Insight into the performance and mechanism of persimmon tannin functionalized waste paper for U(VI) and Cr(VI) removal

Herein, using dialdehyde waste paper (DAWP) as a cross-linking agent to immobilize persimmon tannin (PT) was first used to remove the U(VI) and Cr(VI) via the "waste control by waste" concept. The microscopic and macroscopic surface properties of the as-prepared adsorbent was characterized by the advanced characterization techniques. Factors that affected the elimination process such as variable pH, coexistence ions and equilibrium time were investigated by batch techniques. The results showed that the maximal removal capacities of U(VI) and Cr(VI) on DAWP-PT were 242.3 mg/g (pH = 6.0) and 178.7 mg/g (pH = 2.0) at 298 K, which exhibited competitiveness with most of the reported solid materials. Meanwhile, adsorption data were fitted perfectly to the Langmuir and Pseudo-second-order equations, which indicated that the monolayer and homogenous chemisorption dominated the removal process. The SEM-EDX, DFT and XPS analysis conformed that adsorption of U(VI) was mainly via surface complexation, while the elimination of Cr(VI) was a redox reaction process, and about 65.33% of Cr(III) and 34.67% of Cr(VI) co-existed onto the surface of DAWP-PT. Thus, this study would provide a high-efficiency and low-cost adsorbent for radionuclide and heavy metal treatment.

Plant tannin immobilized Fe3O4@SiO2 microspheres: A novel and green magnetic bio-sorbent with superior adsorption capacities for gold and palladium

In this paper, a new core-shell nanostructured magnetic bio-based composite was prepared by immobilizing persimmon tannin (PT) onto Fe₃O₄@SiO₂ microspheres, and the as designed Fe₃O₄@SiO₂@PT was utilized for adsorptive recovery of Au(III) and Pd(II). The preparation, morphology, composition and magnetic property of Fe₃O₄@SiO₂@PT were characterized. Adsorption parameters of Fe₃O₄@SiO₂@PT towards Au(III) and Pd(II) including initial pH, reaction time, initial concentration of metal ions, effect of acidity and interference of coexisting metal ions were investigated. It is sufficiently confirmed that silica was coated on Fe₃O₄ and persimmon tannin was immobilized on aminated Fe₃O₄@SiO₂. The thickness of silica and loaded persimmon tannin are around 18 nm and 14 nm, respectively. With only 1.00 wt% of persimmon tannin, however, the maximum adsorption capacities of Fe₃O₄@SiO₂@PT for Au(III) and Pd(II) were as high as 917.43 and 196.46 mg·g^-1, respectively. In addition, after adsorption of Au(III) and Pd(II), the magnetization saturation values (Ms) of Fe₃O₄@SiO₂@PT were high enough to guarantee efficient magnetic seperation. Metallic gold could be facilely recovered from wastewaters containing Au(III).

Preparation and characterization of a novel polyethyleneimine cation-modified persimmon tannin bioadsorbent for anionic dye adsorption

A novel and recyclable bioadsorbent (PTP) has been prepared by the cationization of persimmon tannin (PT) using polyethyleneimine (PEI) for application in the removal of the anionic dye methyl orange (MO) from aqueous solution. The physicochemical properties of the prepared PTP were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, Zeta potential measurements, Brunauer-Emmett-Teller and thermogravimetric analysis. Systematic batch adsorption experiments were carried out with pH, bioadsorbent dosage, initial MO concentration and contact time. Kinetic regression analysis indicated that the adsorption processes followed the pseudo-second order model. The equilibrium isotherm was in good fit with the Freundlich model with a maximum adsorption capacity of 225.74 mg/g. Thermodynamics data revealed that the adsorption of MO onto PTP was feasible, spontaneous and endothermic. A possible biosorption mechanism was presented where electrostatic interactions, hydrogen bonding, and π-π interactions dominated the adsorption of MO onto PTP. Moreover, the regeneration of the PTP was easily achieved and MO removal efficiency remained high (81.47%) after six cycles. The actual sewage treatment simulation was evaluated and the PTP had a good preference to adsorption MO. All these results indicated that PTP could be considered a high performance and promising candidate for the effective removal of anionic dyes from aqueous solutions.

