查看更多>>摘要：? 2021 Elsevier Inc.Mesoporous silica nanoparticles are promising candidates to deliver proteins, antibodies, and anticancer drugs and to be served as an adsorbent of various types of substrate. Herein, a theranostic approach, in the preparation of fluorescence-type mesoporous silica for pH-responsive delivery of anticancer drug, doxorubicin, is introduced. By this mean, three types of mesoporous silica were synthesized. The ordinary type of mesoporous silica nanoparticles containing propylamine functional groups was synthesized by a controlled-size technique. Two types of fluorescence mesoporous silica were prepared, doped with gold or quantum dots nanoparticles. The fluorescence imaging has shown that the optical properties of the gold or carbon quantum dots have been transferred to the mesoporous matrix in doping processes. The as-prepared mesoporous materials were conjugated to doxorubicin via Schiff-base linkage. Several characterization techniques were utilized to detect the structure of the particles including FT-IR spectroscopy, XRD, N2 adsorption/desorption, transition, and scanning electron microscopy. The amount of conjugated doxorubicin was analyzed by UV–Vis spectroscopy. The pH-responsive character was proved assessing the release profile in different pH ranges including physiological pH. The safety of the particles was evaluated by cell cytotoxicity assay on breast cancer cell line, MCF-7. As-prepared particles showed no cytotoxic behavior, but when they were loaded by doxorubicin, the appreciable release of the drug and subsequent cytotoxicity resulted against MCF-7 cells. The hemolytic study was conducted to prove the biocompatibility of these particles in the blood. Altogether, the proposed materials are suitable to be considered as safe and to be used as a theranostic platform for therapeutic and imaging purposes.
查看更多>>摘要：? 2021 Elsevier Inc.Commercial zeolites with CHA, MFI, and LTL framework topology are subjected to acid treatment with chromic acid (H2CrO4) solutions with concentrations ranging between 0.1 and 10 w/%. As chromic acid forms polymeric species as a function of concentration, specific effects are obtained with these three zeolites, differing by their framework topology, pore size, Si/Al ratios and crystal size. The etched zeolites are characterized by X-ray diffraction, SEM, TEM, N2 physisorption, ICP-AES, 27Al and 29Si MAS NMR, 29Si{1H} cross-polarization spectra, EDX. Their acidic properties are probed with pyridine and d3-acetonitrile by in situ FTIR. Results indicate that the 8 MR (CHA) and 10 MR (MFI) zeolites are more resistant to acid treatment with chromic acid than the 12 MR (LTL) zeolite. This paves the way for rational control of zeolite dealumination since adjusting chromic acid concentration will generate anions appropriate for treating a particular zeolite.
查看更多>>摘要：? 2021 Elsevier Inc.Nitrogen and phosphorous dual-doped carbon materials are one the promising candidate for the ecofriendly and metal-free heterogeneous catalytic systems owing to the abundance activated sites which is caused by doping the heteroatoms in the carbonaceous materials. The N, P-dual-doped carbon hollow sphere (HPNC-700) precursor prepared via template-assisted strategy by using the SiO2 as the hard template in the presence of glucose, phosphoric acid and melamine as C, P, and N source, respectively. The resultant catalyst was obtained by pyrolyzing process at 700 °C under N2 atmosphere by adding the NaOH solution to remove the template. According to various physicochemical analysis including FE-SEM, TEM, XRD, XPS, and Raman spectroscopy, the catalyst exhibited the desired and acceptable properties. So, based on these outcomes, the catalytic efficiency of the HPNC-700 was evaluated in the selective aerobic oxidation of benzyl alcohols. As expected, the HPNC-700 represented the acceptable proficiency in the mentioned reaction with high TOF value, full conversion (>99%) and also the notable recyclability.
查看更多>>摘要：? 2021 Elsevier Inc.Hierarchical Fe-doped MFI/MCM-41 composites (Fe-HMZs) were one-pot hydrothermal synthesized by partial transformation strategy using conventional CTAB as a dual-functional template. The hierarchical Fe-doped MFI/MCM-41 composites possess ordered mesopores and crystallized MFI structure. The effect of addition amount of NaOH and CTAB as well as the type of the alkali source on the formation of hierarchical Fe-MFI/MCM-41 composites have been investigated in detail. In addition, the temperature-gradient treatment plays the vital roles in the formation of MFI and the possible formation mechanism has been proposed. The obtained hierarchical Fe-HMZ-40 sample exhibits outstanding catalytic performance for phenol hydroxylation and 48% of phenol conversion as well as 89% of dihydroxybenzene selectivity could be achieved, which are ascribed to the more accessible active sites endowed by the significant diffusion ability of ordered mesopores. Compared with Fe-MCM-41 sample, the hydrothermal stability is improved because of the presence of MFI structure.
