Treatment Of Citric Acid Research Articles

Design of Red Emissive Carbon Dots: Robust Performance for Analytical Applications in Pesticide Monitoring.

Synthesis of red emissive carbon dots (CDs) is highly desirable for sensing applications, as they still remain as bottlenecks in terms of precursor synthesis and product purification. Herein, we have designed a new strategy for realizing efficient red emissive CD optimal emission at 610 nm (fluorescence quantum yield ca. 24.0%) based on solvothermal treatment of citric acid and thiourea using dimethylformamide as solvent. Further investigations reveal that the conjugating sp2-domain controlling the incorporation of nitrogen and surface engineering are mainly responsible for the obtained red emission of CDs. Taking advantage of optical properties and abundant surface functional groups, CDs were considered to facilely construct a ratiometric fluorescent platform for quantifying trace levels of organophosphorus pesticides (OPs). Combining the acetylcholinesterase-mediated polymerization of dopamine and the inhibition of pesticide toward the enzyme, the degree of polymerization of dopamine rationally depends on the concentration of OPs. By measuring the fluorescence intensity ratio, the proposed platform exhibited highly selective and robust performance toward OPs, displaying ultrasensitive recognition in the pg L-1 level. The multiexcitation format could efficiently shield background interference from complex samples by introducing a self-calibrated reference signal, which affords accurate and reliable quantitative information, endowing CDs as a universal candidate for a biosensing application by combining target-specific recognition elements.

Dual roles of a transparent polymer film containing dispersed N-doped carbon dots: A high-efficiency blue light converter and UV screen

We report the synthesis of a transparent plastic material with very high performance ultraviolet (UV)-blocking and blue-light (440 nm) emission. Polyvinyl alcohol (PVA) was employed as a transparent plastic matrix that disperses N-doped carbon dots (N-CDs) prepared via hydrothermal treatment of citric acid, ethylene diamine, and HCl solution. Luminescence of these N-CDs is excitation-independent and the quantum yield (QY) is maximal at an excitation wavelength range of 350–370 nm, in the UV-A radiation segment of the solar spectrum. By encapsulating N-CDs in a polyvinyl alcohol (PVA) matrix, the absolute QY achieves 91%, which is higher than in aqueous solution. As the particle concentration increases in PVA matrix or in solution, UV absorbance increases and QY decreases. On the other hand, UV absorbance of the film is proportional to thickness with no appreciable deterioration in QY, a quality that is beneficial for UV light absorption as well as conversion into blue light. We propose that this N-CD/PVA composite is an ideal transparent plastic for UV-ray shielding, as well as being useful for blue light emission, composed only of eco-friendly nontoxic elements. The high UV absorption and strong luminescence of N-CDs are beneficial also for other applications that include anti-counterfeiting (secret inks) and greenhouse sheathing that simultaneously blocks UV-rays while generating blue light to promote plant growth.

HNO2 treatment of sludge: An alternative way of sludge usage as fertilizer

The research was conducted to evaluate the sludge quality as fertilizer after heavy metal removal by using free nitrous acid (FNA, HNO2) solution. To meet up the Korean criteria of fertilizer, FNA treatment with the ultrasonic process was studied here. The sample was taken from a local wastewater and sewage treatment plants and FNA with FNA plus ultrasonic used to treat them. As and Cd concentrations were met the Korean criteria after FNA treatment. In contrast, Al of sludge from sewage treatment plant did not decrease down to the criteria, possibly suggesting that it may be related to the coagulants of the sludge during thickening and dewatering. FNA treatment showed satisfactory results in comparison with the other acidic treatment of citric acid, oxalic acid, HNO3 or HCl. Removal efficiency of the Fenton-like reaction was more effective than the FNA method. Despite this result, the FNA treatment may be better for sludge recycling as fertilizer because the Fenton-like process removed the necessary organic matter, nitrogen as well as metals. Moreover, the addition of ultrasound process has in conserving time and expenditure in metal removal and FNA with ultrasound became more effective in shorter reaction time. Therefore, FNA treated sludge could be a better option for sludge recycling as fertilizer. In conclusion, a proper plan of sludge management should be required for future work to use sludge as fertilizer.

