Designing, characterization, and evaluation of chitosan-zinc selenide nanoparticles for visible-light-induced degradation of tartrazine and sunset yellow dyes.

Employing dyes in different industrial sectors has produced a serious threat to the environment and living organisms of water bodies and land. For the decontamination of such toxic dyes, efforts have been made to develop an efficient, feasible, and low maintenance processes. In this context, chitosan-zinc selenide (CS-ZnSe) nanoparticles were prepared through chemical reduction method as the efficient photocatalysts for the decontamination of toxic dyes through photocatalysis. Photocatalyst's synthesis was confirmed with the help of FTIR spectroscopy. XRD indicated the hexagonal crystal structure of the CS-ZnSe with a crystallite size of 12 nm. SEM micrographs showed the average nano photocatalyst size as 25 nm. EDX analysis was employed to determine the elemental composition of the CS-ZnSe. An excellent photocatalytic degradation efficiency for tartrazine and sunset yellow dyes was obtained using CS-ZnSe. The results showed a 98% and 97% degradation efficiency for tartrazine dye and sunset yellow (SY) dye at optimized conditions of time (3 h), pH (5), dye concentration (30 ppm), catalyst dosage (0.09 g and 0.01 g) , and at a temperature of 35 °C. Findings of the photocatalytic degradation process fitted well with first-order kinetics for both the dyes. Rate constant, 'K' value was found to be 0.001362 min-1 and 0.001257 min-1 for tartrazine and SY dyes, respectively. While value for (correlation coefficient, R2) was 0.99307 and 0.99277 for tartrazine and sunset yellow dyes, respectively. Recyclability of the photocatalyst was confirmed using it for consecutive cycles to degrade organic dyes. Results showed that the CH-ZnS possesses excellent efficiency in decontaminating organic dyes from industrial wastewater.

An Electrochemical Sensor Based on Carbon Paper Modified with Graphite Powder for Sensitive Determination of Sunset Yellow and Tartrazine in Drinks.

The paper describes the development of an electrochemical sensor to be used for the determination of synthetic food colorants such as Sunset Yellow FCF (SY) and Tartrazine (TZ). The sensor is a carbon paper (CP) electrode, manufactured by using hot lamination technology and volume modified with fine-grained graphite powder (GrP). The sensor (GrP/CP) was characterized by scanning electron microscopy, energy dispersive spectrometry, electrochemical impedance analysis, cyclic, linear sweep and differential pulse voltammetry. The mechanism of SY and TZ electrochemical oxidation on GrP/CP was studied. The developed sensor has good electron transfer characteristics and low electron resistance, high sensitivity and selectivity. Applying the differential pulse mode, linear dynamic ranges of 0.005-1.0 µM and 0.02-7.5 µM with limits of detection of 0.78 nM and 8.2 nM for SY and TZ, respectively, were obtained. The sensor was used to detect SY and TZ in non-alcoholic and alcoholic drinks. The results obtained from drink analysis prove good reproducibility (RSD ≤ 0.072) and accuracy (recovery 96-104%).

Green Synthesis of Fluorescent Carbon Dots from Elaeagnus angustifolia and its Application as Tartrazine Sensor.

This article has introduced and examined a novel and green approach for the very first time, which had been developed for the synthesis of carbon dots (CDs) and performed through the utilization of Elaeagnus angustifolia (E. A) as a natural carbon source. This straightforward procedure has been based upon a hydrothermal treatment with a quantum yield of 16.8% that had been designed to synthesize water-soluble CDs in one step and result in a satisfying fluorescence. Additionally, we have attempted to assess the sensing system that had been exerted through the usage of CDs for the detection of food colorant tartrazine, since they can function as a fluorescent sensor due to the interplay that occurs among tartrazine and CDs leading to the quenching of their fluorescence. The detection limit has been measured to be equaled to 0.086 µM (86 nM) and the linear range has been observed to be 0.47-234 µM. The proposed highly sensitive and simple method has exhibited an excellent selectivity and proved to be effectively applicable for distinguishing the tartrazine of real samples.

Disposable Electrochemical Sensor for Food Colorants Detection by Reduced Graphene Oxide and Methionine Film Modified Screen Printed Carbon Electrode.

