Sushmita Banerjee

Rapid scavenging of methylene blue dye from a liquid phase by adsorption on alumina nanoparticles

The adsorption behavior of methylene blue on as-synthesized alumina nanoparticles has been investigated. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), TG/DTA/DTG, X-ray diffractrometry and scanning electron microscopy. N2 adsorption–desorption measurements were carried out to analyze the porous structure and surface area of the adsorbent and results revealed that the adsorbent is mesoporous with a specific surface area of 76 m2 g−1. Batch experiments indicated that solution pH, initial dye concentration, contact time, temperature and the presence of ions had prominent impact on the dye removal process. The sorption kinetic data were found to be in accordance with pseudo-second order kinetics. The mechanistic interaction of the adsorbate–adsorbent system was also interpreted with the help of Weber–Morris model and the Boyd model and it was found that the adsorption process is controlled by a film diffusion mechanism. The investigation of adsorption isotherms suggested that the data fitted Langmuir isotherm model. The values the thermodynamic parameters for the process of removal were determined and the negative values change in free energy, ΔG0, indicated the spontaneous nature of the sorption process. A high desorption efficiency of 90.11% indicated a possible regeneration of the adsorbent. The adsorbent displayed almost the same adsorption capacity even after three cycles of regeneration bringing down the cost of treatment.

Kinetic and equilibrium modeling for removal of nitrate from aqueous solutions and drinking water by a potential adsorbent, hydrous bismuth oxide

The kinetic, equilibrium modeling and adsorption characteristics of hydrous bismuth oxides (HBOs) have been investigated for the removal of nitrate from aqueous solutions. The three HBO samples, designated as HBO1, HBO2 and HBO3 were synthesized by a controlled precipitation method. Among three HBO samples, HBO3 accounts for a maximum nitrate uptake of 0.22 mg N g−1 with an initial nitrate concentration of 14 mg N L−1, therefore this was selected for detailed studies. HBO3 was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive spectrometry. The adsorption characteristics and process variables were investigated by examining different parameters such as pH, contact time, initial nitrate concentration and temperature. Solution pH remarkably influences the nitrate sorption process as the sorption capacity was found to increase from 0.056 to 0.22 mg N g−1 with the increase of pH from 2.0 to 7.0. The sorption capacity was also found to increase with increasing concentration and temperature, while the presence of competing anions such as Cl−, HCO3− and SO42− impeded the nitrate sorption capacity. The sorption kinetic data were found to be consistent with a pseudo-first-order kinetic model. The equilibrium data agree well with Freundlich model and the highest monolayer adsorption capacity of HBO3 for removal of nitrate ions was found to be 0.97 mg N g−1 at 313 K. An investigation of the thermodynamic parameters indicated the spontaneous and endothermic nature of the sorption process. In a nutshell, HBO3 shows significant potential for removal of nitrate ions from aqueous solution as well as drinking water.

Adsorption Characteristics of Modified Wheat Husk for the Removal of a Toxic Dye, Methylene Blue, from Aqueous Solutions

Adsorption characteristics of modified wheat husk for the removal of a toxic cationic dye, methylene blue, from aqueous solutions have been investigated. The adsorbent, wheat husk, was characterized by Fourier transform infrared spectra (FTIR) and scanning electron microscopy (SEM) for its functional group and surface characteristics. The removal decreased by increasing temperature from 303 to 373 K. The removal was found to be pH dependent, and it decreased from 96.2 to 40.7% by varying the pH of the solution from 4.5 to 9.5. It was observed that 93.4% removal of methylene blue was achieved at an initial dye concentration of 13.37 × 10 −2 mol=L at 303 K. Equilibrium adsorption data for the removal of methylene blue were analyzed by Langmuir, Freundlich, and Tempkin isotherm models. Values of thermo- dynamic parameters viz ΔG°, ΔH°, and ΔS° were determined. The negative value of ΔH° confirmed the exothermic nature of removal of methylene blue by adsorption on modified wheat husk. DOI: 10.1061/(ASCE)HZ.2153-5515.0000191.

Application of natural clay as a potential adsorbent for the removal of a toxic dye from aqueous solutions

AbstractApplication of natural clay (NC) was investigated for the removal of a toxic dye, methylene blue (MB) from aqueous solutions. Extensive characterization of NC was carried out. Effect of various parameters on the removal of MB was investigated. During the study of the effect of adsorbent dose, almost a 100% removal was achieved at a higher dose of natural clay. The experiments were carried out at an initial MB concentration of 60 mg/L and at 298 K. The removal of MB by the application of natural clay was feasible, spontaneous, and endothermic in nature. The process of removal was better explained by Langmuir isotherm model.

