Cu-MOFs.Specifically, Cu-MOF-alginate composites present an improved and nearly completed Cr(Ⅵ) elimination at a short time of 15–25 min. Additionally, the congo red(CR) decolorization can be effectively enhanced in the presence of Cr(Ⅵ), and 1-alginate showed superior simultaneous decontamination efficiency of CR and Cr(Ⅵ) with 99% and 78%, respectively. Furthermore, Cu-MOF-alginate composites can maintain a high pollutant removal after over 10 continuous cycles(95% for Cr(Ⅵ) after 14 runs, and 90% for CR after 10runs). Moreover, the Cr(Ⅵ)/CR degradation mechanism for Cu-MOF-alginate composite was investigated.展开更多
The environmental impact of greenhouse gases based on natural gas flaring influences the rate of gas recovery around the world. In the Republic of Congo, the natural gas reserve in 2019 is estimated at 90 billion cubi...The environmental impact of greenhouse gases based on natural gas flaring influences the rate of gas recovery around the world. In the Republic of Congo, the natural gas reserve in 2019 is estimated at 90 billion cubic meters (BCM). In this study, from the Congolese gas reserve we used five gas turbines with a capacity of 150 MW each;these five turbines consume 1.69 billion cubic meters (BCM)/year for the power of 273.750 MW and consumption of 6.57 billion kilowatt-hours. The results of this study revealed that an investment capital of 192,305,137 euros was required with a net profit of 9,581,250 euros at an annual rate of return of 4.98% with an investment payback period of approximately 20 years. This will allow the Congolese government to accomplish its policy of valuing gas and developing the country;the electricity produced by the National Petroleum Company of Congo (SNPC) will be sold to the Electrical Energy of Congo (E<sup>2</sup>C) at 0.06 euro/kWh.展开更多
The assembly of layered double hydroxides （LDHs） and multi-walled carbon nanotubes （MWCNTs） nanohybrids was prepared as MWCNTs/LDHs by co-precipitation. The synthesized nanoparticles were characterized by us...The assembly of layered double hydroxides （LDHs） and multi-walled carbon nanotubes （MWCNTs） nanohybrids was prepared as MWCNTs/LDHs by co-precipitation. The synthesized nanoparticles were characterized by using XRD, FT-IR, SEM/EDX, TGA and BET. XRD and SEM studies proved that MWCNTs phases did not enter into the interlayers of LDHs, they dispersed over the LDHs surface homogeneously. BET results showed that MWCNTs/LDHs possessed hierarchically porous nanostructure with large surface area （124.974 m^2/g） and great pore volume （0.604 cm^3/g）. Batch experiments were conducted to study the adsorption efficiency of Congo red （CR）. It was worthy to note that MWCNTs/LDHs exhibited excellent adsorption performance with the maximum CR adsorption capacity of 595.8 mg/g in weak acidic environment. The adsorption kinetics and isotherm parameters can be well described by the pseudo-second-order and the Langmuir isotherm models, respectively. The thermodynamic studies indicated that the adsorption process was spontaneous and endothermic.展开更多
This research demonstrates the production of mesoporous activated carbon from sargassum fusiforme via physical activation with carbon dioxide.Central composite design was applied to conduct the experiments at differen...This research demonstrates the production of mesoporous activated carbon from sargassum fusiforme via physical activation with carbon dioxide.Central composite design was applied to conduct the experiments at different levels by altering three operating parameters.Activation temperature(766-934℃),CO2 flow rate(0.8-2.8 L·min^-1)and activation time(5-55 min)were the variables examined in this study.The effect of parameters on the specific surface area,total pore volume and burn-out rate of activated carbon was studied,and the influential parameters of methylene blue adsorption value were identified employing analysis of variance.The optimum conditions for maximum methylene blue adsorption value were:activation temperature=900℃,activation time=29.05 min and CO2 flow rate=1.8 L·min(-1).The activated carbon produced under optimum conditions was characterized by BET,FTIR and SEM.The adsorption behavior on congo red was studied.The effect of parameters on the adsorbent dosage,temperature,PH and initial congo red concentration was investigated.The adsorption properties of the activated carbon were investigated by kinetics.The equilibrium removal rate and maximum adsorption capacity reaches up to 94.72%,234 mg·g^-1,respectively when initial congo red concentration is 200 mg·L^-1 under adsorbent dosage(0.8 g·L^-1),temperature(30℃),PH7.展开更多
Mg/Al/Fe layered double hydroxide(MAF-LDH1) was prepared by solvothermal method with the sodium dodecyl sulfate as the template, and the ethanol system was benefit to growth of sample. The nature in the resulting MAF-...Mg/Al/Fe layered double hydroxide(MAF-LDH1) was prepared by solvothermal method with the sodium dodecyl sulfate as the template, and the ethanol system was benefit to growth of sample. The nature in the resulting MAF-LDH was investigated by X-ray diffraction, field emission scanning electron microscopy, Fourier transformed infrared spectra, thermogravimetric analysis, and N2 adsorption-desorption.The morphology of MAF-LDH1 is petal-like with the size of 400-500 nm and the thickness about 10-20 nm. The adsorption performance of the samples was evaluated by absorption of the Congo red(CR) solutions. Compared with Mg/Al layered double hydroxide(MA-LDH), the maximum adsorption capacities of the MAF-LDH1 samples were 943.4 mg/g which was greatly enhanced. Furthermore, after seven cycling tests, the adsorption performance was still up to 90%. Theoretical calculation results revealed that the adsorption process was spontaneous and followed the pseudo-second-order kinetic model and Freundlich model. This work provides a promising alternative strategy to enhance the adsorptive properties of hydrotalcite-like materials.展开更多
