RESUMO
High-efficiency adsorption of aromatic sulfur-containing compounds from liquid hydrocarbon fuels over metal-organic frameworks (MOFs) is challenging because of inert metal sites. A new method, the Ce-enhanced modulation of MOFs' microenvironment, is proposed to modulate the -COO···Cu(II)- coordination microenvironment of Hong Kong University of Science and Technology (HKUST-1) using Ce(III) as a molecular scalpel for fabricating abundant high-efficiency Cu(I) and Cu-coordination-unsaturated sites and improving the pore structures around adsorptive sites. The optimal CH-250 thus exhibits adsorptive capacities for 20.2, 28.0, and 58.3 mg S g-1 of thiophene, benzo-thiophene, and dibenzothiophene, respectively, which are superior to most reported MOFs, zeolites, and nanoporous carbons. The constructed Cu(I) sites show stronger affinity for dibenzothiophene (-0.86 eV) than the initial Cu(II) (-0.74 eV) for out-of-plane adsorption. Further, they are far stronger in-plane adsorption interactions in DBT/CH-250 (-0.90 eV) than those in DBT/HKUST-1 (-0.37 eV). Thus, molecular engineering for modulating the coordination microenvironment of MOFs shows great potential for adsorption desulfurization.
RESUMO
Solid-supported ionic liquid catalysts (SILs) are the simplest form of a heterogenized ionic liquid and have attracted soaring attention because of the high catalytic activity as well as separation. Unfortunately, instability severely hinders their practical application, and the reason for the deactivation of SILs has not been investigated in detail. In the present study, the immobilized ionic liquid catalysts MIL-101-[IA-SO3H][HSO4] and MIL-101-[IA-COOH][HSO4] were prepared and used to study the stability in the esterification reaction. The results show that compared with MIL-101-[IA-COOH][HSO4], MIL-101-[IA-SO3H][HSO4] has a higher catalytic activity and a lower stability. The deactivation mechanism is discussed based on experiments and theoretical analysis: the protons on -SO3H dissociate in a polar solvent and combine with anion HSO4-, and then, the formative H2SO4 molecule will leach out into the solvent. Our discussion indicates that the stability of immobilized ionic liquids is determined by the substituents of ionic liquid cations and becomes the significant factor controlling the stability limits. The study presented here would be important for understanding the deactivation reason and can help in choosing the suitable cation to avoid leaching of the active site during the reaction.
RESUMO
Hierarchical porous carbons equipped with heteroatoms and diffusion pores have a wide application prospect in adsorption. Herein, we report N-autodoped porous carbons (PTPACs), which were derived from rigid N-rich conjugated microporous poly(aniline)s (CMPAs) and show their all-around applicability in heavy metal adsorption. Their molecular structure could be delicately tuned from 3D organic networks to graphitic carbons through simply adjusting the pyrolysis temperature, affording unique hybrid features of hierarchical micro-meso-macroporosity and amount-tunable nitrogen defects, as validated by the enhanced CO2 adsorption capacities reaching 5.0 mmol g-1, a 230% increase compared to the precursor (2.15 mmol g-1). They therefore show promising a Langmuir adsorption capacity of 434.8 mg g-1 toward mercury ions, which could be rapidly achieved within a short 20 min. Based on the comprehensive experimental, characterization, and DFT calculation studies, we rationally reveal these impressive adsorptions arise from the hybrid function of chemisorption contributed by populated nitrogen defects and physical adsorption achieved by synergistic functions in the diffusion and storage pores. Outcomes mark the high merits of PTPACs in addressing recent global challenges in environmental engineering.
RESUMO
The use of conjugated microporous polymers (CMPs) in practical wastewater treatment demands further design on the pore structure, otherwise their adsorption capacities toward heavy-metal ions were moderate. Here, we report a rational design approach, which produces hybrid molecular pores in conjugated microporous poly(aniline)s (CMPAs) for mercury removal. It is achieved through a delicate interval introduction of linkers with differential molecular lengths during polymerization, acquiring both diffusion channels and storage pores for radical enhancement of mass transfer and adsorption storage. The resulting CMPA-M featured a large adsorption capacity of 975 mg g-1 and rapid kinetics that could remove 94.8% of 50 mg g-1 of mercury(II) within a very short contact time of 48 s, with a promising initial adsorption rate h as high as 113 mg g-1 min-1, which was 2.54-fold larger in the adsorption capacity and 45.2-fold faster in the adsorption efficiency compared with the undeveloped CMPAs. More importantly, our CMPA-M-2, with robust stability and easy reusability, was able to scavenge over 99.9% of mercury(II) from the actual wastewater in a harsh condition with a very low pH of 0.77, extremely high salinity of 53,157 mg L-1, and complex impurities, featuring exceptional selectivity that allows us to extract and recycle a high purity of 99.1% of mercury from the wastewater. These outcomes demonstrate the unprecedented potential of CMPs for environmental remediation and real-world mercury extraction and present benchmarks for CMP-based mercury adsorbents.
RESUMO
A simple methodology to controllably tune the pore size and Cr(VI) adsorption capacity was reported herein to synthesize a new series of conjugated microporous polyaniline (CMPA) networks. The well-ordered micropore was acquired through our very recent Bristol-Xi'an Jiaotong method, and the pore size was fine-tuned to increase with the increasing length of linkers, mimicking covalent organic frameworks and metal organic frameworks very much. A selective ultrahigh adsorption capacity of 520.8 mg/g was achieved by CMPA-1 in a very fast manner, with a systematically gradual decrease to 173.9 mg/g of CMPA-3 by enlarging the pore size of the networks, featuring tunable adsorption capacity through molecular-size-recognition mechanism. Additionally, our robust CMPA networks, which were constructed by Buchwald-Hartwig chemistry, showed the complete function of polyaniline and were capable of providing, besides large storage capacity for Cr(III), at least 10 reductant/desorption-free cycles for effective Cr(VI) reduction and detoxication through their novel self-reducible redox states. Outcomes showed that our CMPAs could be applied as new self-healing scavengers in the next generation for Cr(VI) storage and detoxication.
RESUMO
OBJECTIVE: To investigate the effect of mTOR signal transduction pathway and down-regulating anti-oncogene PTEN on the growth of breast cancer MCF-7 cells. METHODS: MCF-7 cells were transfected with the eukaryotic expression plasmid pcDNA3.1-mTOR and non-loaded plasmid, and the expression of mTOR in the cells was detected using Western blotting. Flow cytometry was used to analyze apoptosis and cell cycle of the transfected cells, and the expression of PTEN was detected after transfection. RESULTS: The cells transfected with pcDNA3.1-mTOR showed a increased growth rate than those transfected with the non-loaded plasmid and those without transfection. The expression of the protein PTEN decreased obviously in the cells after mTOR trasnfection. CONCLUSION: mTOR can regulate the expression of PTEN via PI3K/AKT/PTEN pathways through a negative feedback mechanism. Increased mTOR expression promotes MCF-7 cell growth, suggesting the potential value of mTOR specific inhibitor in the treatment of breast cancer.