Bioinspired catecholic activation of marine chitin for immobilization of Ag nanoparticles as recyclable pollutant nanocatalysts

Nanochitin for sustainable and advanced manufacturing

Presently, the rapid depletion of resources and drastic climate change highlight the importance of sustainable development. In this case, nanochitin derived from chitin, the second most abundant renewable polymer in the world, possesses numerous advantages, including toughness, easy processability and biodegradability. Furthermore, it exhibits better dispersibility in various solvents and higher reactivity than chitin owing to its increased surface area to volume ratio. Additionally, it is the only natural polysaccharide that contains nitrogen. Therefore, it is valuable to further develop this innovative technology. This review summarizes the recent developments in nanochitin and specifically identifies sustainable strategies for its preparation. Additionally, the different biomass sources that can be exploited for the extraction of nanochitin are highlighted. More importantly, the life cycle assessment of nanochitin preparation is discussed, followed by its applications in advanced manufacturing and perspectives on the valorization of chitin waste.

Catalyst development for tar reduction in biomass gasification: Recent progress and the way forward

Biomass valorization via catalytic gasification is a potential technology for commercizalization to industrial scale. However, the generated tar during biomass valorization posing numerous problems to the overall reaction process. Thus, catalytic tar removal via reforming, cracking and allied processes was among the priority areas to researchers in the recent decades. This paper reports new updates on the areas of catalyst development for tar reduction. The catalyst survey include metallic and metal-promoted materials, nano-structured systems, mesoporous supports like zeolites and oxides, group IA and IIA compounds and natural catalysts based on dolomite, palygorskite, olivine, ilmenite, goethite and their modified derivatives. The influence of catalyst properties and parameters such as reaction conditions, catalyst preparation procedures and feedstock nature on the overall activity/selectivity/stability properties were simultaneously discussed. This paper not only cover to model compounds, but also explore to real biomass-derived tar for consistency. The area that require further investigation was identified in the last part of this review.

Chemical reduction of methylene blue in the presence of nanocatalysts: a critical review

Methylene blue (MB) (3,7-bis (dimethylamino)-phenothiazin-5-ium chloride) is a harmful pollutant and has been long been known for its detrimental effects on human health. Over the recent years, many strategies including reduction, oxidation, biological and photochemical degradation have been reported for converting this harmful dye into commercially useful products. Among the aforementioned strategies, the nanocatalytic reduction of MB into its reduced counterpart, i.e. leucomethylene blue, is considered more preferable because it has been reported to have numerous applications in various industrial fields in the academic literature. The reduction of MB is the kinetically unfavorable reaction. Henceforth, various nanocatalytic systems utilizing different kinds of stabilization mediums have reportedly been used for speeding up this particular reaction. This article attempts to not only describe the fundamental properties of the reduction reaction of MB but also present the classification of the recently reported nanocatalytic assemblies on the basis of the utilized supporting medium. Various techniques used for the characterization of nanocatalytic systems reported for the reduction of MB have been summarized in this review. The thermodynamics, kinetics and mechanistic studies of this nanocatalytic reaction have also been narrated here. This critical review has been written comprehensively to abridge the recent research progress in the assemblage of nanocatalytic systems used for the reduction of MB and to propose some new ideas for further development in this area.

Graphene oxide enhanced polyacrylamide-alginate aerogels catalysts

Biomass aerogel is a promising catalyst and has attracted extensive attention. However, most of the biomass aerogels are fragile, which limits their practical application. Herein, we significantly enhance the mechanical property of biomass aerogel catalysts by 30 times through incorporating graphene oxide into polyacrylamide and Cu-cross-linked alginate formed supper-strong double network aerogels. In addition to enhance the mechanical property, the graphene oxide also significantly increases the catalytic activity. Graphene oxide enhancement for biomass aerogel catalyst provides a new method to develop next generation supper catalysts.

Preparation, Characterization and Application of Polysaccharide-Based Metallic Nanoparticles: A Review

Polysaccharides are natural biopolymers that have been recognized to be the most promising hosts for the synthesis of metallic nanoparticles (MNPs) because of their outstanding biocompatible and biodegradable properties. Polysaccharides are diverse in size and molecular chains, making them suitable for the reduction and stabilization of MNPs. Considerable research has been directed toward investigating polysaccharide-based metallic nanoparticles (PMNPs) through host⁻guest strategy. In this review, approaches of preparation, including top-down and bottom-up approaches, are presented and compared. Different characterization techniques such as scanning electron microscopy, transmission electron microscopy, dynamic light scattering, UV-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and small-angle X-ray scattering are discussed in detail. Besides, the applications of PMNPs in the field of wound healing, targeted delivery, biosensing, catalysis and agents with antimicrobial, antiviral and anticancer capabilities are specifically highlighted. The controversial toxicological effects of PMNPs are also discussed. This review can provide significant insights into the utilization of polysaccharides as the hosts to synthesize MPNs and facilitate their further development in synthesis approaches, characterization techniques as well as potential applications.