The Ability of Red Fountain Grass to Grow in Cadmium-Contaminated Soil

A pot experiment was conducted during two successive seasons 2017 and 2018 at experimental farm of Faculty of Agriculture, Cairo University, Giza, Egypt. The aim of this study is to determine the ability of Pennisetum setaceum cv. rubrum plant to grow in cadmium (Cd) contaminated soil (100 mg/kg). Also, investigate the effect of citric acid application (1 and 2 mmol/kg) on phyto-extraction of cadmium-contaminated soil. The results clarified that the presence of cadmium (100 mg/kg) in the soil caused low reduction in the herb growth compared to unpolluted soil. The reduction rates in both seasons were 20.33 and 26.47% for herb fresh weight, 5.08 and 14.79% for herb dry weight, 8.86 and 0.0% for number of inflorescences/plant, respectively. The treatment of citric acid 1 mmol/kg increased the Cd content 149.3, 137.5% in the herb, and 221.25, and 170.81% within plant root in both seasons, respectively compared to the control. Also, such treatment raised phenols content in the herb to 102.3 and 93.0% compared to control plants in both seasons, respectively. The results showed that translocation factor (TF) was bigger than one which means that the plants had accumulated the cadmium in their tissues; however the plant tolerated Cd-contaminated soil accompanied with high content in both phenols and catalase enzyme activity. It could be concluded that P. setaceum cv. rubrum is a promising plant for phytoremediation.

Hg2+ detection, pH sensing and cell imaging based on bright blue-fluorescent N-doped carbon dots.

A multifunctional sensing platform based on bright blue-fluorescent nitrogen-doped carbon dots (N-CDs) has been ingeniously designed for the sensitive determination of Hg2+ and pH. The N-CDs were facilely fabricated via a one-step hydrothermal treatment of citric acid and folic acid with admirable merits including exceptional stability, low toxicity and distinguished biocompatibility. Intriguingly, the obtained N-CDs can be utilized to detect Hg2+ on the basis of the dynamic quenching effect, showing a linear range of 0 μM-400 μM as well as a detection limit of 0.124 μM. In addition, the obtained N-CDs revealed a significant emission enhancement with increasing pH from 4.0 to 10.0 and acquired a good linearity in the pH range of 6.8-7.8. Taking advantage of efficient analysis of Hg2+ and pH in aqueous solution, the as-synthesized N-CDs have been extended to the visualization biosensing platform to timely track Hg2+ and pH in living cells.

<p>Doxorubicin-Loaded Carbon Dots Lipid-Coated Calcium Phosphate Nanoparticles for Visual Targeted Delivery and Therapy of Tumor</p>

BackgroundCarbon dots (CDs) have attracted extensive attention in recent years because of their high biocompatibility and unique optical property. But they could not be well applied in the drug delivery system to enable distribution in tumor sites with their low pH sensitivity. They are barriers for drug delivery. CDs as an imaging proper were conjugated with doxorubicin (DOX) lipid-coated calcium phosphate (LCP) nanoparticle, for a pH-sensitive nanocarrier and delivery of the antitumor drugs.Materials and MethodsCDs were prepared by one-step hydrothermal treatment of citric acid and ethylenediamine. The nanoparticles were simply prepared by using microemulsion technology to form calcium phosphate (CaP) core and further coated with cationic lipids.ResultsThe structure was characterized by FTIR, XRD and TEM. In vitro release study revealed that DOX-CDs@LCP was pH dependent. The cytotoxicity assay demonstrated that it exhibited enhanced efficiency compared to the control group (DOX-CDs), but weaker than free DOX. The cellular uptake revealed that these pH-sensitive nanoparticles could be taken up effectively and deliver DOX into the cytoplasm to reach antitumor effect. The fluorescence imaging indicated that DOX-CDs@LCP mostly distributed in the tumor region due to the enhanced permeability and retention effect (EPR) to reduce its systematical toxicity. Importantly, an antitumor activity study demonstrated that the DOX-CDs@LCP nanoparticles had higher antitumor activity than any other groups and lower toxicity. The results showed that LCP could significantly promote the release in tumor microenvironment due to pH-response. The DOX-CDs could enhance load capacity and reduce drug premature releasing; real-time tracking of efficacy as confocal imaging contrast agent. Thus, DOX-CDs@LCP had antitumor capacity and lower systematic toxicity in tumor therapy.ConclusionDOX-CDs@LCP were proven as a promising tumor pH-sensitive and imaging-guided drug delivery system for liver cancer chemotherapy.

