The growing population and urbanization have adversely affected the environment including water. The waste water from industries has affected not only human but also animals. The availability of clean water is one of the foremost needs for living organism. This makes very urgent to find reliable solutions for cleaning waste water. These days catalysis is one the best solutions to remove and degrade organic pollutants. In this work, porous composite polymer films have been designed through facile method which were employed to stabilize zero-valent metal nanoparticles (NPs). The sustainable, environmentally friendly polymer matrix with attached metal NPs was applied for the effective catalytic degradation of both phenolic compounds and organic dyes. The different composite films consist of ZnO NPs embedded in an Oxidized Alginate-Chitosan (OAlg-CS) biomatrix named as OAlg-CS/ZnO with various percentages of ZnO as a support for metallic Cu NPs. The ZnO NPs have been incorporated into OAlg-CS polymer with 10, 15, and 20 wt% and are designated as OAlg-CS/ZnO-10, OAlg-CS/ZnO-15, OAlg-CS/ZnO-20. Various analytical techniques were utilized to investigate the shape, morphology, elemental composition, functional groups and stability of the composite films. All these polymer nanocomposite films were then evaluated for removal of model organic pollutants comprising p-nitrophenol (4-NP), methylene blue (MB), and methyl orange (MO). The Kapp value for 4-NP was 2.19 × 10-1 min-1, 4.68 × 10-1 min-1 for MO and 8.99× 10-1 min-1 for MB. The experimental results demonstrated that OAlg-CS/ZnO-20 films show the highest catalytic activity as compared to OAlg-CS/ZnO, OAlg-CS/ZnO-10, and OAlg-CS/ZnO-15. The order of rate constants for nitrophenol and dyes using OAlg-CS/ZnO-20 was found to be MB ˃ MO ˃ 4-NP, showing the selectivity of these composite films. The prepared composite films were also investigated for their antibacterial activity against Gram-positive and Gram-negative bacteria and all the films exhibited good anti-bacterial activity, with OAlg-CS/ZnO-20 showed the highest anti-bacterial activity.

Acid mine drainage (AMD) is one of the main environmental problems associated with mining activity, whether the mine is operational or abandoned. In this work, several precipitates from this mine drainage generated by the oxidation of sulfide minerals, when exposed to weathering, were used as adsorbents. Such AMD precipitates from abandoned Portuguese mines (AGO, AGO-1, CF, and V9) were compared with two raw materials from Morocco (ClayMA and pyrophyllite) in terms of their efficiency in wastewater treatment. Different analytical techniques, such as XRD diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), N2 adsorption isotherms, and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) were used to characterize these natural materials. The adsorption properties were studied by optimizing different experimental factors, such as type of adsorbent, adsorbent mass, and dye concentration by the Box-Behnken Design model, using methylene blue (MB) and crystal violet (CV) compounds as organic pollutants. The obtained kinetic data were examined using the pseudo-first and pseudo-second order equations, and the equilibrium adsorption data were studied using the Freundlich and Langmuir models. The adsorption behavior of the different adsorbents was perfectly fitted by the pseudo-second order kinetic model and the Langmuir isotherm. The most efficient adsorbent for both dyes was AGO-1 due to the presence of the cellulose molecules, with qm equal to 40.5 and 16.0 mg/g for CV and MB, respectively. This study confirms the possibility of employing AMD precipitates to adsorb organic pollutants in water, providing valuable information for developing future affordable solutions to reduce the wastes associated with mining activity.

The oxidation of multi-walled carbon nanotubes (MWCNTs) using cold plasma was investigated for their subsequent use as adsorbents for the removal of dyes from aqueous solutions. The properties of MWCNTs after plasma modification and their adsorption capacities were compared with pristine and chemically oxidized nanotubes. The modification process employed a reactor where plasma was generated through dielectric barrier discharges (DBD) powered by high-voltage nanosecond pulses. Various modification conditions were examined, such as processing time and pulse voltage amplitude. The degree of oxidation and the impact on the chemistry and structure of the nanotubes was investigated through various physicochemical and morphological characterization techniques (XPS, BET, TEM, etc.). Maximum oxidation (O/C = 0.09 from O/C = 0.02 for pristine MWCNTs) was achieved after 60 min of nanopulsed-DBD plasma treatment. Subsequently, the modified nanotubes were used as adsorbents for the removal of the dye methylene blue (MB) from water. The adsorption experiments examined the effects of contact time between the adsorbent and MB, as well as the initial dye concentration in water. The plasma-modified nanotubes exhibited high MB removal efficiency, with adsorption capacity proportional to the degree of oxidation. Notably, their adsorption capacity significantly increased compared to both pristine and chemically oxidized MWCNTs (~54% and ~9%, respectively). Finally, the kinetics and mechanism of the adsorption process were studied, with experimental data fitting well to the pseudo-second-order kinetic model and the Langmuir isotherm model. This study underscores the potential of plasma technology as a low-cost and environmentally friendly approach for material modification and water purification.

