查看更多>>摘要：The global lithium supply and demand in this century is accelerated by the energy transition from carbon-based fossil fuels to renewable energy where electrical energy storage and electric vehicles heavily depend on the lithium-ion battery. The lepidolite is one of the main resources for extracting lithium, and it is usually enriched by froth flotation separation technology. However, the traditional lepidolite collector is monomer surfactant with only a single hydrophobic group and hydrophilic group, which usually leads to the low flotation separation efficiency. Therefore, to achieve the flotation separation of lepidolite ore more efficiently, in this work, an amine-based Gemini surfactant, hexanediyl-a, ω-bis (Dimethyldodecylammonium bromide) (HBDB), was synthesized, and compared with the conventional single molecule collector dodecylamine (DA). The experimental results show that the optimum pH value of flotation is 3, and the optimum dosage of HBDB and DA are 150 g/t and 300 g/t respectively. In bench-scale flotation experiments, compared with the conventional monomer DA collector (350 g/t), the Gemini HBDB with only 1/2 dosage of DA (175 g/t) increased the recovery of lepidolite by 16.18%. Economic calculation for a lepidolite ore plant, 1500 t/d, demonstrating that using Gemini HBDB can gain more about $ 8.2 million USD per year than using traditional unimolecular DA. Accordingly, this study provides a new and highly efficient collector for the flotation separation of lepidolite ore.
查看更多>>摘要：The metal-organic framework (MOF) UiO-66 was successfully doped with Fe via a facile solvothermal method. Fe-UiO-66 exhibited excellent solar photodegradation performance for sulfonamide antibiotics in water. The degradation rate of sulfameter by Fe-UiO-66 was 89.9% within 300 min under visible light, which confirmed the energy-saving and environmentally friendly properties of the material. Fe doping effectively improved the catalytic activity and reaction efficiency of Fe-UiO-66 by coupling photocatalysis with persulfate-based advanced oxidation. The favorable photocatalytic performance was mainly due to the introduction of Fe, which caused UiO-66 to extend into the solar range. In addition, quenching analysis confirmed that ~·SO_4~(2-) and ~·O2~- free radicals played a more prominent role than ~·OH and h~+. Furthermore, sulfonamide antibiotics were successfully degraded under sunlight. Thus, Fe-based materials have substantial potential for the removal of antibiotic pollutants from wastewater.
查看更多>>摘要：Developing highly dispersed species has been regarded as an effective approach to achieve high catalytic performance. In this work, tungsten-containing precursor were control confined in porous channel of SBA-15. Profiting from the ionic liquid, quantum dots (such as WO3 QDs) in SBA-15 with highly dispersion can be obtained after thermal treatment. This prepared tungsten-based QDs confined SBA-15 materials can deliver excellent catalytic performance for oxidation desulfurization, in which 100 % DBT can be removed in 1 h. The oxidation desulfurization reaction mechanism is also explored and main active specie is determined to be ·OH. This strategy provides an accessible pathway for preparation of other catalysts with highly dispersed species.
查看更多>>摘要：NdFeB sludge is a waste with high economic value. NdFeB waste recycling has the disadvantage that only rare earths are recycled, but iron (Fe) is not recycled, which results in large amounts of secondary solid waste. In this paper, a process flowchart of the co-extracted rare earth elements (REEs) and Fe by co-leaching and stepwise precipitation from NdFeB sludge was developed. The results show that after the NdFeB sludge was pretreated, co-leaching with hydrochloric acid, rare earth precipitation with oxalic acid, and Fe precipitation with reduction iron powder, 98.28% of the REEs were recovered in the form of RE2(C2O4)3·10H2O, and 94.65% of the Fe was recovered in the form of FeC2O4·2H2O. Due to the low solubility product constants of the rare earth oxalates, when oxalic acid was added to the leachate, the REEs precipitated rapidly, while Fe was still present as FeCl_4~-, Fe (C2O4)_2~-, and FeC2O_4~+ in the precipitated REEs solution. Therefore, the selective separation and precipitation of REEs and Fe was achieved. The process has the advantages of high comprehensive utilization of resources and no secondary solid waste or wastewater pollution.
