Color Degradation Research Articles

Enhancing color and chemical oxygen demand degradation in distillery spent wash by electrocoagulation and ozone assisted electrocoagulation

Enhancing color and chemical oxygen demand degradation in distillery spent wash by electrocoagulation and ozone assisted electrocoagulation

Effect of apple peel based edible coating material on physicochemical properties of button mushrooms (<em>Agaricus bisporus</em>) under ambient condition

Button mushroom were coated by dipping in a coating solution for a period of 75s, formulated by dissolving a combination of apple peel powder and CMC into distilled water. A total of nine different combinations with three levels of apple peel powder concentration (1.0, 1.2 and 1.4%w/v) and three levels of CMC concentration (1.2, 1.5 and 1.8%w/v) were used to prepare the coating solution. To analyse the effect of coating materials on physicochemical properties of button mushroom, the physicochemical responses like weight loss, shrinkage ratio, water activity, color variation, microbial load and free radical scavenging activity were assessed. The higher concentration of apple peel powder was resulting in degradation of colour of coated sample during storage due to anthocyanin content of apple peel powder. The moderate concentration of apple peel powder (1.2% w/v) with high level of CMC concentration (1.8% w/v) were found to be the best combination of coating materials which increased the shelf life of button mushroom upto 5 days along with retaining the quality attributes closest to the fresh sample.

Synthesis and Characterization of CuO Nanocomposites Doped with Cr <sup>3+</sup> and Mn <sup>2+</sup> for Efficient Photodegradation of Organic Dyes (MB & MO)

Nanocomposites CuO/CuCr 2 O 4 /CuSO 4 (1) and CuO/CuMn 2 O 4 /CuSO 4 (2) were synthesized by chemical deposition, and their structural, morphological, optical, and thermal properties were investigated by FTIR, XRD, FESEM, TEM, EDX, UV-Vis DRS, and TG-DTA. From the analysis of the obtained data, analysis of FESEM, TEM, and EDS data revealed that nanocomposites have a sheet structure and that the elements are homogeneously scattered throughout the structure. The doped Cr and Mn elements in nanocomposites (1) and (2) form the CuCr 2 O 4 and CuMn 2 O 4 spinel structures, respectively. Thermal analysis shows that the compounds have a high thermal stability. Apart from that, the photocatalytic activity of the compounds is very effective in cationic (MB) and anionic (MO) degradation colored pollutants in the presence of H 2 O 2 and under sunlight. A kinetic study showed that degradation follows the first-order kinetics; therefore, these nanocomposites are good candidates for color degradation with good efficiency in wastewater treatment.

Colour degradation of façade coatings – the effect of nanopigments incorporation

The increasing interest in the use of a wide range of colours in buildings, especially dark colours, may lead to the early degradation of the façades, compromising their aesthetic and thermal performance. On the other hand, the incorporation of nanopigments with high reflectance properties can contribute to reducing the absorption of solar radiation. The nanoparticles contribute to increasing the solar reflectance of coatings, decreasing the surface temperature and improving the coating performance. This work evaluates the natural degradation of the colour of finishing coat with nanopigments in ETICS. The colour parameters were evaluated in different ETICS specimens, considering the colour black and red with and without incorporated nanopigments, under natural ageing. The colour measurement was performed according to ISO 1164-4, using a portable spectrophotometer. The results confirmed that the use of nanopigments improved the colour durability, promoting the maintenance of the colours parameters. The total colour difference was lower than the perceptible by the human eyes, even as the lower variation on chroma and hue parameters of the colours with nanopigments. In summary, the incorporation of nanoparticles in finishing coat of ETICS can contribute to increasing their durability and improve their thermal performance without compromising the aesthetic characteristics.

