The fresh water shortage is a big driving force for scientists worldwide to study on seawater desalination. Recently, the solar steam generation (SSG) based on biomass has already attracted a great ...deal of interest because of its effectiveness and eco-friendliness. In this study, a novel photothermal material for SSG was fabricated by treating fingered citron (FC) with natural polyphenols from green tea extract (GTE) and then with Fe (III) solution to form nano layers of Fe (III) complex on FC surface. Consequently, the developed FC based photothermal material (FCP) exhibited high light absorption capacity. Thanks to its unique structure with honeycomb-like porous pith and scattered linear vascular bundles and hydrophilic property, FCP possessed essential features for good performance of SSG including excellent water transportation, low thermal conductivity, high salt rejection capacity, and stable operation. The FCP based SSG system demonstrated a water evaporation rate of 1.92 kg m−2 h−1 under 1 sun illumination, which is comparable or even superior to those of the reported biomass-based photothermal materials. The simple, cost-effective, and green FCP fabrication technology together with the high water evaporation performance of the FCP based SSG highlight the promising application of FCP in SSG toward sustainable seawater desalination.
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•A novel photothermal materialwas fabricated by treating FC with polyphenols from green tea extract and then with Fe (III) solution.•The unique structure of FC is beneficial for reducing the heat loss through conduction and enhancing water diffusion.•Outstanding thermal management capacity by using heat transported from the bulk water for water evaporation•Numerous hydrophilic groups on the material surface that reduce the evaporation enthalpy of water.•The SSG based FCP material possessed an evaporation rate of 1.92 kg m−2 h−1 under 1 sun.
In this work, CoAl2O4 pigments successfully were prepared via thermal decomposition method by employing green tea extract as precipitating agent and capping agent. The effects of preparation ...parameters such as: calcination temperature, surfactants, solvent and pH were investigated to reach the optimum conditions. The biosynthesized cobalt alumina spinel was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray energy dispersive spectroscopy (EDS), ultraviolet–visible (UV–Vis) spectroscopy and vibrating sample magnetometer (VSM). The photocatalytic activity of CoAl2O4 nanostructures was compared by degradation of methylene blue in aqueous solution under UV light irradiation. Also the hydrogen storage capacity of CoAl2O4 was measured by chronopotentiometry method. The capacity of CoAl2O4 in 1 mA current and 20 cycles obtained 1100 mh/g.
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•Pure CoAl2O4 pigments have been prepared using simple thermal decomposition method.•The effects of preparation parameters were investigated to reach the optimum conditions.•The green tea extract can be used as capping, precipitating agent, and for adjusted pH.•The optical, magnetic properties, hydrogen storage capacity and photocatalytic activity were studied.
•Nanoencapsulates of green tea extract displayed improved physical properties.•Encapsulates showed lighter color, higher hygroscopicity and flowability.•Nanocapsules displayed controlled release and ...better bioactivity control.•All the data showed good correlation with zero order kinetics.
Nano-particles of green tea extract were prepared by ultrasonication, encapsulated in maltodextrin and were subjected to freeze drying to produce nanoencapsulated powders. Different proportions of 30 % solution of maltodextrin and dry tea extract (1:5; 1:10, 1:15) were combined with a small molecule surfactant (Tween 40). Average particle size of 1:5, 1:10, 1:15 based nano-particles were 380.34, 390.26 and 520.45 nm with encapsulation efficiency of 41.27, 45.92 and 57.51% and with negative surface charge of –22.04, −16.40 and −14.91, respectively. Scanning electron microscopy revealed irregular shapes of nanoencapsulated freeze dried powders with variation in appearance. X-ray diffraction patterns showed very low degree of crystanillity after encapsulation. The nanoencapsulated powders showed characteristic bands in infra-red spectra at ∼ 3200, ∼1600 and ∼ 1140 cm1. Nanocapsules displayed controlled release when compared to free green tea extract under simulated intestinal conditions and all the data showed good correlation with zero order kinetics.
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•A novel 2D/2D BiOCl/BiOIO3 heterojunction with oxygen defects has been fabricated.•The oxygen defect enhanced the charge transfer and visible light absorption capacity.•The enhanced ...internal electric field accelerated the charge transfer.•Photocatalytic activities for organic pollutants removal have significantly enhanced.
It is particularly significant that the enhancement of charge transfer efficiency and visible light absorption ability on the removal of organic pollutants by semiconductor photocatalysts, for which the interfacial electric field modulation and defect engineering are the linchpins. Herein, we first report the introduction of oxygen defects to regulate interfacial electric field assisted by nature-derived reduction method with green tea extracting solution. Interestingly, the continuously adjustable visible light response, oxygen defect content, and internal electric field intensity for the as-designed heterojunctions are achieved by simply tuning the concentration of the extract solution. The extract modification BiOCl/BiOIO3 heterojunctions exhibit more efficient photogenerated charge transfer, stronger light-harvesting capacity, and superior photocatalytic performance for ciprofloxacin removal compared with the original BiOCl/BiOIO3 heterojunctions. Deep insights into synergistic promotion of steering charge transfer from the perspectives of oxygen defect introduction and internal electric field modulation are unfolded, exclusively shedding new light on the green bio-inspired tactics for promoting the photoelectrochemical property of semiconductor photocatalysts.