Archaeological textiles represent precious remains from ancient culture; this is because of the historical and cultural importance of the information that can be obtained by such relics. However, the extremely complicated state of preservation of these textiles, which can be charred, partially or totally mineralized, with heavy soil or biological contamination, requires highly specialized and sensitive analytical tools to perform a comprehensive study. Starting from these considerations, the paper presents a combined workflow that provides the extraction of dyes and keratins and keratin-associated proteins in a single step, minimizing sampling while maximizing the amount of information gained. In the first phase, different approaches were tested and two different protocols were found suitable for the purpose of the unique workflow for dyes/keratin-proteins: a slightly modified urea protocol and a recently proposed new TCEP/CAA procedure. In the second step, after the extraction, different methods of cleanup and workflow for proteins and dyes were investigated to develop protocols that did not result in a loss of aliquots of the analytes of interest and to maximize the recovery of both components from the extracting solution. These protocols investigated the application of two types of paramagnetic beads, unmodified and carboxylate-coated hydrophilic magnetic beads, and dialysis and stage-tip protocols. The newly designed protocols have been applied to cochineal, weld, orchil, kermes, and indigo keratin-based dyed samples to evaluate the effectiveness of the protocols on several dye sources. These protocols, based on a single extraction step, show the possibility of investigating dyes and keratins from a unique sample of 1 mg or lesser, with respect to the thresholds of sensitivity and accuracy required in the study of textile artifacts of historical and artistic values.

Dye industry plays an essential role in industrial development, contributing significantly to economic growth and progress. However, its rapid expansion has led to significant environmental concerns, especially water pollution and ecosystem degradation due to the discharge of untreated or inadequately treated dye effluents. The effluents introduce various harmful chemicals altering water quality, depleting oxygen levels, harming aquatic organisms, and disrupting food chains. Dye contamination can also persist in the environment for extended periods, leading to long-term ecological damage and threatening biodiversity. Therefore, the complex effects of dye pollutants on aquatic ecosystems have been comprehensively studied. Recently, zebrafish (Danio rerio) has proved to be an effective biomedical model for this study due to its transparent embryos allowing real-time observation of developmental processes and genetic proximity (approx. 87%) to humans for studying diverse biological responses. This review highlights the various toxicological effects of industrial dyes, including cardiovascular toxicity, neurotoxicity, genotoxicity, hepatotoxicity, and developmental toxicity. These effects have been observed at different developmental stages and dye concentrations in zebrafish. The review underscores that the structure, stability and chemical composition of dyes significantly influence toxicological impact, emphasizing the need for detailed investigation into dye degradation to better understand and mitigate the environmental and health risks posed by dye pollutants.

The art of dyeing fabrics is one of the oldest human activities. In order to improve the fastness properties of dyeing products, various additives are added to optimize the uniformity of fibers and surfaces and improve dye distribution. Unfortunately, these additives can be harmful and very often are not biodegradable. This article reports on the possibility of using a natural additive for dyeing textiles: a polysaccharide extracted from the prickly pear cactus (Opuntia ficus indica). One type of fabric was tested, silk, with different colors. Several samples were prepared and dyed for each color, adding the same additives but also a commercial chemical aid for one of them and the mucilage of Opuntia for another. The fastness of the applied dyes was evaluated by washing at different temperatures with a common liquid detergent. All samples were analyzed before and after washing with a colorimeter to evaluate the color changes. The results of the analyses reported and compared indicate the potential of prickly pear mucilage as an additive for dyeing silk, which is easily accessible, safe, and sustainable compared to other commonly used additives.