A dielectric barrier discharge （DBD） reactor with a rod-plate electrode configuration was used for the oxidative decomposition of Congo red dye in an aqueous solution. Plasma was generated in the gas space above the...A dielectric barrier discharge （DBD） reactor with a rod-plate electrode configuration was used for the oxidative decomposition of Congo red dye in an aqueous solution. Plasma was generated in the gas space above the water interface under atmospheric pressure. Discharge characteristics were analyzed by voltage-current waveforms. Effects of applied voltage, initial conductivity, and initial concentration were also analyzed. Congo red discoloration increased with increased applied voltage and decreased conductivity. The initial conductivity significantly influenced the Congo red discoloration. Under the same conditions, the highest discoloration rate was obtained at 25 mg/L. The presence of ferrous ions in the solutions had a substantial positive effect on Fenton dye degradation and flocculation. At an applied voltage of 20 kV, about 100% of dye was degraded after 4 min of Fe^2＋/DBD treatment. Results showed that adding a certain dosage of hydrogen peroxide to the wastewater could enhance the discoloration rate. Possible pathways of Congo red discoloration by DBD plasma were proposed based on GC/MS, FTIR, and UV-vis spectroscopy analyses.展开更多
Radio frequency （RF） underwater discharge operation was performed for different liquid conductivities driven by different frequencies ranging from 13.56 MHz to 60 MHz, and its application to organic degradation was ...Radio frequency （RF） underwater discharge operation was performed for different liquid conductivities driven by different frequencies ranging from 13.56 MHz to 60 MHz, and its application to organic degradation was investigated. The RF underwater discharge was observed to be generated within the bubble at electrode surface formed by RF and plasma heating. It was shown that the sizes of the bubbles and plasmas increased as the driving frequency and the input power went up. The breakdown voltage decreased rapidly with the increase of the water conductivity and driving frequency. Comparative experiments of the UV-VIS absorbance spectra of Congo Red solution before and after discharge suggested effective degradation of the organic dye due to the active species generated during the discharge, such as .OH, .O, .H, etc. revealed by optical emission spectroscopy. The results show that higher exciting frequency and lower conduc- tivity of the solution are more effective for organic degradation. With the combination of Fourier Transform Infrared Spectroscopy （FT-IR） and Liquid Chromatography-Mass Spectrometry （LC- MS） data, one possible degradation process was proposed and the main conceivable components and structures of the products were also presented.展开更多
A facile eco-friendly hydrothermal route （180 ℃, 12.0 h） has been developed for the first time to the uniform hierarchical porous MgBO2（OH） microspheres without the aid of any organic additive, surfactant or temp...A facile eco-friendly hydrothermal route （180 ℃, 12.0 h） has been developed for the first time to the uniform hierarchical porous MgBO2（OH） microspheres without the aid of any organic additive, surfactant or template, by using the abundant MgCl2·6H2O, H3BO3 and NaOH as the raw materials. The as-obtained porous microspheres exhibit a specific surface area of 94.752 mg·g-1, pore volume of 0.814 cm3.g-1, and ca. 84.0% of which have a diameter of 2.25-3.40 μm. The thermal decomposition of the porous MgBO2（OH） microspheres （650 ℃, 2.5 ℃. min-l） leads to the porous Mg2B2O5 rnicrospheres with well-retained morphology. When utilized as the adsorbents for the removal of CR from mimic waste water, the present porous MgBO2（OH） microspheres exhibit satisfactory adsorption capacity, with the maximum adsorption capacity qm of 309.1 mg-g-1, much higher than that derived from most of the referenced adsorbents. This opens a new window for the facile green hydrothermal synthesis of the hierarchical porous MgBO2（OH） microspheres, and extends the potential application of the 3D hierarchical porous metal borates as high-efficiency adsorbents for organic dyes removal.展开更多
A-site substituted La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites were prepared by sol-gel method and characterized using thermogravimetry/differential thermal analysis（TGA/DTA）, X-ray diffraction（XRD）, ultr...A-site substituted La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites were prepared by sol-gel method and characterized using thermogravimetry/differential thermal analysis（TGA/DTA）, X-ray diffraction（XRD）, ultraviolet-visible（UV-Vis） spectroscopy and transmission electron microscopy（TEM）. XRD analysis showed that the La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites derived after calcination at 800 oC were in single phase with orthorhombic structure. The particle size of all nano perovskites was found to be ~20 nm. The synthesized nano perovskites were tested for the photocatalytic decomposition of an azo dye, Congo red. The sequential behavior of La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nanoperovskites for photocatalytic decomposition of congo red in aqueous solution by visible light at room temperature was studied at various time intervals and the efficiency of degradation of the nanoperovskites was compared. Among all the A-site substituted La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites, Ba substituted compound showed the highest dye degradation.展开更多