Persimmon tannin changes the properties and the morphology of wheat gluten by altering the cross-linking, and the secondary structure in a dose-dependent manner

The effects of persimmon tannin (PT) on the texture, viscoelasticity, thermal stability, and morphology of gluten were studied and the underlying mechanisms were also explored. The results showed that PT increased the hardness and viscoelasticity but lowered the cohesiveness and extensibility of gluten in a dose-dependent manner. Additionally, PT increased the denaturation temperature and enthalpy of gluten, and induced the formation of gluten with compact structure. High concentration of PT (8%) significantly increased the hardness and viscoelasticity of gluten, and induced the formation of compact structure of gluten by disturbing the conformation of gluten, and interfering gluten cross-linking through decreasing disulfide bonds, free sulfydryl groups, and free amino groups. In contrast, low concentration (0.25%) of PT slightly altered the gluten properties and morphology. Our work extended the study on the supplementation of phenolic compounds in wheat flour-based products.

Selective adsorption and recovery of Au(III) from three kinds of acidic systems by persimmon residual based bio-sorbent: a method for gold recycling from e-wastes

A low cost bio-sorbent, named "PPF resin", was prepared by crosslinking the persimmon residual with formaldehyde. The adsorption behavior of PPF resin towards Au(III) from varied HCl and HNO3 concentration solutions was studied. PPF resin could adsorb almost complete Au(III) from high acidic systems. The influence of dilution ratio, solid-liquid ratio and time towards Au(III) from aqua regia leached PCBs liquor was censored in detail by batch and continuous adsorption methods. The PPF resin before and after adsorption was characterized by FT-IR, XRD and XPS spectra which provided evidences for the reduction of Au(III) to Au(0) with a proposed mechanism of Au(III) adsorption-reduction process. After saturated column adsorption of 0.1g PPF resin, 0.0506 g gold (purity: 99.9%) was obtained by the method of incineration. The present results provide a new approach for gold recovery from the secondary resources.

Non-enzymatic electrochemical hydrogen peroxide biosensor based on reduction graphene oxide-persimmon tannin‑platinum nanocomposite

Hydrogen peroxide (H₂O₂) is one of the most universal and essential ingredients in distinct biological tissues. Herein, a novel non-enzymatic sensor based on reduction graphene oxide-persimmon tannin‑platinum nanocomposite (RGO-PT-Pt) was exploited for H₂O₂ detection. RGO-PT-Pt nanocomposite was prepared by reduction procedure with ascorbic acid as reducing agent and characterized by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), ultraviolet visible spectroscopy (UV-vis) and Fourier infrared spectroscopy (FT-IR). Taking advantage of high electro-catalytic efficiency of Pt nanoparticles, high electronic conductivity and large surface area of RGO, and significant adsorption ability of PT on metal ions and its prevention of agglomeration to promote RGO dispersion, RGO-PT-Pt nanocomposite revealed better catalytic ability towards H₂O₂ via a synergistic effect. Under the optimal conditions, the RGO-PT-Pt non-enzymatic biosensor exhibited outstanding electrocatalytic activity towards H₂O₂ reduction. The amperometric response demonstrated a linear relationship with H₂O₂ concentration from 1.0 to100 μM with the correlation coefficient of 0.9931. The limit of detection was 0.26 μM (S/N = 3) and the response time was 3 s. Furthermore, the fabricated sensor exhibited a practical applicability in the quantification of H₂O₂ in human serum samples with an excellent recovery rate. Due to excellent performance such as fast response time, low detection limit, high stability and selectivity, the RGO-PT-Pt non-enzymatic biosensor has potential application in clinical diagnostics.

Extraction, purification and anti-radiation activity of persimmon tannin from Diospyros kaki L.f

In this study, persimmon tannin was extracted from Diospyros kaki L.f. using ultrasound-assisted extraction and purified by D101 macroporous resin column chromatography and polysulfone ultrafiltration membrane. The tannin content of the final persimmon tannin extracts was attained to 39.56% calculated as catechin equivalents. Also, the radioprotective effects of persimmon tannin for HEK 293T cells proliferation and apoptosis after Gamma irradiation were investigated by CCK-8, Hoechst 33258 staining, flow cytometry assay and intracellular reactive oxygen species assay (ROS). Persimmon tannin was pre-incubated with HEK 293T cells for 12 h prior to Gamma irradiation. It was found that pretreatment with persimmon tannin increased cell viability and inhibited generation of Gamma-radiation induced ROS in HEK 293T cells exposed to 8 Gy Gamma-radiation. The percentage of apoptotic cells were only 6.7% when the radiation dose was 8 Gy and pretreated with 200 μg/ml of persimmon tannin. All these results indicated that persimmon tannin offered a potent radioprotective effect on cell vitality and cell apoptosis of Gamma-radiation exposure in HEK 293T cells. This study would serve as a pre-clinical evaluation of persimmon tannin for use in people with radiation protection.

