Bromophenol Blue Research Articles

Organo-Vermiculites Modified by Aza-Containing Gemini Surfactants: Efficient Uptake of 2-Naphthol and Bromophenol Blue.

To explore the effect of spacer structure on the adsorption capability of organo-vermiculites (organo-Vts), a series of aza-containing gemini surfactants (5N, 7N and 8N) are applied to modify Na-vermiculite (Na-Vt). Large interlayer spacing, strong binding strength and high modifier availability are observed in organo-Vts, which endow them with superiority for the adsorption of 2-naphthol (2-NP) and bromophenol blue (BPB). The maximum adsorption capacities of 5N-Vt, 7N-Vt and 8N-Vt toward 2-NP/BPB are 142.08/364.49, 156.61/372.65 and 146.50/287.90 mg/g, respectively, with the adsorption processes well fit by the PSO model and Freundlich isotherm. The quicker adsorption equilibrium of 2-NP than BPB is due to the easier diffusion of smaller 2-NP molecules into the interlayer space of organo-Vts. Moreover, stable regeneration of 7N-Vt is verified, with feasibility in the binary-component system that is demonstrated. A combination of theoretical simulation and characterization is conducted to reveal the adsorption mechanism; the adsorption processes are mainly through partition processes, electrostatic interaction and functional interactions, in which the spacer structure affects the interlayer environment and adsorptive site distribution, whereas the adsorbate structure plays a role in the diffusion process and secondary intermolecular interactions. The results of this study demonstrate the versatile applicability of aza-based organo-Vts targeted at the removal of phenols and dyes as well as provide theoretical guidance for the structural optimization and mechanistic exploration of organo-Vt adsorbents.

Green synthesized Ag decorated CeO2 nanoparticles: Efficient photocatalysts and potential antibacterial agents.

Implication of natural resources for manufacturing of nanoparticles is sustainable, economical and contaminant free approach towards ecological and medical applications. Herein, CeO2 and Ag/CeO2 nanoparticles are green synthesized from Morinda tinctoria plant extract. The phase structure, surface morphology, optical identity, Ce(III) and Ce(IV) valency of the synthesized CeO2 and Ag/CeO2 nanoparticles are explored. The X-ray diffraction analysis indicated the formation of cubic phase CeO2 and cubic silver decorated CeO2 nanoparticles. Fourier transform infrared (FTIR) spectroscopy revealed the metal decoration of CeO2 nanoparticles, metal-oxygen stretching, indicating the plant molecules reduction and stabilization. UV–visible spectroscopy shown the decreased band gap owing to silver modification. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs displayed spherical morphology of the nanoparticles. Elemental composition and sample purity is assessed by energy dispersive spectroscopy (EDS). Double oxidation of Ce, double splitting energy of Ag and lattice oxygen are observed from X-ray photoelectron spectroscopy (XPS). Photocatalytic activity of Ag/CeO2 exposed the enhanced photocatalytic activity up to 94% where CeO2 nanoparticles gave 60% degradation of bromophenol blue (BB). The plasmonic decoration of silver on the ceria surface induced the charge separations and free radical reactions. Moreover, Ag/CeO2 nanoparticles are seen as superior antibacterial agents than CeO2 towards both E.coli and S.aureus. Hence, the silver decorated metal oxide photocatalyst successfully degraded the BB dye and inactivated the bacterial strains. This report established a future research in green synthesis of multipurpose metal nanoparticles.

