This study was aimed at evaluating the removal of different cationic dyes onto phosphoric acid-activated coconut shell carbon. The activated carbon was characterized for surface functional groups, thermal decomposition profiles, surface morphology, and textural properties. The specific area was recorded as 1,221 m2/g with 100% mesoporosity. On molecular basis, the activated carbon adsorbs malachite green, methylene blue, and rhodamine B at maximum capacities of 1.52 mmol/g, 0.80 mmol/g, and 0.58 mmol/g, respectively. It indirectly implies the selectivity of activated carbon toward malachite green, and behaves differently due to steric hindrance of dye molecules. All equilibrium data obeyed Langmuir model, while the kinetic data are closely fitted to pseudo-second order model as concentration increases. To conclude, coconut shell activated carbon is more effective to remove malachite green compared to methylene blue and rhodamine B.
This paper is expected to give a further insight into the valorization of coconut shell into activated carbon, and its re-purpose for the remediation of dye-contaminated streams, for which methylene blue, malachite green and rhodamine B were used as model pollutants. This study aims to contribute to the growing body of research on the selective removal of malachite green over the other two dyes onto coconut shell activated carbon, which to the best of our knowledge is still absent in the open literature.

The escalating issue of environmental pollutants necessitates efficient, sustainable, and innovative wastewater treatment technologies. This review comprehensively analyzes the mechanisms and isotherms underlying the adsorption processes of semi-interpenetrating polymer network (semi-IPN) polysaccharide-based hydrogels to remove heavy metal ions and dyes from wastewater. Polysaccharides are extensively utilized in hydrogel synthesis due to their biocompatibility, cost-effectiveness, and non-toxic nature. The synthesis of these hydrogels as semi-IPNs enhances their mechanical and structural robustness and adsorption capacity. This review explores the key parameters affecting adsorption performance, including pH, temperature, contact time, and adsorbent dosage. Findings highlight that semi-IPN polysaccharide-based hydrogels exhibit remarkable adsorption capabilities through electrostatic interactions, ion exchange, and surface complexation. Furthermore, this review highlights the distinct advantages of semi-IPNs over other polymer networks. Semi-IPNs offer improved mechanical stability, higher adsorption efficiencies, and better reusability, making them a promising solution for wastewater treatment. Detailed isotherm models, including Langmuir and Freundlich isotherms, were studied to understand these hydrogels\' adsorption behavior and capacity for different pollutants. This study highlights the potential of semi-IPN polysaccharide-based hydrogels as effective adsorbents for heavy metals and dyes and as a promising solution for mitigating environmental pollution. The insights provided herein contribute to developing advanced materials for environmental remediation, aligning with global sustainability goals, and advancing wastewater treatment technology.

Mechanochromic materials provide optical changes in response to mechanical stress and are of interest in a wide range of potential applications such as strain sensing, structural health monitoring, and encryption. Advanced manufacturing such as 3D printing enables the fabrication of complex patterns and geometries. In this work, classes of stretchable mechanochromic materials that provide visual color changes when tension is applied, namely, dyes, polymer dispersed liquid crystals, liquid crystal elastomers, cellulose nanocrystals, photonic nanostructures, hydrogels, and hybrid systems (combinations of other classes) are reviewed. For each class, synthesis and processing, as well as the mechanism of color change are discussed. To enable materials selection across the classes, the mechanochromic sensitivity of the different classes of materials are compared. Photonic systems demonstrate high mechanochromic sensitivity (Δnm/% strain), large dynamic color range, and rapid reversibility. Further, the mechanochromic behavior can be predicted using a simple mechanical model. Photonic systems with a wide range of mechanical properties (elastic modulus) have been achieved. The addition of dyes to photonic systems has broadened the dynamic range, i.e., the strain over which there is an optical change. For applications in which irreversible color change is desired, dye-based systems or liquid crystal elastomer systems can be formulated. While many promising applications have been demonstrated, manufacturing uniform color on a large scale remains a challenge. Standardized characterization methods are needed to translate materials to practical applications. The sustainability of mechanochromic materials is also an important consideration.

A scalable and cost-effective solution for removing pollutants from water is to use biodegradable and eco-friendly sorbents that are readily available such as starch. The current research explored the removal of crystal violet (CV) dye from water using chemically modified potato starch. The adsorbent was prepared by cross-linking potato starch with sodium trimetaphosphate (STMP). The impact of various operating factors including pH, temperature, contact time, initial CV concentration, and adsorbent dosage on the removal of CV were investigated using batch experiments. The adsorption data were analyzed using a fuzzy regression approach, which provided a range-based representation of the model\'s output. The cross-linked starch adsorbent was mesoporous, with a mean pore diameter of 9.8 nm and a specific surface area of 2.7 m2/g. The adsorption of CV by the STMP cross-linked potato starch was primarily influenced by the adsorbent dosage, followed by the solution pH, temperature, initial CV concentration, and contact time. The fuzzy regression model accurately predicted the independent experimental data of CV removal with an R2 of 0.985, demonstrating its value as a tool for the continuous monitoring of CV removal as well as optimizing water treatment conditions.

