Progress in Color, Colorants and Coatings
Volume:17 Issue: 3, Summer 2024

Corrosion of mild steel in aggressive environments such as HCl solution poses significant challenges across industries. This research explores the potential of 4-(2-Mercapto-1,3,4-oxadiazole-5-yl)pyridine (MOP) as a corrosion inhibitor for mild steel in HCl solution. Notably, MOP exhibits an impressive inhibition efficiency of 93.6 % at an optimal concentration of 0.5 mM in 1 M HCl. The study comprises a comprehensive analysis, encompassing varying inhibitor concentrations (0.1 to 1 mM), immersion durations (1 to 48 hours), and temperatures (303 to 333 K). Corrosion rate quantification employs weight loss measurements. Additionally, adsorption isotherms unveil MOP's interaction with the mild steel surface. Importantly, Density Functional Theory (DFT) unravels intricate electronic and molecular interactions at the atomic scale. These findings underscore MOP's exceptional corrosion inhibition capacity, making it a promising candidate for mild steel corrosion control in HCl environments. The combined insights from weight loss measurements, adsorption isotherms, and DFT analysis provide a holistic understanding of the inhibition mechanism, opening doors for practical applications in corrosion management.

This work investigates the possibility of identification of natural dyes (madder and cochineal) and mordant types (Al, Sn, Cr, Cu, Fe) in dyed wool fibers using spectral imaging-based methods. For this purpose, technical imaging, including UVL, IRR and UVR, and obtained IRFC and UVFC images were used, along with multispectral imaging (350-1100 nm) and hyperspectral imaging (400-950 nm). The grayscales of multispectral and hyperspectral images were extracted to quantify the imaging data. The grayscale and the first derivative of the reflectance spectra obtained from the hyperspectral camera were investigated using multivariate principal component analysis and hierarchical clustering to separate the different groups of dyed fibers. According to results, aluminum and tin mordanted fibers could be distinguished from other groups as per UVL and IRFC images; similarly, the type of dye (madder or cochineal) was distinguishable from UVFC images. Interestingly, PCA analysis of grayscales of multispectral images provided an appropriate separation of all groups of fibers with different mordants and dyes. The 3d PCA plot and the hierarchical clustering of the first derivative of the reflectance spectra also resulted in better separation and classification of the dyed fiber groups. Nevertheless, the best performance in clustering fibers groups can be seen in the PCA analysis of grayscales obtained from hyperspectral images recorded at 430-830 nm. Therefore, hyperspectral imaging can be considered a more appropriate method for categorizing dyed fibers with different dyes and mordants.

Thin coating layers of cross-linked polydimethylsiloxane (PDMS) and inorganic particles including glass spheres (GS), colloidal and fumed silica (aero and N20), montmorillonite (MMT), and kaolin (K) were attached onto Grade 1 Whatman filter paper (WFP) substrates using the spray-coating procedure to achieve superhydrophobic hybrid paper sheets. Coating formulations were varied in terms of their PDMS molecular masses and inorganic particles to prepare different samples. The effect of PDMS molecular weight and change in inorganic particle composition on the optical properties, surface roughness, barrier properties, surface chemistry, and topography was investigated. Hybrid paper sheets with ΔE00 values lower than 1 could be achieved, the surface roughness of which could be decreased by increasing the PDMS molecular weight in the coating formulation. Scanning electron microscopy studies revealed a homogeneous coating distribution, resulting in significant improvements in both the air and water barrier properties of the hybrid paper sheets. Spectroscopic investigations revealed the presence of interactions between the coating layer and the underlying paper substrate. Moreover, the distribution behavior of the inorganic particles on the spray-coated surfaces using the proposed method was also investigated using model compounds.

A novel series of C-, N-, and F-doped TiO2 photocatalysts were fabricated using a simple sol-gel method, utilizing 4-(trifluoromethyl)nicotinic acid (TFNA) as a precursor for carbon, nitrogen, and fluorine doping. The resulting materials were characterized using different advanced techniques such as X-ray Diffraction (XRD), Diffuse Reflectance Spectroscopy (DRS), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), and Field Emission Scanning Electron Microscopy (FESEM). The synthesis approach involved the creation of nanoparticles with varying weights of TFNA, ranging from 0.3 to 1.6 wt. %, followed by calcination at 400 °C for 120 min in the presence of air. The resulting nanostructures were tested for their efficiency in degrading rhodamine B (RhB) dye under ultraviolet (UV) light irradiation. The experimental findings revealed that the 1.6 wt. % TFNA/TiO2 composite exhibited exceptional photocatalytic activity, with approximately 87.0 % degradation efficiency towards RhB dye in aqueous solutions under UV light. This remarkable performance can be attributed to the increased lifetime of photogenerated electron-hole pairs and accelerated interfacial charge transfer rates.

