This study reports adsorption of Methylene Blue (MB) and Basic Fuchsin (BF) on green reduced graphene oxide. Using modified Hummer's method, Graphene Oxide (GO) was synthesised and reduced using Tamaridus Indica. The synthesised GO and RGO were characterized using XRD, UV-vis spectroscopy, TEM, XPS, FT-IR and BET analysis. Through XRD result, the reduction in a peak corresponding to (001) plane and appearance of new peak at (002) plane confirmed the reduction process. TEM results displayed a hexagonal SAED and lamellar structure in RGO with a d-spacing of 0.346 nm in the (002) plane. Effect of variables such as pH, initial dye concentration, dosage, temperature, sonication time, ultrasonic power and frequency were studied and optimum conditions for the removal of MB and BF were found. From the Langmuir isotherm model, the maximum adsorption capacity was noticed to be 238.095 and 243.90 mg/g respectively for MB and BF. Further, the presence of humic acid and various ions decreased the removal efficiency for both the dyes. The experimental results indicated that the pseudo second order suited well than other kinetic models. Among various error analysis, ARE model provided minimum error for Langmuir isotherm (MB: 7.52, BF: 9.82) and kinetic study (MB: 10.47, BF: 6.04). FTIR and XPS analysis indicated that electrostatic attraction, hydrogen bonding, n-πand π-πinteractions played significantly during adsorption process. The facile synthesis and higher adsorption capacity indicates that the material could be a potential candidate for the removal of textile effluents. © 2019 Elsevier Ltd.

Saravana Kumar M P

Department of Environmental and Water Resources Engineering

School of Civil Engineering

Vellore Campus

Rajumon R

Anand J.C

Ealias A.M

Desai D.S

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Journal of Environmental Chemical Engineering

The present study reports the use of one-dimensional carbon wrapped VO 2 (M) nanofiber (VO 2 (M)/C) as a cost-effective counter electrode for dye-sensitized solar cells (DSSCs); where M denotes monoclinic crystal system. Uniform short length nanofiber was synthesised by a sol-gel based simple and versatile electrospinning and post carbonization technique. The investigation of nanostructure and morphological analysis were performed by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and transmission electron microscope (TEM) with EDAX. The electrochemical response was comprehensively characterized by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization. The electrochemical analysis of the VO 2 (M)/C nanofiber counter electrode exhibits significant electrocatalytic activity towards the reduction of triiodide and low charge transfer resistance at the electrode-electrolyte interface. The DSSCs fabricated with carbon-wrapped VO 2 (M) nanofiber CE showed high power conversion efficiency of 6.53% under standard test condition of simulated 1SUN illumination at AM1.5 G, which was comparable to the 7.39% observed for conventional thermally decomposed Pt CE based DSSC under same test conditions. This result encourages the next step of modification and use of low-cost VO 2 (M) as an alternate counter electrode for DSSCs to achieve a substantial efficiency for future energy demand. © 2019, The Author(s).

Fulltext

Scientific Reports

Pt-free, low-cost and efficient counter electrode with carbon wrapped VO2(M) nanofiber for dye-sensitized solar cells

Textile dyes pose a serious threat in terms of water pollution due to its complex aromatic structures and poor degradability. In order to reduce the toxic effects of Crystal Violet (CV) and Methylene Blue (MB), an ultrasonic-assisted dye adsorption using urchin like α-MnO2 nanostructures was studied. The adsorbent was synthesised by hydrothermal method at low-temperature. The crystallinity and morphology were determined to investigate the growth mechanism of α-MnO2 nanourchins which consists of two main stages. The initial stage includes the formation of α-MnO2 microspheres followed by the epitaxial growth of nanoneedles on to the surface of them. The α-MnO2 was characterised by BET, XRD, FT-IR, XPS, SEM, TEM and TGA. At 5.6, the point of zero charge of α-MnO2 nanostructures was determined. The total pore volume and average pore radius were confirmed to be 4.751 × 10-2 cc/g and 10.99 Å respectively from the BET analysis. Batch adsorption experiments were performed to investigate the effect of pH, adsorbent dosage, sonication time, initial dye concentration, temperature, ultrasonic frequency and power. The adsorption mechanism was studied using several isotherm and kinetic models. The adsorption data of CV and MB at equilibrium was observed to adopt the Langmuir isotherm model and pseudo-second order kinetic model. The maximum adsorption capacities for CV and MB were found to be 5882.3 and 5000 mg/g respectively. The thermodynamic study predicted that the process was exothermic for CV and endothermic for MB. The effects of competitive ions, ionic strength and humic acid on the uptake of both the dyes were also investigated. And finally, the reusability of recovered α-MnO2 after dye adsorption was studied up to five cycles for its potential industrial applications.

