Functionalized Silica Nanoporous Pd complex for Reduction of Nitroarenes and Dyes

Triazine based probes for nitroaniline: Comprehensive optical and DFT approach for dual-phase detection and fingerprint sensing

Extended conjugation in fluorescent probes is crucial for efficient optical characteristics. Herein, two novel triazine based organic compounds ITA and DIT with extraordinary photophysical properties were synthesized through palladium catalyzed Suzuki and Sonogashira coupling reactions, respectively. Solvatochromism and solid-state based comprehensive study of photophysical properties of probes ITA and DIT was investigated for developing dual phase and extremely sensitive and selective fluorescent probes for detection of 4-nitroanilne (4-NA). The probes ITA and DIT were also utilized in the formulation of latent fingerprint sensing and invisible ink. Furthermore, the outstanding fluorescence properties of probes ITA and DIT were efficiently used for the selective sensing of 4-nitroanilne (4-NA) in real samples and portable paper-strips were constructed for the on-site sensing of 4-NA. The sensing approach for selective detection of 4-NA was comprehensively evaluated with the help of spectroscopic analysis including titration NMR, UV-visible spectroscopy, fluorescence studies, dynamic light scattering (DLS) and DFT calculations. DFT calculations included the calculation of RDG analysis, thermodynamic stability, charge transfer and molecular orbital studies as well as QTAIM. All the analysis and theoretical studies supported the existence of non-covalent interactions between probes and 4-NA.

Development of a novel and robust CuO-Co3O4@Biochar nanocomposite using Terminalia chebula leaf extract for reduction of nitro compounds and photodegradation of single and binary mixture of organic contaminants

In this work, Terminalia chebula leaf extract was used to synthesize CuO-Co3O4 nanoparticles, which were then embedded in a rice straw biochar. This new biochar-based nano-catalyst is used to photocatalytically degrade a variety of dyes (Eosin Y, Trypan Blue, Crystal Violet, Methylene Blue, Brilliant Green), as well as a binary mixture of Eosin Y and Trypan Blue dyes. It is also used for the catalytic reduction of nitro compounds (4-NP, 3-NP, and Picric acid). To ascertain the structure, composition, and morphology of the CuO-Co3O4@BC photocatalyst, various analytical techniques were employed, including Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Photoluminescence (PL) spectra, Energy Dispersive X-ray analysis (EDX), Brunauer-Emmett-Teller (BET) analysis, and High-Resolution Transmission Electron Microscopy (HRTEM). The optical properties of the nanocatalyst sample were accurately assessed by the use of UV-Diffuse Reflectance Spectroscopy (UV-DRS). The as-synthesized nanocatalyst's photocatalytic capacity was assessed by observing dye degradation in the presence of visible light. It suggests a significant reduction in the rate of recombination of electrons and holes and therefore better charge separation from the catalyst optical properties. It was discovered that the efficient photocatalytic activity of the nanocatalyst had been brought about as a result of the synergistic interactions that had occurred between the different moieties. The growing organic water pollutants Trypan Blue were found to deteriorate to 96.80 ± 1.25% in 21 min and Eosin Y to 98.12 ± 1.42% in 30 min by the photocatalyst under visible light irradiation. For the photodegradation, pseudo-first-order kinetics were employed, with specific reaction rate constant of 0.1068 min-1 and 0.1429 min-1 for EY and TB, respectively. Studies have also been conducted to determine the effects of additional variables on deteriorating performance, such as water matrices, beginning concentration, catalyst dose, and contact length. With high catalytic characteristics, the developed CuO-Co3O4@BC catalyst completes the reduction reactions of 4-NP, 3-NP, and Picric acid in 3, 2.5, and 5 min, respectively. An affordable CuO-Co3O4@BC is a potential catalyst for turning harmful nitro chemicals into useful products. It also serves as a nano photocatalyst that is stable, can be used again, and is cost-effective.

