12 research outputs found
Removal of Mercury(II) from Aqueous Solutions by Adsorption on Poly(1-amino-5-chloroanthraquinone) Nanofibrils: Equilibrium, Kinetics, and Mechanism Studies
Poly(1-amino-5-chloroanthraquinone) (PACA) nanofibrils were applied as novel nanoadsorbents for highly toxic mercury removal from aqueous solutions. A series of batch adsorption experiments were conducted to study the effect of adsorbent dose, pH, contact time, and metal concentration on Hg(II) uptake by PACA nanofibrils. Kinetic data indicated that the adsorption process of PACA nanofibrils for Hg(II) achieved equilibrium within 2 h following a pseudo-second-order rate equation. The adsorption mechanism of PACA nanofibrils for Hg(II) was investigated by Fourier transform-infrared (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS) analyses. The adsorption isotherm of Hg(II) fitted well the Langmuir model, exhibiting superb adsorption capacity of 3.846 mmol of metal per gram of adsorbent. Lastly, we found out that the as-synthesized PACA nanofibrils are efficient in Hg(II) removal from real wastewater. Furthermore, five consecutive adsorption-desorption cycles demonstrated that the PACA nanofibrils were suitable for repeated use without considerable changes in the adsorption capacity
Removal of Mercury(II) from Aqueous Solutions by Adsorption on Poly(1-amino-5-chloroanthraquinone) Nanofibrils: Equilibrium, Kinetics, and Mechanism Studies
Poly(1-amino-5-chloroanthraquinone) (PACA) nanofibrils were applied as novel nanoadsorbents for highly toxic mercury removal from aqueous solutions. A series of batch adsorption experiments were conducted to study the effect of adsorbent dose, pH, contact time, and metal concentration on Hg(II) uptake by PACA nanofibrils. Kinetic data indicated that the adsorption process of PACA nanofibrils for Hg(II) achieved equilibrium within 2 h following a pseudo-second-order rate equation. The adsorption mechanism of PACA nanofibrils for Hg(II) was investigated by Fourier transform-infrared (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS) analyses. The adsorption isotherm of Hg(II) fitted well the Langmuir model, exhibiting superb adsorption capacity of 3.846 mmol of metal per gram of adsorbent. Lastly, we found out that the as-synthesized PACA nanofibrils are efficient in Hg(II) removal from real wastewater. Furthermore, five consecutive adsorption-desorption cycles demonstrated that the PACA nanofibrils were suitable for repeated use without considerable changes in the adsorption capacity
Highly Productive Synthesis, Characterization, and Fluorescence and Heavy Metal Ion Adsorption Properties of Poly(2,5-dimercapto-1,3,4-thiadiazole) Nanosheets
Poly(2,5-dimercapto-1,3,4-thiadiazole) (PBT) nanosheets were synthesized by chemical oxidative synthesis under mild conditions. The media, oxidant species, monomer concentrations, oxidant/monomer molar ratio, and temperature were optimized to achieve higher yields and better performance. The molecular structure, morphology, and properties of the nanosheets were analyzed by Fourier transform infrared (FT-IR), ultraviolet-visible (UV-Vis), and fluorescence spectroscopies, wide-angle X-ray diffraction (WAXD), matrix-assisted laser desorption/ionization/time-of-flight (MALDI-TOF) mass spectrometry, X-ray photoelectron spectroscopy (XPS), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), and simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC). It was found that the polymerization of 2,5-dimercapto-1,3,4-thiadiazole occurs via dehydrogenation coupling between two mercapto groups to form the –S–S– bond. PBTs show the highest polymerization yield of up to 98.47% and form uniform nanosheets with a thickness of 89~367 nm. poly(2,5-dimercapto-1,3,4-thiadiazole) polymers (PBTs) exhibit good chemical resistance, high thermostability, interesting blue-light emitting fluorescence, and wonderful heavy metal ion adsorption properties. Particularly, the PBT nanosheets having a unique synergic combination of three kinds of active –S–, –SH, and =N– groups with a moderate specific area of 15.85 m2 g−1 exhibit an ultra-rapid initial adsorption rate of 10,653 mg g−1 h−1 and an ultrahigh adsorption capacity of up to 680.01 mg g−1 for mercury ion, becoming ultrafast chelate nanosorbents with a high adsorption capacity. With these impressive properties, PBT nanosheets are very promising materials in the fields of water treatment, sensors, and electrodes
Facile Synthesis, Characterization of Poly-2-mercapto-1,3,4-thiadiazole Nanoparticles for Rapid Removal of Mercury and Silver Ions from Aqueous Solutions
