Nitrated aromatic compounds, the ubiquitous nitrogen-containing organic pollutants, impact the environment and organisms adversely. As industrial raw materials and intermediates, nitrated aromatic compounds and their aromatic precursors are widely employed in the industrial production activities. Nevertheless, their emission from industrial waste gases has so far not been studied extensively. In this study, the concentrations of 12 nitrated aromatic compounds in the particle and gas phases downwind of 16 factories encompassing eight industries (i.e., pharmaceutical, weaving and dyeing, herbicide, explosive, painting, phenolic resin, paper pulp and polystyrene foam industries), were determined by ultra-high-performance liquid chromatography-mass spectrometry. Their concentrations in the particle and gas phases from different factories ranged from 114.7 ± 63.5 to 296.6 ± 62.5 ng m⁻³ and 148.7 ± 7.4 to 309.8 ± 26.2 ng m⁻³, respectively, thus, exhibiting significantly high concentrations as compared to the background sites. Among the 12 detected species, 4-nitrophenol, 5-nitrosalicylic acid, 3-nitrosalicylic acid and 4-methyl-2,6-dinitrophenol were observed to be the predominant species, with total fractions up to 47.9–72.3% and 63.1–70.3% in the particle and gas phases, respectively. Their emission profiles with respect to the industrial activities exhibited large discrepancies as compared to the combustion sources, thus, indicating different formation mechanisms. The emission ratios of particulate nitrated aromatic compounds owing to the industrial activities were estimated between 0.5 ± 0.2 and 4.3 ± 1.5 ng μg⁻¹, which were higher than or comparable to those from various combustion sources. The findings from this study confirm the industrial emission to be an important source of nitrated aromatic compounds in the atmosphere. The substantial emissions of nitrated aromatic compounds from various industries reported in this study provide the fundamental basis for further emission estimation and pollution control.

Dyeing wastewaters are toxic and carcinogenic to both aquatic life and human beings. Adsorption technology, as a facile and effective method, has been extensively used for removing dyes from aqueous solutions for decades. Numerous researchers have attempted to seek or design alternative materials for dye adsorption. However, using various novel adsorbents to remove dyes has not been extensively reviewed before. In this review, the key advancement on the preparation and modification of novel adsorbents and their adsorption capacities for dyes removal under various conditions have been highlighted and discussed. Specific adsorption mechanisms and functionalization methods, particularly for increasing adsorption capacities are discussed for each adsorbent. This review article mainly includes (1) the categorization, side effects and removal technologies of dyes; (2) the characteristics, advantages and limitations of each sort of adsorbents; (3) the functionalization and modification methods and controlling mechanisms; and (4) discussion on the problems and future perspectives about adsorption technology from adsorbents aspects and practical application aspects.

A suite of eight polyhalogenated carbazole (PHCZ) congeners were detected in sediments of the Jiaozhou Bay wetland. 3,6-dichlorocarbazole (36-CCZ), and 3,6-dibromocarbazole (36-BCZ) were detected in all samples. The concentrations of ΣPHCZs ranged from 6.9 to 33.4 ng/g dry weight (dw). The recovery of surrogate standard ranged from 85 to 109%. Significant relationships were found between the concentrations of 36-CCZ and those of the other three detected compounds (36-BCZ, 36-ICZ, and 1368-BCZ). However, with regard to the other chemicals, only 1368-BCZ was related to 36-ICZ. The toxic equivalent (TEQ) was used to assess the relative toxicity of PHCZs, which ranged within 0.1–3.9 pg TEQ/g dw in sediment. The inventory of ΣPHCZs was 58.9 kg. These results indicate that PHCZs are widely distributed in the Jiaozhou wetland and the dyeing and finishing industries may be important contamination sources of PHCZs.