We report on the synthesis of Sn-doped hematite nanoparticles(Sn-α-Fe_(2)O_(3) NPs)by the hydrothermal method.The prepared Sn-α-Fe_(2)O_(3) NPs had a highly pure and well crystalline rhombohedral phase with an avera...We report on the synthesis of Sn-doped hematite nanoparticles(Sn-α-Fe_(2)O_(3) NPs)by the hydrothermal method.The prepared Sn-α-Fe_(2)O_(3) NPs had a highly pure and well crystalline rhombohedral phase with an average particle size of 41.4 nm.The optical properties of as-synthesizedα-Fe_(2)O_(3) NPs show a higher bandgap energy(2.40-2.57 eV)than that of pure bulkα-Fe_(2)O_(3)(2.1 eV).By doping Sn intoα-Fe_(2)O_(3) NPs,the Sn-doped hematite was observed a redshift toward a long wavelength with in-creasing Sn concentration from 0%to 4.0%.The photocatalytic activity of Sn-dopedα-Fe_(2)O_(3) NPs was evaluated by Congo red(CR)dye degradation.The degradation efficiency of CR dye using Sn-α-Fe_(2)O_(3) NPs catalyst is higher than that of pureα-Fe_(2)O_(3) NPs.The highest degradation efficiency of CR dye was 97.8%using 2.5%Sn-dopedα-Fe_(2)O_(3) NPs catalyst under visible-light irradi-ation.These results suggest that the synthesized Sn-dopedα-Fe_(2)O_(3) nanoparticles might be a suitable approach to develop a photocatalytic degradation of toxic inorganic dye in wastewater.展开更多
A series of carboxymethyl cellulose/organic montmorillonite （CMC/OMMT） nanocomposites with different weight ratios of carboxymethyl cellulose （CMC） to organic montmorillonite （OMMT） were synthesized under differ...A series of carboxymethyl cellulose/organic montmorillonite （CMC/OMMT） nanocomposites with different weight ratios of carboxymethyl cellulose （CMC） to organic montmorillonite （OMMT） were synthesized under different conditions. The nanocomposites were characterized by the Fourier transform infrared （FT-IR） spectrophotometer, X-ray diffraction （XRD） method, transmission electron microscope （TEM）, scanning electron microscope （SEM）, and thermal gravimetric （TG） analysis. The results showed that the introduction of CMC may have different influences on the physico-chemical properties of OMMT and intercalated-exfoliated nanostructures were formed in the nanocomposites. The effects of different reaction conditions on the adsorption capacity of samples for Congo Red （CR） dye were investigated by controlling the amount ofhexadecyl trimethyl ammonium bromide （CTAB）, the weight ratio of CMC to OMMT, the reaction time, and the reaction temperature. Results from the adsorption experiment showed that the adsorption capacity of the nanocomposites can reach 171.37 rag/g, with the amount of CTAB being 1.0 cation exchange capacity （CEC） of MMT, the weight ratio of CMC to OMMT being l：l, the reaction time being 6 h, and the reaction temperature being 60~C. The CMC/OMMT nanocomposite can be used as a potential adsorbent to remove CR dye from an aqueous solution.展开更多
文摘This work focused on determining the physico-chemical characteristics (pH, carbon and nitrogen) and trace metal elements (TMEs) content (As, Sb, Cd, Hg, Ni, Pb, Cr, Zn) of soils in the Brazzaville city. Soil samples were taken from a depth of 0 to 20 cm using a hand auger on both banks of five tributaries of the Congo River (Djoué, Mfilou, Mfoa, Tsiémé, Djiri) that flow through the city of Brazzaville. 90 sampling points were defined, with 3 points 250 m apart on the banks and located, for each river, at three sites: upstream, midstream and downstream. Finally, 15 composite samples representative of the study area were taken. The average pH values of the water varied between 6.5 and 7.5. These pH values show that the soils studied are neutral. Total carbon content varied between 0.7% (Djiri) and 1.6% (Djoué). Total nitrogen content ranged from 0.08% (Djiri) to 0.12% (Djoué). TMEs contents varied from 0.5 to 1.8 mg/kg for Sb, from 0.5 to 2.5 mg/kg for As, from 0.1 to 0.18 mg/kg for Cd, from 4.2 to 11.3 mg/kg for Cr, from 0.07 to 0.27 mg/kg for Hg, from 0.7 to 2.4 mg/kg for Ni, from 0 to 158 mg/kg for Pb and from 16 to 105 mg/kg for Zn. The lowest TMEs levels were observed in the soils of the Djiri river, while the highest levels were observed in the soils of the Djoué and Tsiémé rivers. The ANOVA and Bonferroni test did not show significant differences in the means of the parameters measured (p > 0.05). The TMEs levels were below the accepted standards (NF U44-041), with the exception of Pb, which had high levels downstream of the Djoué. According to the pollution index values calculated using soil TME content, the soils on the banks of the Djoué river are considered polluted, while those on the banks of the Tsiémé river are moderately polluted, those on the banks of the Mfoa and Mfilou rivers are slightly polluted, and the soils on the banks of Djiri river are unpolluted.
