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In recent years, the use of biomass for the cost-effective synthesis of nanoparticles has emerged as a promising green technology. Because of their remarkable properties, such as tunable surface plasmon resonance characteristics and high surface areas, bio-synthesised nanomaterials are receiving more scientific and academic attention for their use in various application sectors, especially as catalysts in environmental remediation. Green synthesized nanomaterial's can efficiently contribute to the degradation of a wide range of organic pollutants, including dyes, into harmless by-products. These particles have a cure for recalcitrant organic and inorganic pollutants due to their photocatalytic properties, which largely depend on the production of reactive oxygen species under sunlight or UV illumination. This comprehensive review systematically covers up-to-date knowledge on recent developments in the green synthesis of nanoparticles and composites using plants and microorganisms, unravels underlying mechanisms, and highlights their application areas. It then provides detailed information on their applications in the degradation of potentially toxic organic dyes and the removal of other emerging pollutants, including heavy metals and antibiotics. Finally, the current challenges and perspectives of this technology for future applications are discussed.

Associated environmental hazards with the use of synthetic dyes and toxic metal mordants in the textile industry lead to concerns for alternatives. Natural dyes and biomordants are the new eco-friendly and biocompatible resources for textile coloration obtained from never-ending natural flora. The coloration potential of naphthoquinone-based colorants from Alkanna tinctoria roots on wool was investigated in this study with the application of both metallic mordants as well as biomordants. Color characteristics were evaluated on a spectrophotometer under the D65 illuminant, 10° standard observer, and fastness properties by using standard methods. A wide range of shades was obtained with good color characteristics and fastness results. Iron among metallic mordants, pomegranate peel extract (PPE) and babool among biomordants increased the color yield of dyed wool. Scanning electron microscopy (SEM) confirmed the undamaged physical structure and surface morphology of dyed wool.

The searches for new sources of natural dyes have been recently increased in many countries. This article is aimed to explore the dyeing potential of Cassia fistula as a source of natural dye on wool. In this study, the anthraquinone colorants are extracted from fruit of Cassia fistula by aqueous extraction method. Mordanting and subsequent dyeing of wool with extracted colorants were then performed to study the colorimetric and fastness properties. Three metallic salts aluminum sulfate, ferrous sulfate, stannous chloride and their combinations were used in this study to fix and increase the color as well as fastness properties of the substrate. UV visible and Fourier transform infrared spectroscopy (FTIR) analysis show identification of functional groups in the dye molecule. Colorimetric properties were analyzed by reflectance spectrometry in terms of L*, a*, b*, c*, h○ and K/S values. Color fastness was investigated in terms of light, wash and rub (dry/wet) tests. Results demonstrate that novel and fashionable brown shades with different hue and tone were obtained. Therefore, Cassia fistula has an exciting opportunity to be used as a source of natural dye in textile coloration.

Coloration of textiles with natural dyes involves huge consumption of chemicals; mainly, metal salt mordants, which pose serious environmental challenges. To mitigate this pollution, more and more environmentally friendly, biodegradable, biocompatible and renewable products should be popularized in dyeing industry. This paper proposes a sustainable and metal salt-free dyeing of wool samples by employing natural mordants extracted from pomegranate peel (Punica granatum L), gallnut (Quercus infectoria L) and catechu (Acacia catechu). The color parameters of dyed wool samples were greatly found to be dependent on the chemical compounds present in respective biomordants and their interaction ability with the functional groups of wool and the dye molecules. The investigated biomordants exhibit different interactions with coloring compounds of Butea monosperma (palas) dye resulting in deep brown, olive green, dark brown, cinnamon, burgundy, and yellowish hues on wool. All the biomordants selected in this study improved dye performance and resulted in a broad beautiful spectrum of colors with acceptable fastness properties. The results encourage the search and exploitation of new plant species as a source of biomordants to replace metallic and toxic mordants currently used in textile industry.

