Persimmon tannin functionalized polyacrylonitrile fiber for highly efficient and selective recovery of Au(III) from aqueous solution

An efficient fibrous adsorbent (PANF-TETA-PT) was prepared via grafting triethylenetetramine (TETA) on polyacrylonitrile fiber (PANF), followed by persimmon tannin (PT) immobilizing. Detailed characterization certified that plenty amounts of amino and phenolic hydroxyl groups existed on the surface of PANF-TETA-PT, which would provide excellent active sites for Au(III) adsorption. The batch characteristic results found that the adsorption equilibrium data could be fitted well with Langmuir equation, while the obtained kinetic data were consistent with the Pseudo-second-order equation. The maximum equilibrium adsorption capacity of PANF-TETA-PT towards Au(III) (801.2 mg/g) was apparently superior than that of the reported adsorbents, and the competitive adsorption showed that PANF-TETA-PT had a good preference to adsorption Au(III) in spite of some coexisting pollutants. The characterization analysis of Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffractometer spectrum (XRD) revealed that the electrostatic attraction and chelation dominated the uptake of Au(III) on PANF-TETA-PT, in which a part of loaded Au(III) was reduced to Au particles with the help of reductive functional groups. Thus, this adsorbent could be as a promising candidate to separation and preconcentration of Au(III) from wastewater.

Characterization and deployment of surface-engineered chitosan-triethylenetetramine nanocomposite hybrid nano-adsorbent for divalent cations decontamination

The latency of toxic cations in the ecosystem poses serious ecological problems due to its bioaccumulation potential and toxicity to living organisms. The effective removal of these wastewater cations releasing from multi-industries is a bottleneck issue. Therefore, an attempt has been made to design a suitable sorbent for cations sorption from the aqueous environment. The chitosan biopolymer was modified with triethylenetetramine to incorporate active sites in the polymeric sequence to boost up its cations sorption capacity. Triethylenetetramine molecule anchoring chitosan (CH-TET) was authenticated through elemental assay, Fourier-transform infrared spectroscopy and ¹³C NMR in solid-state, scanning electron microscopy and thermal analysis. The sorption of lead (1.94 mmol g^-1), copper (2.79 mmol g^-1) and nickel (1.53 mmol g^-1) was carried out using the functionalized chitosan from aqueous solution, which showed higher sorption capacity for lead and copper than the pristine chitosan in terms of Langmuir sorption isotherm. To scrutinize the mechanism of sorption and energy of interaction between sorbent and sorbate, Langmuir, Temkin, and Freundlich isotherm models were used for sorption study. The Langmuir model showed the best fitting to the results based on lower error function values and a higher correlation coefficient (R²). It can be concluded that the triethylenetetramine-modified chitosan might be considered as an effective sorbent for cations removal from industrial wastewater.

A sensitive pH fluorescent probe based on triethylenetetramine bearing double dansyl groups in aqueous solutions and its application in cells

pH fluorescent probes possess many advantages, including intracellular detection, rapid response time and nondestructive testing. In this paper, a highly selective and sensitive fluorescent pH probe based on triethylenetetramine bearing double dansyl groups (1) was synthesized. This probe offers fluorescent measurement of pH value in the range of 5.81-7.21 in aqueous solution, with an 8.64-fold enhancement of fluorescent emission intensity over the unmodified probe. Probe 1 shows a fluorescent color change from a pale yellow to bright green when the pH is increased from 5.81 to 7.21. In addition, probe 1 shows good potential as a fluorescent visualizing sensor for pH values in living GS cells of epinepheluscoioides. The mechanism of the fluorescent response of probe 1 to solution pHs was further clarified by NMR, fluorescent spectra, and UV-vis absorption spectra. The results indicate that the fluorescent emission will shift with an increase in solution pHs, due to increasing deprotonation of the nitrogen atom on the sulfonamides. Deprotonation of the sulfonamide group will inhibits the intramolecular charge transfer process between the imino group and the naphthalene ring, resulting in the recognition phenomenon of blue shift and enhancement of fluorescent emission intensity.

Sonochemical-assisted route for synthesis of spherical shaped holmium vanadate nanocatalyst for polluted waste water treatment

Solar photocatalytic process has been shown to be an energy effective and eco-friendly degradation of unwanted pollutants present in the industrial wastewater. The present study introduces the preparation and characterization of novel holmium vanadate (HoVO₄₎ nanostructures that fully used in the photodegradation efficiency of anionic and cationic organic pollutants. HoVO₄ synthesized via a sonochemical-assisted route and triethylenetetramine (TETA) was used as a capping and precipitation agent. The experiments were carried out under a probe as sonication source, and its power was adjusted in 30 W (9 kHz), 50 W (15 kHz) and 80 W (24 kHz) for different samples. The obtained nanostructures were characterized by surface analytical and spectral techniques includes XRD, FT-IR, SEM, TEM and UV-visible spectra measurements. The HR-SEM images reveal that HoVO₄ exists as a spindle-shape with spherical morphology together. HR-TEM images reveal that prepared catalyst has a spherical structure with uniform particle size. The results outline 67.6% elimination of methyl violet dye within 90 min under UV light in the presence of the optimal nano-sized formulation of 24.5 nm size. The prepared photocatalyst possesses high stability and reusability without appreciable loss of catalytic activity up to three runs.