Intracellular pH-propelled assembly of smart carbon nanodots and selective photothermal therapy for cancer cells

A kind of smart carbon nanodots (CNDs) with the pH response feature was prepared by the one-pot hydrothermal treatment of citric acid and dicyandiamide, which was used for the differentiation of cancer/normal cells and the selective photothermal therapy (PTT) of cancer cells. When the smart CNDs were cultured with cells, they were highly internalized in the lysosomes of cells. Since the small-sized CNDs (about 5 nm) tends to form aggregation (as large as about 20 nm or even larger) under an acid condition (pH = 4.7) due to the electrostatic attraction produced by the surface protonation, relatively severer aggregation of the CNDs were observed in liver cancer cells (HepG2 cells) relative to normal ones (LO2 cells) due to a relative lower pH in the lysosomes of HepG2 cells, which endows them a new strong absorption band at longer wavelengths (450−900 nm) and a higher photothermal conversion efficiency (42.13 %), benefiting to differentiated PTT. The flow cytometric data indicates strong photothermal ablation (8 min, 509.6 mW/cm2) for cancer cells with the assistance of these smart CNDs achieves 82 % death rate of cancer cells, while much less damage is observed on the normal cells (6.35 %). To the best of our knowledge, this is the first report about CNDs for selective PTT owing to their intrinsic property without the aid of any other targeting ligands. These smart CNDs are also available for other acid-responsive sensing systems, and this study inspires us in the synthesis of near-infrared featured carbon materials.

Multicolor carbon dots with concentration-tunable fluorescence and solvent-affected aggregation states for white light-emitting diodes

Multicolor emissive carbon dots (M-CDs) have tremendous potential applications in manifold fields of bioimaging, biomedicine and light-emitting devices. Until now, it is still difficult to produce fluorescence tunable CDs with high quantum yield across the entire visible spectra. In this work, a type of M-CDs with concentration-tunable fluorescence and solvent-affected aggregation states was synthesized by solvothermal treatment of citric acid (CA) and 1-(2-pyridylazo)-2-naphthol (PAN) and the formation mechanism was monitored by different reaction time and raw material ratio. The fluorescence spectra of M-CDs in organic solvents can range from 350 to 750 nm by adjusting the concentration. M-CDs possess different aggregation states in water and organic solvents, accompanied by different fluorescence emission, which is attributed to the different surface states of various component CDs in M-CDs. Moreover, the obtained products can be uniformly dispersed into polymethylmethacrylate (PMMA) solutions as well as epoxy resins to fabricate transparent CDs/PMMA films and CDs/epoxy composites, which can effectively prevent the aggregation and produce multicolor and white light-emitting diodes (WLED). In addition, the prepared WLED with Commission Internationale de L’Eclairage (CIE) of (0.29, 0.31) by using M-CDs/epoxy resin as packages, demonstrating the M-CDs exhibit potential applications for light-emitting devices.