In this work, we investigated the use of pomegranate peel extract as an effective functional dye for producing beautiful natural shades on wool and to impart durable antimicrobial properties. Wool is treated with various metal salt mordants in the presence of pomegranate dye under optimum natural dyeing conditions. The structural changes of wool are characterized by SEM and FT-IR techniques. The properties of color strength, color fastness to light, washing, rubbing, and durability of antimicrobial activity to washing are investigated. The experimental results indicate that there is small color variation among shades obtained under identical dyeing conditions. Furthermore, it was found that metal salt mordants improved dyeing depth, fastness properties, and effectively enhanced the durability of antimicrobial activity up to several washing cycles.

This study was undertaken to propose an alternative use of Adhatoda vasica leaves extract as a potential source of natural dye for the coloration of woolen yarn/fibers. Premordanting technique was adopted with double metal salt combinations of ferrous sulfate, stannous chloride, and potassium aluminum sulfate and double biomordant combinations of gallnut, pomegranate, and babool, to achieve dyed textile materials of acceptable colorimetric and fastness properties. Sixty-three sober and elegant shades were developed on wool by varying the nature and the concentration of mordants involved in the combinations. The hue of color developed was found to be in yellow-red coordinate of color space diagram. All the dyed samples presented excellent color strength (K/S) values and highest values were found in case of gallnut + pomegranate peel extract (PPE) combination. Biomordants produced altogether different behavior in comparison to metal mordants in the development of ecofriendly shades of different hue and tune. Majority of the dyed samples showed excellent fastness properties with respect to light, washing, and rubbing which confirmed the possibility of using A. vasica leaves extract as an effective yellow natural dye.

The present article focuses on the effect of different combinations of metal mordants on color characteristics and fastness properties of natural dye extracted from Juglan regia L bark powder. The influence of different types of mordant combinations such as alum + ferrous sulphate, alum + stannous chloride, ferrous sulphate + stannous chloride, and alum + ferrous sulphate + stannous chloride on color parameters has been investigated in terms of CIELab (L*, a*, b*, c*, and h°) and K/S values. The fastness properties with respect to light, washing, and crocking of developed shades were determined according to ISO and AATCC test methods. Based on the experimental results, it has been found that 96 shades with novel and fashionable hues were produced by the use of these metal salt combinations. It was also found that all mordanted samples had satisfactory light and wash fastness ratings. Dry rub fastness was found relatively better than wet rub fastness.

This study was undertaken to propose alternative use for teak leaves, a timber industry byproduct, as potential dyeing source for wool fibers. The coloring potential of anthraquinone colorants from teak leaves were studied on wool with pre-mordanting method using double and triple mix metal salt combinations (ferrous sulphate, stannous chloride and potassium aluminum sulphate) as mordants. Thirty-six sober and elegant shades were developed on wool by varying the type of metal involved in combination as well as concentration of the dye. The hue of color developed ranged from light orange—brown to dark brown. The color strength (K/S) has been found to be very good in dyed woolen yarn samples and particularly was highest for iron + alum combination. Color fastness with respect to light exposure washing, rubbing for the developed shades ranged between good to very good, which confirmed the possibility of using waste leaves of Tectona grandis as a source of effective brown natural dye.

Synthetic dyes produce wide range of shades, but some of them especially azo dyes have been recently discovered to cause severe human health and environmental problems. This has motivated research activities in the exploitation of dyes from natural products for the coloration of different textile materials. In the present investigation, Indian rhubarb (Rheum emodi) was used as a source of natural dye for the development of deep and bright shades on premordanted woollen yarn samples. Dyeing experiments were carried on wool samples pretreated with different combinations of natural and chemical mordants such as 2.5% myrobalan + 10% alum, 2.5% myrobalan + 2% iron, and 2.5% myrobalan + 0.5% tin. The light, wash, and rub fastness properties of dyed woollen yarn samples were evaluated along with the determination of lightness (L*), chroma (c*), hue angle (h°), and strength (K/S) values using 8% concentration of Indian rhubarb dye.