Studies on nano crystalline copper doped Nickel Zinc ferrites for optoelectronic applications

Investigation of optical and dielectric properties of nanocrystalline Ni0.65Zn0.35 Cu x Fe(2-2x/3) O4 (for x = 0.00–0.05 in steps of 0.01) ferrites synthesized using hydrothermal route is successfully carried out. Two distinct analytical spectroscopic methods with Dichloro – 5,6-Dicyano – 1,4-Benzo quinone (DDQ) and Bromo Phenol Blue (BPB) are adopted to observe the UV–visible absorption spectroscopy in the dispersed solutions of all samples. The formation of ion pair complex in the presence of BPB results in two distinct absorption edges in the visible region, around 440 nm and 580 nm in the present ferrite samples. Application of Tauc's formalism gives rise to two optical band gap values Eg1 and Eg2 in the range of 2.12–2.40 eV and 3.583–3.674 eV, respectively. The formation of charge transfer complex with all sample solutions in presence of DDQ reagent results in sharp absorption edges in the UV-region around 306 nm wavelength. An initial rise followed by continuous drop in band gap values ranging from 3.814 to 3.824 eV is observed from Tauc's plots. The optimum refractive index (n) values calculated for the three types of band gap values using empirical relations display the optical absorption potentiality of Ni–Cu–Zn nano ferrites in both Visible and UV – regions. Variation of band gap values is ascribed to the lattice strain effect, quantum confinement and narrowing band gap effects. Real part of dielectric constant (ε′), dielectric loss factor (tanδ) and ac-conductivity(σac) are studied for all samples at room temperature with in the frequency range of 42 Hz to 5 MHz. The values of ε′ and tanδ are observed to decrease with increase in frequency, while that of σac are found to increase with increase in frequency. Improved dielectric properties, existence of optical band-gap values observed in the present Ni–Cu–Zn ferrites promote these materials for their utility in optoelectronic devices and high frequency applications.

Polyethylene glycol capped copper ferrite porous nanostructured materials for efficient photocatalytic degradation of bromophenol blue

Three different types (blank, annealed, and functionalized) of copper ferrite nanoparticles (CuFe2O4) were synthesized by the co-precipitation method. The CuFe2O4 NPs were characterized by Fourier transform infrared (FTIR), Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDX) techniques. FTIR analysis confirmed that 3-APTES is successfully grafted on the surface of CuFe2O4 NPs. XRD results show the amorphous nature of blank CuFe2O4 NPs, and crystalline structure was observed for annealed and functionalized CuFe2O4 NPs. XRD results revealed that crystallite size ranges from 23.6 to 34.6 nm. SEM micrographs of blank CuFe2O4 NPs show the irregular shape and size of the nanostructure. The spherical and strongly linked structure was seen in the micrograph of functionalized CuFe2O4 NPs. EDX analysis revealed the nanostructure composed of Fe, Cu, O, and a small percentage of Si. The photocatalytic degradation efficiency of synthesized CuFe2O4 NPs was examined under UV irradiation in an aqueous medium against bromophenol blue (BPB) dye. The effect of different parameters such as irradiation time and pH on the photodegradation of BPB dye was studied by all three types of CuFe2O4 photocatalyst. Results show that the maximum photocatalytic degradation efficiency was observed for functionalized CuFe2O4 nanoparticles that degraded 98% of BPB dye in the acidic medium at pH = 1. The optimum contact time for dye degradation was 120 min by synthesized photocatalyst. Photodegradation performance of blank and annealed CuFe2O4 NPs is less than 90%. The synthesized CuFe2O4 NPs were recycled and reused, which shows good photocatalytic degradation efficiency up to 4 consecutive cycles. The kinetic model displayed that degradation reaction followed pseudo 1st order kinetics. The blank, annealed, and functionalized CuFe2O4 NPs have turnover numbers of 10.7x10 (Mudhoo et al., 2019), 12.9x10 (Mudhoo et al., 2019), and 22.2x10 (Mudhoo et al., 2019) (kg−1 sec−1) accordingly. In conclusion, all results revealed the high efficiency of prepared photocatalyst for tested hazardous dye from wastewater and encouraged more work on photodegradation of organic pollutants from wastewater.

