Catalytic Reduction Of Methylene Blue Research Articles

The morphology-dependent catalytic activity of anisotropic silver nanoparticles

Anisotropic silver nanoparticles (AgNPs) were phototransformed from spherical seed nanoparticles using LEDs that emit at five different wavelengths, this allowed us to directly compare the effect of size and morphology in their catalytic activity, given that the surface chemistry is the same for this set of AgNPs. The AgNPs were characterized with UV–vis spectroscopy, SEM, dynamic light scattering and Z-potential, and were tested in the catalytic reduction of methylene blue. The reduction kinetics presented a pseudo-first order model for all samples, showing that the sample phototransformed with the 500 nm LEDs had the best catalytic performance.

Biosynthesis of monodispersed stable copper nanoparticles using Syzygium cumini: characterization and potential applications

This study reports a novel, facile and eco-friendly approach for the reduction of CuSO4·5H2O into stable and well-dispersed copper nanoparticles (Cu NPs) using aqueous leaf extract of Syzygium cumini. The reduction was affirmed by UV-Visible spectrophotometer maximum absorbance at 535 nm. The effect of various parameters including temperature, pH, precursor salt concentration and incubation time on particle size of Cu NPs has been evaluated. Fourier-transform infrared spectroscopy showed a strong band at 3,307 cm–1 indicating the O–H groups of alcohols and phenols. Scanning electron microscopy analysis showed spherical morphology of Cu NPs with particle size of 19 nm. The prepared nanoparticles showed excellent catalytic performance for the removal of methylene blue (MB) from the aqueous medium using sodium borohydride (NaBH4) as a reducing agent. The kinetic studies showed that Cu NPs followed pseudo-first-order for catalytic reduction of MB.

Allium paradoxum extract mediated green synthesis of SeNPs: Assessment of their anticancer, antioxidant, iron chelating activities, and antimicrobial activities against fungi, ATCC bacterial strains, Leishmania parasite, and catalytic reduction of methylene blue

Allium paradoxum extract was used to make selenium nanoparticles (A-SeNPs). The morphological features showed the semi-spherical A-SeNPs with an average diameter of 37.5 nm from the TEM image. The EDX and XRD data confirmed the synthesis of A-SeNPs and FT-IR spectrum observed the importance of bio-functional group existing in A-Extract in the fabrication of A-SeNPs. Also, TG/DTA diagram proved the presence of capping agent on the surface of nanoparticles and the stability of these NPs. Furthermore, the efficiency of Methylene blue (MB) dye degradation obtained 100% for 50, 60, and 70 μl of A-SeNPs (700 μg/ml). The antioxidant activity of A-SeNPs (2.73–87.7 μg/ml) was assessed via DPPH radical scavenging assay, demonstrating an IC50 value of 92.55 ± 1.35 μg/ml. In the Ferrozine assay, A-SeNPs (1.33–41.66 μg/ml) showed potent iron chelation activity with an IC50 value of 24.8 ± 0.73 μg/ml. In the antibacterial investigation, A-SeNPs (0.17–175 μg/ml) demonstrated the highest activity against P. aeruginosa and A. baumannii. Besides, our nanoparticles had high antifungal activity against several fungi strains and also presented IC50 value of 35.49 μg/ml against promastigotes. A-SeNPs exhibited anticancer activity on MCF-7 and AGS cells with IC50 values of 33.97 and 22.33 μg/ml, respectively. Therefore, synthesized SeNPs presented high potential in various applications.

Characterization of the biosynthesized intracellular and extracellular plasmonic silver nanoparticles using Bacillus cereus and their catalytic reduction of methylene blue