Characterization of Fe3O4/rGO Composites from Natural Sources: Application for Dyes Color Degradation in Aqueous Solution

The magnetite (Fe3O4) nanoparticle and graphene oxide (GO) have become interesting materials due to their advanced applications. In this work, we investigated the fabrication of Fe3O4 nanoparticles (NPs) from iron sands and reduced graphene oxide (rGO) NPs from natural graphite. The core-shell fabrication of the Fe3O4/rGO was conducted by means of ex-situ method using ethanol as the medium. The crystal structure of Fe3O4/rGO was observed using X-ray diffraction (XRD) and functional groups were examined using Fourier transform infra-red (FTIR) spectroscopy. The characteristic of the disturbance originated by carbon atoms was investigated by Raman spectroscopy. The morphological, particle sizes and formation studied with transmission electron microscopy (TEM). The magnetic properties were analyzed using vibrating sample magnetometer (VSM). Furthermore, analysis of the adsorption performance, namely: dye-removal efficiency (DRE) and degradation rate (DR), as candidate materials absorbent were performed by means of UV-Vis spectroscopy. The data analysis of structure and phase of Fe3O4/rGO presented cubic spinel structure with crystallite size of 26-38 nm. The functional group analysis presented the existence of C-OH, C=O, C-O, and Fe-O. The micrograph analysis from the TEM image showed the particle size of the sample was in the range of 10 - 30 nm. Along with the thickening shell, the saturation magnetization of Fe3O4/rGO decreased from 22.60 to 18.48 emu/g and decreased from 29.21 to 10.45 emu/g for Fe3O4. Finally, the rGO composition affects the shell wall, which encloses Fe3O4 as the core. Interestingly, an increase in absorption characteristic of natural dyes Fe3O4/rGO enhanced by the decrease of the shell thickness.

Shapes Control of Bi2WO6 Nano-Structures as Photo-Fenton Catalysts for Pulping Wastewater Treatment

Bi2WO6 assembled by flower-like microspheres and nanosheets were controllably synthesized through a one-step hydrothermal approach. Multiple technologies, including X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and UV–Vis diffuse reflectance spectrum (UV–Vis), were carried out to characterize the as-synthesized samples. The photocatalytic efficiency of Bi2WO6 synthesized with a series of temperature and pH values shows different morphologies and photocatalytic properties. The photocatalyst (Bi2WO6) synthesized at 220 °C and pH of 7 exhibited the best photocatalytic performance, with the methylene blue (MB) degradation approaching 91.6% after reaction time of 60 min. Free radical capture experiments indicate that •OH is the primary reactive species in the methylene blue (MB) degradation reaction, h+ and •O2− contribute negligible influence, while the addition of H2O2 significantly improves the photocatalytic activity of Bi2WO6. Biodegraded poplar preconditioning refiner chemical alkaline peroxide mechanical pulp wastewater (PPW) was treated over Bi2WO6 under UV light (Bi2WO6/UV/H2O2); chemical oxygen demand (CODCr) and color degradation rate were 85.8% and 92.0%, respectively. These results show that Bi2WO6 semiconductors can be introduced as an efficient and stable photocatalyst for industry wastewater treatment.

Measurement of tropospheric ozone by digital image analysis of indigotrisulfonate-impregnated passive sampling pads using a smartphone camera

In this work, we propose a low cost and portable method for the monitoring of daily tropospheric ozone levels, through the combination of passive sampling and digital analysis of images taken with the camera of a smartphone. The analytical signal used is the degradation of the blue color of indigotrisulfonate deposited on a passive sampling device, depending on its reaction with ozone to form colorless products. The discoloration was measured by tracking the RGB parameters obtained from images taken with the camera. The RGB signals were processed using different mathematical algorithms of digital image analysis, of which the effective absorbance from R channel (EAR) was selected as optimal. The detection limit was 3.3 μg m−3. The linear range obtained was between 11 and 109 μg m−3 for EAR, sufficient for the measurement of usual environmental levels of ozone in urban or rural environments. The practical application of the method was tested by measuring 24 h average levels of ozone in an suburban environment for three months, finding a good precision (RSD = 6.8%), accuracy (relative errors from −14.0 to 5.7%) and an adequate correlation (r = 0.77) against a spectrophotometric reference method. These results demonstrate the potential of the method as an auxiliary tool for the standard instruments, providing a rapid and decentralized measurement of ozone levels with adequate reliability.

