Ramalingam Subramaniam

Microbial lipids from renewable resources: production and characterization.

A number of microorganisms belonging to the genera of algae, yeast, bacteria, and fungi have ability to accumulate neutral lipids under specific cultivation conditions. The microbial lipids contain high fractions of polyunsaturated fatty acids and have the potential to serve as a source of significant quantities of transportation fuels. This paper reviews the current state of the art of this field. It summarizes the various microorganism used, feed stocks available, environmental factors that influence growth of cells and accumulation of lipids, major fatty acid composition of lipids, and the technology.

Equilibrium, kinetic and thermodynamic studies for adsorption of BTEX onto Ordered Mesoporous Carbon (OMC)

Chemical and petrochemical industries produce substantial amounts of wastewater everyday. This wastewater contains organic pollutants such as benzene, toluene, ethylbenzene and xylenes (BTEX) that are toxic to human and aquatic life. Ordered Mesoporous Carbon (OMC), the adsorbent that possesses the characteristics of an ideal adsorbent was investigated to understand its properties and suitability for BTEX removal. Adsorption isotherms, adsorption kinetics, the effects of initial BTEX concentrations and temperatures on the adsorption process were studied. The OMCs were characterized using surface area and pore size analyzer, transmission electron microscopy (TEM), elemental analysis, thermogravimetric analysis (TGA) and fourier transform infrared spectroscopy (FTIR). The results suggested that the Langmuir Isotherm and Pseudo-Second-Order Models described the experimental data well. The thermodynamic parameters, Gibbs free energy (ΔG°), the enthalpy change (ΔH°) and the entropy change (ΔS°) of adsorption indicated that the adsorption processes were physical, endothermic, and spontaneous. In addition, OMC had 27% higher overall adsorption capacities compared to granular activated carbon (GAC).

Process optimization studies of Congo red dye adsorption onto cashew nut shell using response surface methodology

BackgroundHigh cost of commercially available activated carbon increases the treatment cost. Hence, no-cost or low-cost, alternate adsorbents are the current thirst in this area of research. The limitations of conventional methods of experimentation can mislead the optimum operating conditions. The present investigation mainly deals with utilization of the low-cost, agricultural waste adsorbent, cashew nut shell, and the determination of the optimum conditions for Congo red dye removal from an aqueous solution using response surface central composite design methodology.ResultsThe adsorbent, cashew nut shell, can remove the Congo red dye completely from the aqueous solution. The parameters pH, adsorbent dose, initial dye concentration, time, and temperature considered for this investigation play an important role in the adsorption studies of Congo red dye removal. The optimum values of pH, adsorbent dose, initial dye concentration, time, and temperature were found to be 3.2, 24.76 g/L, 20 mg/L, 67 min, and 30°C for complete removal of Congo red dye, respectively. The experimental values were in good agreement with predicted values.ConclusionsAdsorption of Congo red dye from an aqueous solution with a low-cost adsorbent prepared from an agricultural waste was studied to determine the potential use of this adsorbent for complete removal of the dye. Batch studies were performed to address the influence of various parameters such as pH, adsorbent dose, initial dye concentration, time, and temperature. Response surface central composite design methodology was used to find the interaction among the variables and to determine the optimum conditions towards the adsorption of dye from the aqueous solution. The optimum values of pH, adsorbent dose, initial dye concentration, time, and temperature were found to be 3.2, 24.76 g/L, 20 mg/L, 67 min, and 30°C for complete removal of Congo red dye, respectively. The experimental values were in good agreement with predicted values.

Nanocellulose-PE-b-PEG copolymer nanohybrid shish-kebab structure via interfacial crystallization

We report a novel nanohybrid shish-kebab (NHSK) architecture of cellulose nanofibers (CNFs) and a block copolymer, (polyethylene-b-polyethylene glycol) (PE-b-PEG). Cellulose microfibers were ultrasonically dispersed to generate cellulose nanofibers in the size range of 50±10nm in diameter, while the block copolymer was crystallized using a solution crystallization approach to prepare NHSK. This unique approach allows the flocculated NHSK product to transfer quickly from toluene to ethanol, in order to shorten the preparation time. Morphological analysis reveals, for the first time, that nanocellulose can be used to induce crystallization of a block copolymer to generate NHSK and trans-crystalline structure. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results reveals the crystal morphology and crystallinity changes by virtue of crystallization. The ordered periodic growth and alignment of polymer crystals is recognized as the virtue of molecular origin of extended polymer chains. The proposed hypothesis affords elucidation of NHSK architecture and promotes the designing of novel nanohybrids with controllable functionality.

Status of Algae as Vehicles for Commercial Production of Fuels and Chemicals

This chapter provides a brief overview of role of algae for the production of fuels and chemicals. Characteristics of algae and its production in open raceway ponds have been covered to identify the critical areas that require further exploration and development.