Highly luminescent carbon dots as temperature sensors and “off-on” sensing of Hg2+ and biothiols

Here, Carbon dots (CDs) were fabricated through a simple one-step hydrothermal treatment of N-aminoethylpiperazine (AEP) and citric acid (CA). The as-prepared CDs have a bright blue emission with a quantum yield of 56%, with good water solubility, light stability and temperature sensitivity. In addition, the photoluminescence of the CDs deriving from two components was experimentally verified: one is amide molecules resulting from the reaction between AEP and CA, and the other is the carbon nucleus coming from the precursors at high temperatures. More importantly, the fluorescence intensity of the CDs is temperature-dependent, and decreasing linearly from 25 °C to 95 °C, with excellent sensitivity and recoverability. A CD/epoxy composite was prepared by doping the CDs into an epoxy resin, which exhibits superior temperature response that may be caused by the greater dielectric constant of epoxy resin. In addition, the fluorescence of the CDs can be efficiently quenched by Hg2+, and the addition of biothiols restore the quenched fluorescence of CDs. The sensor was applied to detect ions in river water and tap water and satisfied results were achieved.

Branched polyethyleneimine modified carbon nanoparticles as the effective additives of water lubrication

Branched polyethyleneimine (PEI) modified carbon nanoparticles (CNPs-PEI) with an average particle size of 20.1 nm were facile synthesized by hydrothermal treatment of citric acid and PEI. The PEI and oxygen-containing groups on CNPs-PEI endowed them with excellent dispersion stability in water. The tribological properties of CNPs-PEI as the water-based additives were evaluated under the four-ball mode, steel/steel contact and fixed load of 40 N by varying additive concentration. Amazingly, adding only 0.15 wt% of CNPs-PEI made the mean friction coefficient and wear volume of base liquid reduced by 53.4% and 94.9%, respectively, reflecting that the CNPs-PEI could be an effective additive of water lubrication. The wear scar surface analyses indicated that CNPs-PEI as additives promoted the formation of boundary lubrication films on the rubbing surfaces by mending and depositing effects, directly accounting for the distinguished friction-reducing, antiwear and oxidation resistance properties of CNPs-PEI.

Citric acid as soil amendment in cadmium removal by Salix viminalis L., alterations on biometric attributes and photosynthesis

During the past decade, the target in cleaning polluted sites is an application of chelating agents, such as citric acid (CA), which is proposed as a good candidate in the promotion of phytoremediation. Among heavy metals, cadmium (Cd) is one of the most common and dangerous elements, which strongly disturbs morphophysiological properties in plants. A pot experiment was assessed to evaluate the influence of CA in Cd phytoremediation in alkaline soil by Salix viminalis (clone SV068). The effects of CA on Cd bioavailability, mobility, and distribution in plants, various morphometric measurements, and physiological performances as photosynthesis, transpiration, water use efficiency, and pigment content were tested. The highest Cd accumulation was evident after 60 days of growing, in plants subjected to combined treatment of CA with a higher dose of Cd. Application of CA showed a beneficial effect in maintaining the photosynthetic rate as well as gas exchange capacity in willows grown in Cd-contaminated soil. Furthermore, CA slightly increased plant growth and biomass production, depending on applied Cd dose and harvest period. A chelating agent like CA showed strong influence in plant response to combat Cd toxicity.

A facile hydrothermal method for preparation of fluorescent carbon dots on application of Fe3+ and fingerprint detection

The carbon dots (CDs) was prepared by a facile hydrothermal treatment of citric acid and glycine at 180 °C. The CDs at around 3.2 nm was collected after filtration and dialysis. The sample displayed green fluorescence (G-CDs) with a quantum yield of 3.7% in high concentration and the strongest emission peak was at 545 nm under the excitation wavelength of 480 nm; the blue fluorescence CDs (B-CDs) with a quantum yield of 29.8% was obtained after diluted either in solution or in powder, the strongest emission peak was located at 475 nm under the excitation wavelength of 380 nm. The G-CDs possessed a high selectivity to Fe3+, which was in a linear range of 0–3.5 μM with the detection limit of 0.21 μM. The CDs powder with blue fluorescence at a relative low content was obtained and adaptable for the fingerprint detection on substrates of litmus paper, resin tabletop, glass, and orange plastic ruler.

