Asian Journal of Green Chemistry
Volume:8 Issue: 1, Winter 2024

This research investigated the mechanical and thermal properties of starch films reinforced with cellulose Nanofibers and lemon essence, which are used in the food packaging industry. One of the aims of this study is to examine the effect of each parameter (alone and together) and evaluate the amount of starch, cellulose Nanofibers, and lemon essence in the manufacture of films. Furthermore, finding a relation between the different amount of used materials that provides the best properties is another research goal. Biodegradable nanocomposite films based on starch and cellulose nanofibers reinforcing agents were prepared via solvent casting. The physical properties of as-prepared starch and cellulose Nano fibers films, such as thickness, colour, and structure, were studied by XRD and scanning electron microscope (SEM). Moreover, DSC and infrared spectroscopy (FT-IR) were used to investigate their thermal properties, such as glass transition temperature (Tg), melting temperature, and crystallization percentage. The disk diffusion method evaluated the antimicrobial effect of biodegradable films containing different concentrations of essence against Escherichia coli and Staphylococcus aureus bacteria. SEM images show uniform and better dispersion of starch and cellulose Nano fibers containing lemon essence, especially in starch and cellulose Nanofibers on the surface (SNE-4).

PbS quantum dots (PbS-QDs) are one of the best candidates in new generation of LEDs. When the PbS-QDs are exposed to light spectrum, the electrons in the valence band (VB) are excited to the conduction band (CB). The excited electrons then return from the CB to the VB and release extra energy by emitting light. The return of electrons to the VB makes it possible to repeat the light absorption-emission circle. If the size of the PbS-QDs is smaller than the Bohr magneton radius (PMR), the probability of the electron return to the VB decreases. This leads to phenomena named quantum dot blinking (QDB) in light-emitting diodes (LEDs), which is not desirable. In this research, a new approach has been proposed in which the addition of a metal substrate for PbS-QDs with a semiconductor shell with a suitable band edge could increase PbS-QDs efficiency in QD-LEDs and overcome the QDB problem.

Silver nanoparticles (AgNPs) synthesis has attracted a growing attention with an increasing focus on the production of nanoparticles of biomedical importance through ecofriendly means. This study assessed the antioxidant, anti-inflammatory, and α-glucosidase inhibitory potentials of AgNPs synthesized using Ageratum conyzoides aqueous leaf extract in vitro. The extract’s phytoconstituents were determined by GC-MS analysis. AgNPs was synthesized by mixing AgNO3 solution with the aqueous leaf extract of A. conyzoides. AgNPs formation was monitored by UV-Visible spectrophotometry. The obtained AgNPs was further characterized using SEM and FT-IR analysis. Antioxidant potential was evaluated via ferric reducing power, hydrogen peroxide, and ABTS scavenging assays. Anti-inflammatory capacity of the synthesized AgNPs was assessed through inhibition of trypsin activity and albumin denaturation. Furthermore, anti-diabetic potential was evaluated by α-glucosidase inhibitory activity of the AgNPs, all in comparison with controls and standards. GC-MS analysis reveals Oleic acid (25.90%), Oxalic acid, allyl hexadecyl ester (25.49%) and Dodecanoic acid (13.36%) as the main phytoconstituents in A. conyzoides extract. The UV-Visible analysis detected the absorption peak of AgNPs at 420 nm. SEM reveals various morphological forms of the AgNPs i.e. spherical and triangular. The average particle size is 27.85 nm. FTIR analysis showed that the plant phytoconstituents capped and stabilized the synthesized AgNPs. The AgNPs showed substantial ferric reducing power in addition to hydrogen peroxide, DPPH, and ABTS radicals scavenging activities while also inhibiting albumin denaturation, trypsin, and α-glucosidase activities. These findings revealed the suitability of Ageratum conyzoides for AgNPs synthesis and also demonstrated the potentials of the synthesized AgNPs as an antioxidant, anti-inflammatory, and anti-diabetic agent.

A new smart Pd catalyst was created based on functionalized thermo-responsive poly (N-isopropylacrylamide) (PNIPAM) grafted Fe3O4@CQD@Si. For catalyst fabrication, initially, Fe3O4 magnetic nanoparticle was prepared by co-precipitation method, and then it was coated with CQD as sustainable and environmentally friendly support. Chemical modification of Fe3O4@CQD support with polymerizable groups was performed through vinyltriethylsilan (VTES) reaction. Thereafter, PNIPAM was grafted to the modified Fe3O4 via the conventional free radical polymerization technique. The PNIPAM-grafted Fe3O4@CQD@Si was further treated using hydrazine to create the modified amino support, which was then complexed with Pd(OAc)2 to yield the magnetic heterogeneous catalytic system. All materials are characterized using various methods, i.e., FT-IR, SEM, DLS, CHN, XRD, zeta potential, VSM, and TGA analysis techniques. Fe3O4@CQD@Si@PNIPAM-NH2/Pd catalyst was used to produce a range of substituted alkenes in the Mizoroki-Heck cross-coupling reaction with a high turnover number (TON) and good to outstanding yields. Above the LCST temperature of the PNIPAM, the hydrophobic part of the polymer starts to shrink, and this smart catalyst advances the relevant reactions in milder conditions. Easy purification of the substituted alkenes due to the convenient isolation of the magnetic catalyst with an external magnet is the main characteristic of this process.