查看更多>>摘要：? 2021 Elsevier Inc.Micellization of the exterior layer of zeolite precursor seeds with surface passivating organosilane groups is an effective technique to reduce aggregation of growing of crystallites. Simultaneously, this technique produces hierarchically porous material with additional mesopores, to minimise typical diffusional limitations encountered with conventional microporous zeolites. The average particle size and the pore architecture of the zeolite can be altered by changing the synthesis environment of the surface passivation process. In this study, low hazard organic solvents with different hydrophobicities (log P) have been used as an effective matrix for the surface organosilanization and crystallization processes of zeolitic species. A clear interaction of organosilane moieties on the exterior region of hierarchical nanozeolite ZSM-5 clusters is evidenced by solid-state nuclear magnetic resonance (NMR) analysis. In addition, hydrolysis of the organosilane molecules has been followed by mass spectroscopy analysis on the synthesis gel solution, leading to a mechanism proposed for the surface silanization processes of the zeolite nanoparticles using the soft-template surface passivating technique.
查看更多>>摘要：? 2021 Elsevier Inc.A novel magnetic composite with hierarchically porous nature is prepared by a facile synthetic strategy for the highly toxic chromium (Cr(VI)) removal. The magnetic NMPC@mSiO2 with defined mesoporous shell is successfully fabricated by one-step carbonization of ZIF-67@mSiO2, which is prepared through a simple one-pot method. Benefiting from the protection of mSiO2 during pyrolysis process, NMPC@mSiO2-800 owns high specific surface area, hierarchically porous structure and increased C–N content. It shows an excellent Cr(VI) removal performance with an adsorption capacity rising to 158.11 mg·g?1 from 78.60 mg·g?1 (NMPC-800). Moreover, the prepared NMPC@mSiO2-800 exhibits antijamming capability for Cl?1/SO42? with a negligible adverse impact on Cr(VI) removal. The kinetic studies show that the Cr(VI) removal on NMPC@mSiO2-800 confirms to pseudo-second-order model equipped with a relatively large adsorption rate constant, revealing the ability to quickly adsorb Cr(VI). The thermodynamic parameters manifest Cr(VI) adsorption is spontaneous and endothermic. Besides, the NMPC@mSiO2-800 can be quickly recovered from the system due to the magnetic porous carbon. Herein, NMPC@mSiO2-800 has a broad application prospect in Cr(VI) removal due to its excellent adsorption capacity, good antijamming ability, high adsorption rate and easy magnetic separation.
查看更多>>摘要：? 2021 Elsevier Inc.The improvement of pseudo-capacitance is the most important factor affecting performance of supercapacitor. MnO2 is an ideal material for the development of pseudo-capacitance, but its increased load amount while reducing its load thickness still is puzzled. In this study, a two-step method of loading MnO2 on the surface of activated carbon (ZAC) prepared by ZnCl2 activation bagasse was conducted to devote problem. A series of AMCM-X composites (ZAC@α-MnO2/CNTs/δ-MnO2) with layered structures were obtained by sequentially loading linear nano-α-MnO2, CNTs, and sheet nano-δ-MnO2 on ZAC using hydrothermal, freeze-drying, and electrochemical deposition methods, respectively. The loading of CNTs extended external space of substrate and facilitated further loading of δ-MnO2. Further, the AMCM-4 material had a mass specific capacitance of 450 F/g at 1 A/g and the asymmetric supercapacitor of AMCM-4//ZAC still had 92.3% capacitance retention rate after 5000 cycles. Moreover, XPS results showed the thickness of δ-MnO2 (0.35 wt%) was relatively thinner than α-MnO2 (1.93 wt%). The mechanism by which composites improved the electrochemical performance of the supercapacitor was attributed to the ability of building and covering pores of CNTs on substrate. These results will increase the re-negotiation of bagasse and improve the pseudo-capacitance of MnO2 in supercapacitors.
