Biodiesel production using cation-exchange resin as heterogeneous catalyst

Present study deals with the evaluation of biosorptive removal of cadmium by red macro alga Hypnea valentiae. Experiments have been carried out to find the effect of various parameters such as initial cadmium concentration, experimental pH and temperature on the biosorption potential of H. valentiae. Optimum pH for biosorption of cadmium was found to be 6±0.3. A maximum removal of about 17mg of cadmium per g of micro algae was observed at pH 6.0 for 250mgL⁻¹ solution of cadmium. Kinetics of cadmium biosorption by H. valentiae biomass is better described by pseudo first order kinetic model. The equilibrium isotherm data are very well represented by Langmuir isotherm equation, which confirmed the monolayer coverage of cadmium onto H. valentiae biomass. Various thermodynamic parameters such as change in enthalpy, free energy and entropy were estimated. It was also clearly observed that the presence of neutral salts and other metal ions affected the cadmium uptake behavior of the biomass considerably.

Three types of cation-exchange resins (NKC-9, 001x7 and D61) as solid acid catalysts were employed to prepare biodiesel from acidified oils generated from waste frying oils. The results show that the catalytic activity of NKC-9 was higher than that of 001x7 and D61. The conversion of the esterification by NKC-9 increased with increasing in the amount of catalyst, reaction temperature and time and methanol/oil molar ratio. The maximal conversion of reaction is approximately 90.0%. Furthermore, NKC-9 resin exhibits good reusability. Gas chromatography-mass spectrometry analysis reveals that the production is simplex and mainly composed of C16:0 (palmitic), C18:2 (linoleic), and C18:1 (oleic) acids of methyl ester, respectively.