文摘The conversion of forest land to other types of land cover is one of the major issues in the global fight against climate change. Understanding the direct and indirect factors of these conversions from local studies in the tropics is essential to project the future impact of human activities on the preservation of tropical forests in general and the forests of the Republic of Congo in particular. This study, conducted in five localities with different socioeconomic contexts in the Republic of Congo, aims to analyze the variability of drivers of deforestation and forest degradation linked to urbanization in the Congo Basin. Using a series of land cover maps from the years 1986, 2003 and 2019 for the cities of Ouesso, Pokola, Ngombe, Impfondo and Dongou, as well as field data and socio-economic information collected from local and central administrations, a unique model has been developed to understand the explanatory patterns of forest loss. Deforestation around urban centers is mainly due to urban agriculture due to population growth, as well as the spatial expansion of cities, which have a major impact on the stability and integrity of forests. Shifting agriculture is the main direct cause of deforestation and forest degradation, representing 48% of the total sample, followed by the collection of wood fuel (22%), the collection of construction wood (19%), illegal logging (6%) and urban expansion (5%). Forecasts indicate that forest loss around major cities will increase by 487, 20 ha to 5266, 73 ha by 2050 compared to the base year of 2019. This study highlights the need for a new system of land management and poverty alleviation of local populations to ensure the stability of the Congo Basin tropical forests around large and small African cities.
文摘Groundwater,surface water and tap water contamination by PTEs(Potentially Toxic Elements)was assessed in Kipushi town and Lupoto locality of Kipushi administrative territory in the Upper-Katanga province,Democratic Republic of Congo.A total of fifty four water samples including thirty two samples from drilled water wells,ten samples from spade-sunk water wells,six samples from supplied tap water,four samples from a mine effluent and two samples from a river were collected from both localities in November and December 2017 and in January,February and March 2018.Then the samples were analyzed for their PTE contents by ICP-SF-MS(Inductively Coupled Plasma-Sector Field Mass Spectrometry).Twenty PTEs including aluminum,arsenic,barium,bismuth,cadmium,cesium,chromium,cobalt,copper,iron,lead,manganese,molybdenum,nickel,strontium,thallium,tungsten,uranium,vanadium and zinc were detected at various concentrations in each one of the samples.Many samples had concentrations and mean concentrations of PTE,such as arsenic,aluminum,cadmium,iron,lead,manganese and zinc,higher than the respective acceptable limits set for drinking water by the EU(European Union),the USEPA(United States Environmental Protection Agency),and the WHO(World Health Organization)standards.Most PTEs being deleterious to human health even at very low concentrations,people who use the groundwater,surface water and tap water to meet their water needs in both localities are at risk.
基金funded by the National Key Research and Development Program of China(No.2023YFD2401105)the Fujian Science and Technology Planning ProjectSTS Program(No.2021T3013)。
文摘Dye wastewater poses a significant threat to aquatic organisms due to its high toxicity.Reducing or eliminating the dye waste from the water is necessary for a healthy and sustainable aquaculture.This study investigated the adsorption properties of Congo red dye on Mytilus edulis shell powders prepared by calcination at 500℃,700℃,and 900℃.The modified shell powder products were analyzed by SEM(scanning eletron microscopy)and FTIR(fourier transform infrared spectroscopy)for the morphology and structural characterization.The effects of different calcination temperatures,reaction times,reaction temperatures,and initial concentration of Congo red on the adsorption properties were investigated.The adsorption kinetics and isothermal adsorption models were also established.The results revealed that the shell powder calcinated at 900℃showed the best adsorption capacity on Congo red from aqueous solution.The adsorption reaction reached equilibrium after 150 min and followed by the pseudo-second-order kinetic model.At 25℃,96.2%of the Congo red in the solution could be removed,and the adsorption capacity could reach at least 1015 mg g^(–1).The adsorption isotherm is fit with the Freundlich model,indicating a multiphase adsorption process.These results are helpful for cleaning and treating printing and dyeing effluents as well as high-value utilization of shell waste resources.
基金supported by the National Nat-ural Science Foundation of China(22465012)the Key Research and Development Project of Hainan Province,China(ZDYF2024GXJS005)the Major Science and Technology Plan of Hainan Province,China(ZDKJ202016).
文摘Porous materials are excellent adsorbents for the removal of organic dyes from sewage and play a significant role in environmental restoration.Herein,two ferrocene(Fc)-based covalent organic frameworks(Fc-COFs),namely FcTF-COF and FcBD-COF,are successfully synthesized for the first time through a solvothermal method,and the obtained Fc-COFs powders are used to adsorb Congo red(CR)from water.The results show that both FcTF-COF and FcBD-COF have superb adsorption performance towards CR with ultrahigh adsorption capability of 1672.2 mg g−1 and 1983.7 mg g−1 at pH=4.0,respectively,outperforming the majority of the reported solid porous adsorbents.The maximum adsorption of both Fc-COFs agrees with the Sips adsorption isothermal model,indicating that their adsorption was dominated by heterogeneous adsorption.The Coulombic interactions,hydrogen bonding,π-πinteractions and ion-dipolar interactions should all contribute to their ultrahigh CR adsorption capability and high-pH resistance performance regardless of the pH in the range of 4-9.In addition,after five cycles,both COFs still remain their exceptional high CR adsorption capabilities.This study offers a prospective organic porous adsorbent with promising applications for organic dye removal in sewage processing.