The biosynthesis of silver nanoparticles (Ag NPs) has been studied in detail using two different approaches. For the first time, Bacillus cereus is used for one-pot biosynthesis of capsulated Ag NPs, using both intracellular and extracellular approaches. To discriminate between the produced nanostructures by these two approaches, their structures, nanomorphologies, optical properties, hydrodynamic sizes and zeta potentials are studied using different techniques. Fourier-transform infrared spectroscopy was used to identify the bioactive components responsible for the reduction of Ag+ ions into Ag and the growth of stable Ag NPs. Scanning and transmission electron microscopy images displayed spherical and polygon nanomorphology for the intracellular and extracellular biosynthesized Ag NPs. For intracellular and extracellular biosynthesized Ag NPs, a face-centred cubic structure was observed, with average crystallite sizes of 45.4 and 90.8 nm, respectively. In comparison to the noncatalytic reduction test, the catalytic activities of intracellular and extracellular biosynthesized Ag NPs were explored for the reduction of highly concentrated MB dye solution. Extracellular Ag NPs achieved 100% MB reduction efficacy after around 80 min, compared to 50.6% and 24.1% in the presence and absence of intracellular Ag NPs, respectively. The rate of MB reduction was boosted by 22 times with the extracellular catalyst, and by 3 times with the intracellular catalyst. Therefore, the extracellular production process of Ag NPs utilizing Bacillus cereus bacteria might be applied in the industry as a cost-effective way for eliminating the toxic MB dye.

Novel in-situ synthesis of copper oxide nanoparticle in smart polymer microgel for catalytic reduction of methylene blue

The present study involves the synthesis of poly-(N-isopropylmethacrylamide-co-methacrylic acid) [p(NiPmA-mAc)] microgels for the stabilization of copper oxide nanoparticles (CuO NPs) via free radical precipitation approach and synthesized material as a catalyst for catalytic degradation of methylene blue (MB) dye. Results clearly indicate that p(NiPmA-mAc) microgel not only serves as an excellent micro-reactor but also works as an effective stabilizing / fabricating medium for the successful synthesis of CuO NPs. UV–Vis spectra of CuO-[p(NiPmA-mAc)] showed the maximum peak was observed at 400 nm. Scanning electron microscopic (SEM) and X-ray diffraction (XRD) analysis showed spherical morphology of in-situ synthesized CuO NPs with crystalline size of 20 ± 4 nm. Different parameters which affect catalytic reduction reactions such as pollutant/catalyst dose, reductant concentration and effect of time were investigated. Results showed that the apparent rate constant for catalytic reduction of MB was 0.5307 min−1. The application of the CuO NPs loaded p(NiPmA-mAc) microgel catalyst for catalytic degradation of MB has shown excellent results with complete degradation (100%) within 15 min. Further, the recyclability of the CuO-[p(NiPmA-mAc)] catalyst has shown promising results during four consecutive cycles thus, confirming its stability.

Highly loaded silver nanoparticle‐modified monodispersed polystyrene composite microspheres (PS/Ag) for rapid catalytic reduction of methylene blue

AbstractIn this research, monodispersed polystyrene (PS) microspheres were prepared by dispersion polymerization. PS microspheres decorated with silver nanoparticles (PS/Ag composite microspheres) were synthesized by a modified chemical plating method with water as the synthesis medium. The microspheres at each stage were characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), UV–visible spectroscopy (UV–vis), field‐emission scanning electron microscopy (FESEM), and energy‐dispersive spectrometer (EDS). The reduction of methylene blue (MB) was carried out with PS/Ag composite microspheres as a catalyst and NaBH4 as a reducing agent. The results showed that the MB dye was reduced to colorless within 180 s. The reduction of the MB dye followed pseudo‐first‐order kinetics with an apparent rate constant (Kapp) value of 0.01425 s−1. Control experiments were also carried out by adding microspheres from each chemical plating pretreatment stage to the MB, without PS/Ag composite microspheres. The catalytic activity of the PS/Ag composite microspheres was high after five consecutive cycles of recovery, showing promising reusability. The catalytic activity of the prepared PS/Ag catalysts was superior to other catalysts for the reduction of MB.

Ag–SiO2 nanocomposite for the optical detection of Hg(II) ions and catalytic reduction of methylene blue

The adverse impact of heavy metal ions as well as dye effluents is the genuine threat to the environment. We report synthesis of Ag–SiO2 nanocomposite for the optical detection of Hg(II) ions as well as catalytic reduction of methylene blue (MB) dye. Ag–SiO2 nanocomposite was synthesized using a simple two step chemical route. The X-ray diffraction (XRD) pattern, UV–Visible absorbance spectra and X-ray photoelectron spectra (XPS) confirmed the successful synthesis of Ag–SiO2 nanocomposite. Transmission Electron Microscopy (TEM) images showed the decoration of Ag nanoparticles (NPs) of size ~9 nm on spherical ~155 nm sized SiO2 particles. The performance of as prepared nanocomposite towards optical detection of Hg(II) ions demonstrated the sensitive and selective detection by amalgam formation approach with the detection limit of 0.9 μM. Furthermore, the nanocomposite also showed superior catalytic activity towards MB reduction with pseudo first order kinetics rate constant 1.6 × 10−2 sec−1.