Human Visual Perception-Based Multi-Exposure Fusion Image Quality Assessment

Compared with ordinary single exposure images, multi-exposure fusion (MEF) images are prone to color imbalance, detail information loss and abnormal exposure in the process of combining multiple images with different exposure levels. In this paper, we proposed a human visual perception-based multi-exposure fusion image quality assessment method by considering the related perceptual features (i.e., color, dense scale invariant feature transform (DSIFT) and exposure) to measure the quality degradation accurately, which is closely related to the symmetry principle in human eyes. Firstly, the L1 norm of chrominance components between fused images and the designed pseudo images with the most severe color attenuation is calculated to measure the global color degradation, and the color saturation similarity is added to eliminate the influence of color over-saturation. Secondly, a set of distorted images under different exposure levels with strong edge information of fused image is constructed through the structural transfer, thus DSIFT similarity and DSIFT saturation are computed to measure the local detail loss and enhancement, respectively. Thirdly, Gauss exposure function is used to detect the over-exposure or under-exposure areas, and the above perceptual features are aggregated with random forest to predict the final quality of fused image. Experimental results on a public MEF subjective assessment database show the superiority of the proposed method with the state-of-the-art image quality assessment models.

Colour Difference Between Caucasian and Afro-Caribbean Skin Tone Silicone Elastomer Moulded in Type II and Type III Dental Stone.

The colour stability of the silicone is essential for the longevity of facial prostheses. This in vitro study investigates the colour degradation of two different skin shade silicones moulded in Type II and Type III dental stone. Two different types of dental stone were used to fabricate 168 silicone samples (n=42 for each group) using M511 maxillofacial silicone, which was coloured with Spectromatch Procolourants. The polymerisation was carried out at 85°C 1.5 hours. A spectrophotometer was used to record the colour differences (ΔΕ) of each group before and after polymerisation. The CIEL*a*b* formula was used to obtain the measurements and a one-way ANOVA was carried out for the statistical analysis of the data. There is a statistically significant colour difference (ΔΕ) for all groups. For the Afro-Caribbean skin tone, Type III dental stone demonstrated the greatest colour change (ΔΕ = 4.36), whereas, for the Caucasian skin tone, it was the Type II dental stone (ΔΕ = 2.21). This study showed that regardless of the investing material, the colour of the silicone lightens after polymerisation. Both types of dental stone resulted in visible colour changes, with a ΔΕ ranging from 1.64 - 4.36.

Thermal Degradation Kinetics of Total Carotenoid and Colour of Mixed Juice

Thermal degradation kinetics of total carotenoids and colour of mixed juice were evaluated during heating at 70, 80, 90 and 100 °C (0 to 3 h). It was observed that total carotenoid and colour degradation followed a first-order reaction between temperature and time. Higher activation energy for colour of mixed juice indicated its higher temperature sensitivity as compared to total carotenoids. The degradation of antioxidant activity of mixed juice was not linear with temperature. The experimental data fitted to fractional conversion model and kinetic model showed nonlinear relationship between per cent radical scavenging activity of total carotenoids and time.

The Difference in Colour Shifting of Clitoria ternatea L. Flower Extract at pH 1, 4, and 7 During Storage

Objective: A research to evaluate the colour shift of Clitoria ternatea L. flower (CT) extract at pH 1, 4, and 7 during storage at 30oC in the dark has been conducted. Methods: The evaluation comprised of the measurement of colour intensity (CI), violet index (VI), and browning index (BI). Results: The extract was very stable at pH 1, although its colour slightly shifted to redder. Conversely, at pH 4 the extract slightly decreased, but the colour hue remained stable. At pH 7, the extract exhibited much less colour stability by demonstrating considerable decrease of CI and VI. Conclusion: The absence and presence of the colour shift at pH 4 and 7, respectively, indicated that there were two different ways of the colour fading. It was proposed that the colour degradation at pH 4 occurred through the unfolding of hydrophobic interaction, while at pH 7 through the deacylation. The deacylation was proven by the high-performance liquid chromatography analysis equipped by diode array detector at 530 nm.

