•A novel ion pairing between IC and N@C-dots was proposed for the first time.•The interaction resulted in cyan blue color and quenching of N@C-dots fluorescence.•The nanoprobe exhibited good ...sensitivity and selectivity towards IC.•The application of nanoprobe was extended for analysis of IC in beverages.
Indigo carmine (IC) dye is hazardous and allergenic for humans even though it has been excessively used in a wide range of industries. Therefore, the quantitative determination of IC is still challenging. Herein, for the first time, we have developed fluorometric and colorimetric dual-mode nanoprobe derived from the ion-pair association complex between the negatively charged IC and positively charged N@C-dots in pH = 3.0. Consequently, the binding between N@C-dots and IC resulted in cyan blue and quenching of N@C-dots fluorescence. The dependence of the fluorescence response on IC concentrations was linear over the range of 0.73–10.0 µM (R2 = 0.9989) with LOD of 0.24 µM. On the other hand, the linearity of the colorimetric method ranged from 9.97 to 80.0 µM (R2 = 0.9986) with LOD of 3.3 µM. The sensor was applied for estimation of IC in fruit juice and soft drink without the need for exhaustive extraction steps.
Ternary heterostructure nanotubes of In2S3-CdIn2S4@X(X = Ag, Ag3PO4, AgI) were synthesized with enhanced photocatalytic activity for efficiently degrading pollutants. Electron beam irradiation was ...employed to artificially introduce interface defects to the heterostructure nanotubes. The experimental results for degrading carmine and Cr6+ under visible light irradiation showed that the photocatalytic efficiency of In2S3-CdIn2S4 was improved to some extent by the introduction of silver compounds. DRS results confirmed that the band gaps of In2S3-CdIn2S4 were reduced to 1.62 eV and 1.58 eV by introducing Ag3PO4 and AgI, respectively. Interestingly, the band gap of In2S3-CdIn2S4@AgI after electron beam irradiation was further reduced to 1.56 eV, resulting in that the degradation time of both Cr6+ and carmine by In2S3-CdIn2S4@AgI after high-energy electron beam irradiation was shortened to only 5 min. The XRD spectra of the photocatalysts after five cycles could maintain the original crystal form to a large extent. The OH stretching vibration peaks of In2S3-CdIn2S4@AgI after electron beam irradiation at 3387 cm−1 became wider and sharper, thus indicating that the number of free hydroxyl groups on the heterostructure surface significantly increased. PL results showed that electron beam irradiation could significantly reduce the PL emission peak and enhance the utilization of photogenerated charge carriers. EIS results further confirmed that In2S3-CdIn2S4@AgI processed by electron beam irradiation had higher photogenerated electron-hole separation efficiency. Based on the experimental results, a feasible reaction pathway and photocatalytic mechanism for the degradation of carmine was investigated. ESR results showed that the main active groups in the whole photocatalytic system were •O2– and h+.
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•In2S3-CdIn2S4@(Ag, Ag3PO4, AgI) ternary heterostructure nanotube was synthesized.•Silver compounds could greatly enhance the photostability of In2S3-CdIn2S4.•Its narrow band gap could effectively promote carrier separation and migration.•Electron beam irradiation could introduce interface defects to the material.•The treated material possessed enhanced photocatalytic activity for Cr6+ and P-4R.
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•A simple, cost effective and green method was developed for determination of carmine.•This is the first report which uses the CPE for extraction of carmine in real samples.•The ...results demonstrate the method performance to determine the carmine in food samples.
In this paper, a simple and cost effective method was developed for extraction and pre-concentration of carmine in food samples by using cloud point extraction (CPE) prior to its spectrophotometric determination. Carmine was extracted from aqueous solution using Triton X-100 as extracting solvent. The effects of main parameters such as solution pH, surfactant and salt concentrations, incubation time and temperature were investigated and optimized. Calibration graph was linear in the range of 0.04–5.0μgmL−1 of carmine in the initial solution with regression coefficient of 0.9995. The limit of detection (LOD) and limit of quantification were 0.012 and 0.04μgmL−1, respectively. Relative standard deviation (RSD) at low concentration level (0.05μgmL−1) of carmine was 4.8% (n=7). Recovery values in different concentration levels were in the range of 93.7–105.8%. The obtained results demonstrate the proposed method can be applied satisfactory to determine the carmine in food samples.