Ultrasonics Sonochemistry

Facile synthesis, growth process, characterisation of a nanourchin-structured α-MnO2 and their application on ultrasonic-assisted adsorptive removal of cationic dyes: A half-life and half-capacity concentration approach

The adsorption of crystal violet (CV) and malachite green (MG) dyes using carbon-coated Zn-Al-layered double hydroxide (C-Zn-Al LDH) was investigated in this work. The characterisation of both Zn-Al LDH and C-Zn-Al LDH was performed using XRD, SEM, TEM, EDX, XPS, FTIR, BET and TGA. The results indicated that carbon particles were effectively coated on Zn-Al LDH surface. The average total pore volume and pore diameter of C-Zn-Al LDH were observed as 0.007 cc/g and 3.115 nm. The impact of parameters like initial dye concentration, pH and adsorbent dosage on the dye removal efficiency was confirmed by carrying out Box-Behnken design experiments. Langmuir isotherm was well suited for both CV and MG adsorption among other isotherm models. The adsorption capacity was maximally obtained as 129.87 and 126.58 mg/g for CV and MG respectively. Pseudo-second order fits the adsorption kinetics than any other kinetic models for both the dyes. The thermodynamic study indicates that the adsorption process of CV was exothermic, whereas for MG was endothermic. Electrostatic attraction, H-bonding, n-π and π- π interactions were mainly influenced in the adsorption process. This study concludes that C-Zn-Al LDH is an efficient adsorbent for the CV and MG dye removal from aqueous solutions. Graphical abstract ᅟ Graphical abstract contains text below the minimum required font size of 6pts inside the artwork, and there is no sufficient space available for the text to be enlarged. Please provide replacement figure file.Graphical abstract contains text is rewritten with the maximum required font size inside the artwork and provided sufficient space between the text which is enlarged.The new Graphical abstract is attached as an image in the attachment file for your further usage.

Environmental Science and Pollution Research

Facile synthesis of carbon-coated layered double hydroxide and its comparative characterisation with Zn–Al LDH: application on crystal violet and malachite green dye adsorption—isotherm, kinetics and Box-Behnken design

The magnetic iron nanoparticles (MFeNp) were biosynthesised using the extract of Cinnamomum tamala (bay leaf) and examined for its efficacy on sludge dewatering. The characteristics of MFeNp were studied using scanning electron microscope (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectrometer (XPS) techniques. The presence of polyphenolic compounds were confirmed by FTIR and XPS analysis. The reduction in capillary suction time (CST) (71.36 to 16.5 s) and specific resistance to filtration (SRF) (53.71 × 1011 to 1.47 × 1011 m/kg) values have indicated that the use of Fenton nanocatalyst enhanced the sludge dewaterability. The differential scanning calorimetry (DSC) analysis has shown that the mass of bound water in the treated sludge was decreased significantly from 1.45 to 0.92 kg H2O/kg DS. The breakdown of extracellular polymeric substances (EPS) by the MFeNp leads to the significant reduction in proteins, polysaccharides, water content and heavy metals. The optimisation using response surface modelling (RSM) have shown that the maximum removal efficiency of water from the sludge was 85.9 % when the optimum pH (3) MFeNp dosage (50 mg/g DS) and H2O2 dosage (500 mg/g DS) were maintained. The experimental results and the statistical optimisation have suggested that MFeNp can be used as a potential nanocatalyst for the sludge dewaterability and hence it can be used for the agricultural purpose. [Figure not available: see fulltext.] © 2016, Springer-Verlag Berlin Heidelberg.

Biosynthesised magnetic iron nanoparticles for sludge dewatering via Fenton process

Journal of Cleaner Production

Optimization and modeling of simultaneous ultrasound-assisted adsorption of binary dyes using activated carbon from tobacco residues: Response surface methodology

Journal	Data powered by TypesetJournal of Environmental Chemical Engineering
Publisher	Data powered by TypesetElsevier BV
ISSN	2213-3437
Open Access	0