Synthesis, application, and antibacterial activity of new direct dyes based on chromene derivatives

Aim: The goal of this study is to synthesise, analyse, and employ two new direct dyes based on chromenes derivatives as the chromophoric moiety in dyeing wool, silk, and cotton, with good colour strength, light fastness, and other desirable features. Background: The quest for new direct dyes with antimicrobial qualities for Gram-positive, Gram-negative bacteria, and fungus is underway. These dyes are commonly used on cotton, silk, and wool materials, which have great light fastness, washing, rubbing, and sweating fastness. Methods: Antibacterial activity has been measured for all dyeing fabrics. The parent structure 1 has been synthesized previously as part of the experiment. Then, these dyes are prepared by diazotization followed by coupling reaction, Results and Discussion: The p-Aminobenzenesulfonic acid (C1) and 4-Aminoazobenzene-3,4'-disulfonic acid (C2) are diazotized in hydrochloric acid with sodium nitrite, then coupled with compound 1 in a molar ratio (1: 1) at 250C until the pH is fixed at 5. Finally, the monoazo and diazo direct dyes (D1 and D2) are created. Conclusion: Wool, silk, and cotton materials benefit from the synthetic dyes' increased antibacterial action and dyeing qualities (exhaustion and fixing). They also offer better fastness qualities (light, rubbing, and perspiration).

Development of Antimicrobial Cotton Fabric Impregnating AgNPs Utilizing Contemporary Practice

Multifunctional fabrics using conventional processes have piqued increasing global interest. The focus of this experiment was to assess the modification of the cotton fabric surface by utilizing silver nanoparticles (AgNPs) and introducing functional properties along with sustainable dyeing performance. A single-jersey knitted fabric composed of cellulose-enriched 100% natural fiber (cotton) with an areal density of 172 GSM was used in this study. The standard recipe and test methods were employed. FTIR-ATR spectra were used to determine the fixing of AgNPs onto the fiber surface. A comparative assessment was conducted in response to the distribution of color, color fastness to wash, water, perspiration, rubbing, and light. Scanning electron microscopy (SEM) was used to characterize the surface of nano-Ag-deposited specimens. In terms of functional properties, antimicrobial activity was scrutinized. Our findings reveal that the nanoparticles impart remarkable antibacterial effects to cellulose-enriched fabric against S. aureus (Gram-positive) and E. coli (Gram-negative). Direct dyes were used for dyeing the proposed samples, resulting in enhanced dyeing performance. Except for light fastness, the samples dipped with AgNPs showed outstanding color levelness and color durability characteristics. The developed fabrics can be applied in a wide range of functions, including protective clothing, packaging materials, and healthcare, among others.

Green synthesis of nickel oxide nanoparticles using Allium cepa peels for degradation of Congo Red Direct Dye: an environmental remedial approach

Direct dyes are used in different textile operations and processings. The textile industries are disposing of unused direct dyes into the aquatic environment which is posing a serious alarming threat to aquatic lives. The current study deals with the synthesis of nickel oxide nanoparticles using Allium cepa peels aqueous extract. Nickel oxide nanoparticles (NiO-NPs) were characterized by SEM. Synthesized NiO-NPs were used to remove Congo red direct dye. Various experimental factors like concentration of dye & nanoparticles, pH, and temperature were optimized. Congo red direct dye was decolorized up to 90% at optimized conditions (Congo Red Direct dye concentration 0.02%, catalyst dose 0.003 g·L−1, pH 6, and temperature (50 °C). The real textile industry effluent disclosed 70% decolorization at optimized conditions. The percent reduction in TOC and COD were found to be 73.24% and 74.56%, in the case of congo red dye catalytic treatment & the percent reduction in TOC and COD were found to be 62.47% and 60.23%, respectively in the treatment of textile effluent using nickel oxide nanoparticles as a catalyst. Treated and untreated dye samples were exposed to FTIR and UV-Visible spectral analyses too. The reaction products were studied by degradation pathway.

Preparation of Magnetic Alginate-Based Biogel Composite Cross-Linked by Calcium Ions and its Super Efficient Adsorption for Direct Dyes

Magnetic sodium alginate (SA)-based biosorbent Fe₃O₄@SA-Ca gel beads were synthesized by droplet polymerization using Ca2+ ions as crosslinking agent, and characterized by Scanning Electron Microscopy (SEM). Fe₃O₄@SA-Ca polymer was used for the removal of Direct Orange 26 (DO-26) dye from water. The ratio of raw materials and some important conditions affecting the adsorbent performance were carefully examined. The adsorption kinetics, isotherms and thermodynamics were investigated. When the concentrations of SA, CaCl2 and Fe3O4 solutions were 1.9, 10 and 10 g/L, respectively, the black Fe₃O₄@SA-Ca gel beads with about 3 mm diameter were successfully prepared by curing 6h at room temperature. The polymer gel exhibits ultra-high adsorption capacity of 1252 mg/g and removal efficiency of 96.2 % for DO-26 under the conditions of 0.05 g polymer dosage, 2600 mg/L of dye initial concentration, solution pH 2.0 and 90 min of the adsorption time at 298 K. The dye removal efficiency can be all over 92 % in a wide pH range of 2.0 to 10.0. The adsorption process completely accorded with the pseudo-second-order rate model at different temperatures (298 ~ 328 K). The dye adsorption behavior was well in line with Freundlich model. The thermodynamic study indicated that the adsorption reaction was of spontaneous and exothermic nature. SEM analysis showed that the Fe₃O₄@SA-Ca gel beads appeared uneven surface with irregular folds and grooves. A high-cost-effective magnetic biosorbent, Fe₃O₄@SA-Ca can super effectively remove direct dyes from high-concentration wastewater in a wide range of acidity, and can be easily separated and recovered from water after adsorption without secondary pollution, and would have a good application prospect.