Mechanisms of Cu2+, triethylenetetramine (TETA), and Cu-TETA sorption on rectorite and its use for metal removal via metal-TETA complexation

Uptake of metals, organics, and formation of metal-organic complexes on the surface or in the interlayer of clay minerals had been studied extensively over the last half century. In this study, we investigated the uptake mechanisms of Cu²⁺, triethylenetetramine (TETA), and Cu-TETA on rectorite and its use for metal removal via metal-TETA complexation. The uptake of Cu²⁺, TETA, and Cu-TETA by rectorite occurred on the external as well as in the interlayer space, resulting in a change of d₀₀₁-spacing due to differences in sizes of interlayer cations or complexes. Although the uptake of Cu²⁺ and Cu-TETA by rectorite was via a cation exchange process as evidenced by the stoichiometric desorption of dominant interlayer cation Ca²⁺, the uptake of TETA alone on rectorite was via complexation with interlayer cation Ca²⁺. Due to strong affinity of TETA for Cu²⁺, significant amounts of Cu²⁺ uptake occurred on TETA-rectorite. Desorption of Ca²⁺ from TETA-rectorite confirmed the replacement of interlayer cation Ca²⁺ by Cu²⁺. However, the replacement of Ca²⁺ by Cu²⁺ in TETA-rectorite did not involved in removal of TETA. As such, TETA-modified clay minerals may serve as a type of sorbents for the removal of selected heavy metals via surface or interlayer via complexation.

Diabetes-induced alterations in tissue collagen and carboxymethyllysine in rat kidneys: Association with increased collagen-degrading proteinases and amelioration by Cu(II)-selective chelation

Advanced glycation end-products (AGEs) comprise a group of non-enzymatic post-translational modifications of proteins and are elevated in diabetic tissues. AGE-modification impairs the digestibility of collagen in vitro but little is known about its relation to collagen-degrading proteinases in vivo. N(ε)-carboxymethyllysine (CML) is a stable AGE that forms on lysyl side-chains in the presence of glucose, probably via a transition metal-catalysed mechanism. Here, rats with streptozotocin-induced diabetes and non-diabetic controls were treated for 8weeks with placebo or the Cu(II)-selective chelator, triethylenetetramine (TETA), commencing 8weeks after disease induction. Actions of diabetes and drug treatment were measured on collagen and collagen-degrading proteinases in kidney tissue. The digestibility and CML content of collagen, and corresponding levels of mRNAs and collagen, were related to changes in collagen-degrading-proteinases. Collagen-degrading proteinases, cathepsin L (CTSL) and matrix metalloproteinase-2 (MMP-2) were increased in diabetic rats. CTSL-levels correlated strongly and positively with increased collagen-CML levels and inversely with decreased collagen digestibility in diabetes. The collagen-rich mesangium displayed a strong increase of CTSL in diabetes. TETA treatment normalised kidney collagen content and partially normalised levels of CML and CTSL. These data provide evidence for an adaptive proteinase response in diabetic kidneys, affected by excessive collagen-CML formation and decreased collagen digestibility. The normalisation of collagen and partial normalisation of CML- and CTSL-levels by TETA treatment supports the involvement of Cu(II) in CML formation and altered collagen metabolism in diabetic kidneys. Cu(II)-chelation by TETA may represent a treatment option to rectify collagen metabolism in diabetes independent of alterations in blood glucose levels.

Application of alizarin colorimetric measurements for quantification of amine extraction by model food simulants from epoxy polymer

A simple and straightforward method has been proposed for quantification of residual amine in cured epoxy resin. Non-bounded triethylenetetramine was extracted from epoxy polymer and determined via spectrophotometry using alizarin chromophore. Four solvents commonly used as food simulants, namely water, 95% ethanol, 10% ethanol and 3% acetic acid were examined. Released amine induces changes in the absorption spectrum of alizarin, by decreasing the intensity of the maximum at 430 nm band and mutually increasing the 527 nm band. These changes were proportional to the amounts of amine concentration in samples. The statistical significance of obtained calibration curves was validated. Among studied solvents, the highest amine release was observed for water solution and 3% acetic acid, that is approximately 7% w/w. The maximal amount of residual amine extracted with 95% ethanol was about 1.25%, while for 10% ethanol this amount was 2%. The effect of aging of the samples and exposure to artificial sunlight were also examined. The proposed method has been proven to be fast, low cost and directly applicable for analysis of typical epoxy resins.