Environmentally friendly products are the need of the hour, particularly in this pandemic situation because synthetic products need such toxic chemicals for their formulation and finishing which are carcinogenic for the globe. The current study is the utilization of waste black tea leaf (BT)–based tannin brown natural colorant for silk dyeing using microwave treatment. Dye (tannin) has been isolated in various media before and after microwave treatment up to 6 min and applied at various conditions. It has been found that 30 mL of aqueous extract of 3.0 pH obtained from 6.0 g of powder containing 3.0 g/100 mL of salt as an exhausting agent after microwave treatment for 5 min, when employed at 55 °C for 45 min, has given good color yield onto silk. Iron (3%) and acacia extract (2%) as pre-chemical and bio mordant, iron (2%) and pomegranate extract (2%) as post chemical and bio-mordant, and Al (3 %) and pomegranate extract (3%) as meta chemical and bio-mordant have given new shades with good to excellent fastness ratings. It is inferred that waste black tea leaves (BTs) in an aqueous medium have an excellent potential to serve as a source of natural tannin brown dye for the coloration of surface-modified silk fabrics under the influence of cost, energy, and time-effective microwave treatment. Additionally, the utilization of a low amount of sustainable chemical and bio-mordants has valorized the dyeing of silk by developing soothing and sustainable shades with good fastness properties.

The indigo blue dye is widely used in the textile industry, specifically in jeans dyeing, the effluents of which, rich in organic pollutants with recalcitrant characteristics, end up causing several environmental impacts, requiring efficient treatments. Several pieces of research have been conducted in search of effective treatment methods, among which is electrocoagulation. This treatment consists of an electrochemical process that generates its own coagulant by applying an electric current on metallic electrodes, bypassing the use of other chemical products. The purpose of this study was to evaluate the potential use of iron slag in the electrocoagulation of a synthetic effluent containing commercial indigo blue dye and the effluent from a textile factory. The quantified parameters were color, turbidity, pH, electrical conductivity, sludge generation, phenol removal, chemical oxygen demand (COD), and total organic carbon (TOC). The electrocoagulation treatment presented a good efficiency in removing the analyzed parameters, obtaining average removal in the synthetic effluent of 85% of color and 100% of phenol after 25 min of electrolysis. For the effluent from the textile factory, average reductions of 80% of color reaching 177.54 mg Pt CoL⁻¹, 91% of turbidity reaching 93.83 NTU (nephelometric turbidity unit), 100% of phenol, 55% of COD with a final concentration of 298.8 mg O₂ L⁻¹, and 73% of TOC with a final concentration of 56.21 mg L⁻¹, in 60 min of electrolysis. The reduced time for removal of color and phenolic compounds in synthetic effluent demonstrates the complexity of treating the real effluent since to obtain removals of the same order a 60-min period of electrolysis was necessary. The results obtained demonstrate the potential of using iron slag as an electrode in the electrocoagulation process in order to reuse industrial waste and reduce costs in the treatment and disposal of solid waste. Thus, the slag can be seen as an alternative material to be used in electrocoagulation processes for the treatment of effluents from the textile industry under the experimental conditions presented, its only limitation being the fact that it is a waste and therefore does not have a standardization in the amounts of iron present in the alternative electrodes.

Sustainability in all applied fields particularly in textiles is to protect our globe, environment, and community, where green dyed products are playing their role. For the current study, Esfand (Peganum harmala) has been explored using a green isolation tool, i.e., ultrasonic (U.S.) rays, and applied onto fabric. Different dyeing parameters have been explored statistically through response surface methodology by employing temperature (50–80°C), time (25–65 min), extract volume (15–55 mL), salt (1–5 g/100 mL), and dye bath pH (4–7) through series of experiments. For developing new shades, green mordants such as elaichi, neem, turmeric, and zeera have been utilized. It has been found that exposure of 35 mL extract of 7 pH containing 3 g/100 mL of salt as exhausting agent to U.S. rays for 30 min for the dyeing of silk at 70°C for 45 min has given maximum color strength with reddish-yellow shades. Color characteristics obtained in the CIE Lab system reveal that 5% of turmeric as meta bio-mordant has given good quality reddish-yellow shades. It is found that U.S. rays have not only good potential to isolate colorant followed by dyeing of silk under reduced condition but also the application of bio-mordants have made the process more greener, sustainable, and cleaner.