基金Funded by the National Natural Science Foundation of China(No.22262012)the Foundation of Hubei Key Laboratory of Biologic Resources Protection and Utilization(No.PT012214)+1 种基金Science and Technology Research Project of Education Department of Hubei Province(No.D20221903)Enshi Science and Technology Plan Project(No.D20230090)。
文摘A BiOI/BiOBr S-scheme heterojunction photocatalyst was synthesized using a solvothermal method,and its ability to degrade Congo red was thoroughly investigated.The photocatalytic performance of the BiOI/BiOBr heterojunction was compared with that of pure BiOBr and BiOI.The structural,morphological,optical,and electrical properties of the samples were characterized using X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),UV-vis diffuse reflectance spectroscopy(UV-vis DRS),and zeta potential analysis.The degradation rate of Congo red was determined by spectrophotometry,revealing that the BiOI/BiOBr S-scheme heterojunction exhibited excellent photocatalytic performance,achieving a degradation rate of 96.8%for a 50 mg/L Congo red solution within 75 minutes.This rate was significantly higher than those achieved by pure BiOBr(77.2%)and BiOI(83.1%).Theoretical calculations indicate that the S-scheme heterojunction effectively facilitates the separation of photogenerated charge carriers while preserving the strong redox ability of the composite.These characteristics are identified as the key factors underlying the superior photocatalytic degradation efficiency of the BiOI/BiOBr S-scheme heterostructure.
文摘BACKGROUND Thyroid cancer incidence is rising globally,including the Democratic Republic of Congo(DRC).Despite its increasing incidence,limited data exist on physicians’knowledge of thyroid cancer management in the DRC.AIM To evaluate the knowledge levels of Congolese physicians regarding the diagnosis and treatment of thyroid nodules and cancers,and to identify existing gaps and areas for improvement.METHODS A descriptive cross-sectional study was conducted from June to August 2024,involving 369 physicians practicing in healthcare facilities across Kinshasa,DRC.Participants were selected using a multi-stage sampling method.Data were collected via a structured questionnaire covering thyroid cancer epidemiology,diagnostic methods,treatment approaches,and prognosis.Data were analyzed using SPSS version 25,employing descriptive and inferential statistics,with a P value≤0.05 being considered as statistically significant.RESULTS Overall response rate was 96.1%.Of all participants,68%were female and 32%were male physicians.General practitioners constituted 84.8%of respondents,with an average age of 34 years.While 53.7%demonstrated adequate knowledge of hypothyroidism management post-thyroidectomy and 61.2%identified the approach for hypoparathyroidism,only 5.1%recognized the need for radiotherapy in metastatic thyroid cancer cases.Awareness of anaplastic thyroid cancer treatment was limited(6.5%),and 90.2%of physicians were unfamiliar with the surgical complications.Moderate understanding was noted in diagnostic protocols,with 44.2%correctly identifying repeat fine-needle aspiration timing in Bethesda I cases.Knowledge of molecular genetics,recurrence risks,and metastasis patterns was remarkably low.CONCLUSION This study highlights significant knowledge gaps among Congolese physicians regarding thyroid cancer management,especially about advanced treatment modalities and molecular genetics.Targeted educational programs and improved access to diagnostic tools are critical to bridging these deficits.Addressing these gaps can enhance the quality of thyroid cancer care and align clinical practices in the DRC with global standards.
基金supported by the Inner Mongolia Natural Science Foundation(2024QN02011)basic scientific research business expense project of colleges and universities directly under Inner Mongolia(2023QNJS131 and 2024QNJS127)Science and Technology Plan Program of Inner Mongolia Autonomous Region(2023YFDZ0031).
文摘Pure TiO_(2)and copper-modified titania(Cu/TiO_(2))nanoparticles were synthesized through sol gel combined with the pyrolysis method for the removal of Congo red(CR)in wastewater treatment.Surface morphology and structural evaluation utilized XRD,TEM,Raman,FTIR and BET techniques.Cu/TiO_(2)showed rich defects and a higher specific surface area than that of TiO_(2).The 1Cu/TiO_(2)(molar ratio Cu/TiO_(2)of 1/100)showed the best performance to adsorption of CR solution at different reaction conditions(contact duration,CR concentration,adsorbent dose,temperature,and initial pH).Adsorption kinetics and equilibrium isotherms were well-described with a pseudo-second-order kinetics and Freundlich model,respectively.The negative ΔG indicates stable adsorption of CR on the Cu/TiO_(2)surface.The adsorption efficiency only decreases by 6%after 5 cycles of adsorption regeneration.The successful synthesis of Cu/TiO_(2)offers a new possibility to address the problems related to CR dye from aqueous solutions.
基金supported in part by grants from the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0490000 to Z.H.)National Key Research and Development Program(2021YFF0702002 to J.L.,2022YFC2303300 to Z.H.,and 2023YFC2305900 to M.W.)+3 种基金“Youth Commando”project(2023QNTJ-02 TO J.L.)Key Project(2024JZZD-02 to Z.H.)of State Key Laboratory of Virology and BiosafetyWuhan Institute of Virology,the National Natural Science Foundation of China(U22A20336 to Z.H.and Y.Z.)Wuhan Natural Science Foundation(202404071010067 to M.W.and 202404071010068 to J.L.).
