Diversity of Synthetic Dyes from Textile Industries, Discharge Impacts and Treatment Methods

Coloring materials for fabric painting can be produced from natural dyes and synthetic dyes. Natural and synthetic dyes have their respective advantages and disadvantages. The combination of the two colors will give the impression of a brighter color, and slightly reduce environmental pollution. The objectives of this research are: 1) Knowing the processing of synthetic and natural dyes for fabric painting; 2) Knowing the results of applying synthetic and natural dyes to fabric painting. The method used in this research is the research and development approach model Research and Development (R&D) and data analysis. Trials in this study were carried out with dye using 4 types of cloth with the help of a validator as an assessor of the coloring results. The results of this study indicate that synthetic dyes are lighter than natural dyes. Meanwhile, the colors produced from natural dyes tend to be darker. In painting this cloth, the writer needs a combination of dark and light colors. Therefore, the use of synthetic and natural dyes requires mixing of colors. The fading test conducted by the author for the color absorption of diamond crape on the fabric is very good. Thus it can be concluded that the use of natural and synthetic dyes can be applied to fabric painting by conducting trials first to get the right color.

PurposeThis paper aims to select a type of mordant from aluminium salts, namely, aluminium sulphate, aluminium nitrate and polyaluminium chloride (PAC) with the lowest potential for contamination so that their use will minimise pollution from natural dye waste. It also aims to determine the pollution value of natural dye immersion waste from jackfruit wood extract, secang wood, mangsi fruit and several synthetic dyes, to identify potential environmental pollution.Design/methodology/approachDyeing with natural dyes was performed by exhaust at room temperature by the pre-mordant method, while with synthetic dyes it was performed by exhaust according to the dyeing procedure (reactive, vat and naphthol). The groundwater, mordant solutions, natural dye extract and the waste-water from the natural and synthetic dyes were then tested to determine their biological oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), pH, Al and heavy metal contents such as chromium (Cr), copper (Cu), cadmium (Cd), nickel (Ni), cobalt (Co) and lead (Pb).FindingsAluminium sulphate had the lowest pollution load while PAC had the highest, as aluminium sulphate had a higher BOD5/COD ratio (0.62–0.67) than aluminium nitrate (0.56–0.64) or PAC (0.44–0.54). The dyeing waste from the three natural dyes contained an acidic pH of 3.5–4.2, Al of 75.280–621.34 mg/L, Cr of 0.154–0.215 mg/L and Cu of 0.035–0.072 mg/L. The values of TSS, COD and BOD5 are higher than the quality standards of the waste but are environmentally friendly because the ratio of the BOD5/COD values from the waste ranges from 0.44–0.67.Research limitations/implicationsThe findings indicate that as a mordant, aluminium sulphate results in lower pollution loads than aluminium nitrate and PAC. However, all three mordants contain Cr and Cu, albeit in negligible concentrations. Therefore, it is recommended that future studies strive to identify a mordant that has lower pollution loads and does not contain metals but can increase dyeing results to satisfy consumer requirements. It is the hope that, with the discovery of a new mordant, natural dyes will be the solution for the heavy metal pollution caused by synthetic dyes.Practical implicationsThe use of environmentally-friendly mordants and natural dyes in the Indonesian textile and batik industry will give rise to superior quality eco-textile and eco-batik products. Such environmentally-friendly and high-quality products will not only increase competition and consumer interest but increase product sales as well which will, in turn, increase incomes and the economy. Additionally, an increase in the use of natural dyes by the textile and batik industry will serve as additional income to the communities and farmers from which the raw materials for the natural dyes are sourced thereby creating jobs and increasing welfare.Social implicationsAs environmentally-friendly mordants and natural dyes replace the hazardous and toxic materials currently used in the textile and batik industry, it guarantees the health and safety of its consumers and workers. Furthermore, as the waste-water produced is biodegradable, it reduces river and groundwater pollution. It is, therefore, expected that this information will not only lead to a shift in attitude within the textile and batik industries but the adoption of environmentally-friendly materials, for the sake of the environment, as well as the development of eco-textile and eco-batik products.Originality/valueAluminium sulphate is a mordant type of aluminium salt with a lower potential for contamination than aluminium nitrate and PAC. However, PAC has been discovered to be a mordant for natural dyes, as has the fruit of the mangsi shrub, which has recently been discovered as a naturally occurring blue dye.

