Rh 6G Research Articles

Gold nanostructures for the sensing of pH using a smartphone.

Recently, metal nanostructures have been found to be capable of recognizing small changes in their surrounding environment, which can be utilized as significant sensing tools. In this study, we demonstrated colorimetric sensing of pH by gold nanostructures (GNs) using a simple smartphone. An indigenously developed Android app based on the CIELab 1931 analysis, which could run in a smartphone, was used for the precise determination of the pH value of liquid media. The pH value of an unknown solution obtained from the developed Android app was also compared with that obtained from the conventional ratiometric technique and a commercial pH meter. In another endeavor, it was found that the synthesized GNs demonstrated a high energy transfer efficiency from a donor (namely, the rhodamine 6G, (Rh 6G)) dye. This property of the GNs can be utilized further in the future for studying different bimolecular activities within the human body. It was found that the photoluminescence (PL) of Rh 6G was quenched when it was kept in the vicinity of the synthesized GNs, which was explained in terms of the Förster energy transfer mechanism. Thus, the present study will open up a plethora of opportunities for researchers to employ the nanostructures of gold and other metals in developing low-cost and Internet of Things (IoT)-based sensing devices using only a smart phone.

Effective Degradation of Rh 6G Using Montmorillonite-Supported Nano Zero-Valent Iron under Microwave Treatment.

Nano zero-valent iron has drawn great attention for the degradation of organic dyes due to its high reactivity, large specific surface area, lightweight, and magnetism. However, the aggregation and passivation of iron nanoparticles may prohibit the wide use of it. A new composite material was prepared by loading nano zero-valent iron (nZVI) on montmorillonite (MMT) to overcome the above shortcomings and it was further used for the removal of Rhodamine 6G (Rh 6G) under microwave treatment in the present work. The effects of various parameters, including the initial concentration of Rh 6G, microwave power, and pH value were investigated. The new composite material (nZVI/MMT) showed an excellent degradation ability for removing Rh 6G, and the removal amount reached 500 mg/g within 15 min. The degradation rate reached 0.4365 min−1, significantly higher than most previous reports using other removal methods for Rh 6G.

Enhanced Degradation of Rh 6G by Zero Valent Iron Loaded on Two Typical Clay Minerals With Different Structures Under Microwave Irradiation.

Nanoscale zero valent iron has been a widespread concern in various fields due to its large specific surface area and high reactivity. However, nanoscale zero valent iron (nZVI) is very likely to aggregate and be oxidized, which limit its wide application in industry. Most clay minerals have a large adsorption capacity of cations due to their negative charges and high specific surface areas. In the present work, nZVI was loaded onto two typical clay minerals: kaolinite and sepiolite, to inhibit its oxidation and aggregation. The composites were applied to degrade Rhodamine 6G (Rh 6G) under microwave irradiation. The effects of pH value and microwave power on degradation were studied. The results showed that the removal amount of Rh 6G by nZVI/kaolinite was 110 mg/g in 15 min, while it reached 300 mg/g by nZVI/sepiolite. The difference between these two composites was mostly determined by the structures of these two clay minerals.

Effective catalytic reduction of aromatic nitrocompounds using mineral beyerite, CaBi2O2(CO3)2

The synthesis of the mineral beyerite (CaBi2O2(CO3)2) by a single step hydrothermal approach is highly beneficial to demonstrate its multifunctional nature. The present work, deals with the application of CaBi2O2(CO3)2 as a heterogeneous catalyst. The formation of bulk polycrystalline beyerite via hydrothermal method at 140 °C led to the formation of single phase thin rectangular plates as evidenced from PXRD, SEM and TEM characterizations. These rectangular plates of beyerite with sharp edges show excellent reduction catalytic activities of aromatic nitro compounds in the presence of NaBH4. For example, pseudo first order reaction rate constant for the conversion of 4-nitrophenol to 4-aminophenol using beyerite as catalyst is found to be 2.5 × 10−1 min−1. The catalyst is environmental friendly, devoid of expensive noble metals and can be recycled upto five successive catalytic cycles with maximum conversion efficiency. TEM images of the catalyst after reduction reactions showed the possible presence and involvement of metallic bismuth (Bi°). The usage of CaBi2O2(CO3)2 can also be expanded, for the reduction of other (2-nitrophenol, 3-nitrophenol, 2, 4-dinitrophenol) nitro compounds, and also for the reduction of aqueous solutions containing Cr(VI), methyl orange (MO) and Rhodamine-6G (Rh 6G). The demonstration of the mineral beyerite as a reduction catalyst offers new possibilities to develop novel solid state materials for various catalytic applications.