文摘Dear Editor,Crimean–Congo hemorrhagic fever(CCHF),caused by the CCHF virus(CCHFV),is a severe tick-borne illness with a wide geographical distribution,posing a significant threat with case fatality rates ranging from 5%to 70%(Hawman and Feldmann,2023).Due to the lack of approved vaccines and therapeutics,the World Health Organization(WHO)has listed CCHF as one of the priority diseases(Semper et al.,2024).CCHF initially presents as a nonspecific febrile illness,characterized by fever,malaise,myalgia,and nausea,which can rapidly progress to hemorrhagic disease.The hemorrhagic stage is particularly pronounced in severe cases,with rapid progression to disseminated intravascular coagulation(DIC),overt bleeding,kidney or liver failure,and shock(Frank et al.,2024).Up to date,there is an absence of a suitable animal model that can accurately mimic the coagulopathy and bleeding associated with CCHFV infection.Consequently,our understanding of the pathogenic mechanisms underlying these conditions remains limited(Rodriguez et al.,2022).
基金supported by the National Natural Science Foundation of China(Nos.22077099,22171223 and 22307102)the Innovation Capability Support Program of Shaanxi(Nos.2023-CX-TD-75 and 2022KJXX-32)+5 种基金the Technology Innovation Leading Program of Shaanxi(Nos.2023KXJ-209 and 2024QCYKXJ-142)the Natural Science Basic Research Program of Shaanxi(Nos.2023-JC-YB-141 and 2022JQ-151)the Key Research and Development Program of Shaanxi(No.2024GH-ZDXM-22)Young Talent Fund of Association for Science and Technology in Shaanxi,China(No.SWYY202206)the Shaanxi Fundamental Science Research Project for Chemistry&Biology(Nos.22JHZ010 and 22JHQ080)the Yan’an City Science and Technology Project(No.2022SLZDCY-002).
文摘Metal-organic frameworks(MOFs) provide great prospective in the photodegradation of pollutants. Nevertheless, the poor separation and recovery hamper their pilot-or industrial-scare applications because of their microcrystalline features. Herein, this challenge can be tackled by integrating Cu-MOFs into an alginate substrate to offer environmentally friendly, sustainable, facile separation, and high-performance MOF-based hydrogel photocatalysis platforms. The CuⅡ-MOF 1 and CuⅠ-MOF 2 were initially synthesized through a direct diffusion and single-crystal to single-crystal(SCSC) transformation method, respectively,and after the immobilization into alginate, more effective pollutant decontamination was achieved via the synergistic effect of the adsorption feature of hydrogel and in situ photodegradation of Cu-MOFs.Specifically, Cu-MOF-alginate composites present an improved and nearly completed Cr(Ⅵ) elimination at a short time of 15–25 min. Additionally, the congo red(CR) decolorization can be effectively enhanced in the presence of Cr(Ⅵ), and 1-alginate showed superior simultaneous decontamination efficiency of CR and Cr(Ⅵ) with 99% and 78%, respectively. Furthermore, Cu-MOF-alginate composites can maintain a high pollutant removal after over 10 continuous cycles(95% for Cr(Ⅵ) after 14 runs, and 90% for CR after 10runs). Moreover, the Cr(Ⅵ)/CR degradation mechanism for Cu-MOF-alginate composite was investigated.
文摘The environmental impact of greenhouse gases based on natural gas flaring influences the rate of gas recovery around the world. In the Republic of Congo, the natural gas reserve in 2019 is estimated at 90 billion cubic meters (BCM). In this study, from the Congolese gas reserve we used five gas turbines with a capacity of 150 MW each;these five turbines consume 1.69 billion cubic meters (BCM)/year for the power of 273.750 MW and consumption of 6.57 billion kilowatt-hours. The results of this study revealed that an investment capital of 192,305,137 euros was required with a net profit of 9,581,250 euros at an annual rate of return of 4.98% with an investment payback period of approximately 20 years. This will allow the Congolese government to accomplish its policy of valuing gas and developing the country;the electricity produced by the National Petroleum Company of Congo (SNPC) will be sold to the Electrical Energy of Congo (E<sup>2</sup>C) at 0.06 euro/kWh.
基金Project(21476269)supported by the National Natural Science Foundation of ChinaProject(14JJ2014)supported by Natural Science Foundation of Hunan Province,China
文摘The assembly of layered double hydroxides （LDHs） and multi-walled carbon nanotubes （MWCNTs） nanohybrids was prepared as MWCNTs/LDHs by co-precipitation. The synthesized nanoparticles were characterized by using XRD, FT-IR, SEM/EDX, TGA and BET. XRD and SEM studies proved that MWCNTs phases did not enter into the interlayers of LDHs, they dispersed over the LDHs surface homogeneously. BET results showed that MWCNTs/LDHs possessed hierarchically porous nanostructure with large surface area （124.974 m^2/g） and great pore volume （0.604 cm^3/g）. Batch experiments were conducted to study the adsorption efficiency of Congo red （CR）. It was worthy to note that MWCNTs/LDHs exhibited excellent adsorption performance with the maximum CR adsorption capacity of 595.8 mg/g in weak acidic environment. The adsorption kinetics and isotherm parameters can be well described by the pseudo-second-order and the Langmuir isotherm models, respectively. The thermodynamic studies indicated that the adsorption process was spontaneous and endothermic.
