N. Selvaraju

Biosorption potential of a novel powder, prepared from Ficus auriculata leaves, for sequestration of hexavalent chromium from aqueous solutions

A novel biosorbent, powdered Ficus auriculata leaves (FALP), has been used to remove hexavalent chromium from aqueous solutions by use of a batch technique. The biosorbent was characterized by surface area analysis, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The effects on adsorption of pH, initial Cr(VI) ion concentration, amount of FALP, agitation speed, and temperature were investigated. Equilibrium data from the biosorption study were evaluated by use of two and three-variable isotherm models. The equilibrium data were better fitted by use of a three-variable isotherm model. The kinetics of biosorption were examined by use of pseudo-first-order and pseudo-second-order kinetic models and an intraparticle diffusion model. The biosorption data were best fit by the pseudo-second-order kinetic model. Thermodynamic investigation revealed that biosorption of hexavalent chromium ions by FALP is spontaneous in nature, endothermic, and results in increased randomness. The study suggests that FALP could be used as a potential biosorbent for removal of hexavalent chromium from wastewaters.

Removal of Cr(VI) from aqueous solution using Strychnos nux-vomica shell as an adsorbent

AbstractIn the present study, the removal of Cr(VI) from aqueous solution by a Strychnos nux-vomica shell was examined in a batch study. The main process parameters such as adsorbent dose, pH, initial concentration, temperature, agitation speed and contact time were studied. The result shows that the maximum removal of Cr(VI) was observed at pH 2. The progressive changes on surface texture and the confirmation of chromium binding on adsorbent surface at different stages were obtained by the scanning electron microscopy, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectrometer analysis. The equilibrium data from the biosorption study was evaluated by the use of two parameter isotherm models. Langmuir isotherm model seems to fit better with the equilibrium data. Kinetic studies were performed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The biosorption data were found to best fitted for pseudo-second-order kinetic model. The calculated thermodynam...

Hexavalent chromium removal from aqueous solutions by a novel powder prepared from Colocasia esculenta leaves

ABSTRACT In this study, batch removal of hexavalent chromium from aqueous solutions by powdered Colocasia esculenta leaves was investigated. Batch experiments were conducted to study the effects of adsorption of Cr(VI) at different pH values, initial concentrations, agitation speeds, temperatures, and contact times. The biosorbent was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectrometer analysis. The biosorptive capacity of the adsorbent was dependent on the pH of the chromium solution in which maximum removal was observed at pH 2. The adsorption equilibrium data were evaluated for various adsorption isotherm models, kinetic models, and thermodynamics. The equilibrium data fitted well with Freundlich and Halsey models. The adsorption capacity calculated was 47.62 mg/g at pH 2. The adsorption kinetic data were best described by pseudo-second-order kinetic model. Thus, Colocasia esculenta leaves can be considered as one of the efficient and cheap biosorbents for hexavalent chromium removal from aqueous solutions.

Advanced approach for degradation of recalcitrant by nanophotocatalysis using nanocomposites and their future perspectives

Abstract Industrial effluents containing persistent pollutants play a significant role in environmental pollution. Classical techniques such as chlorination, coagulation, ion flotation, membrane process and sedimentation that have been used to decontaminate polluted water are incapable of efficient degradation due to the generation of secondary pollutants. Photocatalysis, an advanced oxidation process in which the photoreaction is accelerated by the irradiation of catalyst, has shown efficient degradation of recalcitrant in water system. Usage of nanoparticles as homogenous photocatalyst has become prevalent due to their improved properties such as large surface-to-volume ratio, controlled uniform particle size and its composition which enhances the degradation rate. The recombination of holes and electron pair which is considered to be the limitation in homogenous system can be overcome by nanocomposites or heterogeneous photocatalysts. This system decreases the rate of recombination, leading to effective degradation of individual pollutants because of their enhanced physicochemical and structural properties. In recent years, heterogeneous nanophotocatalytic processes employing titanium dioxide (TiO2) and zinc oxide (ZnO) composites have gained immense research interest as an effective wastewater treatment method because of its efficacy in decomposing and mineralizing the hazardous organic and inorganic pollutants utilizing the UV and visible photons. This paper reviews about the process, synthesis and parameters influencing photocatalytic reaction and their kinetics with much emphasize on types of nanoparticles and nanocomposites and its application in wastewater treatment.

A holistic approach combining factor analysis, positive matrix factorization, and chemical mass balance applied to receptor modeling.

Rapid urbanization and population growth resulted in severe deterioration of air quality in most of the major cities in India. Therefore, it is essential to ascertain the contribution of various sources of air pollution to enable us to determine effective control policies. The present work focuses on the holistic approach of combining factor analysis (FA), positive matrix factorization (PMF), and chemical mass balance (CMB) for receptor modeling in order to identify the sources and their contributions in air quality studies. Insight from the emission inventory was used to remove subjectivity in source identification. Each approach has its own limitations. Factor analysis can identify qualitatively a minimal set of important factors which can account for the variations in the measured data. This step uses information from emission inventory to qualitatively match source profiles with factor loadings. This signifies the identification of dominant sources through factors. PMF gives source profiles and source contributions from the entire receptor data matrix. The data from FA is applied for rank reduction in PMF. Whenever multiple solutions exist, emission inventory identifies source profiles uniquely, so that they have a physical relevance. CMB identifies the source contributions obtained from FA and PMF. The novel approach proposed here overcomes the limitations of the individual methods in a synergistic way. The adopted methodology is found valid for a synthetic data and also the data of field study.

