Animesh Debnath

Enhanced Adsorption of Hexavalent Chromium onto Magnetic Calcium Ferrite Nanoparticles: Kinetic, Isotherm, and Neural Network Modeling

Calcium ferrite nanoparticles with super-paramagnetic behavior were synthesized via simple chemical precipitation method for effective removal of hexavalent chromium from aqueous media. The properties of synthesized nanoparticles were studied by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), and vibrating sample magnetometer (VSM) measurements. The ferrite nanoparticles have shown polycrystalline nature and high BET specific surface area (229.83 m2/g) with active functional groups on the surface. The adsorption process follows second-order kinetics with the involvement of intra-particle diffusion and adsorption capacity as much as 124.11 mg/g was determined from the Langmuir isotherm. The thermodynamic analysis revealed that the adsorption process was feasible, spontaneous, and exothermic in nature. A three-layer feed-forward back-propagation artificial neural network (ANN) model was employed to predict the removal (%) of Cr(VI) ions as output. Optimal ANN network (4:8:1) shows the minimum mean squared error (MSE) of 0.00161 and maximum coefficient of determination (R2) of 0.984. The adsorption process is mostly influenced by solution pH and followed by adsorbent dosage, initial Cr(VI) concentration, and contact time as illustrated by sensitivity analysis. With small size and high surface area, biocompatibility, ecofriendly nature, easy magnetic separation, and enhanced adsorption capacity towards Cr(VI), calcium ferrite nanoparticles will find its potential application in wastewater remediation. GRAPHICAL ABSTRACT

Simple Chemical Route Synthesis of Fe2O3 Nanoparticles and its Application for Adsorptive Removal of Congo Red from Aqueous Media: Artificial Neural Network Modeling

Nanocrystalline Fe2O3 powder was synthesized by a simple chemical route involving FeCl3 and NaOH. The Fe2O3 powder thus prepared was characterized using x-ray diffraction study, scanning electron microscopy, and Fourier transform infrared spectroscopy. The adsorption properties of crystalline Fe2O3 powder have been investigated with an aim to explore a possible low cost and efficient way to remove Congo red (CR) from waste water. Fe2O3 powder was found as an excellent adsorbent for CR from aqueous medium. Adsorption capacity as much as 203.66 mg g−1 is reported at room temperature. Effect of different experimental parameters such as reaction pH, initial CR dye concentration, adsorbent dose, and reaction temperature were studied on adsorption capacity of Fe2O3 powder and modeled by artificial neural network (ANN). Optimal ANN structure (4–5–1) shows minimum mean squared error (MSE) of 0.00235 and determination coefficient (R2) of 0.991 with Levenberg–Marquardt algorithm. Isotherm analysis of experimental data exhibited better fit to the Langmuir isotherm. The adsorption process was found to follow second-order kinetics as depicted by the analysis of experimental results. Thermodynamic study shows that the adsorption process is endothermic, spontaneous, and thermodynamically favorable in the temperature range of 27°C to 60°C. GRAPHICAL ABSTRACT

A Cognitive Approach in Selection of Source for Water Treatment Plant based on Climatic Impact

The importance of finished water quality from water treatment plants (WTP) is manifold due to its direct impact on consumer health. It is observed from recent studies that change in climatic pattern can affect the concentration of various water quality parameters (WQP) at source itself and change in source water quality may adversely affect the efficiency of WTP also. In the present study Analytical Hierarchy Process (AHP) is utilized to prioritize WQP based on its vulnerability towards climate change. A feed-forward, fully-connected, three-layer neural network model is developed to compute the Vulnerability Index (VI) with the priority vectors of the WQP as determined by AHP approach. The model is utilized to predict the overall vulnerability of three different surface water sources namely river water, lake water and wetland water. The proposed AHP-Neural network model shows that River water is least affected due to climatic abnormalities with minimum VI value and may be considered as the best source water for WTP among the three considered alternatives. The sensitivity analysis of the new model is also carried out. Hence, this proposed model may become a reliable tool to the water supply engineers in the coming days of climate change.

Spectroscopic Studies on Interaction of Congo Red with Ferric Chloride in Aqueous Medium for Wastewater Treatment

Absorption spectroscopic studies of Congo red (CR) in interaction with FeCl3 in aqueous medium have been reported in this article. The interaction of CR with FeCl3 has been investigated with an aim to explore a possible low cost and efficient way to remove CR from industrial waste water. The removal mechanism is based on the formation of a complex of iron with anionic part of the CR molecule in interaction with FeCl3. An exceptionally high removal rate of 2670 mg/g has been observed at 100 mg/L initial CR concentration and enhanced removal rate was found with increasing initial CR concentration.