Porous Pd-Loaded IRMOF-9 as Highly Efficient Recyclable Material Towards the Reduction of Nitroaromatics in Aqueous Media

Nitroaromatic compounds (NACs) cause severe hazardous impacts on human health as well as on the environment. Therefore, there is dire need to develop a robust material to reduce the toxicity of these organic pollutants. In this regard, our group developed a series of porous MOF materials viz., Pdx@IRMOF-9 (x=2 %, 5 % and 10 %) by loading different concentration of Pd(II) on IRMOF-9 and explored them towards reduction of different nitroaromatic compounds. Pd10%@IRMOF-9showed ~30 % greater efficiency for the reduction of 4-NP as compared to Pd2%@IRMOF-9. Pd10%@IRMOF-9showed excellent reduction ability (>85 %) towards 4-NP, 2-NP, 2-NA, 3-NA and 2,4-DNPH. The kinetic studies indicates that the reduction follows the pseudo-first-order kinetics. Moreover, the rate constant value for reduction of 3-NA was ~9 times higher than that of 2-NP. Based on the kinetic parameters, the t1/2 values for all the nitroaromatics have been calculated. The kinetic parameters, Km and Vmax have been calculated from double reciprocal Lineweaver-Burk plot and found to be 65.984 μM and 116×10-6 Mmin-1 respectively. Pd10%@IRMOF-9showed excellent recyclability towards the reduction of 4-NP for few consecutive cycles without any remarkable loss in its activity. Thus, highly efficient, porous and robust material for the reduction of nitroaromatic compounds in aqueous media have been demonstrated.

Fabrication of nano-sized Pd catalyst supported on sodium carboxymethyl cellulose/gum Arabic/sodium alginate functionalized microspheres for catalytic reduction of nitro compounds, organic dyes, K3[Fe(CN)6], and chromium(VI) pollutants

The rapid development of industrialization and urbanization, along with the increasing human population, has led to serious water pollution. Among water pollutants, organic and inorganic pollutants cause serious problems for both the environment and human health due to their toxicity and carcinogenic properties. One of the best ways to eliminate these pollutants is to develop eco-friendly, efficient, and long-life catalysts. For this purpose, in this study, environmentally friendly microspheres containing sodium alginate (SA), sodium carboxymethyl cellulose (Na-CMC), and gum Arabic (GA) were fabricated as potential stabilizers (SA/Na-CMC/GA). Subsequently, newly heterogeneous catalyst system was designed by immobilizing Pd nanoparticles on them and characterized (Pd@SA/Na-CMC/GA). The catalytic reduction ability of Pd@SA/Na-CMC/GA was then investigated against the reduction of 4-nitroaniline (4-NA), 4-nitrophenol (4-NP), 2-nitroaniline (2-NA), 4-nitro-o-phenylenediamine (4-NPDA), methylene blue (MB), methyl orange (MO), Rodamin B (RhB), potassium hexacyanoferrate(III) (K3[Fe(CN)6]), and hexavalent chromium (Cr(VI)) using NaBH4. The Pd@SA/Na-CMC/GA effectively catalyzed these contaminants in a short period of time under mild reaction conditions. As a result of the performed kinetics studies, rate constants were found to be 0.009 s-1, 0.016 s-1, 0.027 s-1, 0.018 s-1, 0.043 s-1, 0.058 s-1, 0.038 s-1 and 0.041 s-1 for the reduction of 4-NP, 2-NA, 4-NA, 4-NPDA, MO, RhB, K3[Fe(CN)6], and Cr(VI), respectively. Additionally, MO was immediately reduced by Pd@SA/Na-CMC/GA. The microsphere nature of Pd@SA/Na-CMC/GA allowed for easy recovery through simple filtration and successful reuse for up to six cycles.

Magnetic boron nitride adorned with Pd nanoparticles: an efficient catalyst for the reduction of nitroarenes in aqueous media

Hexagonal boron nitride (h-BN) is an excellent support material for nanocatalysts due to its two-dimensional (2D) architectural morphology and physicochemical stability. In this study, a chemically stable, recoverable, eco-friendly, and magnetic h-BN/Pd/Fe₂O₃ catalyst was prepared by a one-step calcination process, in which Pd and Fe₂O₃ nanoparticles (NPs) were uniformly decorated on the surface of h-BN via a typical adsorption-reduction procedure. In detail, nanosized magnetic (Pd/Fe₂O₃) NPs were derived from a Prussian blue analogue prototype, a well-known porous metal-organic framework, and then further surface-engineered to produce magnetic BN nanoplate-supported Pd nanocatalysts. The structural and morphological features of h-BN/Pd/Fe₂O₃ were investigated by spectroscopic and microscopic characterization techniques. Moreover, the h-BN nanosheets endow it with stability and appropriate chemical anchoring sites which solve the problems of inefficient reaction rate and high consumption caused by the inevitable agglomeration of precious metal NPs. Under mild reaction conditions, the developed nanostructured h-BN/Pd/Fe₂O₃ as the catalyst shows high yield and efficient reusability in reducing nitroarenes into the corresponding anilines using sodium borohydride (NaBH₄) as a reductant.