Explore the vast range of titles available.

The ubiquitous nature of lignocellulosic biomass on planet earth and its economic viability attracted a great deal of attention from researchers and becomes foremost feedstock for biofuel production particularly bioethanol. However, due to complexity in structure, its pretreatment is essentially required prior to actual use. In the present study, a promising approach has been proposed through the development of acid-functionalized magnetic nanocatalysts. Two different acid-functionalized magnetic nanocatalysts i.e. alkylsulfonic acid functionalized magnetic nanoparticles (Fe3O4-MNPs-Si-AS) and butylcarboxylic acid functionalized magnetic nanoparticles (Fe3O4-MNPs-Si-BCOOH) were developed and their efficacy was studied in the pretreatment of sugarcane straw at varying concentrations (100, 200, 300, 400, 500 mg/g of straw). The enhanced concentration dependent production of sugar (xylose) was reported in case of both the nanocatalysts. The maximum 17.06 g/L for Fe3O4-MNPs-Si-AS and 15.40 g/L for Fe3O4-MNPs-Si-BCOOH sugar was reported at 500 mg which is comparatively higher than normal acid (H2SO4) (14.63 g/L) and non-treated (0.24 g/L) sugarcane straw. Further, both the nanocatalysts were recovered by applying an external magnetic field and reused for the next two subsequent cycles of pretreatment. It was observed that with every reuse of nanocatalysts the concentration of sugar production was reduced. Moreover, generation of very less amount of toxic inhibitors was reported in the hemicellulosic hydrolyzate obtained in the present study. Considering these facts, it is believed that such nanocatalysts can be used as an effective, eco-friendly and economically viable alternative to the conventional pretreatment agents like mineral acids.

Mineral acids have been used effectively for the pretreatment of cellulosic biomass to improve sugar recovery and promote its conversion to ethanol; however, substantial capital investment is required to enable separation of the acid, and corrosion-resistant materials are necessary. Disposal and neutralization costs are also concerns because they can decrease the economic feasibility of the process. In this work, three acid-functionalized nanoparticles were synthesized for pretreatment and hydrolysis of lignocellulosic biomass. Silica-protected cobalt spinel ferrite nanoparticles were functionalized with perfluoroalkylsulfonic acid (PFS), alkylsulfonic acid (AS), and butylcarboxylic acid (BCOOH) groups. These nanoparticles were magnetically separated from the reaction media and reused. TEM images showed that the average diameter was 2 nm for both PFS and BCOOH nanoparticles and 7 nm for AS nanoparticles. FTIR confirmed the presence of sulfonic and carboxylic acid functional groups. Ion exchange titration measurements yielded 0.9, 1.7, and 0.2 mmol H+/g of catalyst for PFS, AS, and BCOOH nanoparticles, respectively. Elemental analysis results indicated that PFS and AS nanoparticles had 3.1 and 4.9% sulfur, respectively. Cellobiose hydrolysis was used as a model reaction to evaluate the performance of acid-functionalized magnetic nanoparticles for breaking β-(1→4) glycosidic bonds. Cellobiose conversion of 78% was achieved when using AS nanoparticles as the catalyst at 175℃ for 1 h, which was significantly higher than the conversion for the control experiment (52%). AS nanoparticles retained more than 60% of their sulfonic acids groups after the first run, and 65 and 60% conversions were obtained for the second and third runs, respectively.

A new facile strategy was designed to prepare the phenyboronic acid-functionalized Fe3O4 magnetic nanoparticles (Fe3O4@PBA) via direct silanization and thiol-ene click chemistry for the selective adsorption of ortho-dihydroxy-containing compounds. The three kinds of Fe3O4@PBA nanoparticles obtained showed excellent adsorption capacity and selectivity for ortho-dihydroxy-containing compounds including adenosine and o-dihydroxybenzene. Among them, the Fe3O4@MPS@MPBA exhibited the highest adsorption capacity and selectivity for adenosine and o-dihydroxybenzene, followed by Fe3O4@MPTES@AAPBA and Fe3O4@MPTES@VPBA. A synthesis method of superparamagnetic and boronate affinity nanocomposites with mild reaction conditions and simple process has been developed, which also provides a novel way for the synthesis of other types of enrichment materials of ortho-dihydroxy-containing compounds.

The surface of silica-coated CoFe 2 O 4 magnetic nanoparticles (CoFe 2 O 4 @SiO 2 ), which is resistant to the oxidation due to silicone coating, was functionalized using chlorosulfonic acid and used as an efficient and recyclable catalyst for the preparation of 3-pyrrolin-2-ones from diethyl acetylenedicarboxylate, an aldehyde and aniline in ethanol solvent at 60 °C. In the presented study, some fascinating chracteritics of such catalyst, such as magnetically separable, simple workup and obtaining a high purity of products by simple recrystallization, have been successfully obtained. The structural features of CoFe 2 O 4 @SiO 2 -SO 3 H catalyst were elucidated by X-ray powder diffraction (XRPD), thermo-gravimetric studying (TGA), scanning electron microscopy (SEM) and FT-IR spectra. Graphical Abstract Sulfnic acid-functionalized silica-coated magnetic nanoparticles as a reusable catalyst for the preparation of pyrrolidinone derivatives under eco-friendly conditions