In the current pandemic scenario, sustainable green products particularly antiviral, antioxidant, and antibacterial in nature are gaining worldwide fame in almost every walk of life. Cassia obovata (C. obovata) has been valorized as a source of yellow natural dye for nylon dyeing. For the isolation of dye extracts and for surface tuning, nylon fabrics were treated with microwave rays up to 10 min. For getting new shades with good to excellent fastness characteristics, sustainable bio-mordants in comparison with chemical mordants have been used at 60 °C, 70 °C, and 80°C. It has been found that for getting effective colorant yield, acidic extract should be exposed to MW ray treatment up to 6 min, and for getting improved fastness rating, bio-mordants have given excellent color characteristics. Statistical optimization of dyeing variable shows that application of 40 mL of C. obovata acidic extract of RE of 6 pH containing 3 g/100 mL of salt when employed at 55 °C for 45 min has given excellent results onto irradiated nylon fabric (RNF). It is inferred that Cassia obovata has an excellent potential for coloration of surface-modified fabrics, where the application of low amount of bio-mordants under statistical optimized conditions has made process more ecological, economical, and sustainable.

Natural products particularly natural colorants have attained worldwide importance and being eco-friendly can be considered an alternative to toxic dyes in order to reduce environmental pollution. The current study is based on the exploration of natural coloring behavior of bitter gourd leaves extract for cotton dyeing. Colorant was extracted using different extraction media like aqueous, alkali, organic, and acidic at different conditions. It has been found that on application of 50 ml of acidic extract having 6 g/100 ml of table salt for 55 min at 60 C°, maximum color yield has been obtained onto cotton. Upon using chemical and bio-mordants, new shade with good color fastness rating was obtained. FTIR analysis of extract showed the presence of flavonoids. It is concluded that under mild condition, bitter gourd leaves extract can be considered potential source of natural colorant for cotton dyeing and the presence of bio-mordant has made the process more soothing and sustainable in nature.

Ecofriendly exploration of Arjun bark (Terminalia arjuna) is a herbal natural colorant for cotton dyeing. This is because the demand for natural dyes has been increased worldwide due to their therapeutic usage and other food, textiles, agriculture, engineering, and medical applications. Therefore, this study has been carried out due to the isolation of colorant from Arjun bark in an acidified methanolic medium after exposure to ultrasonic rays up to 60 min. Additionally, using bio-mordants, it has been found that the application of 10% of Zeera (Cuminum cyminum) extract as meta-bio-mordant, 3% of Ilaichi (Elettaria cardamomum) extract as meta-bio-mordant, and10 % of Harmal (Peganum harmala) and Neem (Azadirachta indica) extract as meta-bio-mordants has given excellent color strength. These bio-mordants have not only made the coloration process more eco-friendly, viable, and greener, but also improved color strength with various tonal effects from red to reddish brown shades. Thus, it has been found that ultrasonic treatment as an environment-friendly tool has not only enhanced the color strength of natural colorant isolated from Arjun bark onto the cotton fabric under mild conditions.

Sustainability in the utilization of products in all fields particularly food textiles, solar cells, etc. is of prime concern to the global community. In this study, licorice (Glycyrrhiza glabra L.) as a source of herbal-based coloring agent for cotton dyeing has been explored under the influence of ultrasonic (US) waves. Methanolic extract of licorice bark after US treatment for 20 min has shown excellent color depth (K/S) onto ultrasonically treated cotton fabric at 65°Cfor 45 min. Applying bio-mordants, it has been found that acacia extract (1%), henna (5%), and pomegranate and turmeric extracts (7%) as pre-bio-mordant, whereas acacia, turmeric, and henna extracts (7%) and pomegranate extract (5%) as post-bio-mordants, exhibited superb color strength. Salts of Al (7%) and salts of Fe (3%) as pre chemical mordants, while salts of Al (3%) and salts of Fe (5%) as post chemical mordants, have given good results. Overall, it has been found that salt of Fe (3%) as pre-chemical mordant and extract of turmeric (7%) as post bio-mordant have shown superb color strength. It can be concluded that US treatment being an environmentally safe means has only improved the color strength of colorant onto cotton fabric and the adding of bio-mordants has contrived the method more sustainable.