A facile synthesis of reduced graphene oxide (rGO) and methionine film modified screen printed carbon electrode (rGO-methionine/SPCE) was proposed as a disposable sensor for determination of food colorants including amaranth, tartrazine, sunset yellow, and carminic acid. The fabrication process can be achieved in only 2 steps including drop-casting of rGO and electropolymerization of poly(L-methionine) film on SPCE. Surface morphology of modified electrode was studied by scanning electron microscopy (SEM). This work showed a successfully developed novel disposable sensor for detection of all 4 dyes as food colorants. The electrochemical behavior of all 4 food colorants were investigated on modified electrodes. The rGO-methionine/SPCE significantly enhanced catalytic activity of all 4 dyes. The pH value and accumulation time were optimized to obtain optimal condition of each colorant. Differential pulse voltammetry (DPV) was used for determination, and two linear detection ranges were observed for each dye. Linear detection ranges were found from 1 to 10 and 10 to 100 µM for amaranth, 1 to 10 and 10 to 85 µM for tartrazine, 1 to 10 and 10 to 50 µM for sunset yellow, and 1 to 20 and 20 to 60 µM for carminic acid. The limit of detection (LOD) was calculated at 57, 41, 48, and 36 nM for amaranth, tartrazine, sunset yellow, and carminic acid, respectively. In addition, the modified sensor also demonstrated high tolerance to interference substances, good repeatability, and high performance for real sample analysis.

Curious Results in the Prospective Binding Interactions of the Food Additive Tartrazine with ß-Lactoglobulin.

The detailed characterizations of the binding interactions between food additive tartrazine (TZ) and ß-lactoglobulin (ß-LG) have been investigated through spectroscopic techniques combined with a molecular modeling study. A series of analyses, such as hyperchromic change in the UV-visible spectra, temperature-dependent quenching constant, time-resolved fluorescence, and Rayleigh scattering measurements, show that quenching of ß-LG proceeds by a static quenching mechanism. TZ specifically binds with ß-LG in a stoichiometry ratio of 1:1, and the observed binding constants (104, K) are 7.64, 9.13, 9.72, and 10.79 at 293, 298, 303, and 308 K, respectively. However, the curious results of binding constants (K) with temperature, encountered in the static quenching, have been well explained on the basis of Le Chatelier's principle. Thermodynamic data and pH-dependent studies along with the surface hydrophobicity binding displacement assay reveal that the durable mode of binding is chiefly entropy-driven, revealing noteworthy interactions of such ionic molecules with the hydrophobic part of ß-LG. The modulation of protein conformation has been investigated through steady-state absorption spectroscopy, synchronous emission spectroscopy, circular dichroism, and dynamic light scattering studies. TZ acts as a potential inhibitor in fibrillogenesis. Furthermore, the molecular docking study offers accurate insights about the binding of TZ with ß-LG, in consistence with the experimental results. This study would be helpful in pharmaceutical, food, and industrial engineering chemistry research.

Characterizing the noncovalent binding behavior of tartrazine to lysozyme: A combined spectroscopic and computational analysis.

Tartrazine is a stable water-soluble azo dye widely used as a food additive, which could pose potential threats to humans and the environment. In this paper, we evaluated the response mechanism between tartrazine and lysozyme under simulated conditions by means of biophysical methods, including multiple spectroscopic techniques, isothermal titration calorimetry (ITC), and molecular docking studies. From the multispectroscopic analysis, we found that tartrazine could effectively quench the intrinsic fluorescence of lysozyme to form a complex and lead to the conformational and microenvironmental changes of the enzyme. The ITC measurements suggested that the electrostatic forces played a major role in the binding of tartrazine to lysozyme with two binding sites. Finally, the molecular docking indicated that tartrazine had specific interactions with the residues of Trp108. The study provides an important insight within the binding mechanism of tartrazine to lysozyme in vitro.

Optimized adsorption onto biosolids-based activated carbon for tartrazine removal from wastewater.