Edge-rich MoS2 nanosheets anchored on layered Ti3C2 MXene for highly efficient and rapid catalytic reduction of 4-nitrophenol and methylene blue

In this work, we report a simple one-step hydrothermal synthesis strategy for depositing edge-rich MoS2 nanosheets on conductive layered Ti3C2 MXene, and demonstrate the formed MoS2/Ti3C2 heterostructure has significant active site exposure and effective charge carrier flow. The resulting MoS2/Ti3C2 exhibits enhanced activity and excellent stability for the catalytic reduction of 4-nitrophenol (4-NP). The optimal MoS2/Ti3C2 catalyst displays a high pseudo-first-order rate constant of 0.61 min−1, a conversion efficiency of 96.2% within 5 min and almost unchanged activity after six consecutive reaction cycles, which is better than the pristine MoS2 nanosheets. Moreover, the MoS2/Ti3C2 catalyst achieves a pseudo-first-order rate constant as high as 0.779 min−1 for the catalytic reduction of methylene blue (MB). This study opens up new opportunities for the design and development of cost-effective, efficient and reusable alternatives to noble metal catalysts based on molybdenum disulfide for environmental applications.

Hydrothermal preparation of Ag/Fe3O4/Cellulose nanocrystals nanocomposite and its application in methylene blue removal

The preparation of reusable and eco-friendly materials from renewable biomass resources such as cellulose is an inevitable choice for the sustainable development. In this paper, Ag/Fe3O4/cellulose nanocrystals (CNC) nanocomposite was prepared and investigated its application in methylene blue (MB) removal. In the procedure, CNC was isolated from Vietnamese coconut husk fibers (CCH) biomass via a formic/peroxyformic acid process treatment and hydrochloric acid hydrolysis. The obtained CNC was used as a starting material to prepare Ag/Fe3O4 nanostructure by facile and green hydrothermal method. The nanocomposite was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), and magnetic properties via vibrating sample magnetometer (VSM) analysis. The results showed that Ag/Fe3O4 was formed with a particle structure and dispersed on the CNC surface. All samples exhibited magnetic properties and the saturation magnetization (Ms) of Ag/Fe3O4 composite was reduced from 48 to 12 emu/g with adding CNC. Ag/Fe3O4/CNC magnetic nanocomposite demonstrated good adsorption of MB solution and exhibited a fast catalytic reduction of MB after immersion treatment by NaBH4, which showed potential applications in water treatment.

Ultrasonic preparation of a new composite poly(GMA)@Ru/TiO2@Fe3O4: Application in the catalytic reduction of organic pollutants

This work concerns the preparation of a new composite material based on poly(Glycidyl methacrylate), Ru/TiO2 and Fe3O4 using ultrasound treatment. Several composites were prepared by varying the percentage of Ru/TiO2 and Fe3O4. Then, they were applied as catalysts for the reduction of several organic pollutants. 4-Nitrophenol (4-NPh), Methylene blue (MB) and Orange G (OG) were used as a model to study the photocatalytic reduction process in the presence of NaBH4 at room temperature. The obtained photocatalysts were characterized by different methods such as XRD, FTIR, XPS, SEM, EDX, TEM, STEM, TGA, ultraviolet–visible (UV–vis) spectroscopy and Zeta potential measurements. The results showed that the use of ultrasound gave a good dispersion of all species into the polymeric matrix. These solids have shown good activity via the photocatalytic reduction of organic pollutants. The best performance was obtained for the photocatalyst having the higher content of metal NPs “CP(30)”. The rate constant Kapp of composite CP(30) towards catalytic reduction of MB, OG and 4-NPh reached a high level up to 0.55 min−1, 0.241 min−1 and 0.3 min−1, respectively. Finally, the recyclability of the photocatalyst CP(30) was also evaluated. The results showed that the performance of this photocatalyst was satisfactory during its reuse.