Photocatalytic Active Bismuth Fluoride/Oxyfluoride Surface Crystallized 2Bi2O3-B2O3 Glass–Ceramics

The present article deals with 2Bi2O3-B2O3 (BBO) glass whose photocatalytic activity has been enhanced by the method of wet etching using an aqueous solution of hydrofluoric acid (HF). X-ray diffraction of the samples reveals that etching with an aqueous solution of HF leads to the formation of BiF3 and BiO0.1F2.8 phases. Surface morphology obtained from scanning electron microscopy show granular and plate-like morphology on the etched glass samples. Rhodamine 6G (Rh 6G) has been used to investigate the photocatalytic activity of the as-quenched and etched glasses. Enhanced visible light-driven photocatalytic activity was observed in HF etched glass-ceramics compared to the as-quenched BBO glass. Contact angle of the as-quenched glass was 90.2°, which decreases up to 20.02° with an increase in concentration of HF in the etching solution. Enhanced photocatalytic activity and increase in the hydrophilic nature suggests the efficient treatment of water pollutants by using the prepared surface crystallized glass–ceramics.

Self-Assembled 3D Hierarchical Copper Hydroxyphosphate Modified by the Oxidation of Copper Foil as a Recyclable, Wide Wavelength Photocatalyst.

In this work, three-dimensional flower-like and petal-like copper hydroxyphosphate Cu5(OH)4(PO4)2 (CHP) based on the self-assembly of numerous nanosheets has been successfully fabricated on a copper foil by a mild one-pot wet-chemical method without ligand assistance. This research contributes to the development of the method to change the morphology of the CHP active material by varying the degree of substrate oxidation. The two different CHP architectures were used to photocatalytically degrade rhodamine 6G (Rh 6G) under solar light, which can absorb wide-range light wavelength from the UV to the near-infrared region. They all exhibit high photocatalytic activity and good durability, which are potential candidates for high performance and recyclable wide wavelength photocatalysis.

Synthesis of solvothermal derived TiO2 nanocrystals supported on ground nano egg shell waste and its utilization for the photocatalytic dye degradation

TiO2 nanoparticles with excellent crystallinity were synthesized via solvothermal method and supported on the ground nano-sized egg shell waste at different loading concentrations. The photocatalytic degradation of the mixture of Methylene blue (MB) and Rhodamine 6G (Rh 6G) in aqueous solution utilizing prepared TiO2 nano composite under visible light irradiation was analysed. Different characterizations including UV–Visible (UV–Vis) spectroscopy, Field emission scanning electron microscopic (FE-SEM), energy dispersive studies (EDS), Transmission electron microscopy (TEM) were performed to investigate the physicochemical properties of the prepared catalyst. In addition, FE-SEM and EDS analysis of the prepared egg shell support were carried out to confirm the morphology, particle size distribution, and composition. The solvothermal derived TiO2 nanocrystals supported on ground nano-sized egg shell waste exhibited enhanced photocatalytic activity as compared to the as-prepared TiO2 nanoparticles. The synergistic effect of TiO2 nanoparticles and nano egg shell support is attributed to the effective dispersion of TiO2 that offers high specific surface area.

Enhanced photocatalytic activity of nanoporous BiVO4/MCM-41 co-joined nanocomposites for solar energy conversion and environmental pollution abatement

BiVO4/MCM-41 nanocomposite photocatalysts were prepared by hydrothermal reaction taking bismuth nitrate and ammonium vanadate as precursors. Different wt% of BiVO4 (2.5, 5 and 10wt%) have been loaded on nanoporous MCM-41 supports and also the hydrothermal synthetic time has been varied to design a series of photocatalysts. XRD suggests well formation of crystalline BiVO4, TEM confirms small sized BiVO4 nanocrystals uniformly distributed on nanoporous MCM-41 support, UV–vis DRS and PL indicates red shift and lower recombination of BM nanocomposites. The photocatalytic water splitting to generate O2 and toxic organic dye (Rh 6G) degradation studies have been evaluated using these efficient nanocomposite photocatalysts. 5wt% BiVO4/MCM-41@4h (BM-4) catalyst shows the best results in both O2 generation (691.3μmol in 4h) and 98% of Rhodamine 6G degradation respectively. The enhanced photocatalytic activity may be attributed to nanoporous architecture, quantum size of BiVO4, high surface area, better light harvestation and electron transfer.