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•We report a colorimetric assay for detection of H2O2 based on the oxidation ABTS.•The rGO was prepared using the green tea extract agent and decorated by HRP.•H2O2 can be catalysed ...by HRP-rGO and converted into water and oxygen.•The detection limit of analysis was ≈15 nM.•Also, the biosensor was adapted to monitor H2O2 in different beverages.
We reported a simple and sensitive colorimetric assay for detection of hydrogen peroxide (H2O2) based on the oxidation of 2,2׳-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) by UV–Vis spectroscopy method. The reduced graphene oxide (rGO) was prepared using green tea extract as bio-reducing and stabilizer agent and decorated by horseradish peroxidase (HRP). The surface of Au interface was modified with HRP-rGO hybrid. The formation of HRP-rGO hybrid was confirmed by cyclic voltammetry, scanning electron microscopy (SEM), energy-dispersive X-ray Spectroscopy (EDX) and Raman spectroscopy·H2O2 can be catalysed by HRP-rGO hybrid and converted into water and oxygen. The ABTS substrate takes up oxygen to form a green coloured product that has absorption peaks at 421, 655 nm and 737 nm. The colour development is linearly dependent on HRP in the range of 4–50 µg/L. The color of the green product solution is stable for 20 min. The absorption intensity is strongly related to the hydrogen peroxide concentration. The absorption intensity of the formed product scaled linearly with the hydrogen peroxide concentration in the ranges of 0.3–20 µM and 20–8000 µM with a detection limit of ≈15 nM could be achieved. The biosensor with excellent limit detection and wide linear ranges was adapted to monitor H2O2 in different beverages.
Our study focused on the preparation and characterization of biocomposite films consisting of poly(vinyl alcohol) (PVA) and green tea extract (GTE) with a small amount of glycerol as a plasticizer. ...Scanning electron microscopy (SEM) showed that both the surface and cross-section of the GTE-PVA biocomposite films were smooth and uniform. Incorporation of GTE could considerably alter the optical and mechanical properties of the pure PVA film. Notably, the GTE-PVA biocomposite films presented better water vapor and UV–vis light barrier properties and higher mechanical strength than the pure PVA film. The antioxidant ability of the biocomposite films was evaluated by measuring the 2,2-diphenyl-1-picrylhydrazyl radical scavenging and ferric reducing power in terms of the total phenolic content. The GTE-PVA biocomposite films showed higher antioxidant activity than the pure PVA film, and the antioxidant activity increased with increasing GTE concentration. The color of the GTE-PVA biocomposite films became yellow when the pH was lower than 6 and became dark red when the pH was higher than 6. Moreover, color variations were observed in the GTE-PVA biocomposite films by changing the pH. These results suggest that GTE-PVA composite films may be used as a promising antioxidant and visible pH-sensing food packaging materials.
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•Active food packaging film was developed by GTE biomass compounded with PVA.•GTE-PVA films have better water vapor and UV barrier properties than pure PVA.•Mechanical properties of GTE-PVA films were improved with the content of GTE increased.•GTE-PVA films show antioxidant activity and pH-sensitive color change.
The removal of C. difficile inoculated on fresh spinach leaves washed with antimicrobial solutions was investigated. In addition, the effect of washing solutions on the total aerobic mesophilic ...bacteria (TAMB) and Enterobacteriaceae in the fresh spinach was examined. The fresh spinach was washed through immersion in different concentrations (MIC, 2xMIC, and 4xMIC) of the natural disinfectant solution (NDS) consisting of EDTA, borax, and epigallocatechin gallate (EGCG) content developed in our laboratory and green tea extract-acetic acid (GTE-AA) for varying contact times (5 and 15 min). Different concentrations (50, 100, and 200 ppm) of sodium hypochlorite (NaOCl) and tap water as the control group were used to compare the effectiveness of the NDS. In addition, the effects of washing on the color, texture, and total phenol content of the spinach were determined. No statistical difference was observed in the washing of the spinach leaves with NDS prepared at 2xMIC and 4xMIC concentrations, while inhibition of C. difficile ranged between 2.11 and 2.32 logs. The highest inhibition was observed in the application of 50 ppm NaOCl for 15 min with a decrease of 2.88 logs in C. difficile spores. The GTE-AA and NDS decreased the number of TAMB by 2.27–3.08 log and, 3.21–3.66 log, respectively. Washing spinach leaves with natural disinfectant for 5 min caused a decrease of 2.58 logs in Enterobacteriaceae load, while washing with 50 ppm NaOCl for 15 min reduced Enterobacteriaceae load by 4 logs. Tap water was ineffective in reducing any microbial load. No difference was detected in the color parameters of the spinach through all washes. Although all antimicrobial washes made a difference in the texture of the spinach, the greatest loss in firmness was observed in the spinach washed with NaOCl. Washing spinach with epigallocatechin-based wash solutions can remove C. difficile in possible C. difficile contamination, thereby reducing the environmental load of C. difficile. Epigallocatechin-based disinfectants can be an alternative to chlorine-based disinfectants in improving the microbial quality of vegetables.