This study investigates optimized tartrazine uptake by activated carbon prepared from biosolids (BBAC). Different tartrazine concentrations (10-20 mg/L), adsorbent dosages (1.0-2.0 g), pH (2.0-4.0), and contact times (60-120 min) were tested. These independent variables formed a 24 full factorial experiment arranged as central composite rotative design (CCRD). Response surface methodology (RSM) analyzed the responses of 50 experimental runs. Tartrazine removal efficiency fluctuated between 76.2% and 99.9%. The experimental data were best fitted by a quadratic model (R2  > 0.95, p > 0.0001). All variables exerted statistically significant (p < 0.05) effects on the tartrazine uptake (initial concentration, p = 0.0011; BBAC dosage, p = 0.0004; pH, p < 0.0001; contact time, p < 0.0001). Optimized tartrazine uptake efficiency of 97.4% can happen when variables mutually correlate at 10.1 mg/L of tartrazine concentration, 1.07 g of adsorbent dosage, 2.13 of pH, and 116.9 min of contact time. PRACTITIONER POINTS: Production of biosolids-based activated carbon (BBAC) is presented. Adsorptive affinity to tartrazine in aqueous solution was experimented. Experimental conditions optimized by Response Surface Methodology.

Visible light assisted Fenton oxidation of tartrazine using metal doped bismuth oxyhalides as novel photocatalysts.

This research focused on the abatement of the model food dye, tartrazine, using visible light photo-Fenton oxidation with novel bismuth oxyhalide catalysts. Bismuth-oxyhalide and metal doped bismuth oxyhalide catalysts (BiOCl, Cu-BiOCl, and Fe-BiOCl) were synthesized via the facile co-precipitation method. The catalysts were characterized by SEM-EDX, XRD, BET, and DRS analyses and the results showed that Cu-BiOCl possess a unique flower-like nanostructure with narrow band gap (2.53 eV) which enhanced its visible light photocatalytic activity remarkably which was proven by catalyst screening experiments. A detailed experimental study was carried out to investigate the effects of operating parameters on the degradation and decolorization of the dye and from this the optimum values were determined as 0.25 g/L for photocatalyst loading, 100 W for visible light power, 6 for initial pH, 6 mM for initial H2O2 concentration, and temperature of 70 °C. Approximately 91% degradation, 95% decolorization, and 59% TOC reduction were obtained at optimum conditions. The results for the kinetic study showed that the degradation and decolorization reactions are in the pseudo-first order and obey the simplified Langmuir-Hinselwood kinetic model. The activation energies were calculated as 86.54 and 69.39 kJ/mol for degradation and decolorization, respectively.

Oxidation of tartrazine with ultraviolet light emitting diodes: pH and duty cycles effects.

The presence of tartrazine (TAR) in the water cycle poses serious threats to human health. This study investigated the used of light emitting diodes (LEDs) in the advanced oxidation of TAR under different pH and duty cycle (DC) conditions. The first order reaction rate constant for TAR oxidation was positively correlated with DC, negatively correlated with pH, and typically greatest at pH 6. Chemical byproduct analysis indicated that OH addition, H abstraction, and electron transfer without molecule transfer were among the relevant reaction mechanisms for TAR degradation. Six byproducts were identified, four were reported for the first time, and two demonstrated that TAR rings were cleaved. This research is the first to determine the optimal pH for UVLED-driven oxidation of TAR and the first to identify new TAR-related byproducts from UVLED-based water treatment.

Advanced Oxidation of Tartrazine and Brilliant Blue with Pulsed Ultraviolet Light Emitting Diodes.

This study investigated the effect of ultraviolet light-emitting diodes (UVLEDs) coupled with hydrogen peroxide as an advanced oxidation process (AOP) for the degradation of two test chemicals. Brilliant Blue FCF consistently exhibited greater degradation than tartrazine, with 83% degradation after 300 minutes at the 100% duty cycle compared with only 17% degradation of tartrazine under the same conditions. These differences are attributable to the structural properties of the compounds. Duty cycle was positively correlated with the first-order rate constants (k) for both chemicals but, interestingly, negatively correlated with the normalized first-order rate constants (k/duty cycle). Synergistic effects of both hydraulic mixing and LED duty cycle were manifested as novel oscillations in the effluent contaminant concentration. Further, LED output and efficiency were dependent upon duty cycle and less efficient over time perhaps due to heating effects on semiconductor performance.

Experimental study and artificial neural network modeling of tartrazine removal by photocatalytic process under solar light.