Fe/Fe3C nanoparticles loaded on Fe/N-doped graphene as an efficient heterogeneous Fenton catalyst for degradation of organic pollutants

Heterogeneous Fenton catalyst with high activity and excellent durability is highly demanded for efficient removal of organic pollutants via well-known Fenton reaction. In this work Fe/Fe3C nanoparticles loaded on iron/nitrogen-doped graphene (Fe/Fe3C@Fe/N-Graphene) were synthesized via spontaneous oxidative polymerization of dopamine (DA) on graphene oxide (GO) surface in the presence of iron (III) chloride, followed by thermal annealing. The Fenton catalytic performance of as-prepared Fe/Fe3C@Fe/N-Graphene was evaluated by degrading rhodamine 6G (Rh 6G) as a model organic pollutant. It is found that as-prepared catalyst demonstrates good activity with a rate constant of 0.080min−1 under optimal hydrogen peroxide (H2O2) concentration and catalyst dosage. Moreover, its catalytic activity shows negligible decrease even after 13 successive cycles, exhibiting excellent catalytic durability. The possible mechanism behind the improved Fenton catalytic activity and durability was further discussed.

Fluorescent polymeric optical fibre illuminator

Compact fluorescent optical fibre illuminator is presented. The fabrication and characterisation of polymethyl methacrylate fibre with fluorescent tip are presented. The luminescent properties of Perylene (Per) and Rhodamine 6G (Rh 6G) of co-doped polymeric fibre were used for 405 nm laser diode radiation conversion inside the polymeric fibre. The spectrum shape and chromaticity coordinates show possibility of application as white light (ca. 3350 K) illuminator. The intensity characteristics of fabricated illuminator are also shown. The small dimensions and high flexibility assure numerous applications of presented construction.

Influence of metallic and semiconducting nanostructures on the optical properties of dye-doped polymer thin films

Dye-doped polymer thin films were obtained by spin-coating of 8% polyvinylpyrrolidone (PVP) solutions (in ethanol). Ni or ZnO nanowires were incorporated in Rhodamine 6G doped polymer films (10−4M dye concentration). Optical and morphological properties of simple dye-doped polymer films and films containing metallic or semiconducting nanostructures were investigated. Optical microscopy and scanning electron microscopy were used to image the nanowires. The presence of Ni nanowires induces a small shift (2–3nm) to longer wavelengths on the emission band of Rh 6G doped PVP film. The ZnO nanowires' presence was confirmed by X-ray diffraction measurements. An enhancement of the emission of the dye doped polymer is induced by the semiconducting structures.

Removal of Rhodamine 6G from wastewater using solar irradiations in the presence of different additives

The present work investigates the intensification aspects for the solar-induced photocatalytic degradation of basic dye Rhodamine 6G (Rh 6G) using different additives. The effect of basic operating parameters as pH and initial concentration has been investigated initially followed by studies related to understanding the effect of different additives and deciphering the controlling mechanism for intensification of degradation. The effect of catalysts such as TiO2, CuO and CaO as well as process intensifying additives such as FeSO4 and CuSO4 over the loading range of 1.5–4.5 g/L has been investigated. Among the different additives investigated in the work, TiO2 was observed to give maximum effectiveness for process intensification. The effect of radical scavengers such as methanol (CH3OH), n-butanol (n-C4H9OH) and Na2CO3 has also been investigated to elucidate whether the free radical attack is the controlling mechanism of degradation. The extent of degradation was significantly affected at higher loadings of the radical scavengers confirming the major role of hydroxyl radicals in deciding the extent of degradation. Overall, it has been observed that maximum degradation as 96.5% was obtained under optimal conditions of pH as 12.5 and initial concentration of 10 ppm using the photocatalytic approach based on TiO2 as the catalyst and CuSO4 as additive.