Hierarchical self-assembly of 0D/2D β-Bi2O3 crossandra flower morphology exhibits excellent photocatalytic activity against bromophenol dyes

Crossandra flower shape morphology of β-Bi2O3 nanoflakes was achieved successfully by the solvothermal method. Synthesized β-Bi2O3 nanoflakes were characterized using various characterization techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectra, Ultraviolet–Visible diffuse reflectance spectroscopy (UV-DRS), X-ray photoelectron spectrometer (XPS), N2 adsorption-desorption isotherms (BET), liquid chromatography with mass spectrometry LCMS, Dynamic light scattering (DLS) and Zeta potential (ZP). Moreover, thermal stability and phase change were studied using thermogravimetric analyzer (TGA) and differential thermal analyzer (DTA). The size, shape, and extent of growth was studied using transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX), and field emission scanning electron microscopy (FESEM). The crossandra flower shape morphology was achieved due to the effect of temperature (350 °C); this was due to the uniform shifting of heat throughout the material during calcination, which allows material growth along the c-axis. The obtained material was partially in de-agglomerated and agglomerated form, and agglomeration was due to electrostatic forces of attraction. Besides this, the synthesized β-Bi2O3 was utilized to investigate photocatalytic activity for the degradation of bromophenol blue (BPB) and bromocresol purple (BCP). β-Bi2O3 shows the effective catalytic activity as it degrades the phenolic dyes effectively. The degradation was 96% (160 min) and 94% (200 min) for BPB and BCP, respectively. Overall, β-Bi2O3 nanoflakes were more responsive as a photocatalyst for BPB, which took minimal time as compared to BCP.

Development of Spectrophotometric Procedures for the Simultaneous Determination of Voxilaprevir, Sofosbuvir and Velpatasvir in Pure Form and in Tablets Ion-Association Complex Method

Two spectrophotometric procedures are developed for the estimation of three antihepatitic drugs namely Voxilaprevir (VOXL), Sofosbuvir (SOFOS) and Velpatasvir (VELP) in pure form and in different pharmaceutical formulations. The first method is based on the oxidation of velpatasvir and sofosbuvir with potassium iodate in an acidic medium followed by extracting the liberated iodine with cyclohexane and measurement at λ= 525 nm. Beer’s law is valid in the concentration ranges from 10–400 and 5–400 µg/ml for velpatasvir and sofosbuvir, respectively. The apparent molar absorptivity of the resulting-colored complex was found to be 1.34 × 10 for velpatasvir and sofosbuvir, respectively. The second method is based on the interaction of the antithepatatis drugs, Voxilaprevir, Velpatasvir and sofosbuvir in 1,2-dichloroethane with bromophenol blue (BPB), bromocresol green (BCG) and bromocresol purple (BCP) in the same solvent to produce stable colored ion pairs with maximum absorbance at 385–405 nm. Regression analysis of Beer’s plots showed good correlation in the concentration ranges 10–60, 10–60 and 5–40 µg/mL for voxilaprevir and 1.64 × 103 l.mol−1.cm−1 for velpatasvir, 10–150, 10–150 and 10–60 µg/mL−for sofosbuvir with BPB, BCG and BCP reagents, respectively. The limit of detection is 0.46–7.69 µgml11 for sofosbuvir and 10–250, 10–150 and 10–100 µgml−1 and limits of quantitation range between 1.52–8.53 µgml1. The optimum assay conditions were investigated and the recovery of the drugs from their dosage forms ranged from 99.33% to 100.5%. Intraday relative standard deviations (RSD) were 0.029–1.397% and the correlation coefficients ranged from 0.9992 to 1. The two methods can be applied successfully for the determination of these drugs in tablets. The results of analysis were validated statistically through recovery studies.

Spectrophotometric Determination of Alprazolam in Pure and Pharmaceutical Forms using Triphenyl Methane Dyes

Three simple and sensitive extractive spectrophotometric methods have been described for the assay of Alprazolam either in pure form or in pharmaceutical formulations. The developed methods involve formation of coloured chloroform extractable ion-pair complexes of the drug with bromothymol blue (BTB), bromophenol blue (BPB) and bromocresol green (BCG) in acidic medium. The extracted complexes showed absorbance maxima at 410, 408 and 405nm with use of the cited reagents, respectively. The stoichiometry of the complex is found to be 1:1 in each case. Beer’s law is obeyed in the concentration ranges 3.0-25, 4.0-30, and 4.5-40μg/ml with BTB, BPB and BCG respectively. The effect of concentration of dye, pH, and interference of excipients have been studied and optimized. The limits of detection and quantification have been determined for three methods. All the three methods have been validated as per the guidelines of ICH. The methods have been applied to the determination of drug in commercial tablets and results of analysis were validated statistically through recovery studies.