Effects of environmental stresses on physiochemical stability of β-carotene in zein-carboxymethyl chitosan-tea polyphenols ternary delivery system

β-Carotene is a natural nutrient that serves as a natural food colorant. However, the weak physical stability restricts its development in food industrial production. Here, the influences of a variety of external environmental conditions on the stability of β-carotene enriched zein-carboxymethyl chitosan (CMCS)-tea polyphenols (TP) ternary composite nanoparticles were investigated. Compared with zein unitary and zein-CMCS binary complexes, it was interesting to note that ternary complexes had the best stability against color fading and there was little impact on its nanoparticle size during storage with change in temperature. Besides excellent antioxidant properties, ternary complexes were extremely effective in inhibiting β-carotene color degradation when exposed to ultraviolet light. Based on our results, the novel zein-CMCS-TP nanoparticles are expected to be an effective delivery system to encapsulate hydrophobic bioactive compounds, which is a promising approach to improve their storage stability against external environmental stresses.

Color Degradation of Printed Images

Numerous color images are digitally reproduced today, mainly using the cyan, magenta, yellow and black ink set. The information in a printed image, however, may be distorted or lost due to the image's gradual color degradation as the result of ink fading and diffusion on the substrate. The degradation behavior of the inks can be difficult to predict when catalytic fading is introduced by a variety of ink mixtures produced in the printing process. In this article, we prove that the fading or diffusion rate has an equivalent interpretation as the hazard function in reliability modeling, and the degradation model of printed images with constant fading and diffusion rates can be reformulated as a Markov process model. Hence, the degradation of printed images with time-varying fading and diffusion rates can be modeled as a semi-Markov process. The semi-Markov process model provides a deterministic degradation prediction. We further propose a spatio-temporal Wiener process model for stochastic prediction of the ink fading and diffusion of printed images. Numerical examples and a real-life case study are provided to illustrate the proposed approach.

ANTHOCYANIN AS NATURAL COLORANT: A REVIEW

On this era, people very concern to their food. The first sensory quality which is seen to choose the food are the color. However, during food processing is often occurred the color degradation, so the colorant is added to the food. Today, natural colorant is consumer’s selection because it has functional function. One of natural colorant is anthocyanin. Anthocyanin gives red, blue, and purple color. Anthocyanin has different types, it is depended to sugar and hydroxyl which bounded into structure. The types are pelargonidin, malvidin, cyanidin, delphinidin, petunidin, and peonidin. This pigment is stable on acid condition, away from light and oxygen, cold temperature, and away from polyphenol oxidase enzyme. Beside as colorant, anthocyanin also act as antioxidant because the structure is very reactive. The consequences of having antioxidant activity, anthocyanin can prevent cardiovascular disease, cholesterol, atherosclerosis, or colon cancer by blocking fat oxidation and DNA mutation. Anthocyanin source is very broad like from flowers, fruits, tubers, or fruit peels.

English

Tomato is widely consumed in the world and its concentrated paste represents the main product from industrial tomato cultivars. One of the industry's biggest challenges is to produce in a sustainable and effective chain to simultaneously fulfill the cost reduction and quality improvement demands. This study aimed to show the loss of tomato paste quality attributes along its industrial processing chain, focusing on three parameters: (1) ascorbic acid content; (2) color and (3) consistency. Samples of tomato paste (29 °Brix) were subjected to thermal treatment at 60, 70 and 80°C, cooled down and analyzed for the mentioned attributes by kinetic parameters. Both ascorbic acid (z = 62.8°C, R2 = 0.9499) and instrumental color (z = 19.0°C, R2 = 0.9924 for a*/b*, and z = 16.3°C, R2 = 0.9897 for TPS) parameters degradation were well described by first-order kinetic models. Consistency attributes were not affected by the thermal treatment temperature. The temperature effect at each stage of processing allowed identifying the sterilization and storage steps as responsible for the greater degradation of color and ascorbic acid, respectively. The industry must control sterilization and increase sun protection in the offseason to preserve color and ascorbic acid, ensure lower losses of sensorial quality without reducing its productive flexibility, always prioritizing food safety.   Key words: Color, storage, shelf life, vitamin C, consistency.