Visible light transformation of Rhodamine 6G using tetracarbazole zinc phthalocyanine when embedded in electrospun fibers and in the presence of ZnO and Ag particles

Herein, we report the photocatalytic transformation of Rhodamine 6G (Rh 6G) using tetracarbazole zinc phthalocyanine (TCbZnPc) when alone or when conjugated with ZnO macroparticles (ZnOMPs) and silver nanoparticles (AgNPs), represented as TCbZnPc–ZnOMPs and TCbZnPc–AgNPs, respectively. The photocatalysts were supported onto electrospun polystyrene fibers. The efficiency of TCbZnPc was improved by the presence of both ZnOMPs and AgNPs. HPLC equipped with UV–vis was used to study phototransformation products. The mechanism of transformation was via the N-de-ethylation of Rh 6G.

SERS spectroscopy of nanocomposite porous films containing silver nanoparticles

It is demonstrated that surface-enhanced Raman scattering spectroscopy allows detecting 10−10 M Rhodamine 6G (Rh 6G) on nanocomposite films containing silver nanoparticles with an amplification factor of 3 × 107. The films used for SERS, which exhibit gradients of thickness and have silver particles and pores of different size, were obtained by pulse laser deposition from the low-energy backward erosion flux. To activate the SERS signal, the films were treated in solutions of metal chlorides and hydrogen chloride to achieve formation of anions of [AgCl2]− complexes. The composition of shells of silver nanoparticles, in particular, replacement of silver compounds preventing Rh 6G adsorption by anions of [AgCl2]− complexes enabling adsorption of Rh 6G cation between them, has been monitored by means of SERS spectroscopy. The obtained SERS spectra of Rh 6G in several locations on the film surface allowed determining the area with an optimal size of silver nanoparticles that gives rise to highest SERS signal intensity. The transmission spectra of the films revealed narrowing of the band corresponding to the local surface plasmon absorption, its shift toward the blue spectral region, and enhancement of plasmon resonance upon introduction of chlorine anion. The changes in absorption spectra of the films correlate with the activation of the Rh 6G SERS spectra.

Use of activated carbon prepared from Prosopis spicigera L. wood (PSLW) plant material for the removal of rhodamine 6G from aqueous solution

The removal of rhodamine 6G dye from aqueous solution using carbon prepared from cheaply available agro-product, Prosopis spicigera L. wood (PSLW), was investigated. This work involves studies of physical and chemical properties of adsorbent, batch sorption experiments, and continuous run in a packed column at laboratory scale. Optimum condition for rhodamine 6G dye adsorption on PSLW carbon was determined by varying pHs, adsorbate concentrations, contact time, adsorbent dosage, and temperature. Lower solution pH favored the adsorption of Rh 6G dye. Adsorption onto the surface, surface mass transfer, and pore diffusion of dye molecules were the main process involved in the removal of Rh 6G dye. The adsorption followed Langmuir isotherm and the maximum adsorption capacity was found to be 8.86 mg/g for an initial concentration of 30 mg/L at 30°C. Thermodynamic parameters indicated that the adsorption interaction was spontaneous and exothermic in nature. The column study was explained using Thomas model.

Surface-functionalized silica gel adsorbents for efficient remediation of cationic dyes

AbstractThe toxic and non-biodegradable nature of organic dyes necessitates the design and synthesis of novel adsorbents for their effective removal from the environment. This study reports an effective remediation behavior of surface-functionalized silica gel against water-soluble cationic dyes (up to 98 % removal). Thiol groups were functionalized at the surface of silica gel (SiO2–SH). The surface-tethered –SH groups were further oxidized to sulfonic acid groups to generate the negatively charged moieties at the surface of silica gel (SiO2–SO3 H). The morphology of the developed adsorbents and the surface modifications were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Uptake study of three cationic dyes, namely, rhodamine B (Rh B), rhodamine 6G (Rh 6G), and crystal violet (CV) with SiO2–SH and SiO2–SO3 H adsorbents was performed by varying the adsorbent amount, contact time, pH of solution, and temperature. The presence of negatively charged species at the surface of SiO2–SO3 H results in an increased electrostatic interaction with the cationic dyes, which leads to better remediation characteristics for SiO2–SO3 H as compared to SiO2–SH. The reusability of the developed adsorbents was also assessed by investigating adsorption/desorption of dyes. The simple fabrication process provides a facile avenue to the adsorbents with efficient remediation towards cationic dyes.