Simple Extractive Spectrophotometric Method for Determination of Favipiravir from Pharmaceutical Formulation

Simple sensitive and accurate extractive spectrophotometric methods have developed for the estimation of favipiravir in pharmaceutical dosage form. The methods are based on the formation of coloured complexes by the drug with reagents like bromophenol blue, solochrome dark blue and bromocresol green in acidic medium. The ion associated complexes were formed and quantitatively extracted under the experimental condition in chloroform. The absorbance values were measured at 420nm, 495nm and 430nm respectively. The proposed methods were validated statistically. Recoveries of methods were carried out by standard addition methods. The linearity was found to be 1.0-12.0μg/ml, 2-20μg/ml, 1-16μg/ml for methods 1, 2 and 3 respectively. The low values of standard deviation and percentage RSD indicate high precision of methods. Hence these methods are useful for routine estimation of favipiravir in tablets.

Synthesis of TiC@C-anatase/rutile@polyvinyl alcohol/xylan: a powerful photocatalyst for degradation of organic pollutant under visible light.

In this study, a composite bearing titanium carbide (TiC), titanium dioxide (TiO2), polyvinyl alcohol and xylan (TiC@C-anatase/rutile@polyvinyl alcohol/xylan) was synthesized and applied as a photocatalyst for the degradation of bromophenol blue (BPB) solution through several steps. Nanostructure of TiC and TiO2 in the anatase and rutile phases was obtained through heat treatment of TiC at different times and temperatures (TiC@AR) which led to a reduction in energy bandgap from UV to visible light, in addition to the enhancement of the surface activity. After TiC@AR polymerization by xylan and polyvinyl alcohol and obtaining TiC@AR/PX, the energy bandgap reduced to IR range (52% of the sunlight) while showing an enhancement in the surface activity. The photocatalytic activity of the compounds was tested by studying the decomposition of BPB solution under visible light. The result illustrated the ability of TiC and TiC@AR to decrease the concentration of BPB after 150 min by 35% and 37%, respectively, while this reduction was 72% for TiC@AR/PX. Considering the effective parameters, the energy bandgap and the surface layer played key roles in photocatalytic degradation.

Spectrophotometric determination of Ciprofloxacin Hydrochloride, Moxifloxacin Hydrochloride and Roxithromycin Hydrochloride in Pure Form

A straightforward, sensitive, and quick spectrophotometric approach was created and validated for the detection of Ciprofloxacin hydrochloride, Moxifloxacin hydrochloride, and Roxithromycin hydrochloride in pure form. These techniques were based upon the fact that these antibiotics produced dark yellow ion pairs when combined with bromophenol blue. The binary complex in universal buffer solution of the optimum pH values was demonstrated at absorption maxima at 633 nm, 632 nm, and 633 nm for the three drugs, respectively, with bromophenol blue. Various parameters, such as the effect of time and the effect of reagent concentration, were optimized. Beer’s law plots were obeyed in the concentration ranges 2– 8 µg ml-1, 1– 4 µg ml-1, and 1– 6 µg ml-1, for the three drugs, respectively, with bromophenol blue. The detection limits were found to be 1.65, 0.83 and 0.79 μg mL-1, respectively, for Ciprofloxacin hydrochloride, Moxifloxacin hydrochloride, and Roxithromycin hydrochloride with bromophenol blue. The correlation coefficient value suggests that all three systems are linearly consistent.