Organic anionic dyes are major water pollutants due to their low degradability caused by complex aromatic structures. Not only do they exert toxic, mutagenic, teratogenic, tumorigenic, and genotoxic effects, but they also decrease fertility and cause irritation to the skin and respiratory system in humans. This long-term toxicity has detrimental effects on aquatic organisms and their surroundings, resulting in an imbalanced ecosystem. In this study, a Cs@Fe3O4 magnetic biosorbent was synthesised to uptake three anionic dyes and characterised for FTIR, BET/BJH, XRD, TGA, VSM, and FESEM analyses. The biosorbent average surface area was confirmed to be 52.6524 m2/g, with average pore sizes of 7.3606 nm and 6.9823 nm for adsorption-desorption processes, respectively. Batch adsorption studies pH values, contact times, temperature, initial dye concentrations, and adsorbent dosages were examined. Several isotherm and kinetic models were studied to determine the adsorption mechanism. The adsorption data of these dyes at equilibrium was observed to match Langmuir\'s isotherm and pseudo-second-order kinetic models. The thermodynamic study revealed that the adsorption process for these dyes was an exothermic reaction. Maximum adsorption capacities for congo red, methyl orange, and metanil yellow were 117.77 mg/g, 137.77 mg/g, and 155.57 mg/g, respectively. The reusability of recovered Cs@Fe3O4 after dye adsorption was evaluated up to five continuous adsorption-desorption cycles for its possible industrial applications.

Dyes have conventionally been used in medicine for staining cells, tissues, and organelles. Since these compounds are also known as photosensitizers (PSs) which exhibit photoresponsivity upon photon illumination, there is a high desire towards formulating these molecules into nanoparticles (NPs) to achieve improved delivery efficiency and enhanced stability for novel imaging and therapeutic applications. Furthermore, it has been shown that some of the photophysical properties of these molecules can be altered upon NP formation thereby playing a major role in the outcome of their application. In this review, we primarily focus on introducing dye categories, their formulation strategies and how these strategies affect their photophysical properties in the context of photothermal and non-photothermal applications. More specifically, the most recent progress showing the potential of dye supramolecular assemblies in modalities such as photoacoustic and fluorescence imaging, photothermal and photodynamic therapies as well as their employment in photoablation as a novel modality will be outlined. Aside from their photophysical activity, we delve shortly into the emerging application of dyes as drug stabilizing agents where these molecules are used together with aggregator molecules to form stable nanoparticles.

Motivated by sustainability and environmental protection, great efforts have been paid towards water purification and attaining complete decolorization and detoxification of polluted water effluent. Textile effluent, the main participant in water pollution, is a complicated mixture of toxic pollutants which seriously impact human health and the entire ecosystem. Developing effective materials for potential removal of the water contaminants is urgent. Recently, cryogels have been applied in wastewater sectors due to their unique physiochemical attributes(e.g. high surface area, lightweight, porosity, swelling-deswelling, and high permeability). These features robustly affected the cryogel\'s performance, as adsorbent material, particularly in wastewater sectors. This review serves as a detailed reference to the cryogels derived from biopolymers and applied as adsorbents for the purification of textile drainage. We displayed an overview of: the existing contaminants in textile effluents (dyes and heavy metals), their sources, and toxicity; advantages and disadvantages of the most common treatment techniques (biodegradation, advanced chemical oxidation, membrane filtration, coagulation/flocculation, adsorption). A simple background about cryogels (definition, cryogelation technique, significant features as adsorbents, and the adsorption mechanisms) is also discussed. Finally, the bio-based cryogels dependent on biopolymers such as chitosan, xanthan, cellulose, PVA, and PVP, are fully discussed with evaluating their maximum adsorption capacity.

Dye decolorization through biological treatment techniques has been gaining momentum as it is based on suspended and attached growth biomass in both batch and continuous modes. Hence, this review focused on the contribution of moving bed biofilm reactors (MBBR) in dye removal. MBBR have been demonstrated to be an excellent technology for pollution extraction, load shock resistance, and equipment size and energy consumption reduction. The review went further to highlight different biocarrier materials for biofilm development this review identified biochar as an innovative and environmentally friendly material produced through the application of different kinds of reusable or recyclable wastes and biowastes. Biochar as a carbonized waste biomass could be a better competitor and environmentally friendly substitute to activated carbon given its lower mass costs. Biochar can be easily produced particularly in rural locations where there is an abundance of biomass-based trash. Given that circular bioeconomy lowers dependency on natural resources by turning organic wastes into an array of useful products, biochar empowers the creation of competitive goods. Thus, biochar was identified as a novel, cost-effective, and long-term management strategy since it brings about several essential benefits, including food security, climate change mitigation, biodiversity preservation, and sustainability improvement. This review concludes that integrating two treatment methods could greatly lead to better color, organic matter, and nutrients removal than a single biological MBBR treatment process.