KCC-1/Pr-SO3H as an efficient heterogeneous catalyst for production of n-butyl levulinate from furfuryl alcohol

Bio-based nanocomposite hydrogels derived from poly (glycerol tartrate) and cellulose: Thermally stable and green adsorbents for efficient adsorption of heavy metals

The eco-friendly polymeric nanocomposite hydrogels were prepared by incorporating dendritic fibrous nanosilica (DFNS) and apple peel (AP) as reinforcements into the crosslinked polymer produced by cellulose (CL) and poly (glycerol tartrate) (TAGL) via gelation method and used for efficient adsorption of Pb2+, Co2+, Ni2+, and Cu2+ metal ions. DFNS and DFNS/TAGL-CL/AP samples were characterized by FESEM, FTIR, TEM, TGA, and nitrogen adsorption/desorption methods. The results of TGA analysis showed that the thermal stability of the prepared hydrogels improved significantly in the presence of DFNS. Both synthetic and environmental parameters were investigated and the adsorption capacity reached 560.2 (pH = 4) and 473.12 (pH = 5) mg/g for Pb2+ and Cu2+ respectively, using initial ion concentration of 200 mg/L. Also, the maximum adsorption capacity was 340.9, and 350.3 mg/g for Co2+ and Ni2+, respectively under optimum conditions (pH = 6, initial ion concentration of 100 mg/L). These experiments indicated that the DFNS/TAGL-CL/AP nanocomposite hydrogel has an excellent performance in removal of Pb2+ and can adsorb this toxic metal in only 30 min while the optimum contact time for other metals was 60 min. Pseudo-second-order and Langmuir models were used to define the kinetic and adsorption isotherms, respectively and thermodynamic studies demonstrated that the adsorption was endothermic for Co2+, Ni2+ and Cu2+, exothermic for Pb2+, and spontaneous in nature for all metal ions. Furthermore, the reusability tests indicated that the hydrogels could maintain up to 93% of their initial adsorption capacity for all metal ions after four cycles. Therefore, the prepared nanocomposite hydrogels can be suggested as efficient adsorbents to remove the toxic metals from wastewater.

Titania Nanotubes-Bonded Sulfamic Acid as an Efficient Heterogeneous Catalyst for the Synthesis of n-Butyl Levulinate

The titania nanotubes-bonded sulfamic acid (TNTs-NHSO₃H) catalyst was designed and successfully fabricated by the post-synthesis modification method. The as-prepared catalyst was characterized by a variety of characterization techniques, including Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and thermogravimetry-differential thermal gravimetry (TG-DTG). The crystal structure of the TNTs still maintained during the modification process. Although the BET surface area was decreased, the amount of Brønsted acid sites can be efficiently fabricated on the TNTs. The catalytic activity of TNTs-NHSO₃H was examined for the synthesis of n-butyl levulinate (BL) from levulinic acid (LA) and furfuryl alcohol (FA). A relatively high selectivity (99.6%) at 99.3% LA conversion was achieved for esterification of levulinic acid owing to the strong Brønsted acidity sites. And also, the TNTs-NHSO₃H catalyst exhibited a higher reactivity for alcoholysis of FA and the yield of BL reached 90.4% with 100% FA conversion was obtained under the mild conditions.

Direct conversion of cellulose to ethyl levulinate catalysed by modified fibrous mesoporous silica nanospheres in a co-solvent system

A KCC-1/Al–SO₃H catalyst with Si/Al = 5 was prepared to directly catalyse the synthesis of ethyl levulinate from cellulose in an ethanol/toluene co-solvent system. A reaction yield of 28.8 mol% was achieved after 6 h at 200 °C.

Biomedical applications of dendritic fibrous nanosilica (DFNS): recent progress and challenges

Dendritic fibrous nanosilica (DFNS), with multi-component and hierarchically complex structures, has recently been receiving significant attention in various fields of nano-biomedicine. DFNS is an emerging class of mesoporous nanoparticles that has attracted great interest due to unique structures such as open three-dimensional dendritic superstructures with large pore channels and highly accessible internal surface areas. This overview aims to study the application of DFNS towards biomedical investigations. This review is divided into four main sections. Sections 1–3 are related to the synthesis and characterization of DFNS. The biomedical potential of DFNS, such as cell therapy, gene therapy, immune therapy, drug delivery, imaging, photothermal therapy, bioanalysis, biocatalysis, and tissue engineering, is discussed based on advantages and limitations. Finally, the perspectives and challenges in terms of controlled synthesis and potential nano-biomedical applications towards future studies are discussed.

Dendritic fibrous nanosilica (DFNS) , with multi-component and hierarchically complex structures, has recently been receiving significant attention in various fields of nano-biomedicine.

Functionalized Silicas for Metal-Free and Metal-Based Catalytic Applications: A Review in Perspective of Green Chemistry

Heterogeneous catalysis plays a key role in promoting green chemistry through many routes. The functionalizable reactive silanols highlight silica as a beguiling support for the preparation of heterogeneous catalysts. Metal active sites anchored on functionalized silica (FS) usually demonstrate the better dispersion and stability due to their firm chemical interaction with FSs. Having certain functional groups in structure, FSs can act as the useful catalysts for few organic reactions even without the need of metal active sites which are termed as the covetous reusable organocatalysts. Magnetic FSs have laid the platform where the effortless recovery of catalysts is realized just using an external magnet, resulting in the simplified reaction procedure. Using FSs of multiple functional groups, we can envisage the shortened reaction pathway and, reduced chemical uses and chemical wastes. Unstable bio-molecules like enzymes have been stabilized when they get chemically anchored on FSs. The resultant solid bio-catalysts exhibited very good reusability in many catalytic reactions. Getting provoked from the green chemistry aspects and benefits of FS-based catalysts, we confer the recent literature and progress focusing on the significance of FSs in heterogeneous catalysis. This review covers the preparative methods, types and catalytic applications of FSs. A special emphasis is given to the metal-free FS catalysts, multiple FS-based catalysts and magnetic FSs. Through this review, we presume that the contribution of FSs to green chemistry can be well understood. The future perspective of FSs and the improvements still required for implementing FS-based catalysts in practical applications have been narrated at the end of this review.

Study of a New Process for the Preparation of Butyl Levulinate from Cellulose

Butyl levulinate (BL) is a versatile chemical utilized widely in food and chemical industries, the production of which by using cellulose in biomass resources is of great significance to its sustainable development. Traditional synthesis processes for n-butyl levulinate are confronted with various problems such as high cost of raw materials, difficulty in separating products, etc. In this paper, a novel process for the preparation of BL from cellulose is proposed. The process is composed of five main unit operations including fed-batch hydrolysis, decolorization, extraction, esterification and purification. A 171.63 g/L concentration of the intermediate levulinic acid was obtained at the fifth feeding through the fed-batch hydrolysis process. The resin-activated carbon secondary decolorization method was adopted to remove the soluble humin byproducts with an accumulative decolorization rate of 89%. In the extraction process, the product BL was chosen as the extractant to avoid the introduction of new impurities. After purification, the purity of the final product BL reaches up to 98 wt %. The proposed technique allows for cost-effective and eco-friendly production of BL from biomass resources.

Improving the size uniformity of dendritic fibrous nano-silica by a facile one-pot rotating hydrothermal approach

This article provides a facile, low-cost, and reproducible one-pot rotating hydrothermal approach to synthesize dendritic fibrous nano-silica with outstanding uniformity.

AQUIVION® perfluorosulfonic acid resin for butyl levulinate production from furfuryl alcohol

Multivariate analysis allowed the optimization of a reaction catalyzed by a robust solid acid Aquivion® P87S.