The degree of photochemical cleavage of epoxidized and non-epoxidized oils of sunflower (Helianthus annuus), soybean (Glycine max), and olive (Olea europaea) exposed to 1000 watts ultraviolet light (UV) at different times were studied using iodine value and infrared spectroscopy.  The epoxidation was conducted with a mole ratio of 1:0.5:2 for the oil, hydrogen peroxide and formic acid, respectively, for 6 hours at 50 oC. The oxirane oxygen content and their percentages of conversion to epoxides for the oils were: sunflower oil (6.75, 89.52 ± 0.25%), soybean oil (7.10, 95.95 ± 0.33%), and olive oil (4.25, 84.89 ± 0.18%), respectively. The results showed that the difference in oxirane oxygen content between sunflower and soybean oils corroborate the slight increases in iodine value of the irradiated oils. The oxirane oxygen content of epoxidized olive oil established the baseline value for monounsaturated oils. The results for the UV irradiation showed that after twelve hours of irradiation, the iodine value increased for non-epoxidized sunflower oil and non-epoxidized soybean oil, while it decreased for non- epoxidized olive oil. However, the iodine values of epoxidized sunflower oil and epoxidized soybean oil increased, while the epoxidized olive oil decreased. It was suggested that the increases observed in the iodine values for non-epoxidized and epoxidized sunflower and soybean oils were as a result of molecular rearrangement of the alkene functional groups and recyclization of the cleaved epoxides residues after irradiation due largely to multiple bond effect. This effect is more marked in sunflower oil with 63% polyunsaturated fatty acid content, than in soybean oil with 61% polyunsaturated fatty acid content. This result corroborates the C-H deformation vibration at 1379 cm-1 as evidences of cyclized products. The monounsaturated olive oil characterized by a marked reduction in iodine value for both the non-epoxidized and epoxidized oils indicated marked reduction in unsaturation as it has only one double bond per molecular chain. Thus, the possibility of molecular rearrangement or recyclization of epoxidized residues is unlikely as shown by the results. Hence, the monounsaturated olive oil produced more stable cleaved products as evidenced by a marked reduction in the iodine value of the products.

Microwave assisted organic synthesis is an environment friendly approach to synthesis as it is simple, innovative, gives high yield at low cost, and reduces the use of solvents. Conventional methods used in chemical synthetic processes involve the use of substances that are harmful to the environment. To cope with this issue, chemists were in search of a green alternative to conventional chemical practices that resulted in the development of a new branch of chemistry known as “Green chemistry”. It foresees minimum impact to the environment as aprimary criteria while developing any new chemical process. This predetermined target of green chemistry is achieved by considering different gist areas such as elimination of the use of traditional organic solvents if possible, finding alternative reaction media, conditions to minimize undesirable chemical waste formation, reaction rate enhancement using microwaves as energy source, etc. Microwave technique involves energy transfer that leads to rapid and uniform heating of the dielectric materials which often results in homogeneity and increased yield of the resultant products. It has numerous advantages over conventional thermal process such as shorter reaction time, better yield product, and less energy consumption. The present article describes microwave irradiation as a valuable energy efficient alternative to the conventional heating for greener organic synthesis.

Dyes are extensively used across a variety of industries, raising concerns about their potential to contaminate water sources. Therefore, effective and environment-friendly removal techniques are essential. The potential of MXenes as adsorbents for dye adsorption from water is thoroughly examined in this review. Two-dimensional transition metal carbides or nitrides, known as MXenes, have extraordinary physicochemical characteristics, such as a large surface area, variable surface chemistry, and superior adsorption capability. This study examined the structural properties of MXenes, their methods of production, and their special adsorption processes for dye removal. In addition, a thorough analysis of the effects of several variables, including the pH, contact time, initial dye concentration, and temperature, on the adsorption efficiency of MXenes was performed. This article also highlights the current developments in the MXenes modification to increase the effectiveness of their dye adsorption. Furthermore, this report addresses the difficulties in applying MXenes as adsorbents in practice and suggests future research avenues to overcome these restrictions. Overall, this study offers insights into the prospective use of MXenes in water treatment technologies and portrays them as promising and long-lasting adsorbents for the removal of synthetic dyes from water.