Impact of chitosan extracted from shrimp shells on the shrinkage and mechanical properties of cement-based composites using dendritic fibrous nanosilica.

Dendritic fibrous nanosilica (DFNS) was functionalized using microcrystalline chitosan, derived from shrimp exoskeletons, to act as a robust anchor, resulting in DFNS@Chitosan. In order to prevent the restacking of chitosan sheets, the supramolecular polymerized chitosan not only served as a spacer but was also incorporated into cement-based composites. The physical-chemical characteristics of DFNS@Chitosan were assessed through various analytical techniques such as TEM, SEM, TGA, FTIR, AFM, XPS, and EDX. The potency and auto-induced contraction of Cement-based composite materials fortified with DFNS@Chitosan were probed. The incorporation of DFNS@Chitosan resulted in an increase in both compressive and interfacial stretching potency of the cement-based composites. Furthermore, the presence of DFNS@Chitosan effectively inhibited the occurrence of auto-induced contraction in the cement-based paste. This research endeavor is anticipated to promote an alternative utilization of DFNS and shrimp waste shells in the development of sustainable building materials.

Enhanced simultaneous adsorption of As(iii), Cd(ii), Pb(ii) and Cr(vi) ions from aqueous solution using cassava root husk-derived biochar loaded with ZnO nanoparticles.

This study presents the modification of cassava root husk-derived biochar (CRHB) with ZnO nanoparticles (ZnO-NPs) for the simultaneous adsorption of As(iii), Cd(ii), Pb(ii) and Cr(vi). By conducting batch-mode experiments, it was concluded that 3% w/w was the best impregnation ratio for the modification of CRHB using ZnO-NPs, and was denoted as CRHB-ZnO3 in this study. The optimal conditions for heavy metal adsorption were obtained at a pH of 6-7, contact time of 60 min, and initial metal concentration of 80 mg L-1. The heavy metal adsorption capacities onto CRHB-ZnO3 showed the following tendency: Pb(ii) > Cd(ii) > As(iii) > Cr(vi). The total optimal adsorption capacity achieved in the adsorption of the 4 abovementioned metals reached 115.11 and 154.21 mg g-1 for CRHB and CRHB-ZnO3, respectively. For each Pb(ii), Cd(ii), As(iii), and Cr(vi) metal, the maximum adsorption capacities of CRHB-ZnO3 were 44.27, 42.05, 39.52, and 28.37 mg g-1, respectively, and those of CRHB were 34.47, 32.33, 26.42 and 21.89 mg g-1, respectively. In terms of kinetics, both the pseudo-first-order and the pseudo-second-order fit well with metal adsorption onto biochars with a high correlation coefficient of R 2, while the best isothermal description followed the Langmuir model. As a result, the adsorption process of heavy metals onto biochars was chemisorption on homogeneous monolayers, which was mainly controlled by cation exchange and surface precipitation mechanisms due to enriched oxygen-containing surface groups with ZnO-NP modification of biochar. The FTIR and EDS analysis data confirmed the important role of oxygen-containing surface groups, which significantly contributed to removal of heavy metals with extremely high adsorption capacities, comparable with other studies. In conclusion, due to very high adsorption capacities for metal cations, the cassava root husk-derived biochar modified with ZnO-NPs can be applied as the alternative, inexpensive, non-toxic and highly effective adsorbent in the removal of various toxic cations.

Reduction of 4-nitrophenol and 2-nitroaniline using immobilized CoMn2O4 NPs on lignin supported on FPS.

In the present work, fibrous phosphosilicate (FPS) was functionalized by using octakis[3-(3-aminopropyltriethoxysilane)propyl]octasilsesquioxane (APTPOSS) groups that act as strong performers. In this regard, the nanoparticles of CoMn2O4 were dispersed, properly, on FPS microsphere (CoMn2O4/APTPOSS@FPS) fibers. Agricultural and industrial waste waters contain nitrophenols. They are amongst the most common organic pollutants. In water, low concentrations are harmful to human health and aquatic life owing to the potential mutagenic and carcinogenic influences of nitrophenols. 4-Nitrophenol (4-NP), as well as 2-nitroaniline (2-NA), are known hazardous toxic waste contaminants and are included in the United States Environmental Protection Agency (USEPA) list. Thus, to eliminate them, novel methods are necessary. In addition, o-phenylenediamine (o-PDA) and 4-aminophenol (4-AP) are considered as significant intermediates for the synthesis of dyes and drugs, which are synthesized from 2-NA and 4-NP. Nanoparticles of CoMn2O4/APTPOSS@FPS utilized for the reduction of 2-NA and 4-NP, increase the efficiency of the reaction with considerable chemoselectivity. The results showed that the P and O atoms of lignin-FPS gold nanoparticles (NPs) were stable and the morphology and structure of FPS increased the catalytic activity.

