One-pot green synthesis of gold nanoparticles and its supportive role in surface activation of non-woven fibers as heterogeneous catalyst

Comparative study of response surface methodology and artificial neural network for optimization of process parameters for synthesis of gold nanoparticles by Desmostachya bipinnata extract

Green synthesis of nanoparticles has gained attention due to its eco-friendly and sustainable approach to synthesize nanoparticles at a reduced cost. Artificial neural network (ANN) and response surface model (RSM) are important to reduce experimental efforts in nanoparticle synthesis. In this work, optimization of gold nanoparticle synthesis by Desmostachya bipinnata extract was performed using the volume of plant extract, concentration of auric chloride, reaction time, pH, and temperature as process parameters, and the output was absorbance. The experimental design was obtained from RSM and the model was optimized further using ANN. Thirty-two experimental runs generated by RSM were performed and the results obtained experimentally were compared with those generated by RSM and ANN. Different algorithms of ANN were tested to obtain the best one. The optimization studies resulted in a maximum response for 20^th run with 15 ml, 2.5 mM, 45 min, 7, and 40 °C as parameters. Optimized input parameters obtained by RSM were 10 ml, 2 mM, 30 min, 6, and 30 °C. The formation of gold nanoparticles was confirmed by UV spectroscopy, XRD, and SEM. Different algorithms of ANN, such as leven marquardt, scaled conjugate gradient, and bayesian network were used. Leven marquardt algorithm was found to be the most suitable algorithm for the current study.

Biowaste- and nature-derived (nano)materials: Biosynthesis, stability and environmental applications

Due to the environmental pollution issues and the supply of drinking/clean water, removal of both inorganic and organic (particularly dyes, nitroarenes, and heavy metals) to non-dangerous products and useful compounds are very important transformations. The deployment of sustainable and eco-friendly nanomaterials with exceptional structural and unique features such as high efficiency and stability/recyclability, high surface/volume ratio, low-cost production routes has become a priority; nonetheless, numerous significant challenges/restrictions still remained unresolved. The immobilization of green synthesized metal nanoparticles (NPs) on the natural materials and biowaste generated templates have been analyzed widely as a greener approach due to their environmentally friendly preparation methods, earth-abundance, cost-effectiveness with low energy consumption, biocompatibility, as well as adjustability in various cases of biomolecules as bioreducing agents. Natural and biowaste materials are widely considered as important sources to fabricate greener and biosynthesized types of metal, metal oxide, and metal sulfide nanomaterials using plant extracts. Integrating green synthesized nanoparticles with various biotemplates offers new practical composites for mitigating environmental challenges. In this review, degradation of dyes, reduction of toxic nitrophenols, absorption of heavy metals, and other hazardous/toxic environmental pollutants from contaminated water bodies using biowaste- and nature-derived nanomaterials are highlighted.

High-efficiency reduction of p-nitrophenol on green-synthesized gold nanoparticles decorated on ceria nanorods

A green synthesis using extract from Citrus maxima peel was developed to fabricate Au–Ce catalysts for the reduction of p-nitrophenol (PNP). Au nanoparticles with a diameter of 6.6 ± 2.5 nm were deposited onto the surface of CeO₂ nanorods with a length of 33.1 ± 15.0 nm and a diameter of 7.1 ± 2.1 nm. The mesoporous and non-porous capillary structures of these materials were observed. The interaction between Au and CeO₂ increased the specific surface area, pore diameter, and pore volume compared with pure CeO₂ (90 m² g⁻¹, 23.8 Å, and 0.110 cm³ g⁻¹versus 72 m² g⁻¹, 23.0 Å, and 0.089 cm³ g⁻¹). The splitting peaks of the surface oxygen and their shifting at lower temperatures compared with CeO₂ nanorods were found thanks to the Au–CeO₂ interaction, suggesting that their reduction occurred more easily. The synthesized Au–Ce catalysts exhibited excellent activity in the reduction of PNP to p-aminophenol. The 0.2Au–Ce catalyst was the most efficient one for PNP reduction, enabling the conversion of PNP in 30 minutes with a catalyst concentration of 20 mg L⁻¹ and a PNP/NaBH₄ molar ratio of 1/200. Moreover, the 0.2Au–Ce catalyst could be reused for at least five consecutive cycles without considerable loss of its activity.