Measurement of spatial and temporal behavior of Hα emission from Aditya tokamak using a diagnostic based on a photomultiplier tube arraya)

A photo multiplier tube (PMT) array based spectroscopic diagnostic with fast time response of 10 μs and spatial resolution ∼3 cm has been developed and installed on Aditya tokamak to study the spatial and temporal behavior of Hα emissions from typical discharges. Collimated light has been collected from the plasma along 16 lines of sight passing through entire plasma poloidal cross section of Aditya and detected by two 8 channels PMT arrays after selecting Hα emission using interference filter. The studies are carried out during plasma formation phase of Aditya by changing vertical field and its delay with respect to loop voltage. It is observed that plasma initiated in the high field side in typical discharges of Aditya. The plasma formation position is matched with null field location estimated through simulation.

Alumina Nanoparticles and Alumina-Based Adsorbents for Wastewater Treatment

Alumina is one of the extensively investigated adsorbent materials due to its unique surface properties, such as high porosity and surface area, high thermal stability, and cost effectiveness. Alumina-based adsorbents were reportedly widely employed for the decontamination of various organic and inorganic pollutants from the waste streams. This chapter entails a brief overview related to some of the important synthesis techniques of alumina nanoparticles. Moreover the chapter intends to provide adsorption behavior of various alumina-based adsorbents for different pollutant types. Furthermore the effectiveness of the adsorbents was also interpreted under different physicochemical conditions.

Physicochemical and Heavy Metal Analysis of Pond Water Quality of Mau-Aima Vicinity, Allahabad (India)

Surface water is an important source of water which is commonly used for multiple uses such as in agriculture, drinking purposes, small scale industrial applications, and for household works. Due to rapid industrial growth, population explosion, and increased fertilizer application the surface and ground water have been continuously polluted. In the present study, monitoring and assessment of some physicochemical parameters of different pond water of Mauaima area (Allahabad district, India) has been carried out to decipher the pollution load in the fresh water ecosystem. Several physicochemical parameters such as turbidity, salinity, total hardness, TDS, DO, BOD, COD, and heavy metals (Cd, Cu, Pb, Cr, and Zn) have been analyzed for water samples.

Layered Double Hydroxides Nanomaterials for Water Remediation

Layered double hydroxides (LDHs) belong to a general class called anionic clay minerals and have both synthetic and natural origin. LDHs are also known as hydrotalcite-like compounds (HTLCs). These materials are interesting because their layer cations can be changed among a wide selection, and the interlayer anion can also be freely chosen. Like cationic clays, they can be pillared and can exchange interlayer species thus increasing applications and making new routes to synthesize the derivatives. The present chapter deals with brief introduction of LDHs, their structure, properties, synthesis, and their applications in environmental remediation with reference to water treatment.

A Study on La0.6Sr0.4Co0.3Fe0.8O3 (LSCF) Cathode Material Prepared by Gel Combustion Method for IT-SOFCs: Spectroscopic, Electrochemical and Microstructural Analysis

Perovskite oxides of La0.6Sr0.4Co0.3Fe0.8O3, (LSCF) were synthesized as a new cathode material for intermediate temperature-solid oxide fuel cell (IT-SOFC) by gel-combustion method. Nitrates of La, Sr, Co and Fe were used as precursor and citric acid as self combustion reaction matter. The as-prepared cathode material was characterized for BET surface area, X-rays diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal analysis, and conductivity. Electrochemical impedance was measured at different temperatures by sintering the LSCF pellets at 900°C for 2 h. The conductivity measurement showed the highest value as 0.89 S cm−1 at 700°C. The result shows that the LSCF can efficiently work as an intermediate temperature cathode material for solid oxide fuel cells.

Perovskite of Ba0.2 Sr0.8 Ni0.8 Fe0.2 O3-δ as a cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC): Electrochemical performance and micro-structural characteristics

Nickel containing and cobalt free Perovskite oxides of Ba 0.2 Sr 0.8 Ni 0.8 Fe 0.2 O 3 - δ (BSNF) were synthesized as a new cathode material for intermediate temperature – solid oxide fuel cell (IT - SOFC) by glycine nitrate process (GNP). Nitrates of Ba, Sr, Ni and Fe were used as precursor and glycine as self combustion reaction matter. Elec trochemical impedance, conductivity, X - rays diffraction (XRD), and scanning electron microscopy (SEM) measurements were carried out of newly synthesized BSNF cathode material. Electrochemical impedance was measured at different temperatures by sintering th e BSNF pellets at 900°C for 2 h. The conductivity measurement showed the highest value as 0.081 S cm - 1 at 650°C. Temperature dependence area specific resistance (ASR) of BSNF cathode material was also calculated and the minimum ASR value measured was 0.783 Ω cm 2 at 650°C. The results shows that BSNF can work as a good alternative of cobalt free, low - cost and intermediate temperature cathode material for solid oxide fuel cell.