Synthesis of MnFe2O4 and Mn3O4 magnetic nano-composites with enhanced properties for adsorption of Cr(VI): artificial neural network modeling

This study reports adsorptive removal of Cr(VI) by magnetic manganese ferrite and manganese oxide nano-particles (MnF-MO-NPs) composite from aqueous media. The X-ray diffraction pattern of MnF-MO-NPs revealed a polycrystalline nature with nanoscale crystallite size. The prepared adsorbent with high Brunauer-Emmett-Teller specific surface area of 100.62 m2/g and saturation magnetization of 30.12 emu/g exhibited maximum Cr(VI) removal at solution pH 2.0 and was easily separated from water under an external magnetic field. Adsorption capacity as much as 91.24 mg/g is reported and electrostatic interaction between positively charged adsorbent surface and anionic metal ion species is the main driving force in this adsorption. Adsorption experimental data followed Langmuir isotherm and second order kinetics. Partial involvement of intra-particle diffusion was also observed due to the mesoporous nature of MnF-MO-NPs. The thermodynamic studies revealed that the process was favorable, spontaneous and exothermic in nature. An artificial neural network model was developed for accurate prediction of Cr(VI) ions removal with minimum mean squared error (MSE) of 15.4 × 10-4 and maximum R2 of 0.98. Owing to large surface to volume ratio, advantage of easy magnetic separation, and high adsorption capacity towards Cr(VI), the reported MnF-MO-NPs appear to be a potential candidate in Cr(VI) contaminated wastewater remediation.

Carbon nano tubes functionalized with novel functional group- amido-amine for sorption of actinides

The manuscript presents the results on the sorption of U(VI), Am(III) & Eu(III) from pH medium by a novel amido-amine functionalized multiwalled carbon nanotube (MWCNT). The novel functional group was introduced in the MWCNT by two step processes and characterized by various instrumental techniques like Scanning Electron Microscopy (SEM), Raman and X-ray Photoelectron Spectroscopy (XPS). The sorption process was found to be highly dependent on the pH of the solution with maximum sorption for both 233U, 241Am & 152+154Eu at pH 7.0. Kinetics of sorption was found to be fast with equilibrium reached in ∼15min and the sorption was found to be following pseudo 2nd order kinetics for the radionuclides. The sorption for both 233U and 152+154Eu followed Langmuir sorption model with maximum sorption capacity of 20.66mg/g and 16.1mg/g respectively. This has been explained by DFT calculations which shows that more negative solvation energy of U(VI) compared to Am(III) and Eu(III) and stronger U-MWCNT-AA complex is responsible for higher sorption capacity of U(VI) compared to Am(III) and Eu(III).The synthesized amido-amine functionalized MWCNT is a very promising candidate for removal of actinides and lanthanides from waste water solution with high efficiency.

Mesoporous Iron-Manganese Magnetic Bimetal Oxide for Efficient Removal of Cr(VI) from Synthetic Aqueous Solution

A facile co-precipitation method was established for synthesis of mesoporous iron-manganese magnetic bimetal oxide (MIMO) and its adsorption property was studied for removal of toxic metal ion hexavalent chromium from aqueous solution. XRD pattern of MIMO confirms the existence of Fe2O3 and Mn3O4 particle, out of which Mn3O4 is ferrimagnetic in nature. Synthesized MIMO has shown high saturation magnetization (23.08 emu/g), high BET surface area (178.27 m2/g) and high pore volume (0.484 cm3/g), which makes it a potential adsorbent. Adsorption process followed second order kinetic and Langmuir isotherm model. Involvement of intra-particle diffusion is also confirmed from kinetic data, which can be attributed to the mesoporous nature of the MIMO. Cr(VI) adsorption shows high pH dependency and maximum adsorption capacity of 116.25 mg/g is reported at pH 2.0. Electrostatic attraction between anionic chromium species and protonated MIMO surface is the predominant mechanism in this adsorption process.

Facile additive-free synthesis of hematite nanoparticles for enhanced adsorption of hexavalent chromium from aqueous media: Kinetic, isotherm, and thermodynamic study

ABSTRACT Facile additive-free synthesis of hematite nanoparticles via a chemical co-precipitation technique is reported for adsorptive removal of Cr(VI) from aqueous media, and adsorption capacity as much as 43.05 mg/g at solution pH 2.0 is observed. Langmuir isotherm model was fitted nicely with adsorption experimental data, whereas kinetic studies reveal that both surface adsorption and intra-particle diffusion are involved in the adsorption mechanism. Thermodynamic studies established the favorability, spontaneity, and exothermic nature of the adsorption process. Regeneration studies revealed the stability of the adsorbent up to three consecutive cycles, indicating it as a potential adsorbent for Cr(VI)-contaminated wastewater remediation.