A rapid microwave-assisted synthesis of silver nanoparticles using Ziziphus jujuba Mill fruit extract and their catalytic and antimicrobial properties

An eco-friendly and sustainable approach was developed for the synthesis of silver nanoparticles (AgNPs) of Ziziphus jujuba Mill (ZJM) fruit extract by a microwave-assisted technique. The developed method was simple, economically viable, sustainable, and eco-friendly. Concentrations of AgNO3 and ZJM fruit extract and reaction time were optimized for the final properties of synthesized AgNPs. The prepared AgNPs were characterized by UV-visible and FTIR spectrophotometers, powder XRD, TEM, and DLS. XRD results showed a face-centered cubic structure for the prepared AgNPs. The obtained size of AgNPs was 8 ± 1 nm with spherical shape. The FTIR spectrum indicates that ZJM is a good capping agent to stabilize AgNPs. A negative zeta potentials value of − 21.2 mV indicates the stability of AgNPs. The AgNPs has good stability over a wide range of pH and ionic strength. The role and efficacy of AgNPs in the catalytic degradation of methylene blue (MB) and Congo red (CR) dye were studied, and the reduction reaction rate constants were found to be 0.033 s−1 (180 s) and 0.025 s−1 (200 s) respectively. The synthesized AgNPs showed rapid and excellent catalytic reduction of MB and CR dyes. The rapid catalytic reduction reactions followed pseudo-order kinetics. The ZJM fruit extract-capped AgNPs showed good antimicrobial activity against tested bacterial and fungal cultures.

Ultrasonic-assisted green synthesis of silver nanoparticles using Mentha aquatica leaf extract for enhanced antibacterial properties and catalytic activity

In the current paper, ultra-small Ag nanoparticles (AgNPs) were synthesized by green and straightforward biogenic technique using Mentha aquatica leaf (MAL) extract as reducing and capping agent. The phytochemicals present in the extract could reduce the Ag+ ions to Ag0 and form nanoparticles. Several analytical techniques including UV–VIS spectroscopy, Transmission microscopy (TEM) coupled to energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and Fourier transforms infrared spectroscopy (FTIR) were performed to the characterization of biosynthesized AgNPs. The effective parameters on synthesis were fully optimized to achieve small nanoparticles. The results showed that applying the ultrasound during the synthesis could result in smaller AgNPs (8 nm) with enhanced antibacterial activity by lowering the minimum inhibitory concentration (MIC). In particular, the MIC values for ultrasound-assisted synthesized AgNPs against P. aeruginosa, E. coli, B. cereus, and S. aureus were 2.2, 58, 20 and 198 μg/mL. In addition, the as-synthesized ultrasound-assisted AgNPs showed considerable catalytic activity for reduction of different types of dyes as environmental pollutants. The effective parameters on the catalytic reduction of methylene blue were fully optimized, where 807.69 s−1 g−1 was found as normalized first-order kinetic constant for catalytic degradation of methylene blue under optimized conditions. This study provides an insight into the controlled green synthesis AgNPs and how to manipulate their activities for different applications.

Highly efficient flow-through catalytic reduction of methylene blue using silver nanoparticles functionalized cotton

Organic dye pollution has become a serious problem threating environment and human health. Noble metal nanoparticles based catalytic degradation of organic dyes has attracted intensive attentions due to their outstanding catalytic activities. Compared with the catalytic systems using free noble metal nanoparticles, the flow-through systems based on the immobilized noble metal nanoparticles are more suitable for both high efficiency reaction and recycling of nanoparticles. In this study, the fibrous natural material cotton is selected as the support of silver nanoparticles (Ag NPs) and used for flow-through catalytic reduction of methylene blue (MB). Ag NPs were one-step immobilized onto cotton by immersing the cotton into a mixture solution of silver nitrate, poly (ethylene glycol) methyl ether thiol and dopamine. The reaction rate constant K of Ag NPs functionalized cotton towards MB reached high up to 0.478 min−1. The flow-through system with Ag NPs functionalized cotton was operated to achieve a super high permeation flux of 2000 L m−2 h−1 and also a very high MB reduction of more than 99%, which is far better than the reported results (below 500 L m−2 h−1). Moreover, the Ag NPs on cotton were very stable and released very slowly. After 24 h flowing-through test, only 0.9% of silver lose from the cotton. Our work provides a facile and applicable way to prepare the low-cost catalysts with high performances for continuous and efficient dye-containing waste water treatment.