The kinetics of colour degradation, chlorophylls and xanthophylls loss in pistachio nuts during roasting process

Abstract Objectives Colour is amongst the parameter which is used for process control during roasting. Materials and Methods In this study, the effects of hot air roasting temperature (120, 130, 145, 160, and 170°C) and hot air velocity (0.6, 1.3, and 2 m/s) on colour change kinetics of pistachio nuts were investigated by employing image analysis and simultaneously chlorophylls and xanthophylls (lutein and β-carotenoid) concentration were determined by spectrophotometric measurement method. Results We found that roasting temperature and hot air velocity had significant effect on colour changes. There is a correlation between a- and b-value with chlorophylls and xanthophylls concentration, respectively. The roasting temperature was found to be the main factor affecting colour development. The variations in the pigments concentration and colour parameters of pistachio nuts were adequately simulated by quadratic and cubic polynomials. The changes in L-, b-values, and xanthophylls degradation were well-fitted to the first-order kinetic model while a-value and chlorophylls degradation followed the zero-order kinetic. The activation energy was determined at 113.9, 116.7, and 117.2 kJ/mol with R2 ≥ 99.9 and 191, 195, and 163.2 kJ/mol with R2 ≥ 99.5 and 73.7, 71.3, and 81.6 kJ/mol with R2 ≥ 99.9 for L-, b-, and a-value in hot air velocity of 0.6, 1.3, and 2 m/s, respectively. Conclusions Activation energy of chlorophylls and xanthophylls degradation were in the range of the activation energy for the yellowness (b-value) and redness (a-value) reactions.

Development of Intelligent Food Packaging from Turmeric (Curcuma longa)

In this study, intelligent food packaging in the forms of film and coating were developed based on starch, chitosan and curcumin extracted from turmeric. Solution casting method was applied to develop the film. Both of the film and coating were evaluated and compared by their chemical, physical and biological properties. The film was evaluated in terms of tensile strength measurement, FTIR spectroscopy, antioxidant activity and antimicrobial activity as well as color difference parameters after application on the strawberry. The results obtained showed that the film has a tensile strength of 1.37 MPa, elongation at break of 18.9%, antioxidant activity of 95.65% and high antimicrobial activity as the film had successfully delayed the formation of mould on the strawberry after 5 days of storage. In addition, the stability of both film and coating were evaluated based on their applications on strawberries at two different conditions which are at room temperature and chiller temperature during 5 days storage to identify their potential use as intelligent food packaging. After 5 days, it was found that the film at room temperature had been partially degraded and the coating had caused colour degradation and texture deterioration of the strawberry. In contrast, the film and coating stored at chiller temperature remained the same in terms of physical structure and able to monitor and extend the shelf life of the strawberry. For the evaluation of the film as pH sensing film, the colour of the film changed after 5 days from 53.46 to 48.92 for L*, 26.01 to 22.68 for a* and 42.49 to 44.65 for b* at chiller temperature, while at room temperature, the values of L* changed from 53.96 to 48.96, 25.54 to 20.36 for a* and 46.34 to 44.10 for b*. These showed that the film was able to monitor the freshness of the strawberry by changing its colour in respond to pH changes of the strawberry. The results obtained revealed that both of the film and coating have a greater stability at chiller temperature as compared to storage at room temperature and both have a strong antioxidant activity and strong antimicrobial activity that they delayed the spoilage of the strawberries. Therefore, the film and coating based on starch, chitosan and curcumin can be used to monitor freshness of refrigerated food and have the potential to be used as intelligent food packaging.

Ascorbic Acid Derivatives as Potential Substitutes for Ascorbic Acid To Reduce Color Degradation of Drinks Containing Ascorbic Acid and Anthocyanins from Natural Extracts.