Novel extractive visible spectrophotometric method for determination of antihypertensive drug irbesartan with sulfonephthalein acid dyes in tablets

Irbesartan (IRB) is one of the drugs used for the treatment of hypertension. The present work develops and validates two methods for the evaluation of irbesartan in bulk and tablets. Sulfonephthalein acid dyes, bromophenol blue (BPB), and bromocresol purple (BCP) were used to produce stable yellow ion-association complexes with the basic drug IRB in dry chloroform. The colored products are quantified spectrophotometrically at their corresponding λmax. The relation between the absorbed signal and the drug concentration was linear up to 45.0 μg mL-1 (n = 6, r ≥ 0.9998). LOD reaches 40 ng mL-1. The composition of the ion associates was found 1:1 by Job’s and mole ratio methods. Application of the suggested methods to dosage forms is presented with percentage recoveries ranging from 99.33% to 101.67%. The results of the analysis were validated statistically and compared with the official method. No interference was observed from common pharmaceutical adjuvants.

Development and validation of a colorimetric method for determination of tadalafil using ion-pair complexation with bromophenol blue

Tadalafil belongs to the class of phosphodiesterase (PDE5) inhibitors used for the management of erectile dysfunction and other conditions. The study reports a colorimetric method for the determination of tadalafil. The method is based on the reaction of the drug with bromophenol blue in acetate buffer (pH 2.8) to form a yellow coloured complex showing maximum absorbance at 415 nm. A linear calibration curve was obtained between 2 and 22 μg/mL of tadalafil with correlation coefficient (r2) of 0.972 and molar absorptivity of 15,267 Lmol-1cm-1. The method similarly demonstrated good precision with intra-day precision ranging from 3.68-5.89 %RSD and inter-day precision of 0.66 – 4.45 % RSD. The developed method was successfully applied to the analysis of tadalafil in tablet formulation and could serve as a useful tool in the quality assessment of this medication.

Novel sustainable composites made of car's waste and sodium titanate for the efficient photocatalytic removal of the bromophenol blue dye: study under solar and UV-Vis light.

In this research, W-doped sodium nanotube titanate (NaTNT) nanoparticles were used for the photocatalytic degradation of the bromophenol blue (BPB) dye. The NaTNT powder was mixed with car's tire powder (TP) to enhance its light absorption or was supported on recycled car's air filters (AFs) to facilitate its removal from the cleaned water after the degradation of the BPB. The SEM analysis indicated that the NaTNT nanoparticles and the TP had sizes in the range of 150-325nm and 8-37µm, respectively. Both powders were also studied by X-ray diffraction and found that the sodium titanate corresponds to the Na2Ti6O13 with monoclinic phase, while the TP is formed by rubber, silicon, ZnS, and ZnO. The photocatalytic activity of the NaTNT powder was evaluated for the degradation of BPB dye (20ppm) and obtained a maximum degradation of 95 and 80% under UV-Vis and natural solar light, respectively, after 4h of irradiation. For the NaTNT + TP composite mixture, the maximum degradation was 87 and 68% under UV-Vis and solar light, respectively. The NaTNT and NaTNT + TP powders were supported on the AFs to form the AF + NaTNT and AF + NaTNT + TP composites. Those ones produced maximum degradation of 86% and 74% (under UV-Vis light), respectively. Besides, several initial pHs were tested for the contaminated water and determined that the maximum degradation of BPB (93-95%) is reached for the pHs of 3 and 7. Reuse experiments (3 cycles) revealed that the diminution of the BPB degradation percentage was 23% and 20% for the NaTNT and NaTNT + TP powders, respectively. Overall, it was demonstrated that the wasted car's air filters can be used as a support for photocatalytic powders, and this combination of AF + powder degrades the BPB with high efficiency.