查看更多>>摘要：The photocorrosion behavior of semiconductors was a widely concerned problem, which has posed a great challenge to the durability of photocatalysts. In this paper, a photocatalyst with the Z-scheme structure (N-C3N4/ Cu/Cu2O) was prepared in order to alleviate Cu2O photocorrosion. Its physicochemical properties were systematically characterized and the photocatalytic activity was evaluated by degrading tetracycline. The results indicated that, compared with C3N4, Cu2O and even the composite of them, the N-C3N4/CU/Cu2O exhibited the best photocatalytic performance. Nitrogen doping significantly increased the photocatalytic activity of C3N4, and thus improved the photocatalytic performance of the composite N-C3N4/CU/Cu2O. Additionally, metallic Cu was introduced at the interface between N-C3N4 and Cu2O to construct Schottky junctions, with the help of which a Z-scheme structure was constructed. Consequently, the recombination of photoexcited carriers was effectively inhabited, thus alleviating Cu2O photocorrosion. Even if a part of Cu2O was photocorroded, N-C3N4 could still form another heterojunction with CuO (possibly generated due to photocorrosion), so that the overall photocatalytic activity of the composite could be maintained to the most extent. Meanwhile, the degradation pathways of tetracycline and the global toxicity evolution were elucidated, which was important for the tetracycline-related wastewater treatment with respect to minimizing the potential ecological risks.
查看更多>>摘要：In this study, a magnetic Fe3O4@SiO2@La2O3 nano-catalyst with a core-shell structure was synthesized to improve the efficiency of catalytic ozonation of cinnamyl alcohol. The structure, morphology, and elemental composition of the catalyst were analyzed with the help of catalyst characterization methods. The mechanism of strengthened degradation efficiency and mineralization of cinnamyl alcohol in catalytic ozonation system in the existence of the catalyst were further discussed according to the analysis results. The results showed that the Fe3O4@SiO2@La2O3 catalyst can not only greatly improve the degradation of cinnamyl alcohol, but also has good reusability and stability. And its economic efficiency is relatively good. The degradation rate of cinnamyl alcohol could reach up to 99.8% at 30 min, and the COD could be removed by 28.5% at 60 min with the help of the catalyst. The degradation efficiency of cinnamyl alcohol by ozone oxidation alone was only 52.1% at 30 min, and the COD removal rate was only 24.2% at 60 min in the same experimental conditions. Besides, the possible degradation pathway and degradation mechanism of cinnamyl alcohol were proposed according to the intermediate products detected by gas chromatography-mass spectrometry.
查看更多>>摘要：In this study, geopolymer zeolite microspheres (GZMs) were prepared from metakaolin by suspension dispersion solidification and in-situ conversion method. Different GZMs were prepared by adjusting n(Na2O)/n(Al2O3), n (H2O)/n(Na2O), curing time and temperature. The data showed that NaA structure was easily formed under low temperature and low alkalinity conditions, which was transformed into sodalite (SOD) with more stable structure under high temperature and high alkalinity conditions. When n(Na2O)/n(Al2O3) = 1.9 and n(H2O)/n(Na2O) = 12, the sphericity of GZMs was the best according to the sphericity and particle size distribution results. Furthermore, different ZMs were prepared by adjusting the curing temperature and time. These ZMs showed maximum adsorption capacities for Pb~(2+) of 529.67 mg/g (NaA), 345 mg/g (NaA + SOD: the mixture of NaA and sodalite) and 308.30 mg/g (SOD), following pseudo-second-order kinetic model and the Langmuir isotherm model. The fresh and post-adsorption GZMs were analyzed by SEM-EDX, XRD, FTIR and XPS, and the Ac (Pb~(2+)): Ac (Na~+) = 1: 1.92 (≈1:2) in the solition, which confirmed chemisorption phenomenon via ion exchange mechanism. Moreover, the adsorption rate of Pb~(2+) on NaA ZMs was higher than that of traditional zeolite materials. This study accredited to its simplicity, low cost and remarkable adsorption performance of the NaA ZMs for Pb~(2+), can be deemed of potential value in practical application of wastewater processing.