Chitosan modification persimmon tannin bioadsorbent for highly efficient removal of Pb(II) from aqueous environment: the adsorption equilibrium, kinetics and thermodynamics

Lead (Pb) pollution has triggered a great threat to ecological system as well as public health due to its highly toxic and mutagenic properties. In this study, chitosan surface modified persimmon tannin (PT-CS) biomass composite as an environmental-friendly bioadsorbent for highly efficient removal of Pb(II) from aqueous solutions was investigated. Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy and Zeta potential were used to elucidate the adsorption mechanism. Combining oxidation reaction, electrostatic interaction and chelation reaction, PT-CS exhibited fine adsorption to Pb(II). The maximum adsorption capacity was 179.3 mg/g. Equilibrium isotherm for the adsorption of Pb(II) was analyzed by the Langmuir, Freundlich and Temkin models, and the Langmuir isotherm (R² > 0.99) was the best. The pseudo-first-order, pseudo-second-order and intraparticle diffusion equations were used to analyze the kinetic data of the adsorption process and the pseudo-second-order kinetic (R_s² > 0.98) model was fitted well. Moreover, thermodynamic parameters including ΔG⁰< 0, ΔH⁰ (150.57 KJ/mol) > 0 and ΔS⁰ (456.13 J/mol K) > 0 showed that the process of Pb(II) adsorption by PT-CS was spontaneous and endothermic. All these results illustrated that PT-CS would be a promising and low-cost alternative bioadsorbent of Pb(II) in wastewater treatment.

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.

Interaction of characteristic structural elements of persimmon tannin with Chinese cobra PLA2

To more fully understand the mechanism by which persimmon tannin (PT) inhibited phospholipase A2 (PLA2) and the structural requirements of PT for the inhibition, the interactions between PLA2 and seven characteristic structural elements of PT including epigallocatechin-3-gallate (EGCG), myricetin, epicatechin-3-gallate (ECG), epicatechin-3-gallate-(4β → 8, 2β → O → 7)-epicatechin-3-gallate (A-type ECG dimer), epigallocatechin-3-gallate-(4β → 8, 2β → O → 7)-epigallocatechin-3-gallate (A-type EGCG dimer), epicatechin-(4β → 8, 2β → O → 7)-epicatechin (A-type EC dimer) and epicatechin-(4β → 8)-epicatechin (B-type EC dimer) were studied by enzymatic and spectroscopic methods. Molecular docking was also used to explore the possible residues involved in the interactions. The results revealed that A-type EGCG dimer and A-type ECG dimer showed higher inhibitory effects on the catalytic activity of PLA2 than monomers and B-type dimer. They induced greater conformational changes in PLA2 than other structural elements. In addition, molecular docking studies revealed that expect for lysine residues, other residues such as Trp18, Try27, Gly29, His47 and Tyr63 were involved in the interactions. We propose that A-type EGCG and ECG dimer units may be structural requirements for the interaction between PT and PLA2. Our data provide an additional structural basis for anti-PLA2 activity of persimmon tannin.