Spectrophotometric quantitative analysis of lesinurad using extractive acid dye reaction based on greener selective computational approach

Computational studies introduce an integral approach for finding greener methods through testing solvents for reactions and extractions. Lesinurad is a novel selective uric acid reabsorption inhibitor prescribed for the treatment of chronic gout. Computational calculations were achieved to choose the best acid dye used for sensitive visible spectrophotometric determination of lesinurad. The calculations were performed using Gaussian 03 software based on density functional theory method with B3LYP/6-31G(d) basis set. The obtained results revealed that bromophenol blue was preferred for lesinurad than other acid dyes based on the higher calculated interaction energy. The described method was based on the reaction of lesinurad with the theoretically selected acid dye bromophenol blue to form a yellow ion-pair complex. The absorption spectra showed maximum sharp peaks at 418 nm. Different factors affecting the reaction were optimized. Beer's law was demonstrated over the concentration range of 2–12 μg/mL lesinurad. The described reaction was utilized for the spectrophotometric determination of lesinurad in pure form and in the pharmaceutical preparation. The greenness of the described method was assessed using four different tools namely, the national environmental method index, the analytical eco-scale, the green analytical procedure index and the novel analytical greenness metric. The proposed method seemed to be superior to the reported HPLC method with respect to the metrics of the greenness characters.

Spectrophotometric quantitative analysis of remdesivir using acid dye reagent selected by computational calculations

Remdesivir was approved by the Food and Drug Administration for the treatment of COVID −19 in hospitalized adult and pediatric patients. Application of computational calculations for choosing the sensitive reagent in spectrophotometric quantitative analysis is very limited. Computational and theoretical studies were used for choosing the best acid dye for selective visible spectrophotometric quantitative analysis of remdesivir. The calculations were performed using Gaussian 03 software with the density functional theory method using B3LYP/6-31G(d) basis set. The theoretical studies revealed that bromophenol blue is a better match for remdesivir than other acid dyes due to the higher calculated interaction energy. The proposed method was based on the reaction of remdesivir with the computationally selected acid dye bromophenol blue to form a yellow ion-pair complex. The spectra showed absorption peaks at 418 nm. Various factors affecting the reaction were optimized. The method was successfully applied for the determination of remdesivir in the pharmaceutical preparation with good accuracy and precision. Beer's law was observed in the concentration range of 2–12 μg/mL of remdesivir. The proposed reaction was used as a basis for the spectrophotometric determination of remdesivir in pure form and in the pharmaceutical preparation.

Determining spoilage of whiteleg shrimp (Litopanaeus vannemei) during refrigerated storage using colorimetric strips.

A reliable spoilage assessment method is needed to ensure sufficient quality control of shrimp. Colorimetric dye-based indicators that change color in response to pH changes can monitor food quality changes in a simple, quick, and accurate way and generate easy-to-interpret results. Significant positive correlations with storage time were observed for the results of the bromophenol blue (BPB) strips (r=0.8513, p<0.0001) and the rose bengal strips (r=0.8981, p<0.0001). The results of both colorimetric methods significantly correlated with sensory and chemical quality indicators, including sensory attributes "salty water-like", "natto water-like" and "sour milk-like", and volatile compounds such as 3-methyl-3-butenol, 2-methyl-1-butanol, 3-methyl-1-butanol, hexanol, 2-methyl-1-butanal, and 3-methyl-1-butanal. The BPB strips and rose bengal strips have the potential to be used as objective, accurate, and cost-efficient methods to evaluate shrimp quality and lead to consistent and easy-to-interpret results.

Modeling the Dichromatic Behavior of Bromophenol Blue to Enhance the Analytical Performance of pH Colorimetric Sensor Arrays

The dichromatism of Bromophenol blue (BPB) was investigated by varying its concentration in the absence and presence of surfactant. A model of the indicator behavior was carried out, justifying the experimental shapes of the sigmoidal profiles of the hue (H) coordinate. The model applied to the solution was compared with the performance of colorimetric sensor arrays (CSAs) with increasing BPB concentrations. The H shape and the prediction errors of the CSAs were very similar to those predicted. The experimental results enable the changing of the slope of the calibration profiles, at will, by varying only the BPB concentration.