•Tap water was not effective in reducing any microbial load in spinach.•The highest inhibition (2.88 logs) was observed in the application of 50 ppm NaOCl.•NDS may be a feasible alternative to chlorine (50 ppm).
In this green synthesis approach for copper oxide (CuO) nanoparticles (NPs), the reducing agent obtained from Camellia sinensis (Tea) extract was used. X-ray diffraction (XRD), Fourier transform ...infrared spectroscopy (FTIR), ultraviolet visible (UV-Vis) spectroscopy, field emission scanning electron microscope (FESEM) with energy-dispersive X-ray (EDX), high resolution transmission electron microscope (HRTEM) and Selected Area Electron Diffraction (SAED) techniques were used for as-prepared sample characterization. From XRD result, the crystallite size estimated by Scherrer method was found to be 35 nm. Morphological results reveals that the CuO NPs possesses small particle size with the range of 40–45 nm, led to high surface area, which enhances the absorption of more number of dye molecules, which results in high degradation efficiency. Present work reveals that degradation of malachite green (MG) dye in aqueous solutions under sonocatalytic treatment. CuO NPs exhibit excellent degradation efficiency against MG dye (95 % removal in 70 min). Moreover, the rate constant for the degradation efficiency was investigated with pseudo- first and second order kinetics. Moreover, CuO NPs possesses potential antibacterial activity against human pathogens such as Gram-positive (Staphylococcus pyogenes) and Gram-negative (Pseudomonas aeruginosa).
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•Copper Oxide nanoparticles (CuO NPs) were synthesized by facile green method.•Green synthesized CuO NPs was tested against the degradation of malachite green dye under sonocatalytic treatment.•The comparisons of different dye concentrations on three different catalyst dosage levels were studied.•CuO NPs possesses magnificent degradation efficiency for MG dye in 70 min sonication.•Moreover, the CuO NPs possesses potential antibacterial activity against human pathogens.
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•A novel EGCG/Fe2+/PDS process was proposed to oxidize organic contaminant.•EGCG accelerates the cycle of Fe(II)/Fe(III) and chelates with iron ions.•Generation of sulfate and ...hydroxyl radicals was verified in the system.•The addition of EGCG performs better than hydroxylamine and ascorbic acid.
A kind of green tea extract, epigallocatechin-3-gallate (EGCG) was introduced into Fe2+ activated persulfate (Fe2+/PS) system to enhance the degradation efficiency of atrazine. The involvement of EGCG improved atrazine degradation significantly in the pH range of 2.0–7.0, which could be interpreted by the strong reducing and chelating ability of EGCG. EGCG showed a better performance than hydroxylamine and ascorbic acid in modified Fe2+/PS systems, as the presence of EGCG could not only accelerate the transformation of Fe3+ to Fe2+, but prevent the formation of iron precipitation. Batch experiments were conducted and atrazine degradation depended upon the dosage of EGCG, persulfate, Fe2+, and other water quality parameters including initial pH, co-existing anions and natural organic matters. Radical quenching test and electron paramagnetic resonance (EPR) analysis were also performed and results showed that two kinds of radicals (sulfate radicals and hydroxyl radical) were verified to exist and play a significant role on atrazine degradation in the Fe2+/EGCG/PS system. Moreover, possible intermediates of atrazine were identified by HPLC/MS/MS and degradation pathways of atrazine and EGCG were proposed. This study aims to provide a comprehensive understanding on the potential application of EGCG to enhance degradation of refractory organics in water.
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•Green tea mediated synthesis of gold nanoparticles (GT-AuNPs) was successfully synthesized.•Various techniques were proposed to characterize the biosynthesized GT-AuNPs.•GT-AuNPs ...effectively exert their anti-proliferative action on the PC-3 cell line.
This study examines the biological synthesis of gold nanoparticles using Camellia sinensis L. (green tea) and their cytotoxicity against human PC-3 prostate cancer cells. The green tea extract-mediated biogenic synthesis of gold nanoparticles (GT-AuNPs) via green tea extract synthesis was validated using UV–vis spectroscopy, SEM, EDS, TEM, DLS, and XRD techniques. Additionally, the tetrazolium assay was utilized to investigate the anti-proliferative effect of GT-AuNPs generated by biosynthesis. The findings suggest that the biosynthesized GT-AuNPs reduced PC-3 cell proliferation with an IC50 of 19.71 g/mL during 24 h. These findings imply that GT-AuNPs exert their anti-proliferative action on the PC-3 cell line by inhibiting growth, decreasing DNA synthesis, and triggering apoptosis. After treatment, morphological examination of PC-3 cells exhibited surface detachment, cell shrinkage, and cell body distortion, indicating that GT-AuNPs had a cytotoxic effect on PC-3 cells.