Effect of Dealumination of Citric Acid-Modified Hβ Molecular Sieve on Hydroisomerization Performance of n-Hexadecane

Hβ molecular sieves with SiO2/Al2O3 ratio of 40 were modified by citric acid dealumination (Hβ-Cn) and Hβ-Cn loading Pd (0.5 wt%) bifunctional catalysts(Pd/Hβ-Cn) were prepared by hydrothermal synthesis and incipient wetness impregnation. The structure, morphology, pore and acid properties of Hβ-Cn and Pd dispersion of Pd/Hβ-Cn were characterized using XRD, SEM, N2 physical adsorption, NH3-TPD and H2 chemical absorption. The skeleton structure of all Hβ-Cn was not damaged and their relative crystallinity increased somewhat after the treatment of citric acid. With the increase of citric acid concentration, the change of morphology,structure and pore properties of Hβ-Cn was very little, but the amount of weak acid, strong acid and total acid of Hβ-Cn, and Pd dispersion for Pd/Hβ-Cn decreased significantly. It was known from hydroisomerization perforamce of n-C16H34 that the hydroisomerization reaction temperature over Pd/Hp-Cn slightly rises under the condition of the same conversion of n-C16H34, but the amount of multi-branched iso-C16H34 over Pd/Hβ-Cn, especially Pd/Hβ-C2 (60.51%) and Pd/Hβ-C3 (57.84%) was much higher than that over Pd/Hβ (36.99%). This could be due to the remove of partial skeleton aluminum species with strong acid sites to effectively inhibit the further cracking of the muti-branched isomerized products.

Photoluminescence measurements of carbon quantum dots within three-dimensional hydrogel matrices using a high throughput 96 well plate method

Solid or liquid platforms have been traditionally employed for measuring the fluorescent properties of quantum carbon dots (QCD). Hydrogels possess both liquid and solid properties which allow them to overcome several shortfalls of both solid and liquid sensing platforms. Hydrogels offer a three dimensional platform which can house nanoparticles with different attributes (i.e. fluorescent QCD’s) and prevents their aggregation. Here, we incorporate QCD’s (made from the hydrothermal treatment of 1-naphthylamine and citric acid) into the matrix of a zinc oxide hydrogel. This nanocomposite was shown to have hexavalent chromium (Cr6+) specific fluorescence quenching properties. Detailed fluorescence analysis of the hydrogel with Cr6+ was conducted in a high throughput manner by loading the hydrogel into wells of a black 96-well plate. Fluorescence quenching of the hydrogel-QCD-nanocomposites in the presence of dilutions of Cr6+ was measured using a fluorescence spectrophotometer and showed incremental fluorescence decreases with increasing Cr6+ concentration. Furthermore, this was quantitatively confirmed by Stern–Volmer plots showing a linear quenching trend (R2 = 0.9975) when comparing fluorescence intensities against increasing Cr6+ concentrations (0.234–1.875 μM). This technology can be applied for routine water quality testing in agricultural, natural and potable water sources for the early detection of heavy metal pollutants.

Effect of citric acid and sucrose concentration on the quality of passion fruit jelly with dutch eggplant

The effect of citric acid and sucrose concentration on the quality of passion fruit jelly (Passiflora edulis) with dutch eggplant (Solanum betaceum) was aimed to determine the effect of citric acid and sucrose concentration on the quality of passion fruit jelly with dutch eggplant. This study used a completely randomized factorial design, with a comparison of citric acid concentration with dutch passion fruit and eggplant juice, which consisted of 2 factors: the ratio of citric acid concentration to passion fruit and dutch eggplant, and the second factor was the ratio of sucrose concentration. The results showed that the higher the concentration of citric acid, the water content, total acid, vitamin C levels and organoleptic values increased, while ph decreased. the higher the concentration of sucrose, the water content, total acid, vitamin C levels and organoleptic values increase, while ph decreases. the combination treatment of citric acid and sucrose concentration had a very significant effect on pH and organoleptic value, but the effect was not significant on water content, vitamin C content and total passion fruit passion fruit with dutch eggplant.