The bioremediation and electro-oxidation (EO) processes are included among the most promising cleaning and decontamination mechanisms of water. The efficiency of bioremediation is dictated by the ...biological actuator for a specific substrate, its suitable immobilization and all involved biochemical concepts. The EO performance is defined by the anode efficiency to perform the complete mineralization of target compounds and is highlighted by the low or null use of reagent. Recently, the combination of both technologies has been proposed. Thus, the development of high efficient, low cost and eco-friendly anodes for sustainable EO, as well as, supporting devices for immobilization of biological systems applied in bioremediation is an open field of research. Therefore, the aim of this work was to promote the bio-electrochemical remediation of indigo carmine dye (widely common in textile industry), using new anode based on a microporous activated carbon fiber felt (ACFF) and ACFF with immobilized Laccase (Lcc) from Pycnoporus sanguineus. The results were discolorations of 62.7% with ACFF anode and 83.60% with ACFF-MANAE-Lcc anode, both for 60 min in tap water. This remediation rates show that this new anode has low cost and efficiency in the degradation of indigo dye and can be applied for other organic pollutant.
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•The combination of biochemical and electrochemical oxidation processes is proposed.•An activated carbon fiber felt is used with dual function of anode and bioreactor.•The efficiency of isolated and combined technologies is compared.
A continuous mode fixed-bed up-flow column adsorption analysis was conducted utilizing Acacia nilotica sawdust activated carbon (ASAC) as an adsorbent for the adsorption treatment of toxic Indigo ...Carmine Dye (ICD). The effect on the adsorption characteristics of ASAC of the influent ICD concentration, flow rate, and column bed depth has been investigated. According to the column study, the highest efficiency of ICD removal was approximately 79.01% at a preliminary concentration of 100 mg/L with a flow rate of 250 mL/h at a bed depth of 30 cm and adsorption power of 24.67 mg/g. The experimental work confirmed the dependency of break-through curves on dye concentration and flow rate for a given bed depth. Kinetic models were implemented by Thomas, Yoon-Nelson, and Bed-depth-service-time analysis along with error analysis to interpret experimental data for bed depth of 15 cm and 30 cm, ICD concentration of 100 mg/L and 200 mg/L and flow rate of 250 mL/h, and 500 mL/h. The analysis predicted the breakthrough curves using a regression basin. It indicated that all three models were comparable for the entire break-through curve depiction. The characteristic parameters determined by process design and error analysis revealed that the Thomas model was better followed by the BDST and Yoon-Nelson models in relating the procedure of ICD adsorption onto ASAC. B-E-T surface area and B-E-T pore volume of ASAC were 737.76 m
/g and 0.2583 cm
/g, respectively. S-E-M and X-R-D analysis reveal the micro-porous and amorphous nature of ASAC. F-T-I-R spectroscope indicate distinctive functional assemblies like -OH group, C-H bond, C-C bond, C-OH, and C-O groups on ASAC. It could be computed that the ASAC can be used efficiently as an alternative option for industrial wastewater treatment.
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•Graphene oxide/locust bean gum aerogels were synthesized by ice crystal templating.•The aerogels showed a network-like 3D structure with large specific surface area.•The aerogels ...exhibited good adsorption efficiency and selectivity for Rhodamine-B.•Almost 92.4 % of removal rate could be remained after ten cycles.
Graphene oxide/locust bean gum (GO/LBG) aerogels, synthesized in an ice crystal template without using any chemical modifiers, were used for the treatment of water pollution. Various characterization results showed that GO/LBG aerogel exhibited a network-like three-dimensional (3D) structure with large specific surface area. The adsorption data revealed that GO/LBG aerogels with GO/LBG mass ratio of 1:4 (GO/LBG-1 aerogels) exhibited more prominent adsorption properties for Rhodamine-B (RhB, 514.5 mgg−1) than Indigo Carmine (IC, 134.6 mgg−1). Simultaneously, GO/LBG-1 aerogels could selectively remove RhB from a binary mixed solution of RhB-IC dyes. Furthermore, GO/LBG-1 aerogels also displayed excellent reusability and could still reach 92.4 % after ten cycles. Based on the above results, GO/LBG-1 aerogel could be considered as an ideal adsorbent with potential application value for removing water-soluble RhB from wastewater.