Industrial pollution by heavy metal ions such as Hg2+ and Ag+ is a universal problem owing to the toxicity of heavy metals. In this study, a novel nano-adsorbent, i.e., poly-2-mercapto-1,3,4-thiadiazole (PTT), was synthesized and used to selectively adsorb mercury and silver ions from aqueous solutions. PTT nanoparticles were synthesized via chemical oxidative dehydrogenation polymerization under mild conditions. Oxidant species, medium, monomer concentration, oxidant/monomer molar ratio, and polymerization temperature were optimized to obtain optimum yields. The molecular structure and morphology of the nanoparticles were analyzed by ultraviolet-visible (UV-Vis), Fourier transform infrared (FT-IR), matrix-assisted laser desorption/ionization/time-of-flight (MALDI/TOF) mass and X-ray photoelectron (XPS) spectroscopies, wide-angle X-ray diffraction (WAXD), theoretical calculations and transmission electron microscopy (TEM), respectively. It was found that the polymerization of 2-mercapto-1,3,4-thiodiazole occurs through head-to-tail coupling between the S(2) and C(5) positions. The PTT nanoparticles having a peculiar synergic combination of four kinds of active groups, S–, –SH, N–N, and =N– with a small particle size of 30–200 nm exhibit ultrarapid initial adsorption rates of 1500 mg(Hg)·g−1·h−1 and 5364 mg(Ag)·g−1·h−1 and high adsorption capacities of up to 186.9 mg(Hg)·g−1 and 193.1 mg(Ag)·g−1, becoming ultrafast chelate nanosorbents with high adsorption capacities. Kinetic study indicates that the adsorption of Hg2+ and Ag+ follows the pseudo-second-order model, suggesting a chemical adsorption as the rate-limiting step during the adsorption process. The Hg2+ and Ag+-loaded PTT nanoparticles could be effectively regenerated with 0.1 mol·L−1 EDTA or 1 mol·L−1 HNO3 without significantly losing their adsorption capacities even after five adsorption–desorption cycles. With these impressive properties, PTT nanoparticles are very promising materials in the fields of water-treatment and precious metals recovery
Spadix-Bract Structured Nanobowls for Bimodal Imaging-Guided Multidrug Chemo-Photothermal Synergistic Therapy
Multifunctional
nanoparticles (NPs) simultaneously having functions
of multimodal therapy and imaging are highly needed in biomedical
applications. A unique monstera flower-like gold nanorod/polydopamine
bowl (GNR/PDA bowl) with spadix-bract nanostructure was fabricated
by a novel and facile approach. The possible formation mechanism of
the GNR/PDA bowl spadix-bract NPs was proposed by monitoring the synthetic
process. The obtained monstera flower-like GNR/PDA bowl spadix-bract
NPs were further selectively functionalized with 1-dodecanethiol (DT)
on GNR domains (spadix) to achieve efficient hydrophobic drug delivery
capability; meanwhile, the PDA bowl (bract) can load the hydrophilic
anticancer drug doxorubicin (DOX). The resultant monstera flower-like
DT-GNR/PDA bowl spadix-bract NPs possess an excellent biocompatibility,
high dual-drug-loading contents, excellent photothermal conversion
efficiency, strong near-infrared (NIR) absorbance, effective attenuation
of X-rays, and pH/NIR dual-responsive properties, which enable the
NPs to be applied for synergistic bimodal computed tomography/photoacoustic
(CT/PA) imaging-guided multidrug chemotherapy and photothermal therapy
(PTT). Moreover, the synthetic approach could be extended to prepare
Au/PDA bowl NPs and Fe<sub>2</sub>O<sub>3</sub>/PDA bowl NPs, which
may greatly expand the application of the PDA-based bowl NPs
Ultrahigh Metal Content Carbon-Based Catalyst for Efficient Hydrogenation of Furfural: The Regulatory Effect of Glycerol
The development of high-content non-noble metal nanocatalysts
is
important for multiphase catalysis applications. However, it is a
challenge to solve the agglomeration in the preparation of high-content
metal catalysts. In this paper, a carbon-based catalyst (Co@CN-G-600)
with 71.28 wt % cobalt metal content was prepared using a new strategy
of gas-phase carbon coating assisted by glycerol. The core of this
strategy is to maintain the spacing of metallic cobalt by continuous
replenishment of dissociated ligands during pyrolysis over gas-phase
glycerol. This approach is also applicable to other non-noble metals.
When Co@CN-G-600 was further used as a catalyst for the selective
hydrogenation of furfural (FF) to prepare furfuryl alcohol (FOL),
the yield of FOL was >99.9% under mild conditions of 80 °C,
compared
to only 8.23% catalytic yield at up to 130 °C for Co@CN-600 without
glycerol. The excellent catalytic performance mainly lies in the fact
that the introduction of glycerol modulates the size effect, electronic
effect, and acidic site intensity of the high-content Co catalyst,
which promotes the activation of FF and hydrogen. Meanwhile, the optimized
specific surface area and pore structure by glycerol improve the accessibility
of high-density active sites and promote more efficient mass transfer.
In addition, the introduction of glycerol produced a graphitic carbon
layer encapsulation structure relative to Co@CN-600, which substantially
improved the cycling stability of the catalyst. This study resolves
the paradox of high content and high dispersion of non-noble metal
catalysts in the synthesis process and provides a general pathway
and example for the preparation of stable high-content metal catalysts