Steven Lim

Synthesis, characteristics and sonocatalytic activities of calcined γ-Fe2O3 and TiO2 nanotubes/γ-Fe2O3 magnetic catalysts in the degradation of Orange G

In this work, γ-Fe2O3 and TiO2 NTs/γ-Fe2O3 composites with good magnetism and sonocatalytic activity were prepared by a facile polyol method and utilize the principle of isoelectric point method, respectively. The structural and magnetic features of the prepared calcined γ-Fe2O3 and composite catalysts were investigated by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), surface analysis, UV-Vis diffuse reflectance spectra (UV-Vis DRS), vibrating sample magnetometry (VSM) and zeta potential analysis. The effects of calcination temperature on γ-Fe2O3 phase variation, physical properties and sonocatalytic properties were investigated. The porosity, specific surface area, band gap energy and sonocatalytic activity of γ-Fe2O3 were gradually decreased with calcination temperature increased. TiO2 NTs/γ-Fe2O3 with appropriate composition and specific structural features possess synergetic effects such as efficient separation of charge carriers and hydroxyl radicals produced by heterogeneous fenton and fenton-like reactions. This enhanced the sonocatalytic activity for the degradation of Orange G under ultrasonic irradiation. The sonocatalytic reactions obeyed pseudo first-order kinetics. All these information provide insight into the design and development of high-efficiency catalyst for wastewater treatment.

In situ reactive extraction of Jatropha curcas L. seeds assisted by ultrasound: Preliminary studies

ABSTRACT Esterification is required to reduce the high free fatty acid (FFA) content of crude Jatropha oil to below 3% prior to transesterification. In this study, raw decorticated Jatropha seeds were employed as the feedstock in in situ reactive extraction assisted by ultrasound in the presence of sulfuric acid (H2SO4) as a catalyst. Extraction efficiency, esterification efficiency, and fatty acid methyl ester (FAME) yield were optimized as a function of ultrasonic pulse mode, amplitude, and H2SO4 amount. The optimum extraction efficiency of 83.96%, esterification efficiency of 71.10%, and FAME yield of 38.58% were achieved at a pulse mode of 5 s on/2 s off, an ultrasonic amplitude of 60%, and an H2SO4 amount of 5 mL in reaction time of 150 min.

Application of Organosolv Pretreatment on Pennisetum Purpureum for Lignin Removal and Cellulose Recovery

Pennisetum Purpureum or Napier Grass, a native to African grass happened to be one of the most promising candidates for bioethanol production. However, literature studies on the organosolv pretreatment process for P. Purpureum were relatively rare. Therefore, in this research, organosolv pretreatment on P. Purpureum was studied and compared with different types of solvent (1-pentanol and ethylene glycol) and homogeneous catalysts (sodium hydroxide and sulfuric acid) in order to provide the feasibility study and filling the current research gap. The chemical composition of P. Purpureum was found to comprise of 21.50% lignin, 54.67% alpha cellulose and 23.83% of beta cellulose and hemicellulose. The substantial composition of cellulose and hemicellulose in P. Purpureum proved its promising potential as a raw material for bioethanol production. Ethylene glycol with concentration of 50.0 v/v% with addition of 2.0 v/v% of sodium hydroxide had proven to be the most effective organosolv pretreatment combination in removal of lignin (83.4%). In terms of lignocellulosic component recovery, this pretreatment solvent achieved up to 70.10% alpha cellulose recovery and 97.90% beta cellulose and hemicellulose recovery.