This research focuses on the application of an artificial neural network (ANN) to predict the removal efficiency of tartrazine from simulated wastewater using a photocatalytic process under solar illumination. A program is developed in Matlab software to optimize the neural network architecture and select the suitable combination of training algorithm, activation function and hidden neurons number. The experimental results of a batch reactor operated under different conditions of pH, TiO2 concentration, initial organic pollutant concentration and solar radiation intensity are used to train, validate and test the networks. While negligible mineralization is demonstrated, the experimental results show that under sunlight irradiation, 85% of tartrazine is removed after 300 min using only 0.3 g/L of TiO2 powder. Therefore, irradiation time is prolonged and almost 66% of total organic carbon is reduced after 15 hours. ANN 5-8-1 with Bayesian regulation back-propagation algorithm and hyperbolic tangent sigmoid transfer function is found to be able to predict the response with high accuracy. In addition, the connection weights approach is used to assess the importance contribution of each input variable on the ANN model response. Among the five experimental parameters, the irradiation time has the greatest effect on the removal efficiency of tartrazine.

Photocatalytic degradation of tartrazine dye using CuO straw-sheaf-like nanostructures.

Straw-sheaf-like CuO nanostructures were fruitfully synthesized using a chemical precipitation approach for the photocatalytic degradation assessment of tartrazine. Phase identification, composition, and morphological outlook of prepared CuO nanostructures were established by X-ray diffraction and scanning electron microscopy analysis. The photocatalytic performance of the synthesized CuO nanostructures was appraised in the presence of visible light and the possible intermediates formed during the photocatalytic degradation were analyzed by gas chromatography-mass spectrometry. A suitable degradation pathway has also been proposed.

Quantitative assessment of photostability and photostabilisation of Fluvoxamine and its design for actinometry.

Despite the numerous concerns that have been raised in relation to considering 0(th), 1(st) and 2(nd)-order kinetic treatments for photodegradation characterisation and assessment of drugs, they still are employed, as they are the only tools available for these types of studies. The recently developed Φ-order kinetic models have opened new perspectives in the treatment of photoreaction kinetics and stand as the best known alternative to the classical approach. The Φ-order kinetics have been applied here to Fluvoxamine (Fluvo) with the aim of setting out a detailed and comprehensive procedure capable of rationalising photodegradation/photostability of drugs and proposing a platform for photosafety studies. Our results prove that quantum yields of drugs (0.0016 < Φ(λirr)(Fluvo) < 0.43) should a priori be considered wavelength-dependent; their photostabilisation (up to 75% for Fluvo) by means of absorption competitors can explicitly be related to a decrease of the photokinetic factor, and photoreversible drugs can be developed into efficient actinometers (as Fluvoxamine in the 260-290 nm range). A pseudo-rate-constant factor was proposed as a descriptive parameter, circumventing the limitations of overall rate-constants and allowing a comparison between kinetic data of drugs obtained under different conditions.

Chitinolytic Bacteria-Assisted Conversion of Squid Pen and Its Effect on Dyes and Pigments Adsorption.

The aim of this work was to produce chitosanase by fermenting from squid pen, and recover the fermented squid pen for dye removal by adsorption. One chitosanase induced from squid pen powder (SPP)-containing medium by Bacillus cereus TKU034 was purified in high purification fold (441) and high yield of activity recovery (51%) by ammonium sulfate precipitation and combined column chromatography. The SDS-PAGE results showed its molecular mass to be around 43 kDa. The TKU034 chitosanase used for the chitooligomers preparation was studied. The enzyme products revealed that the chitosanase could degrade chitosan with various degrees of polymerization, ranging from 3 to 9, as well as the chitosanase in an endolytic manner. Besides, the fermented SPP was recovered and displayed a better adsorption rate (up to 99.5%) for the disperse dyes (red, yellow, blue, and black) than the water-soluble food colorants, Allura Red AC (R40) and Tartrazine (Y4). The adsorbed R40 on the unfermented SPP and the fermented SPP was eluted by distilled water and 1 M NaOH to confirm the dye adsorption mechanism. The fermented SPP had a slightly higher adsorption capacity than the unfermented, and elution of the dye from the fermented SPP was easier than from the unfermented. The main dye adsorption mechanism of fermented SPP was physical adsorption, while the adsorption mechanism of unfermented SPP was chemical adsorption.

