V. Sivasubramanian

Kinetic study on the effect of temperature on biogas production using a lab scale batch reactor.

In the present study, biogas production from food waste through anaerobic digestion was carried out in a 2l laboratory-scale batch reactor operating at different temperatures with a hydraulic retention time of 30 days. The reactors were operated with a solid concentration of 7.5% of total solids and pH 7. The food wastes used in this experiment were subjected to characterization studies before and after digestion. Modified Gompertz model and Logistic model were used for kinetic study of biogas production. The kinetic parameters, biogas yield potential of the substrate (B), the maximum biogas production rate (Rb) and the duration of lag phase (λ), coefficient of determination (R(2)) and root mean square error (RMSE) were estimated in each case. The effect of temperature on biogas production was evaluated experimentally and compared with the results of kinetic study. The results demonstrated that the reactor with operating temperature of 50°C achieved maximum cumulative biogas production of 7556ml with better biodegradation efficiency.

EQUILIBRIUM, KINETICS, AND BREAKTHROUGH STUDIES FOR ADSORPTION OF Cr(VI) ON CHITOSAN

Wastewater containing low levels of pollutants can be effectively treated by the adsorption technique. In the present work, an adsorption study was carried out using chitosan as adsorbent in a fixed-bed column for the removal of Cr(VI) from wastewater solutions. The column performance of Cr(VI) adsorption onto chitosan was studied at different bed heights (3–9 cm), flow rates (50–200 mL/min), initial metal concentrations (2–10 mg/L), pH values (2–7), and temperatures (30°–60°C). The equilibrium data for the batch adsorption of Cr(VI) on chitosan were tested using the Langmuir, Freundlich, and BET isotherm models. The Langmuir model was found to be the most suitable, with a maximum adsorption capacity of 35.7 mg/g and a correlation coefficient (R 2) = 0.952. The experimental data were found to fit well with the pseudo-second-order kinetic model, with R 2 = 0.999. The dynamics of the adsorption process was modeled using the Adams-Bohart, Thomas, and mass transfer models. The models were used to predict the breakthrough curves of adsorption systems and to determine the characteristic design parameters of the column. The adsorption data were observed to fit well with all three models. The model parameters were derived using MATLAB software. In order to compare quantitatively the applicability of adsorption dynamic models in fitting to experimental data, the percentage relative deviation (P) was calculated and found to be less than 5, confirming that the fit is good for all three models.

Nanoscale zerovalent iron-Sargassum swartzii biocomposites for the removal of malachite green from an aqueous solution

ABSTRACT A novel nanoscale zerovalent iron-Sargassum swartzii (nZVI-SS) biocomposite was tested for its ability to remove malachite green from aqueous solutions. Batch equilibrium tests at different pH conditions showed that at pH 10, a maximum removal of 142.85 mg/g was observed according to Langmuir model. Involvement of various functional groups of the biosorbent in preferential biosorption of cationic dye was observed using Fourier transform infrared spectroscopy. Morphological changes occurring on the biocomposite materials were characterized using scanning electron microscopy. Furthermore, temperature and kinetic profiles during the biosorption process were also reported.

Analysis of pre-heated crude palm oil, palm oil methyl ester and its blends as fuel in a diesel engine

Diesel engines are widely used in the surface transport system. They are the main source of economic growth of a nation. Nowadays, awareness of the environment compels people to adopt stringent emission norms. The rapid depletion of fossil fuels and the increase in the emission levels have caused concerns globally. An eco-friendly alternate is required to fulfil the growing demand. This paper focuses on alternate fuels and the importance of choosing palm oil. The energy density and higher cetane number are its major advantages. Also it reduces environmental pollution drastically. The viscosity of palm oil is a problem like other vegetable oils, which affects the fuel spray pattern. It reduces the efficiency of the combustion to a large extent. To overcome the problem, the pre-heating technique and transesterification process are adopted in this work. Performance tests were conducted on a single cylinder, four-stroke, direct injection diesel engine coupled with eddy current dynamometer, and emission was monitored using an AVL exhaust gas analyser. The results indicated that vegetable oil fuels have lower brake thermal efficiency compared to that of diesel. Pre-heated oil and methyl ester showed an appreciable reduction in hydrocarbon (HC) and carbon monoxide (CO) emissions and higher exhaust temperature and nitric oxide (NOx) emission.