This study presents the application of three commercial non-ionic surfactants, namely nonylphenol polyethylene glycol ether (Kenon), sorbitan ester polyethylene glycol ether (Tween), and oleic acid polyethylene glycol ester (Keol), to improve the extraction process of weld, madder, and walnut green husk natural dyes. The critical micelle concentration (CMC) values of Keol, Kenon, and Tween were 0.15, 0.19, and 0.25 g/L, respectively. The introduction of non-ionic surfactants into the solution markedly improved colorant extraction from plant sources, leading to a significant increase in the percentage of dye extracted in water. The wool dyeing with extracted dyes was also found to benefit from the presence of Tween, resulting in up to 11, 29 and 28 % increase in the color strength for weld, madder and walnut green husk extracts, respectively. Moreover, non-ionic surfactants improved dyeing and levelling properties of wool samples, and did not negatively impact on the general fastness ratings of dyed samples. Overall, this study suggests that the use of non-ionic surfactants provides a favorable manner for improving the extraction process of natural dyes and enhancing their dyeing properties.

Nowadays, sustainable approaches for the colouration of textiles are in high demand. Functional textiles remain a top choice for the user as they serve dual functions. The present study focuses on the utilisation of turmeric natural dye for dyeing of cotton using a novel method. A mosquito-repellent ethyl anthranilate was diazotised in the presence of sodium nitrite and hydrochloric acid. The diazotised derivative of ethyl anthranilate was reacted with turmeric-treated fabric by in-situ azoic dyeing method. The developed dyed fabric was evaluated for fastness and colour measurements. Functional effects provided by dyed fabrics (mosquito repellency and UV protection) were also assessed using standard methods. Dyed fabrics indicated excellent UV protection and 100 % mosquito repellency. The introduction of functional groups (azo and aromatic) of the developed dye in the cotton was also confirmed through FTIR analysis. A novel functional finishing-cum-dyeing approach for the functionalization of cellulosic fabrics was explored using turmeric extract and ethyl anthranilate.

This research investigates the impact of pollutant degradation on the nanocomposite in the presence of ultraviolet light. In this study, the experimental design method was used to optimize the experimental conditions and analyze the removal of rhodamine B dye by the hydrogel/zinc oxide/carbon dots nanocomposite under ultraviolet light. The key parameters examined in this process are the amount of adsorbent (ranging from 0.25 to 1.5 g) and time (ranging from 30 to 135 min). The influence of pH on adsorption is disregarded due to its negligible effect. The analyses demonstrate a strong correlation between the predicted values and the experimental data. The study demonstrates the successful degradation mechanism under ultraviolet light. The results confirm the selection of degree 2 models based on a greater P-value at a confidence level above 95 %. The regression coefficient (R2 = 0.9454) validates the suitability of the model. The relationship between time and the adsorbent amount is investigated through response surface diagrams, revealing that an increase in both parameters leads to a higher percentage of removal. Consequently, the maximum removal is achieved at 135 min and 1.5 g of adsorbent. Furthermore, the contour diagram predicts the adsorption yield based on the amount of adsorbent and time. Overall, the results indicate that the use of the nanocomposite with ultraviolet light is an effective approach for pollutant removal. The removal percentage increases with longer exposure times and greater adsorbent amount.

This study investigates the impact of carbon nanotubes on the structure of poly(vinyl chloride). Carbon nanotubes derived from corn cobs (1 g) and molten sodium hydroxide (3 g) at a weight ratio of 1:3 were used as additives. These doped poly(vinyl chloride) samples were analyzed. Different concentrations of carbon nanotubes (0.25, 0.50, and 0.75) were incorporated into the poly(vinyl chloride) lattice. The effects of these additions demonstrated remarkable resistance to continuous ultraviolet light exposure, effectively countering photodegradation. Before introducing the nanoparticles, volatile substances generated free radicals, leading to reduced weight and molecular weight in PVC thin films. To counteract degradation, stabilizers were introduced to the polymer. Photostability was achieved by doping PVC with carbon nanotubes, with monitoring of carbonyl groups (ICO), polyene (IC=C), and hydroxyl (IOH) growth against irradiation time. Upon adding carbon nanotubes, ICO values increased from 0.16 to 0.24, and IC=C values rose from 0.17 to 0.28. Conversely, IOH decreased from 0.14 to 0.058, mitigating photodegradation. Crystalline size and micro-strain were calculated. The study also tracked surface morphology and weight loss changes in nanocomposite PVC thin films upon irradiation. The findings demonstrated the effective UV-blocking capabilities of carbon nanotube-PVC blends, providing substantial protection to thin films. Additionally, weight loss calculations, polymeric thin film surface changes, and viscosity assessments were conducted.