Fast foods and variety food items are populating among the food lovers. To improve the appearance of the food product in surviving gigantic competitive environment synthetic or natural food dyes are added to food items and beverages. Although regulatory bodies permit addition of natural colorants due to its safe and nontoxic nature in food, synthetic dyes are stringently controlled in all food products due to their toxicity by regulatory bodies. Artificial colors are need certification from the regulatory bodies for human consumption. To analyze food dyes in different food samples many analytical techniques are available like high pressure liquid chromatography (HPLC), thin layer chromatography (TLC), spectroscopic and gas chromatographic methods. However all these reported methods analyzed only synthetic dyes or natural dyes. Not a single method has analyzed both synthetic and natural dyes in a single run. In this study a robust ultra-performance liquid chromatographic method for simultaneous identification of 6 synthetic dyes (Tartrazine, Indigo carmine, Briliant blue, Fast green, malachite green, sunset yellow) and one natural dye (Na-Cu-Chlorophyllin) was developed using acquitic UPLC system equipped with Mass detector and acquity UPLC HSS T3 column (1.8 μm, 2.1 × 50 mm, 100Å). All the dyes were separated and their masses were determined through fragments’ masses analyses.

A review of history, properties, classification, applications and challenges of natural and synthetic dyes

This Systematic Literature (SLR) identifies the studies conducted so far on developing natural dyes for textiles. Synthetic dyes are harmful to the environment as they are not naturally degradable. Using natural dyes in the textile industry is one of the solutions to reduce the environmental impact. Currently, natural dyes are primarily used in the textile and handicraft industry at the level of small and medium enterprises (SMEs), where the industry still carries out planting to extraction. If natural dyes are to be applied as textile dyes, especially batik, an industry that develops natural dyes is needed to maintain the continuity and availability of natural dyes. In this study, we conducted a systematic review to synthesize empirical knowledge relevant to the sustainability of the textile natural dye industry. The literature study used articles published between 2019-2023 in reputable journals. From the literature review results, we found that most of the studies covered the sources of natural dyes and their extraction processes, as well as the sustainability of natural dyes. The literature review found that studies on natural textile dyes still need to be developed, including how to develop natural dye agro-industry institutions to guarantee their continuity and availability.

An Analysis of Long-run Environmental Impacts and Multi-criteria-based Prioritisation of the Natural Dyes in the Indian Textile Industry

Rapid separation and determination of synthetic and natural yellow dyes in food and drinks using mini-column packed with polyamine-modified silica.

The textile industry uses many raw materials (natural and synthetic dyes and fibers) and different dyeing techniques that can be considered important pollutants with a negative impact on the environment (toxic working conditions, discharged wastewater, and contamination). Although synthetic dyes are intensively used, offer a wide range of colors and hues and properties of adhesion, longevity, and resistance to sunshine and chemical processes, and are cost-effective, they have begun to be restricted by many textile producers because they are nonbiodegradable and have toxic, carcinogenic, and mutagenic effects that generate some imbalances in plant, animal, and human life. Natural dyes of plant and animal origin exhibit very good tolerance to washing, rubbing, and light and are biodegradable and nontoxic; these properties have led to a call for the renewed use of these dyes. Modern analytical techniques (solid-phase extraction, spectrophotometry, HPLC, HPTLC, capillary electrophoresis) with different spectroscopy (UV-Vis, diode-array detection, pulsed amperometric detection) and/or MS/tandem mass spectrometry detectors have an important role in the textile industry in obtaining essential information about dyeing techniques, material origin, historical trade routes of ancient textiles, and environmental pollution. For this purpose, isolation, separation, and quantification methods of natural and synthetic textile dyes from various matrices (ancient and modern fabrics, water, biota, etc.) are presented.