A probe to study the toxic interaction of tartrazine with bovine hemoglobin at the molecular level.

Tartrazine is an artificial azo dye commonly used in food products, but tartrazine in the environment is potentially harmful. The toxic interaction between tartrazine and bovine hemoglobin (BHb) was investigated using fluorescence, synchronous fluorescence, UV-vis absorption, circular dichroism (CD) and molecular modeling techniques under simulated physiological conditions. The fluorescence data showed that tartrazine can bind with BHb to form a complex. The binding process was a spontaneous molecular interaction, in which van der Waals' forces and hydrogen bonds played major roles. Molecular docking results showed that the hydrogen bonds exist between the oxygen atoms at position 31 of tartrazine and the nitrogen atom NZ7 on Lys99, and also between the oxygen atoms at position 15 of tartrazine and the nitrogen atom NZ7 on Lys104, Lys105. The results of UV-vis and CD spectra revealed that tartrazine led to conformational changes in BHb, including loosening of the skeleton structure and decreasing α helix in the secondary structure. The synchronous fluorescence experiment revealed that tartrazine binds into the hemoglobin central cavity, and this was verified using a molecular modeling study.

Photocatalytic degradation of an azo-dye on TiO2/activated carbon composite material.

A sequential adsorption/photocatalytic regeneration process to remove tartrazine, an azo-dye in aqueous solution, has been investigated. The aim ofthis work was to compare the effectiveness of an adsorbent/photocatalyst composite-TiO2 deposited onto activated carbon (AC) - and a simple mixture of powders of TiO2 and AC in same proportion. The composite was an innovative material as the photocatalyst, TiO2, was deposited on the porous surface ofa microporous-AC using metal-organic chemical vapour deposition in fluidized bed. The sequential process was composed of two-batch step cycles: every cycle alternated a step of adsorption and a step of photocatalytic oxidation under ultra-violet (365 nm), at 25 degreeC and atmospheric pressure. Both steps, adsorption and photocatalytic oxidation, have been investigated during four cycles. For both materials, the cumulated amounts adsorbed during four cycles corresponded to nearly twice the maximum adsorption capacities qmax proving the photocatalytic oxidation to regenerate the adsorbent. Concerning photocatalytic oxidation, the degree of mineralization was higher with the TiO2/AC composite: for each cycle, the value of the total organic carbon removal was 25% higher than that obtained with the mixture powder. These better photocatalytic performances involved better regeneration than higher adsorbed amounts for cycles 2, 3 and 4. Better performances with this promising material - TiO2 deposited onto AC - compared with TiO2 powder could be explained by the vicinity of photocatalytic and AC adsorption sites.

Spindle shaped Fe-Ni metal organic frameworks wrapped with f-MWCNTs for the efficacious sensing of tartrazine.

A facile hydrothermal route was employed for the synthesis of iron-nickel bimetal organic frameworks (Fe-Ni bi-MOFs) and composite with an acid functionalized multi-walled carbon nanotubes (Fe-Ni MOF/f-MWCNTs) for electrochemical detection of tartrazine. The as-prepared Fe-Ni MOF/f-MWCNTs was confirmed by the several physicochemical studies. A micro spindle shaped, highly porous, and crystalline Fe-Ni MOF/f-MWCNTs was noticed. The high sensitivity and stability of Fe-Ni MOF/f-MWCNTs/GCE modified electrode was analyzed. Due to its high porosity nature, the analyte molecule effectively gets adsorbed on the modified electrode and undergo electrochemical oxidation effectively. The modified electrode exhibits low limit of detection (LOD) and limit of quantification (LOQ) as 0.04 × 10-6 mol/L and 0.13 × 10-6 mol/L towards tartrazine. These results reveal the potential applications of Fe-Ni MOF/f-MWCNTs/GCE as modified electrode material for sensitive detection of tartrazine along with its robust reproducibility, stability, and effective sensing properties.

Novel composite from chitosan and a metal-organic framework for removal of tartrazine dye from aqueous solutions; adsorption isotherm, kinetic, and optimization using Box-Benkhen design.

