Current Green Chemistry - Volume 9, Issue 2, 2022

Due to the hazardous effects of chemicals used, Green chemistry replaces the conventional techniques involved in nanotechnology. Green chemistry is a branch of science dealing with microbiology, phytology, and chemical engineering with the development of products by manipulating these three domains. Green synthesis is an interdisciplinary domain that relies on the use of non-toxic, bio-safe reagents, which are eco-friendly and safe to use in bio-nanotechnology and provide environmental benefits as an option other than the conventional physical and chemical methods for developing technology. This article will critically present the various approaches and methods for nanoparticle synthesis using microorganisms like bacteria, fungi, yeasts, archaea, viruses, algae, etc. By optimizing with laboratory conditions, nanoparticles of different ranges of physical characteristics can be synthesized. Nanoparticles with well-defined properties have been reported to be synthesized by green chemistry, for many biomedical applications. Green synthesis of nanoparticles is non-toxic, eco-friendly, and compatible to be used for medical procedures, and the rate of nanoparticle formation and their size could be regulated by various controlling factors like pH, temperature, concentration, time exposure, etc. The use of microbes for nanoparticle synthesis can be broadly divided into intracellular and extracellular based on their being produced from the extracts of microorganisms, which can be employed either as reducing agents or protective agents for the synthesis either extracellular or intracellular in the presence of enzymes generated by cells. This review aims to summarize nanoparticles of Au, P, Ag, Pt, CdS, Pt ZnO, etc as the primary focus. Additionally, a short glimpse often hybrid chemical-biological methods have also been presented.

In this review, recent progress on the application of the polyaniline-supported palladium catalysts in different organic transformations focusing on different C-C bond-forming reactions such as Suzuki coupling, Heck reactions, oxidative Heck coupling, Ullmann coupling, Sonogashira coupling, and related chemistry are covered. Effect of catalyst preparation, characteristic of the support and supported palladium species on the outcome of the catalyst efficiency are also highlighted. Finally, the emerging trend is summarized for the future of this unique modular catalytic system.

Introduction: Deacetylation of cellulose acetate restores hydroxyl groups on the surface of fibers and improves hydrophilicity. From an environmental point of view, the conventional deacetylation process involves alkalinity and large effluent volume. The goal of this work is to introduce a new ecofriendly bio-treatment process. Methods: In this study, cellulose acetate fabrics were bio-treated with laccase enzyme. Then, the untreated and bio-treated fabrics were dyed with direct and disperse dyes. Laccase pretreatment improved color strength (16%) and crocking durability. After bio-treatment, the bending rigidity decreased for the warp (17.8) and weft (10.8) directions. The Freundlich model was the best model to describe the adsorption of direct dye onto the untreated fabric. In contrast, the Langmuir model better described the adsorption behavior of bio-treated fabric. Results: Nernst model was suitable for disperse dyes adsorption. The partition coefficient was increased after laccase treatment. Thermodynamic analysis showed that the dye sorption was endothermic and nonspontaneous. Conclusion: It was also found that bio-treated fabrics require less external energy. All performed experiments approved the efficiency of the deacetylation process, which led to an improvement in dyeing properties.

Introduction: Owing to the restoration of hydroxyl groups, cellulose acetate fibers can be dyed with direct dyes. There are some drawbacks in the conventional deacetylation process of cellulose acetate from environmental point of view. Methods: This process involves high temperature, alkalinity and large volume of effluent. The goal of this work is to improve the dyeing properties of cellulose acetate fabric using an eco-friendly treatment process. In this paper, cellulose acetate fabric was treated with ultraviolet light (UVB) at an air pressure of 1 atm to improve dyeability. Then, the untreated and UV treated fabrics were dyed with direct and disperse dyes. UV treated cellulose acetate fabric showed higher dye adsorption compare to that of untreated cellulose acetate fabric. Five adsorption isotherm models including sold solution, Langmuir, Freundlich, Temkin and BET were applied to determine the adsorption behavior. At all temperatures studied, experimental data were better fitted with the Freundlich and Nernst models for direct and disperse dyes respectively. Thermodynamic parameters such as change in free energy (ΔG⁰), the enthalpy (ΔH⁰), and the entropy (ΔS⁰) were also evaluated. Results: The calculated thermodynamic values showed that the adsorption of these dyes onto the cellulose acetate fabric was a physical adsorption process and endothermic in nature. These data also implied that the adsorption of direct dye onto cellulose acetate fabric was spontaneous at the experimental temperature range and adsorption of disperse dyes can be spontaneous at higher temperatures. Moreover, the ΔG⁰ values for the adsorption of disperse dyes onto the UV-treated fabrics were less than those for untreated fabrics suggesting that UV treated fabrics require less external energy. Conclusion: Among the kinetic models studied, it was found that the pseudo second-order kinetic model was the best model to describe the dye sorption process on the UV treated and untreated cellulose acetate fabrics. The UV treatment led to an improvement in the boundary layer diffusion effect.