基金financially supported by the Zhejiang Provincial Natural Science Foundation of China(LY16B060014)the Program for the Joint Research Fund for Overseas Chinese,Hong Kong and Macao Scholars of National Natural Science Foundation of China(Grant No.21628601)the Innovation and Development of Marine Economy Demonstration。
文摘This research demonstrates the production of mesoporous activated carbon from sargassum fusiforme via physical activation with carbon dioxide.Central composite design was applied to conduct the experiments at different levels by altering three operating parameters.Activation temperature(766-934℃),CO2 flow rate(0.8-2.8 L·min^-1)and activation time(5-55 min)were the variables examined in this study.The effect of parameters on the specific surface area,total pore volume and burn-out rate of activated carbon was studied,and the influential parameters of methylene blue adsorption value were identified employing analysis of variance.The optimum conditions for maximum methylene blue adsorption value were:activation temperature=900℃,activation time=29.05 min and CO2 flow rate=1.8 L·min(-1).The activated carbon produced under optimum conditions was characterized by BET,FTIR and SEM.The adsorption behavior on congo red was studied.The effect of parameters on the adsorbent dosage,temperature,PH and initial congo red concentration was investigated.The adsorption properties of the activated carbon were investigated by kinetics.The equilibrium removal rate and maximum adsorption capacity reaches up to 94.72%,234 mg·g^-1,respectively when initial congo red concentration is 200 mg·L^-1 under adsorbent dosage(0.8 g·L^-1),temperature(30℃),PH7.
基金Funded by the Science and Technology Development Plan Project of Shandong Province,China(No.2013GSF11714)the Open Project of Hunan Sustentation Fund:Key Laboratory of Applied Environmental Photocatalysis,China(No.ccsu-KF-1501)
文摘Mg/Al/Fe layered double hydroxide(MAF-LDH1) was prepared by solvothermal method with the sodium dodecyl sulfate as the template, and the ethanol system was benefit to growth of sample. The nature in the resulting MAF-LDH was investigated by X-ray diffraction, field emission scanning electron microscopy, Fourier transformed infrared spectra, thermogravimetric analysis, and N2 adsorption-desorption.The morphology of MAF-LDH1 is petal-like with the size of 400-500 nm and the thickness about 10-20 nm. The adsorption performance of the samples was evaluated by absorption of the Congo red(CR) solutions. Compared with Mg/Al layered double hydroxide(MA-LDH), the maximum adsorption capacities of the MAF-LDH1 samples were 943.4 mg/g which was greatly enhanced. Furthermore, after seven cycling tests, the adsorption performance was still up to 90%. Theoretical calculation results revealed that the adsorption process was spontaneous and followed the pseudo-second-order kinetic model and Freundlich model. This work provides a promising alternative strategy to enhance the adsorptive properties of hydrotalcite-like materials.
基金supported by National Natural Science Foundation of China(No.51377075)the Natural Science Foundation of Jiangsu Province of China(Nos.BK20131412,BK20150951)
文摘A dielectric barrier discharge （DBD） reactor with a rod-plate electrode configuration was used for the oxidative decomposition of Congo red dye in an aqueous solution. Plasma was generated in the gas space above the water interface under atmospheric pressure. Discharge characteristics were analyzed by voltage-current waveforms. Effects of applied voltage, initial conductivity, and initial concentration were also analyzed. Congo red discoloration increased with increased applied voltage and decreased conductivity. The initial conductivity significantly influenced the Congo red discoloration. Under the same conditions, the highest discoloration rate was obtained at 25 mg/L. The presence of ferrous ions in the solutions had a substantial positive effect on Fenton dye degradation and flocculation. At an applied voltage of 20 kV, about 100% of dye was degraded after 4 min of Fe^2＋/DBD treatment. Results showed that adding a certain dosage of hydrogen peroxide to the wastewater could enhance the discoloration rate. Possible pathways of Congo red discoloration by DBD plasma were proposed based on GC/MS, FTIR, and UV-vis spectroscopy analyses.
基金supported by Natural Science Foundation of Jiangsu Education Committee of China (No.09KJA140005)
文摘Radio frequency （RF） underwater discharge operation was performed for different liquid conductivities driven by different frequencies ranging from 13.56 MHz to 60 MHz, and its application to organic degradation was investigated. The RF underwater discharge was observed to be generated within the bubble at electrode surface formed by RF and plasma heating. It was shown that the sizes of the bubbles and plasmas increased as the driving frequency and the input power went up. The breakdown voltage decreased rapidly with the increase of the water conductivity and driving frequency. Comparative experiments of the UV-VIS absorbance spectra of Congo Red solution before and after discharge suggested effective degradation of the organic dye due to the active species generated during the discharge, such as .OH, .O, .H, etc. revealed by optical emission spectroscopy. The results show that higher exciting frequency and lower conduc- tivity of the solution are more effective for organic degradation. With the combination of Fourier Transform Infrared Spectroscopy （FT-IR） and Liquid Chromatography-Mass Spectrometry （LC- MS） data, one possible degradation process was proposed and the main conceivable components and structures of the products were also presented.