Packed bed column investigation on hexavalent chromium adsorption using activated carbon prepared from Swietenia Mahogani fruit shells

AbstractThe removal of Cr(VI) from aqueous solution by a novel Swietenia Mahogani fruit shell physically activated carbon (SMFS-PAC) was examined in a packed bed column study. The effects of significant parameters such as feed flow rate, bed depth, and initial Cr(VI) concentration were studied. Column data obtained at different conditions were described using the Thomas, Bed depth service time (BDST), Adams–Bohart, and Yoon–Nelson model in order to predict the breakthrough curves and to evaluate the model parameters of the packed bed column studies data. Among the models used, Thomas, BDST, and Yoon–Nelson model, respectively, fitted to the experimental data very well. The SMFS-PAC column study states the value of the good adsorption capacity for the removal of Cr(VI) from aqueous solution.

Optimisation of radiolysis of Reactive Red 120 dye in aqueous solution using ionising 60Co gamma radiation by response surface methodology

In recent years, employing radiation technology is gaining great interest in degradation of industrial effluents. In this work the possibility of using gamma irradiation to degrade Reactive Red 120 (C.I.292775) was explored. The effects of pH, dose of gamma irradiation and concentration of dye were examined and their interaction were also established based on their response. For the analysis and optimisation of variables, three factor three level Box-Wilson face centred central composite design (CCF) was used. Analysis of variance with R(2) = 0.9988, adjusted R(2) = 0.9981 and the adequate precision value of 122.303 indicates that the CCF model can be used. The coefficient of variation (0.54%) indicates the reliability of the model. The dose of gamma irradiation (kGy) and the concentration of dye (mg/L) showed significant effects on the degradation of RR 120, while a difference of 6 to 10% degradation was observed in extending the pH towards the acid or alkali range from pH 7.00. The maximum concentration of dye degraded was observed as 347.509 mg/L at initial pH: 7.0, dose of gamma irradiation: 5.94 kGy and initial concentration of dye: 500 mg/L. This predicted value was found to be in agreement with the experimental value on the optimised conditions.

Marine microalgal culturing in open pond systems for biodiesel production—Critical parameters

In the present scenario, petroleum sourced fuel consumption is unsustainable; therefore, there is a high demand for the development of renewable transport fuels for environmental and economic sustainability. Microalgal fuel, with the significant feature of being carbon neutral, serves as one of the potent tools for tackling the fuel crisis. Enormous researches have been explored using fresh water species on biodiesel production; nevertheless, marine species are still in a grey area, even though reported to have higher lipid content. The current review focuses on a wide spectrum of marine microalgal sources with phycology under the criteria of open pond systems for algal oil production. The discussion on the lipid expression in the marine species have been critically analysed through the vital parameters such as solar irradiation, temperature, pH, nutrient pressure, agitation, CO2 supply, culture depth, aeration, etc. The parameters are interdependent and, if scrutinized wisely, could result in enhanced li...

Hydrous Cerium Oxide Nanoparticles Impregnated Enteromorpha sp. for the Removal of Hexavalent Chromium from Aqueous Solutions

AbstractA novel nanobiocomposite, hydrous cerium oxide nanoparticles impregnated Enteromorpha sp. (HCONIE) was used effectively for the adsorption of Cr(VI) from aqueous solutions. The chemical and structural characteristics of the nanobiocomposite were investigated using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis. Adsorption studies were determined as a function of pH, contact time, initial concentration of Cr(VI), HCONIE dose, and temperature. The equilibrium adsorption data were modeled using two parameter isotherms, including Langmuir, Freundlich, Dubinin–Radushkevich (D–R), Temkin, Jovanovic, Halsey, and Harkin–Jura. Adsorption data were well described by the Freundlich and Halsey isotherm. The kinetics data were analyzed using adsorption kinetic models like the pseudo-first-order, pseudo-second-order and intraparticle diffusion equation. Kinetic data showed good agreement with the pseudo-second-order kin...

Optimization of adsorption process parameters by response surface methodology for hexavalent chromium removal from aqueous solutions using Annona reticulata Linn peel microparticles

Fruit peel microparticles of Annona reticulata Linn were used as biosorbent for the sequestration of hexavalent chromium (CR(VI)). Characterization of the biosorbent was done using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDXS), Fourier transfer infrared spectroscopy (FTIR), gas chromatography-mass spectrometry (GCMS), carbon, hydrogen, nitrogen and sulphur (CHNS) elemental analysis, mercury intrusion porosimetry and point of zero charge. Influential parameters were optimized using response surface methodology (RSM) with a total of 17 experimental runs based on the Box-Behnken design and found to be pH 1.0, temperature 25 °C and 100 mg/L initial chromium concentration. pH and concentration were found to be more influential than temperature. The analysis of variance indicated that a second-order polynomial regression equation was the most suitable for fitting the experimental data. The experimental runs showed a good correlation with the predicted responses (R2 = 0.9956). The biosorption process fitted well with the Langmuir isotherm with an adsorption capacity of 108. 32 mg/g out of the other isotherms such as Freundlich and Dubinin-Radushkevich that were analyzed. Non linear pseudo first order, pseudo second order, and intraparticle diffusion kinetics were applied to describe the interaction between the biosorbent and Cr(VI). Desorption and regeneration performances showed that fruit peels of Annona reticulata Linn can be an environmental friendly option for hexavalent chromium removal from aqueous solutions.