Cosmetics, textiles, foodstuffs, and medicines frequently contain the yellow dye tartrazine. It has carcinogenic properties and can trigger allergies. In this study, a unique NH2-MIL-101(Cr)/chitosan composite (MIL/chitosan composite) was created using a hydrothermal process. The effectiveness of this composite in removing Tartrazine (TZ) from aqueous solutions was investigated. It was characterized via FT-IR, XPS, XRD, and BET analysis. The surface area of the MIL/chitosan nanoadsorbent sample was 1256.64 m2/g, where after five times recycling, it was reduced to 1068.14 m2/g. The study analyzed the impact of dye concentration, pH, temperature, and MIL/chitosan composite dosage. Experimental measurements were taken for the equilibrium isotherms of dye adsorption. The kinetic models and adsorption isotherm were used to analyze the results. The adsorption process was found to match Langmuir and pseudo-second-order kinetic models. Chemisorption was the mechanism of the adsorption process. Based on thermodynamic parameters, it was determined that the adsorption process was endothermic. The MIL/chitosan composite was recycled up to five cycles. Using the MIL/chitosan composite towards the adsorption of the tartrazine from the real sample has been checked. The interaction process between the MIL/chitosan nanoadsorbent and Tartrazine adsorbate has been investigated. The TZ electrical characteristics, reactivity, and shape were ascertained through the application of density functional theory (DFT). The placement of electrophilic and nucleophilic attack sites is in good agreement with the molecular orbitals (HOMO and LUMO) and MEP results, according to DFT. The optimization of adsorption results was accomplished using Box-Behnken design (BBD).

Microwave-enhanced UV/H2O2 degradation of an azo dye (tartrazine): optimization, colour removal, mineralization and ecotoxicity.

This study optimizes two factors, pH and initial [H2O2], in the ultraviolet (UV)/H2O2/microwave (MW) process through experimental design and assesses the effect of MWs on the colour removal of an azo-dye (tartrazine) solution that was favoured by an acidic pH. The estimated optimal conditions were: initial [H2O2] = 2.0 mmol L(-1) and pH = 2.6, at 30 +/- 2 degrees C. We obtained colour removals of approximately 92% in 24 min of irradiation (EDL, 244.2 W), following zero order kinetics: k = (3.9 +/- 0.52) x 10(-2) a.u. min(-1) and R2 = 0.989. Chemical and biological oxygen demand were significantly removed. On the other hand, the carbon content, biodegradability and ecotoxicity (Lactuca sativa) remained approximately the same. The UV/H2O2/MW process was shown to be eight times faster than other tested processes (MW, H2O2, H2O2/MW, and UV/MW).

Unveiling the tartrazine binding mode with ds-DNA by UV-visible spectroscopy, electrochemical, and QM/MM methods.

Here, we studied the interaction between the food colorant tartrazine (TZ) and double stranded DNA (dsDNA), using spectroscopic, electrochemical, and computational methods such as QM/MM combined with TD-DFT. Despite the UV-vis spectroscopy is widely used to study the interaction between molecules, for the case of TZ there are discrepancies in the analyses presented in the literature available, presenting both hyperchromic and hypochromic effects and consequently different rationalizations for their results. Herein we propose the combination of UV-vis experiments with the design of high-level computational models capable of reproducing the experimental behavior to finally define the proper binding mode at the molecular scale together with the rationalization of the experimental optical response due to the complex formation. To complement the UV-vis experiments, we propose the use of electrochemical measurements, to support the results obtained through UV-vis spectroscopy, as it has been successfully used for the determination of interaction modes between small molecules and biomolecules in any condition. Our UV-vis spectroscopy experiments showed only a hypochromic effect of the absorption spectra of TZ after interaction with DNA, indicative of TZ being deeply buried in the DNA structure. The effect of ionic strength in the experimental procedures led to the dissociation of TZ, thus indicating that the interaction mode was groove binding. On the other hand, the electrochemical studies showed an irreversible reduction peak of TZ, which after the interaction with DNA exhibited a positive shift in potential that can be attributed to groove binding. The binding constant for TZ-DNA was calculated as 4.45x104M-1 (UV-vis) and 5.75x104M-1 (electrochemistry), in line with other groove binder azo dyes. Finally, through the QM/MM calculations we found that the minor-groove binding mode interacting in zones rich in adenine and thymine was the model best suited to reproduce the experimental UV-vis response.