Synthetic dyes are more available than natural dyes were in the past, because of lower prices and wider ranges of bright shades with considerably improved color fastness properties. In current years, concern for the environment has created an increasing demand for natural dyes, which are friendlier to the environment than are synthetic dyes. The aim of this work is to study the effect of dyeing cotton fabrics with both a natural dye (henna) and a synthetic dye (Remazol blue) on some mechanical properties and those of stability to light exposure. The undyed and dyed cotton fabrics were tested for their mechanical behaviors expressed as tenacity (N), elongation %, and work-breaking (N · m). They were also tested for shrinkage and crease recovery angle. The stability to light before and after 100 h exposure was examined by investigating the microstructure [using x-ray diffraction (XRD)] and macrostructure [using a scanning electron microscope (SEM)] and the reflection spectra. The results proved that the cotton samples dyed with Henna dye have higher mechanical properties than those dyed with “Remazol” reactive dye. Moreover, the light fading behaviors of both synthetic and natural dyes were studied in terms of the reflection spectra (400–800 nm), microstructure, and macrostructure of the sample's fibers.

The main goal of the study is to produce eco-friendly furniture dyes by using bio-colorants and to determine the color stability of these dyes in outdoor conditions. In this regard, dye extracts obtained from red beet (Beta vulgaris), safflower (Carthamus tinctorius L.), and purple cabbage (Brassica oleracea), as a bio-colorant source, were applied to MDF test panels by mixing with water-based synthetic lacquer coatings. Also, three different synthetic dyes were applied to MDF test panels in order to compare the results with eco-friendly natural dyes. Natural dyes were mixed with metal and natural mordants such as iron sulfate, aluminum sulfate and vinegar. Lacquer coated test panels, coated with natural and synthetic dyes, were exposed to outdoor conditions for 50 days in Denizli/Turkey in order to assess the change in color. As a result, the maximum color stability occurred in the test panels lacquer coated with synthetic black dye, while the minimum color stability occurred in the test panels lacquer coated with synthetic light blue dye. It was determined that the thickness of the color coating layer applied to test panels increases color stability. It was also observed that the color stability performance of natural dyes is as good as that of synthetic dyes.

Photosensitizers have an important role in increasing the ability to capture light. One of the main components of dye-sensitized solar cells (DSSCs) is dye. In general, DSSC fabrication uses synthetic dyes such as N719 and DN-F01. However, synthetic dyes have the potential to have negative impacts on human health and the environment. In this research, DSSC fabrication was carried out using natural dyes and synthetic dyes at large sizes (one cell with an active area of 18 cm2 and two cells with an active area of 15 cm2). The natural dyes used are anthocyanin from red dragon fruit (dragon fruit dyes) and curcumin from turmeric powder (turmeric dyes). Natural and synthetic dyes were characterized using UV-Vis and FTIR spectroscopy. Meanwhile, DSSC performance was characterized by the I-V meter. The best electrical performance for natural dyes was obtained with an active area of 15 cm2 which was sensitized using turmeric dyes with a performance of Eff = 0.020%, Jsc = 0.142 mA.cm-2, Voc = 0.372 V, and FF = 0.461. Furthermore, the best electrical performance for synthetic dyes was obtained with an active area of 15 cm2 which was sensitized using N719 with a performance of Eff = 0.264%, Jsc = 1.303 mA.cm-2, Voc = 0.510 V, and FF = 0.398. Based on these results, natural dyes are less effective than synthetic dyes, but natural dyes are more environmentally friendly and cheap.