As a promising disinfection technique to replace chlorination, ozonation has been demonstrated to be efficient in water treatment. This paper describes an effective way to enhance the ozonation of ...indigo by using carbon nanotubes functionalized with carboxyl groups (CNTs-COOH) as catalysts. The result of kinetic studies showed that the presence of CNTs-COOH dramatically increased the decolorization rate of indigo. Different types of catalysts were compared to further elucidate the internal mechanism of the catalytic reaction and the special nanostructure and the functional –COOH groups are considered to play an important role in the catalytic ozonation process. Four aromatic intermediate products were identified using an electrospray time-of-flight mass spectrometer and further rationalized by the frontier electron density calculations. Ion chromatography analysis revealed that the nitrogen atom of indigo was released predominantly as ammonium and to a lesser extent as nitrate. The presence of the catalyst CNTs-COOH leads to a higher mineralization degree than single ozonation, as suggested by the total organic carbon (TOC) measurement. Three major carboxylic acids (i.e., oxalic, formic and acetic acids) were also identified as oxidation by-products, and they contributed significantly to the residual TOC after 2 h of ozonation. In addition, the toxicity evolution during the degradation was investigated through two aquatic model species to evaluate the potential ecological risks of the intermediate products.
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•The CNTs-COOH promoted indigo decolorization in ozonation process.•The special nanostructure and –COOH groups favored the catalytic reaction.•The presence of CNTs-COOH leads to a higher mineralization degree.•Four intermediates were revealed by LC-MS technique and FED calculations.•The reaction solution became harmless after 20 min of ozonation.
In this paper, we have studied the electrochemical behavior of indigo carmine (IC) in the presence and absence of mediator molecules. We have used three azo dyes as mediators in our studies and the ...effect of mediator molecules on the electron transfer between the IC solution and the electrode surface was explained from the cyclic voltammograms data. Among these dyes, 4-(4-nitrophenilazo)N-benzyl,N-ethylaniline (NBE) showed good performance as an electron transfer mediator. The NBE/carbon paste was characterized with Fourier transform infrared spectroscopy and scanning electron microscopy methods. The redox peak currents of IC were enhanced significantly compared with those obtained at the unmodified electrode. Some parameters affecting sensor response were optimized and then the calibration curve was plotted. The oxidation peak current was proportional to the concentration of IC from 1 to 100μmolL–1. The detection limit was 0.36μmolL–1. The proposed electrode was successfully applied to the determination of IC in various real samples without complex sample pretreatment.
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•The electrochemical behavior of IC in the presence and absence of mediator molecules was studied.•The results showed that NBE molecules were an effective mediator for the electron transfer.•The redox peak currents of IC were enhanced significantly compared with that obtained at the unmodified electrode.•The proposed electrode was applied to the determination of IC in various real samples without complex sample pretreatment.
γD-crystallin is among the most abundant γ-crystallins in the human eye lens which are essential for preserving its transparency. Aging, and environmental changes, cause crystallins to lose their ...native soluble structure and aggregate, resulting in the formation of cataract. Current treatment of cataract is surgical removal which is costly. Pharmaceutical therapeutics of cataract is an unmet need. We report a screen for small molecules capable of inhibiting aggregation of human γD-crystallin. Using a highly amyloidogenic hexapeptide model 41GCWMLY46 derived from the full-length protein, we screened a library of 68 anthraquinone molecules using ThT fluorescence assay. A leading hit, the cochineal Carmine, effectively reduced aggregation of the model GDC6 peptide in dose dependent manner. Similar effect was observed toward aggregation of the full-length γD-crystallin. Transmission electron microscopy, intrinsic Tryptophan fluorescence and ANS fluorescence assays corroborated these results. Insights obtained from molecular docking suggested that Carmine interaction with monomeric GDC6 involved hydrogen bonding with Ace group, Cys, Met residues and hydrophobic contact with Trp residue. Carmine was non-toxic toward retinal cells in culture. It also reduced ex vivo the turbidity of human extracted cataract material. Collectively, our results indicate that Carmine could be used for developing new therapeutics to treat cataract.
Indigo and its derivatives are dyes and pigments with a long and distinguished history in organic chemistry. Recently, applications of this ‘old’ structure as a functional organic building block for ...organic electronics applications have renewed interest in these molecules and their remarkable chemical and physical properties. Natural‐origin indigos have been processed in fully bio‐compatible field effect transistors, operating with ambipolar mobilities up to 0.5 cm2/Vs and air‐stability. The synthetic derivative isoindigo has emerged as one of the most successful building‐blocks for semiconducting polymers for plastic solar cells with efficiencies > 5%. Another isomer of indigo, epindolidione, has also been shown to be one of the best reported organic transistor materials in terms of mobility (∼2 cm2/Vs) and stability. This progress report aims to review very recent applications of indigoids in organic electronics, but especially to logically bridge together the hereto independent research directions on indigo, isoindigo, and other materials inspired by historical dye chemistry: a field which was the root of the development of modern chemistry in the first place.
Indigo and its derivatives are natural‐origin molecules with a long history, and have been at the center of the development of modern chemistry. Today, these substances are making a come‐back in the field of organic electronics.