Uniform and reactive hydrogen polysilsesquioxane hollow spheres immobilized with silver nanoparticles for catalytic reduction of methylene blue

The facile synthesis of a new class of reactive hydrogen polysilsesquioxane (HPSQ, (HSiO1.5)n,) hollow spheres is reported in this work. HPSQ hollow spheres can be controllably fabricated from triethoxysilane (TES, HSi(OEt)3) as a sole precursor through a polystyrene template-directed sol–gel process under aqueous acid-catalyzed conditions followed by template removal. The particle size and shell thickness of the spheres could be fine-tuned by utilizing different amounts of TES. Total preservation of SiH bonds and formation of a Si-O-Si framework in the HPSQ hollow spheres are confirmed by FTIR and 29Si NMR. Reactive SiH moieties combined with a hollow structure make HPSQs suitable as carriers for noble metal nanoparticles. HPSQ hollow spheres function not only as a host that can adsorb Ag ions but also as a mild reducing agent for these ions. TEM studies show that the synthesized AgNPs are dispersed well on the HPSQ hollow spheres with an average particle size of 2–10 nm. XRD studies indicate that the resulting AgNPs are highly crystalline with a face-centered cubic geometry. SEM-EDS shows that the Ag content on the selected surface is 4.76 wt%. HPSQ hollow spheres loaded with AgNPs exhibit high performance when utilized as a catalyst to reduce methylene blue.

Mild synthesis of single-nanosized plasmonic copper nanoparticles and their catalytic reduction of methylene blue

In this study, we report a mild synthesis of sub-10 nm Cu nanoparticles (NPs) in ethylene glycol (EG) at room temperature using l-ascorbic acid (AA) as the reducing agent in the presence of 1-amino-2-propanol (AMIP). To the best of our knowledge, this work is the first report of the room-temperature synthesis of sub-10 nm Cu NPs using a nontoxic reducing agent. The as-prepared colloidal suspension of Cu NPs exhibited surface plasmon resonance absorption at 515 nm. Transmission electron microscopy observations revealed well-dispersed spherical Cu NPs with an average particle size of 4.1 ± 0.8 nm. The use of AMIP as a ligand was found to be critical to producing sub-10 nm Cu NPs in EG under such mild conditions. Moreover, the sub-10 nm Cu NPs were an effective catalyst for the reversible methylene blue–AA reaction system.

Green synthesis of MOF@Ag nanocomposites for catalytic reduction of methylene blue

In this study, a novel catalyst (ZBD@Ag) based on silver nanoparticles (AgNPs) grown on the surface of Zn2(bdc)2(dabco) metal-organic framework (ZBD), was synthesized using a green in-situ approach. The ZBD@Ag nanocomposite was characterized by various techniques, and its catalytic performance was investigated in the reduction of methylene blue (MB) in the presence of NaBH4. It was found that the catalyst possesses outstanding performance even at deficient concentrations and that acidic pH is more suitable for the catalytic reduction. The catalytic reduction of MB completed in 6 min, and the reaction followed the first-order kinetics (K = 0.37 min−1 ≈30.5 s−1 g−1). The developed catalyst could well suppress the other similar catalysts for the same reaction, showing its potential to be used for the removal of hazardous materials like organic dyes.