The textile industry releases significant amounts of toxic pollutants. In the aquatic environment, the presence of these compounds can impact fauna and flora. The aim of this study was to verify if synthetic (95% purity) and natural indigo blue dye obtained from Indigofera tinctoria plants pose a risk to the aquatic fauna. To investigate ecotoxicological effects of these dyes at concentration of 100 mg.L-1, adult females and males of Danio rerio were exposed in chronic tests. At the end of the twenty-first day, reproduction was performed to evaluate the endpoints: number of eggs, egg viability, larvae survival, and gonadal histology, and the same experiments were repeated after another 21 days in clean water to evaluate the potential of biological recovery. All of the analyzed reproductive parameters were significantly reduced in the organisms exposed to both synthetic and natural indigo blue dyes in relation to the control, and males exposed to the synthetic dye, and females exposed to both natural and synthetic dyes presented gonadal histological alterations, evidencing an important chronic effect of these substances to the reproduction of D. rerio. After the biological recovery period, organisms exposed to both types of dyes showed histological improvements and they recuperated offspring production, but those exposed to the natural dye showed better reproductive performance. Overall, our findings suggested that levels of natural and synthetic indigo dyes permitted by the current legislations must be reviewed, and the substitution of synthetic by natural indigo whenever possible is recommended.

Both natural and synthetic dyes have gained increasing attention in the leather dyeing process due to environmental and health considerations. This research was designed to determine and compare the antimicrobial efficacy of four natural dyes (Acacia catechu, Trema orientalis, Camellia sinensis, Swietenia macrophylla) with four synthetic dyes (brown BFR, brown NG, brown EDK, red G) to develop safer leather dyeing process. The above eight dyes were evaluated against eight prevalent pathogenic and opportunistic pathogenic bacteria Bacillus megaterium, Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Salmonella sp., Escherichia coli, Shigella sp., Pseudomonas aeruginosa, and four fungi. Dyestuff from Acacia catechu, Trema orientalis, and Swietenia macrophylla was effective against the three Bacillus strains, and Staphylococcus aureus with an inhibition zone extending from 6.3 mm to 11 mm. Synthetic dye brown BFR was effective against the three Bacillus strains, and Staphylococcus aureus with zone diameter of 14.8 mm to 19.7 mm. Brown EDK and Red G showed activity against Bacillus megaterium and Bacillus cereus. Camellia sinensis and brown NG showed no antimicrobial efficacy. Also, all eight dyes showed no antifungal activity. For both types of dyes, the zone of inhibition increased approximately linearly as dye concentrations increased. Of the natural dyes, Acacia catechu showed the highest activity. Brown BFR showed the maximum zone diameter of the eight dyes tested. The results indicated that both natural and synthetic dyes were quite effective. Synthetic dyes had remarkable antibacterial properties compared to natural dyes. These dyes having antimicrobial activity can be used in a safer leather dyeing process.

The aim of this study was to compare the fastness properties and wastewater quality in obtaining the same color on 100% woven wool fabric with natural (madder) and synthetic (1:1 metal complex) dyes. The same color, with similar wet fastness properties, was obtained on the wool fabric when dyed with either dye. On the other hand, conductivity, chemical oxygen demand (COD), and the ammonia nitrogen (NH3-N) content of dyeings carried out with the synthetic dye mixture were considerably higher than dyeing with madder root extract, and its pH was more acidic. However, the amount of volatile suspended solids and color obtained in natural dyeing was higher than the amount in the synthetic dyeing wastewater.

Veneer dyeing is typically carried out to achieve a desired colour in the veneer while allowing the grain to show through or to reduce colour variations and achieve a more uniform appearance. In this study, the influence of dyeing temperature, dyeing time and the addition of mordants on the colour and lightfastness of oak and maple veneers was investigated. Wood veneers were dyed using two synthetic dyes (reactive and acid) and two natural dyes (madder and logwood). The study analysed colour change, colour strength and grain contrast after dyeing, as well as colour stability and depth of colour change after artificial exposure. The results showed that temperature, time, and mordant addition had a greater impact on the colour change and colour strength of veneers dyed with natural dyes compared to those dyed with synthetic dyes. On most veneers, higher grain contrast was achieved at lower dyeing temperature and shorter dyeing time. Additionally, mordants reduced the grain contrast of reactive and natural dyes. Furthermore, veneers dyed with natural dyes exhibited less colour change during artificial exposure compared to those dyed with synthetic dyes. Among the tested dyes, the best lightfastness for oak and maple veneers was achieved with madder natural dye.