This study demonstrated the synthesis of Fe2MnO4 modified by citric acid, a biodegradable acid, using a simple co-precipitation method. Characterization was performed using qualitative analysis techniques such as Fourier-transformed infrared spectroscopy, scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, X-ray diffraction, selected-area electron diffraction, N2 adsorption-desorption, and zero-point charge. The prepared nanoparticles had a rough and porous surface, and contained oxygenous (-OH, -COOH, etc.) functional groups. The specific surface area and average pore size distribution were 83 m2/g and 5.17 nm, respectively. Net zero charge on the surface of the prepared nanoparticles was observed at pH 7.5. The prepared nanoparticles were used as an adsorbent to remove methylene blue dye from water under various conditions. Using small amounts of the adsorbent (2.0 g/L), even a high concentration of MB dye (60 mg/L) could be reduced by about ~58%. Exothermic, spontaneous, feasible, and monolayer adsorption was identified based on thermodynamics and isotherm analysis. Reusability testing verified the stability of the adsorbent and found that the reused adsorbent performed well for up to three thermal cycles. Comparative analysis revealed that the modified adsorbent outperformed previously reported adsorbents and unmodified Fe2MnO4 in terms of its partition coefficient and equilibrium adsorption capacity under different experimental conditions.

In this study, it was aimed to analyze the effects of liposomes on the dyeing of polyacrylonitrile fabrics. For this purpose, firstly liposome synthesis was carried out, and then liposome production was confirmed by Fourier transform infrared spectroscopy analysis. Additionally, zeta potential measurements were carried out to see whether stable structures were formed. Then, a selected basic dye was encapsulated with a liposome and the possibilities of using these capsules as alternative to retarders in the dyeing of polyacrylonitrile fabrics were examined. According to results obtained, it can be said that the 1% solution of synthesized liposomes creates a more stable suspension with a polydispersity index of 0.472 and the average particle size of 165.2 nm. On the other hand, it has been revealed that if 1% liposome is used in dyeing, a kind of retarder effect can be achieved in the dyeing of polyacrylonitrile fabrics. Moreover, it can be said that the decrease in color efficiency, that is, the loss of yield, caused by the use of liposome at the end of dyeing is lower compared to the retarder. This is also a very important issue, because a good retarder is expected to slow down the dye uptake, but not reduce the dye intake too much at the end of the dyeing. Dyeing levelness (%) was found to be 96.1, 97.4, and 97.1 for dyeings without auxiliary, with 1% cationic retarder and with 1% liposome, respectively. Beyond this, no significant difference was observed in terms of fastness of dyeing.

Pharmaceuticals and personal care products and dyes have low biodegradability and high toxicity, seriously threaten the human health and ecological environment. Therefore, seeking effective removal methods has become the focus of research. In this study, silver-based metal-organic framework (Ag-MOF) and chitosan (CS) hybrid adsorbent (Ag-MOF-CS) was synthesized via solvothermal one-pot synthesis to remove diclofenac sodium (DCF) and acid Red 1 (AR1) from water for the first time. The morphology and structure of Ag-MOF-CS were confirmed by various characterizations. The effect on adsorption was investigated by changing the adsorbent dosage, pH and other conditions. The adsorption kinetics, adsorption isotherms and thermodynamics were analyzed. Ag-MOF-CS showed a high adsorption capacity. And the maximum adsorption capacity of Ag-MOF-CS for DCF and AR1 was 351.75 mg/g and 678.83 mg/g, respectively. The adsorbent bound to DCF and AR1 may via electrostatic forces, π-π interactions, hydrogen bonding. Even after four cycles of Ag-MOF-CS, the DCF removal can still be higher than 80 %. The eco-friendly Ag-MOF-CS demonstrated significant potential for utilization in treating wastewater.

In the United States, illicit fentanyl is often trafficked as blue tablets mimicking the legitimate M-30 oxycodone tablet produced by Mallinckrodt. The analysis of dyes extracted from seized fentanyl tablets could provide a useful tool for law enforcement to establish linkages between cases and could prove useful for attributing a seizure to a given trafficking organization. Fentanyl tablet seizures associated with a particular drug trafficking organization (DTO), either through investigative or intelligence information, were used as the sample set for this study. The blue dye from the tablets was isolated by solid phase extraction and then qualitatively and quantitatively analyzed via ultraviolet-visible spectroscopy. This research revealed that the illicit tableting facilities use a different dye than several known pharmaceutical companies. The concentration of dye in individual tablets within a seizure proved to be very minimal, and the small sample size made it difficult to draw linkages from case to case. Analysis of the dyes could not effectively differentiate between the drug trafficking organizations in the tested population due to each DTO using the same dye; however, it is important to note that the dye found was consistent between illicit tablets.

Neuromuscular blocking drugs (NMBAs) and Patent Blue V dye sodium salt 2.5% (Guerbet, Roissy, France) are frequently implicated in perioperative allergic immunoglobulin E (IgE) mediated anaphylaxis. Most cases of anaphylaxis during surgery occur at induction of anaesthesia, although reactions to vital dyes injected into soft tissues often show a delayed onset. We present the case of a female in her 60s who suffered perioperative anaphylaxis to Patent Blue V dye and possibly suxamethonium during oncological breast surgery. Allergy clinic follow-up confirmed sensitivity to both drugs which may explain the unusual bi-phasic nature of the reaction. Intradermal testing also found cross-sensitivity to methylene blue, but not to other common allergens or NMBAs. This case demonstrates the importance of thorough post-anaphylaxis follow-up and raises the possibility of cross-sensitivity between unrelated compounds.

Upon introducing bulky aromatic groups into benzodifuranone derivatives, crystals with unprecedented solid-state emission were obtained. A crystallographic analysis revealed that the emissive properties should most likely be attributed to the absence of stacking between the dye scaffolds. In addition to the solid-state emission, the compound showed responsivity to external stimuli, i.e., luminescent mechanochromism and thermosalient effect.