Smart synthesis of silver nanoparticles supported in porous polybenzoxazine nanocomposites via a main-chain type benzoxazine resin

In this article, novel silver nanoparticles immobilized on macroporous polybenzoxazine nanocomposites (Ag-poly(BA-ddm)xmain) were prepared as catalysts for catalytic reduction reaction. For this purpose, a main-chain type benzoxazine was cured in dimethyl sulfoxide by thermally activated ring-opening polymerization at 180°C for 2days followed by the reduction of silver nitrate in homogeneous polybenzoxazine solution. The porous structure of the resin was confirmed by scanning electron microscope (SEM) analysis and N2 adsorption/desorption studies. Besides, transmission electron microscopy images showed that spherical particles (around 3–10nm in sized) are dispersed in Ag-poly(BA-ddm)xmain network. The catalytic activity of the as-prepared nanocomposite has been investigated by photometrically monitoring the reduction of methylene blue by an excess of NaBH4. The kinetic data of the reduction reaction was explained by the assumption of a pseudo-first-order reaction with regard to methylene blue (MB). As evidence by Ultraviolet (UV) spectral analysis, the Ag-poly(BA-ddm)xmain catalyst possesses excellent catalytic reduction of MB, and no deactivation or poisoning of the catalyst was observed. The results demonstrate that porous polybenzoxazine supported silver nanoparticles can be applied as reusable catalysts with satisfied catalytic activity.

Ag-loaded thermo-sensitive composite microgels for enhanced catalytic reduction of methylene blue

In this work, we report the synthesis of composite system pNAC, composed of silver nanoparticles embedded in pure thermo-sensitive crosslinked polymer network of poly(N-isopropylacrylamide-co-acrylamide) (pNA), using as a catalyst for the reduction of methylene blue (MB) dye by sodium borohydride (NaBH4). The pNA was prepared by conventional free radical polymerization technique using sodium dodecyl sulfate as stabilizing agent, followed by in situ reduction of AgNO3 inside the polymer network by NaBH4 for the synthesis of composite systems pNACs. The synthesized pNA and pNACs were characterized by FTIR, dynamic light scattering, thermo-gravimetric analysis, scanning electron microscopy and UV–visible spectroscopy techniques. The materials were found sensitive toward temperature change of the medium. The entrapment ability of pNA toward different amounts of AgNO3 solution was studied, and effect of metal content on particle size of pNACs was analyzed. The pNACs were applied as a catalyst for the reduction of MB in which they exhibit high catalytic activity and reusability toward the reaction.

Wet chemical method for synthesizing 3D graphene/gold nanocomposite: catalytic reduction of methylene blue

In this paper, a simple and environmentally-friendly approach was reported to synthesize a novel 3D composite of graphene/gold nanoparticles (3DG/Au NPs) in one step. A 3D interlaced framework of graphene, which exhibited hierarchically porous structures, generated directly through the distinct driving force during the hydrothermal growth. Meanwhile, Au NPs with high dispersity, which displayed tunable morphologies, were immobilized on the framework, where the as-prepared graphene was employed as the endogenous reducing agent. Compared with AuNPs, the obtained 3DG/Au NPs exhibited remarkably convenient recyclability and high activity for the reduction of methylene blue which is a kind of organic dye.

Synthesis and catalytic performance of SiO2@Ni and hollow Ni microspheres

Nickel (Ni) catalyst has been widely used in catalytic reducing reactions such as catalytic hydrogenation of organic compounds and catalytic reduction of organic dyes. However, the catalytic efficiency of pure Ni is low. In order to improve the catalytic performance, Ni nanoparticle-loaded microspheres can be developed. In this study, we have prepared Ni nanoparticle-loaded microspheres (SiO2@Ni) and hollow Ni microspheres using two-step method. SiO2@Ni microspheres with raspberry-like morphology and core–shell structure are synthesized successfully using SiO2 microsphere as a template and Ni2+ ions are adsorbed onto SiO2 surfaces via electrostatic interaction and then reduced and deposited on surfaces of SiO2 microspheres. Next, the SiO2 cores are removed by NaOH etching and the hollow Ni microspheres are prepared. The NaOH etching time does no have much influence on the crystal structure, shape, and surface morphology of SiO2@Ni; however, it can change the phase composition evidently. The hollow Ni microspheres are obtained when the NaOH etching time reaches 10 h and above. The as-synthesized SiO2@Ni microspheres exhibit much higher catalytic performance than the hollow Ni microspheres and pure Ni nanoparticles in the catalytic reduction of methylene blue. Meanwhile, the SiO2@Ni catalyst has high stability and hence it can be recycled for reuse.