查看更多>>摘要：? 2021 The AuthorsMicroporous organic polyimides are well suited for carbon dioxide separation from gas mixtures based on their polar surface and their tendency towards ultramicroporosity. Nevertheless, their application potential is limited due to an inherent insolubility and infusibility, preventing an easy processing into functional objects like membranes. By establishing a three-step synthesis procedure for the literature known network NPI-I, here, a solution to this challenge is demonstrated. The central step is electrospinning of a solution of the linkers tetrakis(4-aminophenyl)methane and naphthalene 1,4,5,8-tetracarboxylic dianhydride and the auxiliary polymer polyvinylpyrrolidone into a precursor fiber mat. The mat was then heated to polymerize the linkers into the polyimide. Subsequently, PVP was removed by pyrolysis obtaining a robust, flexible and self-standing membrane. The NPI-I fiber mat exhibits a remarkable microporosity with a BET surface area of 222 m2/g, a total pore volume of 0.121 cm3/g and a high amount of ultramicropores. Its CO2 uptake of 3.0 mmol/g (0 °C, 1 bar) and its CO2/CH4 selectivity of about 20 (0 °C, 1 bar) even exceed the literature values for bulk NPI-I. This study reveals that PVP acts as a template on molecular level influencing, primarily the micropore formation, reducing the BET surface area by roughly a factor of three compared to the bulk material. In contrast, the ultramicroporosity of the porous polyimides remains mainly unaffected. We envision that this three-step synthesis can be transferred to a broad variety of porous polymers. With electrospinning the large-scale production of self-standing membranes becomes realistic rendering the application of porous polymers for gas separation more likely.
查看更多>>摘要：? 2021 Elsevier Inc.The covalent triazine frameworks (CTFs) have great application prospects in gas adsorption and separation, pollutant adsorption and heterogeneous catalysis due to their high specific surface area, rich nitrogen content and high physicochemical stability. Moreover, the simultaneous introduction of Lewis acid active sites (cation part) and Lewis base active sites (halogen anion) into the structure of CTFs will not only increase the adsorption capacity of CO2, but also greatly improve the catalytic performance of the CO2 cycloaddition reaction. Herein, two novel cationic CTFs (CCTFs) based on 1,3,5-Tris(4-cyanopyridinium-1-ylmethyl)-benzene tribromide (TPM) were successfully synthesized by using anhydrous ZnCl2 as a catalyst and reaction medium to force the cyanide group into trimerization. The obtained CTF-TPMs with ample pyridine cationic sites have outstanding chemical and thermal stability even in strong acid and strong base solutions, high specific surface area (up to 1206 m2 g?1) and high CO2 adsorption capacity (up to 61.4 cc g?1, at 1 bar and 273 K). In addition, in the absence of co-catalyst and noble metal, CTF-TPMs can synergistically catalyze the cycloaddition of CO2 with epoxy compounds to form corresponding cyclic carbonates with the synergy effect of the pyridinium salts and halide ions. More importantly, the catalytic performance of CTF-TPMs and their structural framework basically remain unchanged after 5 times recycles, which makes them excellent practical application prospect.
查看更多>>摘要：? 2021 Elsevier Inc.Fe-MOF/g-C3N4 is a kind of typical II structure photo-catalyst. Some works reported that this catalyst's photo-performance has intimate relations with Fe-MOFs’ morphology. But the effect of g-C3N4’ morphology has been ignored. In this work, we prepared three kinds of different morphological g-C3N4 (bulk, tubulous and rod) to support MIL-88A by ball milling method. For tubulous g-C3N4 has larger surface area and largest volume and pore size, ball milling method leads to strong and intimate interaction between g-C3N4 and wrapped MIL-88A, the 6%MIL-88A@tubulous g-C3N4 exhibits high h+-e- separation, which benefits to the formation of main reactive species, performs the best photo-Fenton activity, which is almost 241.5 times of tubulous g-C3N4 and 6.3 of MIL-88A, respectively. Besides, MIL-88A could be encapsulated by tubulous g-C3N4 and keep well stability in the process of wastewater remediation. This work is of significance to promote the large-scale application of Fe-MOF/g-C3N4 in waste water remediation.
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