Fixing CO2 into ß-oxopropylcarbamates in neat condition by ionic gelation/Ag(i) supported on dendritic fibrous nanosilica.

In this research, a novel approach to produce a novel nanocatalyst, AgBr supported on an ionic gelation (IG)-based nanomaterial, was developed through the aqueous coprecipitation approach for the dendritic fibrous nanosilica (DFNS) production and the wet impregnation method for IG coating, taking into account TPP as the cross-linking agent. In addition, DFNS/IG@Ag(i) had heterogeneous features that contributed to the quick improvement of the catalyst by filtration separation. The catalytic activity of DFNS/IG@Ag(i) was examined to synthesize ß-oxopropylcarbamates through a multicomponent coupling of CO2, amines and propargyl alcohols in moderate conditions. The DFNS/IG@Ag(i) NPs were completely investigated by taking advantage of TG, TEM, FESEM and FT-IR spectroscopy analyses. The DFNS/IG@Ag(i) nanocatalyst indicated high stability in the reaction for five cycles without considerable loss of some properties like activity, which could be because of the high loading of IG on the catalyst surface.

Synthesis and characterization of a novel ruthenium(ii) trisbipyridine complex magnetic nanocomposite for the selective oxidation of phenols.

Anchoring ruthenium(ii) trisbipyridine complex [Ru(Bpy)3]2+ into a magnetic dendritic fibrous silica nanostructure produces an unprecedented strong nanocatalyst, FeNi3/DFNS/[Ru(Bpy)3]2+. Impressive oxidation of phenols to 1,4-benzoquinones catalyzed by FeNi3/DFNS/[Ru(Bpy)3]2+ is obtained in acetonitrile and water solution with molecular dioxygen as oxidant. Exclusively, apparently inert phenols such as phenol itself and mono-alkyl-substituted phenols are impressively oxidized to produce 1,4-benzoquinones through activation of the C-H bond in the position para to the carbon-oxygen bond under mild conditions. In addition, the production of industrially significant quinones that are known intermediates for vitamin combinations is investigated and studied FeNi3/DFNS/[Ru(Bpy)3]2+ magnetic nanoparticles were produced, and their properties were investigated by AFM, FTIR, XRD, TGA, SEM, TEM, and VSM.

Synthesis and characterization of a novel CNT-FeNi3/DFNS/Cu(ii) magnetic nanocomposite for the photocatalytic degradation of tetracycline in wastewater.

Herein, Cu(ii) complexes were anchored within the nanospaces of a magnetic fibrous silicate with a high surface area and easily accessible active sites via a facile approach, leading to the successful synthesis of a novel potent nanocatalyst (FeNi3/DFNS/Cu). Furthermore, FeNi3/DFNS/Cu was supported on carbon nanotubes (CNTs) via an usual nozzle electrospinning method (CNT-FeNi3/DFNS/Cu). In addition, its performance as a photocatalyst for the degradation of tetracycline was tested in a batch reactor. Tetracycline is an antibiotic that is commonly utilized in veterinary medicine and in the treatment of human infections, but is hazardous to aquatic environments. However, the usual processes for the removal of tetracycline are not efficient. The eco-friendly attributes of this catalytic system include high catalytic activity and ease of recovery from the reaction mixture using an external magnet, and it can be reused several times without significant loss in its performance. Also, protocols such as hot filtration, and mercury poisoning provided complete insight into the nature of this heterogeneous catalyst.

Photooxidation of triarylphosphines under aerobic conditions in the presence of a gold(iii) complex on cellulose extracted from Carthamus tinctorius immobilized on nanofibrous phosphosilicate.

Triarylphosphines were converted to the corresponding oxides via photooxidation as a novel method. In this study, cellulose was extracted from the Carthamus tinctorius plant and then oxidized by sodium metaperiodate. A gold complex was supported on this natural cellulose. Then, a gold complex on natural cellulose supported on FPS (FPS/Au(iii)) was synthesized for the reduction of phosphine oxides to corresponding phosphines with remarkable chemoselectivity. The morphology of FPS led to higher catalytic activity. FPS/Au(iii) NPs were thoroughly characterized using TEM, FESEM, FTIR, TGA, and BET.

Synthesis of benzimidazolones by immobilized gold nanoparticles on chitosan extracted from shrimp shells supported on fibrous phosphosilicate.

Here we demonstrate the synthesis of benzimidazolones from o-phenylenediamines and carbon dioxide in the presence of gold nanoparticles supported on a composite material based on microcrystalline chitosan from shrimp shells and fibrous phosphosilicate (CS-FPS/Au). The results showed that the gold nanoparticles were stable with the P, N and O atoms of CS-FPS. The morphology and structure of FPS leads to a higher catalytic activity. The CS-FPS/Au NPs were thoroughly characterized using TEM, FESEM, TGA, FTIR, and BET.