Hydrothermal synthesis of nitrogen and boron co-doped carbon quantum dots for application in acetone and dopamine sensors and multicolor cellular imaging

Nitrogen and boron co-doped carbon quantum dots (NB-CQDs) were prepared via one-pot hydrothermal treatment of citric acid, borax, and p-phenylenediamine.The synthesized NB-CQDs were characterized by transmission electron microscopy, Fourier-transform infrared spectra, X-ray photoelectron spectra, dynamic light scattering, ultraviolet-visible absorption and fluorescence spectra to characterize their surface morphology, crystal structure, functional groups and elemental composition, and optical properties. It was found that N and B species were efficiently doped into the carbon framework of the dots, the N- and B-Containing groups formed on the surface of NB-CQDs during the hydrothermal reaction. The element doping and surface functionalization of NB-CQDs efficiently modulated their physicochemical properties. The NB-CQDs were nearly mono-disperse with an average particle diameter of 3.53 nm, and the excitation/emission wavelengths were 360/490 nm, respectively. The NB-CQDs showed regular photoluminescence (PL) emission under different excitation wavelengths, and possessed pH-dependent and solvent polarity-dependent PL properties. In addition, the NB-CQDs and a NB-CQD/poly(vinyl alcohol) composite film showed good PL responses to acetone solution and vapor. A PL sensor for the determination of acetone solution with a limit of detection (LOD) of 0.54 μM (R2 = 0.9956) was then designed. The NB-CQDs were also used for the determination of dopamine. The PL intensity of the NB-CQDs was inversely proportional to the concentration of dopamine in the range of 0.1–70 μM (R2 = 0.9958). The LOD of dopamine was 11 nM, and PL quenching occurred via a static quenching mechanism. Additionally, these NB-CQDs can be used for multicolor cellular imaging and showed good uptake by Hepg2 cells.

Dual-channel fluorescence detection of mercuric (II) and glutathione by down- and up-conversion fluorescence carbon dots

The fluorescent carbon dots (CDs) with high fluorescent quantum yield (φf = 62%) and down- and up-conversion fluorescence properties were synthesized by one-pot hydrothermal treatment of citric acid and tris(hydroxymethyl)methyl aminomethane. The CDs displayed the capability to absorb excitation wavelength at 660 nm and 330 nm with fluorescence emission wavelength at 398 nm and 399 nm, respectively. The CDs showed high selectivity towards Hg2+ against various metal ions. Around 70% fluorescence was quenched by 40 μM Hg2+ through dynamic and static quenching mechanisms. Because of stronger affinity between the thiol and Hg2+, over 90% fluorescence was recovered by adding 40 μM glutathione to CDs-Hg2+ system. The calibration curves exhibited wide linear region for Hg2+ (0–4 μM) and glutathione (0–30 μM). The limits of detection with down- and up-conversion for Hg2+ were calculated to be 0.23 μM and 0.25 μM, and for glutathione were 0.28 μM and 0.29 μM, respectively. Inspired by the sensing results, logic gates with Hg2+ and glutathione as inputs were also established. Most importantly, this method was applied to detect Hg2+ and glutathione in tap water and lake water, and the recovery values were obtained to be 96.2%–110.4% and 93.4%–96.9%.