Ascorbic acid is widely used in the food industry as a source of vitamin C or as antioxidant. However, it degrades quickly in beverages at acidic pH and can accelerate the degradation of anthocyanins, natural dyes used in beverages, leading to a loss of color. In this work, we investigated the possibility to replace ascorbic acid by ascorbic acid derivatives to prevent its degradation effect on anthocyanins from natural extracts (black carrot, grape juice, and purple sweet potato). For this, the thermal and photolytic stabilities under air and under N2 of ascorbic acid (as reference) and of some ascorbic acid derivatives (3-O-ethyl-l-ascorbic acid, 2-O-α-d-glucopyranosyl-l-ascorbic acid, l-ascorbic acid 2-phosphate sesquimagnesium salt hydrate, l-ascorbyl 2,6-dibutyrate, glyceryl ascorbate, (+)-5,6-O-isopropylidene-l-ascorbic acid), soluble in aqueous model beverages, were studied alone and in the presence of anthocyanins from the natural extracts in citrate buffer at pH 3. The stability was followed by UV-visible spectrometry. To extend the investigation, some properties of the ascorbic acid derivatives (pKa, oxidation potential, bond dissociation energy, ionization potential) were also determined. Moreover, the addition of chlorogenic acid was examined to further stabilize the mixture of anthocyanins with 2-O-α-d-glucopyranosyl-l-ascorbic acid, a promising ascorbic acid derivative.

A cleaner and one-step approach for robust coloration of polyester fibers via hydrophobic magnetically recoverable photocatalyst fatty acids/nano iron oxide coating

Recently, nanoparticles are applied broadly for nanocoloration of textiles as new class of colorants along with imparting diverse properties. However, lack of being environmentally friendly and feasible, having proper coloration properties such as good color fastness against rubbing, washing and acid spotting and being magnetically recoverable is perceived. Herein, we described a cleaner one-step approach for robust nanocoloration of polyester fibers via hydrophobic magnetically recyclable photocatalyst fatty acids/nano iron oxide coating for the first time. Introducing clean facile route as a possible replacement method of conventional textile coloration, eliminating hazardous dyes and auxiliaries, reducing textile effluents via using safe and magnetically recoverable colorant and photocatalytic dye degradation ability are the advantages of this route. A diverse color from light to dark brown with excellent color fastness ratings against washing, rubbing, acid and alkaline spotting and light was achieved for fabricated composites. Iron oxide nanoparticles along with fatty acids as safe coating not only improve the safety of the process but also enhance all the color fastness of the prepared samples along with forming very good hydrophobic behavior with water contact angle of 127 and 148°. The fabricated samples displayed proper magnetic feature with saturation magnetization of 1.69 emu/g at room temperature expressed the feasible and simple recovery of the possible released nanoparticles in waste water from washing. Appropriate photocatalytic performance (90.73%) towards discoloration of methylene blue after 48 h under daylight was also achieved. This route renders the idea of utilizing magnetic nanoparticles along with fatty acids for cleaner and facile nanocoloration of various fibers with multifunctional properties.

The effect of reactive red 2 initial concentration on COD and colour degradation by using Fenton, Fenton/TiO2, Fenton/UV, and Fenton/TiO2/UV methods

One area that is developing in Indonesia is in the area of textile industry. These industries absorb a lot of labor and contribute to the country’s foreign exchange but have a negative impact in the form of wastewater produced. The wastewater produced generally contains synthetic dyes such as Reactive Red 2 (RR2). This synthetic coloring material will pollute the environment if it is not well treated first before being discharged into the environment. In this study, RR2 will be used as a pollutant model. RR2 will be treated by several methods. Pollutant concentration is an important parameter in determining the most appropriate treatment method. The purpose of this research was to study the effect of RR2 initial concentration on reducing COD and color using Fenton, Fenton/TiO2, Fenton/UV, and Fenton/TiO2/UV methods. RR2 concentration was varied between 150-300 ppm. As the results, RR2 concentration from 150-300 ppm does not significantly affect the percentage of color degradation. However, at high concentration of 250 and 300 ppm, the percentage of COD degradation decrease by increasing concentration of RR2. When using 150 ppm of RR2, the highest COD and color degradation of 98.8 % and 89.5 %, respectively were achieved by using the Fenton/TiO2/UV methods.