C-C and C-H coupling reactions by Fe3O4/KCC-1/APTPOSS supported palladium-salen-bridged ionic networks as a reusable catalyst.

This study investigates the potential application of an efficient, easily recoverable and reusable magnetically separable Fe3O4/KCC-1/APTPOSS nanoparticle-supported salen/Pd(ii) catalyst for C-C and C-H cross-couplings. The Fe3O4/KCC-1/APTPOSS/salen/Pd(ii) MNPs were thoroughly characterized by using TEM, FE-SEM, TGA, XRD, VSM, FT-IR, ICP-MS, and BET. This observation was exploited in the direct and selective chemical reaction of 2-acetyl-benzaldehyde with cyclopentadiene for the synthesis of pentafulvene. The recycled catalyst has been analyzed by ICP-MS showing only minor changes in the morphology after the reaction, thus confirming the robustness of the catalyst.

Synthesis of spiroindenopyridazine-4H-pyran derivatives using Cr-based catalyst complexes supported on KCC-1 in aqueous solution.

An efficient bis(2-dodecylsulfanyl-ethyl)-amine·CrCl3 complex supported on KCC-1 (KCC-1/SNS/Cr) has been developed for the synthesis of spiroindenopyridazine-4H-pyran, providing excellent yields of the corresponding products with remarkable chemoselectivity. This morphology ultimately leads to higher catalytic activity for the KCC-1-supported nanoparticles. The KCC-1/SNS/Cr NPs were thoroughly characterized by using TEM, SEM, TGA, FT-IR, ICP-MS, and BET. The recycled catalyst has been analyzed by ICP-MS showing only minor changes in morphology after the reaction, thus confirming the robustness of the catalyst.

Green synthesis of PbCrO4 nanostructures using gum of ferula assa-foetida for enhancement of visible-light photocatalytic activity.

Photocatalytic selective oxidation has attracted considerable attention as an environmentally friendly strategy for organic transformations. Some methods have been reported for the photocatalytic oxidation of sulfides into sulfoxides in recent years. However, the practical application of these processes is undermined by several challenges, such as low selectivity, sluggish reaction rates, requirement of UV-light irradiation, use of additives, and instability of the photocatalyst. Pure monoclinic lead chromate nanoparticles were prepared via a new simple way as Pb and Cr sources. PbCrO4 NPs were synthesized via a green method in the presence of gum of ferula assa-foetida from Pb(NO3)2 and CrCl3 as lead and chromium resources, respectively. The structural analysis of the samples confirmed the formation of PbCrO4 nanostructures in the range of 30 ± 5 nm. The PbCrO4 nanocatalyst was thoroughly characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX) study. Considering the large ionic internal character and high mechanical and thermal stability as well as long-term colloidal stability, this system can be considered as a perfect nanocatalyst by using the host-guest approach. A green and ecofriendly method for oxidation of sulfides to sulfones in the presence of O2 as an oxidant was examined for the synthesised PbCrO4 NPs. The easy and applied reusability of the catalyst was observed after the completion of the reaction under visible-light irradiation.

Quinuclidine Stabilized on FeNi3 Nanoparticles as Catalysts for Efficient, Green, and One-Pot Synthesis of Triazolo[1,2-a]indazole-triones.

A new magnetically separable catalyst consisting of quinuclidin-3-thiol supported on propylsilane-functionalized silica-coated FeNi3 nanoparticles (FeNi3 /quinuclidine) has been prepared. The synthesized catalyst was characterized by powder X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The immobilized FeNi3 /quinuclidine was shown to be an efficient heterogeneous catalyst for the synthesis of triazolo[1,2-a]indazole-triones under solvent-free conditions at room temperature. The catalyst is readily recovered by simple magnetic decantation and can be recycled several times with no significant loss of catalytic activity.

Magnetic nanoparticle supported hyperbranched polyglycerol catalysts for synthesis of 4H-benzo[b]pyran.

ABSTRACT: A magnetic nanoparticle supported hyperbranched polyglycerol catalyst was prepared readily from inexpensive starting materials in aqueous medium that catalyzed the synthesis of 4H-benzo[b]pyran under solvent-free conditions at room temperature. X-ray diffraction, transmission electron microscopy, thermal gravimetric analysis, vibrating sample magnetometry, and selected-area electron diffraction were employed to characterize the properties of the synthesized catalyst. Its high catalytic activity and ease of recovery from the reaction mixture using an external magnet, and the possibility of reusing several times without significant loss of performance are additional eco-friendly attributes of this catalytic system. GRAPHICAL ABSTRACT: .