Sonocatalytic and sonophotocatalytic degradation of rhodamine 6G containing wastewaters

The present work deals with degradation of aqueous solution of Rhodamine 6G (Rh 6G) using sonocatalytic and sonophotocatalytic treatment schemes based on the use of cupric oxide (CuO) and titanium dioxide (TiO2) as the solid catalysts. Experiments have been carried out at the operating capacity of 2L and constant initial pH of 12.5. The effect of catalyst loading on the sonochemical degradation has been investigated by varying the loading over the range of 1.5–4.5g/L. It has been observed that the maximum degradation of 52.2% was obtained at an optimum concentration of CuO as 1.5g/L whereas for TiO2 maximum degradation was observed as 51.2% at a loading of 4g/L over similar treatment period. Studies with presence of radical scavengers such as methanol (CH3OH) and n-butanol (C4H9OH) indicated lower extents of degradation confirming the dominance of radical mechanism. The combined approach of ultrasound, solid catalyst and scavengers has also been investigated at optimum loadings to simulate real conditions. The optimal solid loading was used for studies involving oxidation using UV irradiations where 26.4% and 28.9% of degradation was achieved at optimal loading of CuO and TiO2, respectively. Studies using combination of UV and US irradiations have also been carried out using the optimal concentration of the catalysts. It has been observed that maximum degradation of 63.3% is achieved using combined US and UV with TiO2 (4g/L) as the photocatalyst. Overall it can be said that the combined processes give higher extent of degradation as compared to the individual processes based on US or UV irradiations.

Removal of hazardous Rhodamine dye from water by adsorption onto exhausted coffee ground

Exhausted coffee ground powder (CGP) was proved to be an efficient adsorbent for the removal of Rhodamine dyes (i.e. Rhodamine B and Rhodamine 6G) from aqueous solutions by batch adsorption experiments. The morphology, chemical structure as well as the surface property of the as-prepared CGP adsorbent were investigated by using SEM, FT-IR and contact angle meter analytical techniques. The adsorption kinetics and isotherm behaviors of Rhodamine molecules onto CGP were studied and compared using pseudo-1st, pseudo-2nd and Langmuir/Freundlich models, respectively. The maximum adsorption capacities of Rh B and Rh 6G were calculated at 5.255 and 17.369μmolg−1 by Langmuir model fitting. The effects of temperature, ionic strength, solution volume and the co-existing anions on the sorption behavior were also investigated. Furthermore, the adsorption mechanism responsible for the efficient removal of dyes is discussed in terms of adsorption process caused by electrostatic and intermolecular forces.

Visible light-induced photodegradation of rhodamine dyes over BiOCl, and the vital importance of the frontier orbital energy of the dye molecules in the reaction kinetics

The interfacial adsorption process and the white-light-induced photosensitized degradation of different rhodamine dyes (rhodamine B, rhodamine 6G, and rhodamine 101) on the wide-band-gap semiconductor BiOCl have been investigated. Adsorption of all the rhodamine molecules on BiOCl is an exothermic process and the saturated adsorption capacities were best deduced by Langmuir model fitting. By using quantum chemical calculations (Gaussian 03 software), the relationship between the frontier orbital energy of the dye molecules and the rate of photodegradation was also established. The calculated absolute value of E LUMO was found to increase in the order Rh 101 < Rh 6G < RhB, which was similar to the trend of photodegradation reaction kinetics rate fitted by use of the pseudo-zero-order kinetics model.

Silver nanoparticles doped agarose disk: Highly sensitive surface-enhanced Raman scattering substrate for in situ analysis of ink dyes

Raman spectroscopy is a preferred analytical tool for forensic trace analysis due to its non-invasive nature. This technique has been utilized in examination of organic colorants present in fibers and ink, but high fluorescent nature of these compounds is a problem. In the present study, silver-doped agarose gel disk, having property of quenching fluorescence and enhancing Raman signals, is found to be effective as surface-enhanced Raman scattering (SERS) substrates for analysis of rhodamine 6G (Rh 6G) and crystal violet (CV) dyes. As-prepared and well characterized by UV, TEM-EDAX and XRD techniques, the investigated silver-doped agarose gel disk proves to have minimal invasive as confirmed by the ATR-FTIR method and effective for in situ SERS analysis of blue and red ballpoint ink. The disk is stable upon storage and hence can be re-used and re-examined. The present method offers new possibilities in trace forensic analysis with minimal destruction.