基金Supported by the National Natural Science Foundation of China(21276141)the State Key Laboratory of Chemical Engineering,China(SKL-Ch E-17A03)
文摘A facile eco-friendly hydrothermal route （180 ℃, 12.0 h） has been developed for the first time to the uniform hierarchical porous MgBO2（OH） microspheres without the aid of any organic additive, surfactant or template, by using the abundant MgCl2·6H2O, H3BO3 and NaOH as the raw materials. The as-obtained porous microspheres exhibit a specific surface area of 94.752 mg·g-1, pore volume of 0.814 cm3.g-1, and ca. 84.0% of which have a diameter of 2.25-3.40 μm. The thermal decomposition of the porous MgBO2（OH） microspheres （650 ℃, 2.5 ℃. min-l） leads to the porous Mg2B2O5 rnicrospheres with well-retained morphology. When utilized as the adsorbents for the removal of CR from mimic waste water, the present porous MgBO2（OH） microspheres exhibit satisfactory adsorption capacity, with the maximum adsorption capacity qm of 309.1 mg-g-1, much higher than that derived from most of the referenced adsorbents. This opens a new window for the facile green hydrothermal synthesis of the hierarchical porous MgBO2（OH） microspheres, and extends the potential application of the 3D hierarchical porous metal borates as high-efficiency adsorbents for organic dyes removal.
文摘A-site substituted La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites were prepared by sol-gel method and characterized using thermogravimetry/differential thermal analysis（TGA/DTA）, X-ray diffraction（XRD）, ultraviolet-visible（UV-Vis） spectroscopy and transmission electron microscopy（TEM）. XRD analysis showed that the La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites derived after calcination at 800 oC were in single phase with orthorhombic structure. The particle size of all nano perovskites was found to be ~20 nm. The synthesized nano perovskites were tested for the photocatalytic decomposition of an azo dye, Congo red. The sequential behavior of La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nanoperovskites for photocatalytic decomposition of congo red in aqueous solution by visible light at room temperature was studied at various time intervals and the efficiency of degradation of the nanoperovskites was compared. Among all the A-site substituted La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites, Ba substituted compound showed the highest dye degradation.
基金the financial support of Vietnam Academy of Science and Technology under project VAST01.04/18-19.
文摘We report on the synthesis of Sn-doped hematite nanoparticles(Sn-α-Fe_(2)O_(3) NPs)by the hydrothermal method.The prepared Sn-α-Fe_(2)O_(3) NPs had a highly pure and well crystalline rhombohedral phase with an average particle size of 41.4 nm.The optical properties of as-synthesizedα-Fe_(2)O_(3) NPs show a higher bandgap energy(2.40-2.57 eV)than that of pure bulkα-Fe_(2)O_(3)(2.1 eV).By doping Sn intoα-Fe_(2)O_(3) NPs,the Sn-doped hematite was observed a redshift toward a long wavelength with in-creasing Sn concentration from 0%to 4.0%.The photocatalytic activity of Sn-dopedα-Fe_(2)O_(3) NPs was evaluated by Congo red(CR)dye degradation.The degradation efficiency of CR dye using Sn-α-Fe_(2)O_(3) NPs catalyst is higher than that of pureα-Fe_(2)O_(3) NPs.The highest degradation efficiency of CR dye was 97.8%using 2.5%Sn-dopedα-Fe_(2)O_(3) NPs catalyst under visible-light irradi-ation.These results suggest that the synthesized Sn-dopedα-Fe_(2)O_(3) nanoparticles might be a suitable approach to develop a photocatalytic degradation of toxic inorganic dye in wastewater.
基金supported by the Special Fund for National Forestry Industry Scientific Research in the Public Interest of China (Grant No. 201104004)the Natural Science Foundation of China (Grant No. 20867004)the Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region
文摘A series of carboxymethyl cellulose/organic montmorillonite （CMC/OMMT） nanocomposites with different weight ratios of carboxymethyl cellulose （CMC） to organic montmorillonite （OMMT） were synthesized under different conditions. The nanocomposites were characterized by the Fourier transform infrared （FT-IR） spectrophotometer, X-ray diffraction （XRD） method, transmission electron microscope （TEM）, scanning electron microscope （SEM）, and thermal gravimetric （TG） analysis. The results showed that the introduction of CMC may have different influences on the physico-chemical properties of OMMT and intercalated-exfoliated nanostructures were formed in the nanocomposites. The effects of different reaction conditions on the adsorption capacity of samples for Congo Red （CR） dye were investigated by controlling the amount ofhexadecyl trimethyl ammonium bromide （CTAB）, the weight ratio of CMC to OMMT, the reaction time, and the reaction temperature. Results from the adsorption experiment showed that the adsorption capacity of the nanocomposites can reach 171.37 rag/g, with the amount of CTAB being 1.0 cation exchange capacity （CEC） of MMT, the weight ratio of CMC to OMMT being l：l, the reaction time being 6 h, and the reaction temperature being 60~C. The CMC/OMMT nanocomposite can be used as a potential adsorbent to remove CR dye from an aqueous solution.