A green synthesis using extract from Citrus maxima peel was developed to fabricate Au–Ce catalysts for the reduction of p-nitrophenol (PNP).

Effect of Pluronic P103 Concentration on the Simple Synthesis of Ag and Au Nanoparticles and Their Application in Anatase-TiO2 Decoration for Its Use in Photocatalysis

Silver and gold nanoparticles were synthesized under environmentally-friendly reaction conditions by using a biodegradable copolymer and water as a solvent. The triblock copolymer Pluronic P103 was utilized as a stabilizing agent or soft template to produce Ag and Au nanoparticles (NPs) of different sizes. Moreover, in the synthesis of Au NPs, the polymer acted as a reducing agent, decreasing the number of reagents used and consequently the residues produced, hence, rendering the procedure less complicated. It was observed that as the concentration of the polymer increased, the size of the metallic NPs augmented as well. However, AgNPs and AuNPs prepared with 1 and 10 wt% Pluronic P103, respectively, showed a significant decrease in particle size due to the presence of polymeric soft templates. The hybrid materials (metal/polymer) were characterized by UV-Vis spectroscopy, DLS, and TEM. The pre-synthesized nanoparticles were employed to decorate anatase-TiO2, and the composites were characterized by DRS, XRD, BET surface area measurements, the TEM technique with the EDS spectrum, and XPS spectroscopy to demonstrate NPs superficial incorporation. Finally, methylene blue was used as a probe molecule to evidence the effect of NPs decoration in its photocatalytic degradation. The results showed that the presence of the NPs positively affected methylene blue degradation, achieving 96% and 97% removal by utilizing TAg0.1 and TAu10, respectively, in comparison to bare anatase-TiO2 (77%).

Gold Nanoparticles Synthesis and Antimicrobial Effect on Fibrous Materials

Depositing nanoparticles in textiles have been a promising strategy to achieve multifunctional materials. Particularly, antimicrobial properties are highly valuable due to the emergence of new pathogens and the spread of existing ones. Several methods have been used to functionalize textile materials with gold nanoparticles (AuNPs). Therefore, this review highlighted the most used methods for AuNPs preparation and the current studies on the topic in order to obtain AuNPs with suitable properties for antimicrobial applications and minimize the environmental concerns in their production. Reporting the detailed information on the functionalization of fabrics, yarns, and fibers with AuNPs by different methods to improve the antimicrobial properties was the central objective. The studies combining AuNPs and textile materials have opened valuable opportunities to develop antimicrobial materials for health and hygiene products, as infection control and barrier material, with improved properties. Future studies are needed to amplify the antimicrobial effect of AuNPs onto textiles and minimize the concerns related to the synthesis.

Determination of Antimicrobial and Toxic Metal Removal Activities of Plant-Based Synthesized (Capsicum annuum L. Leaves), Ecofriendly, Gold Nanomaterials

Nanoparticles are valuable materials with widespread use. The fact that these materials are obtained by biological resources with an environmentally friendly method contributes to the development of studies in this field. Gold nanoparticles (AuNPs) from waste vegetable sources (green leaves of Capsicum annum L.) are economically and easily synthesized. The obtained particles are characterized by UV-vis spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analysis. The antimicrobial activity of the particles on the pathogenic microorganisms Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 29213, Bacillus subtilis bacteria, and Candida albicans yeast are found to have a significant suppressive effect. The removal activities of eight toxic metals (Pd, Cd, Fe, Ni, Co, Mn, Zn, Pb) in Diyarbakır drinking water and artificially prepared water within different pHs are investigated. Gold nanoparticles synthesized from Capsicum annuum L. leaves are found to be effective in toxic metal removal in water samples.