Magnetic MXene-NH2 decorated with persimmon tannin for highly efficient elimination of U(VI) and Cr(VI) from aquatic environment

Herein, a magnetic MXenes based composite (Fe₃O₄@Ti₃C₂-NH₂-PT) was constructed by loading Fe₃O₄ nano-particles into the interlamellar spacing of persimmon tannin-functionalized Ti₃C₂-NH₂. The structure, morphology and physicochemical properties of the as-prepared adsorbents were probed by advanced spectroscopy techniques, while the impact of various experimental conditions like pH values, amount of adsorbent and contact time on the removal trend were examined by batch experiments. The elimination results revealed that Fe₃O₄@Ti₃C₂-NH₂-PT could be applied in a wide range of initial concentrations, and exhibited outstanding removal efficiency for U(VI) (104.9 mg/g, pH = 5.0) and Cr(VI) (83.8 mg/g, pH = 2.0). Meanwhile, the adsorption process was described well with the Langmuir isotherm and Pseudo-second-order kinetics models, which indicated that the monolayer chemical adsorption occurred during elimination of the two contaminants. The spectral analysis results manifested that elimination of U(VI) followed an inner-sphere configuration, whereas uptake of Cr(VI) was determined by electrostatic interaction and adsorption-reduction process. This work opened a new opportunity in designing MXenes based adsorbents in the application for environmental remediation.

Activity and potential mechanisms of action of persimmon tannins according to their structures: A review

One distinguishing feature of the persimmon, that differentiates it from other fruits, is its high proanthocyanidins content, known as persimmon tannin (PT). Despite the poor absorption of PT in the small intestine, results from animal studies demonstrate that PT has many health benefits. Our goal in this review is to summarize the literature that elucidates the relationship between PT structure and activity. In addition, we also summarize the potential mechanisms underlying the health benefits that result from PT consumption; this includes the hypolipidemic, hypoglycemic, antioxidant, anti-inflammatory, antiradiation, antibacterial and antiviral, detoxification effects on snake venom, and the absorption of heavy metals and dyes. Studies show that PT is a structurally distinct proanthocyanidins that exhibits a high degree of polymerization. It is galloylation-rich and possesses unique A-type interflavan linkages in addition to the more common B-type interflavan bonds. Thus, PT is converted into oligomeric proanthocyanidins by depolymerization strategies, including the nucleophilic substitution reaction, acid hydrolysis, and hydrogenolysis. In addition, multiple health benefits exerted by PT mainly involve the inactivation of lipogenic and intracellular inflammatory signaling pathways, activation of the fatty acid oxidation signaling pathway, regulation of gut microbiota, and highly absorptive properties.

Persimmon tannin unevenly changes the physical properties, morphology, subunits composition and cross-linking types of gliadin and glutenin

To answer which is the key component caused the alterations of gluten in the presence of persimmon tannin (PT), the changes on physical properties, morphology, subunits coposition and cross-linking types of glutenin and gliadin were investigated. The results showed that compared with gliadin, glutenin was more sensitive to PT due to the greater changes in the thermal stability, network structure and aggregation behavior. This might be explained by the remarkable decreases in soluble subunits content, free sulfhydryl groups (SH), disulfide bonds (SS) and free amino groups (-NH₂) cross-linking of glutenin after 8% of PT addition, as well as the varying degree in subunits composition. Therefore, glutenin played a more important role in the changes in the properties and network structure of gluten induced by PT than gliadin. Our work provided a guidance for the incorporation of phenolic compounds in wheat flour-based products.

The effects of inulin on solubilizing and improving anti-obesity activity of high polymerization persimmon tannin

High polymerization persimmon tannin has been reported to have lipid-lowering effects. Unfortunately, the poor solubility restricts its application. This research aimed to investigate the effect and mechanism of inulin on solubilizing of persimmon tannin. Furthermore, we examined whether the addition of inulin would affect the attenuated obesity effect of persimmon tannin. Transmission electron microscope (TEM), Isothermal titration calorimetry (ITC) and Fourier transform infrared spectroscopy (FT-IR) results demonstrated that inulin formed a gel-like network structure, which enabled the encapsulation of persimmon tannin through hydrophobic and hydrogen bond interactions, thereby inhibiting the self-aggregation of persimmon tannin. The turbidity of the persimmon tannin solution decreased by 56.2 %, while the polyphenol content in the supernatant increased by 60.0 %. Furthermore, biochemical analysis and 16s rRNA gene sequencing technology demonstrated that persimmon tannin had a significant anti-obesity effect and improved intestinal health in HFD-fed mice. Moreover, inulin was found to have a positive effect on enhancing the health benefits of persimmon tannin, including improving hepatic steatosis and gut microbiota dysbiosis. it enhanced the abundance of beneficial core microbes while decreasing the abundance of harmful bacteria. Our findings expand the applications of persimmon tannin in the food and medical sectors.