Application of Different Organic Acids on Phosphorus Solubility from Rock Phosphate

An incubation experiment was conducted on P solubilization from rock phosphate (RP) through different organic acids such as oxalic acid, citric acid, acetic acid, humic acid and sulphur in the laboratory of the Department of Soil and Environmental Sciences, KP Agricultural University Peshawar during fall 2011. The experiment was laid in a complete randomize design. There were three replications with six treatments. The organic acids were used at the rate of 2 % for 50 g RP in 250 ml conical flasks. These samples were kept in an incubator at 250c for four months and analysed for Mehlic-3 extractable P and pH values after 20 days interval. Statiscal analyses were made and maximum P concentration of 1.52% was observed in the treatment of oxalic acid mixed with RP followed by the treatments of RP mixed with humic acid with P concentration of 0.368% (Fig. 1). Rapid increases in P solubility from RP by mixing with oxalic acids were noted up to 60thdays of incubation period and then remained stable after this period. Solubilization of P from RP by mixing with other organic acids was inconsistent. The pH in treatment of citric acid mixed with RP was noted as 5.64, followed by the treatments of oxalic acid with pH values of 6.31. A dramatic increase in pH value of 9.33 was observed in the treatment of RP mixed with humic acid. It is because the humic acid contains sodium salt and sodium hummate causes increase in its pH values.

Aplicación de ácido cítrico incrementa la calidad y capacidad antioxidante de germinados de lenteja

El contenido de compuestos antioxidantes en germinados de lenteja se relaciona con la prevención y el tratamiento de enfermedades degenerativas. Este tipo de compuestos podrían incrementarse por la aplicación de elicitores como el ácido cítrico, el cual promueve la sintésis de compuestos derivados de los fenilpropanoides y activa cascada de señalización que incrementan la actividad antioxidante. El objetivo de la presente investigación fue evaluar el efecto de la aplicación por aspersión de ácido cítrico (0, 10-2, 10-3, 10-4 y 10-5 M) en el contenido de compuestos fenólicos totales, flavonoides totales, capacidad antioxidante total de germinados de lenteja. Se utilizó un diseño completamente al azar con seis repeticiones de tratamiento. Los resultados mostraron que el ácido cítrico incremento significativamente los compuestos fenólicos y flavonoides totales. El valor más alto de compuestos fenólicos y flavonoides se obtuvo con el tratamiento 10-2 M de ácido cítrico con 185.5, 150 mg 100 g-1 peso fresco respectivamente. Igualmente, la capacidad antioxidante fue mayor con el mismo tratamiento (10-2 M), lo cual concuerda con los resultados de correlación obtenidos que indican que la capacidad antioxidante se debe en 86 y 78% a los compuestos fenólicos y flavonoides, respectivamente. Se concluye que la aplicación de concentraciones molares de moléculas inductoras del metabolismo secundario durante la etapa de desarrollo de germinados es un método útil y efectivo para estimular la biosíntesis de fitoquímicos bioactivos y mejorar la capacidad antioxidante de este tipo de alimento.

Facile microwave assisted synthesis of N-rich carbon quantum dots/dual-phase TiO2 heterostructured nanocomposites with high activity in CO2 photoreduction

In this work, several efficient heterostructured nanocomposites with enhanced CO2 photoreduction activity were successfully constructed by anchoring carbon quantum dots onto TiO2 using a facile microwave assisted synthesis strategy. The carbon quantum dots obtained by microwave treatment of thiourea and citric acid acted as a sensitizer in the composites to enhance light absorption. The high-resolution transmission electron microscopy (HR-TEM) revealed that a closely integrated interface between carbon quantum dots and TiO2 nanosheets was formed in the heterostructured nanocomposites. Furthermore, the photogenerated charge transfer and separation in the heterogeneous nanocomposites were demonstrated to be significantly improved when compared with that in pristine TiO2. Consequently, a remarkable enhancement of photocatalytic activity evaluated for CO2 photoreduction under simulated solar light irradiation can be found in the nanocomposites. Maximum CH4 and CO yields of 0.769 and 1.153 μmol, respectively, have been obtained from the photoreduction after one hour irradiation without any noble metal loaded on photocatalyst. The amounts of CH4 and CO generated over nanocoposite are 7.79 and 7.61 times as high as those on pristine TiO2. This encouraging performance in CO2 photoreduction shows that these nanocomposites might be a prospective material in environmental protection and energy conversion.