查看更多>>摘要：Graphene-based laminates show great potential in gas separation, where graphene slit serving as an important part has significant effect on the gas transport. In this study, molecular dynamics simulations were performed to investigate the mechanism of the CO2 and N2 permeation through graphene slit. CO2 was confirmed to permeate through the slit mainly via surface flux, thus the adsorption capacity of graphene largely determines the CO2 permeability. Besides, the N2 permeation is gready dominated by direct flux, the contribution of which increases with enlarging the graphene slit. The adsorption capacity of graphene was modified to adjust the permselective transport of the CO2/N2 mixture. Increasing the gas-graphene interaction obviously enhanced the N2 permeation and retarded the CO2 permeation. A triple enhancement of the gas-graphene attraction could achieve a quadruple increase of the N2/CO2 selectivity. This work guides to improve the performance of graphene-based membranes in the CO2/N2 mixture separation.
查看更多>>摘要：Inorganic membranes hold great potential for various mainstream applications such as in wastewater treatment drug manufacturing, food and beverage production, and dairy purification. There are numerous commercially available ceramic membranes which possess high corrosion resistance, high strength, and good heat resistance However, these membranes are still prone to fouling causing a considerable decline in membrane performance and hence shorter life-times. Conventional methods for flux recovery include rigorous chemical backwashing producing large amounts of sludge leading to disposal problems. In this work, commercial a-Alumina (Al2O3) ultrafiltration (UF) membranes were coated with titanium through an e-beam deposition process. The titanium coating rendered the membrane conductive, without changing the superhydrophilicity and average pore size of the membrane. Thermal degradation profiles suggested good thermal characteristics of the membrane. Good electrocatalytic activity for hydrogen evolution reaction was observed for the membrane, with an over-potential of 450 mV and 400 mV vs. Reference Hydrogen Electrode in acid and base solutions. The conductive membrane allowed for periodic electrolysis which is a fast and simple technique for fouling control and prevention. The j membrane was used as a cathode during a cross-flow filtration setup, where 2.0 V was applied for 5 min during intervals. Without electrolysis, a considerable decline in flux was observed reaching almost 10% and 40% of its original value during yeast and sodium alginate (SA) filtration respectively. However, substantial flux recovery to 87% and 97.5% was achieved after the first cleaning cycle during yeast and sodium alginate (SA) filtration respectively. Thereafter, considerable flux recovery was achieved during each subsequent electrolysis cycle. Membrane's good electrocatalytic properties led to the generation of hydrogen bubbles which helped in sweeping away the foulants from the membrane's surface.
查看更多>>摘要：The effective draw agent is vital for developing the forward osmosis (FO) process in water reclamation applications. We have explored the feasibility of using gas-responsive magnetic nanoparticles (NPs) as a novel draw agent for the FO-based separation process. These NPs were fabricated by growing CCvresponsive poly [2-(dimethylamino)ethyl methacrylate] on magnetic Fe3O4 NPs surface (Fe3O4@PDMA). The successful growth of PDMA brushes on the Fe3O4 NPs was confirmed by FTIR, XRD, SEM, VSM, EDS, DLS, Zeta and TGA analysis. Then, the FO water flux, pH and CO2-responsibility, regeneration and dye-removal performance of Fe3O4@PDMA were thoroughly evaluated. The Fe3O4@PDMA NPs were exhibited considerable water flux in acidic conditions. Moreover, the CO2 purging time on water flux was studied. Experimental results revealed that the FO water flux increased with the increase in C02-purging time. The water flux driven by the Fe3O4@PDMA NPs was found to be a strong function of the net polymer coverage on M NPs, that is, net available hydrophilic groups. The results showed that the water flux of Fe3O4@PDMA-12 h (high content) was much higher than that of Fe3O4@PDMA-4 h (low content). In addition, tunable protonation/deprotonation of PDMA brushes allows us to recycle the draw agent using an external magnetic field with minimum energy consumption. Furthermore, high water flux was achieved for Fe3O4@PDMA in colored wastewater treatment via the FO process.
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