Arachis hypogaea shell – An approach towards waste utilization for cationic and anionic dye removal

In this work, the treatment of an anionic dye (Bromophenol Blue (BB)) and a cationic dye (Methyl Green (MG)) using activated biomass waste as an adsorbent was explored. Using Peanut shells as a precursor, chemically activated carbon was synthesized. The activation was carried out using different activation ratios of Arachis hypogaea : KOH (1:4, 1:5, and 1:6). The synthesized Arachis hypogaea Shell Activated Carbon (ASAC) was analyzed for its surface morphology using SEM, the porous characteristics using BET analysis, and chemical composition using FT-IR analysis. Further, the effect of various parameters like pH (3–11), adsorbent dosage (1–5 g/l), and contact time on color and COD removal of BB and MG aqueous solutions were studied. At optimum condition 500 mg/g and 555.55 mg/g maximum adsorption capacity for BB and MG respectively was obtained. The adsorption kinetics and different isotherm models were used to analyze the experimental data.The isotherm model that fitted well with the experimental data for both the dyes was Langmuir and adsorption followed pseudo-second-order kinetics.

Pengembangan Indikator Bromofenol Biru dan Metil Merah pada Label Pintar sebagai Sensor Kematangan Buah Tomat

The novel on-package color indicator label has been fabricated based on bromophenol blue and a mixture between bromophenol blue and methyl red, and tests have been conducted to assess the ripeness of tomatoes (Lycopersicum commune). Bromophenol blue (BPB) and a mixture between bromophenol blue and methyl red (MM) were immobilized onto the Whatman paper membrane via the adsorption method. The BPB and mixture between BPB and MM/ Whatman paper membrane as color indicator work based on pH decrease as the volatile organic compounds. They are produced gradually in the package headspace during the development of tomato fruit. Subsequently, the combination indicator between bromophenol blue and methyl red changes from purple to red foul conditions, while the bromophenol blue indicator changes from blue to yellow foul conditions that can be seen visually. The results showed the color indicator can be used to determine the maturity conditions of tomatoes (Lycopersicum commune) at room temperature and chiller temperature. Furthermore, there are also changes in several parameters (pH, texture, weight loss, sensory evaluation) that are commonly used for the ripeness characteristics of tomatoes (Lycopersicum commune). Therefore, this indicator can be used for visual monitoring of the maturing of the tomatoes in packaging.

Sequestration of thiazolyl blue tetrazolium bromide and bromophenol blue onto biochar derived from American sycamore leaves

ABSTRACT Biochars have received much attention as efficient adsorbents for water pollutants. Besides, the chemical treatment of biochars performed to increase the adsorption capacity usually causes secondary chemical pollution and increases the cost of the process. The biomass feedstock utilised in biochar preparation impacts significantly the surface properties and adsorption capacity. Thus, the need to prepare new biochars from new feedstock with potentially high uptake capacities. Herein, we prepared new biochar (POBC) from Platanus occidentalis waste leaves (POL), which was utilised for the ultrasonic-aided adsorption of bromophenol blue (BRB) and thiazolyl blue tetrazolium bromide (TTB). The FTIR, SEM, EDX, TGA, BET, pHpzc, and elemental characterisations of POBC revealed potent surface characteristics desirable for efficient dye adsorption. An increase in the surface area from 14.31 m2/g to 31.94 m2/g and the pore volume from 0.0214 cm3/g to 0.0326 cm3/g was obtained after the conversion of the POL to POBC. Besides, the SEM images of POBC revealed a highly porous surface structure of the adsorbent. The Freundlich and pseudo-second-order model presented the best fit to the isotherm and kinetics based on the high coefficient of determination (R2 > 0.9) and low sum square errors (SSE < 0.31). The heterogeneous surface nature of POBC was inferred from the independent-oriented site model. The monolayer adsorption capacity of 45.03 mg/g and 48.8 mg/g were obtained for BRB and TTB, respectively. Thermodynamics showed an endothermic, feasible, and random uptake, and POBC displayed efficient potentials to be reused. The obtained results revealed that novel POBC is an efficient low-cost biochar with high adsorption capacity for dyes.