Wasana Kowhakul

Improvement of oxidation stability of biodiesel by an antioxidant component contained in spent coffee grounds

ABSTRACT In this work, biodiesel was produced from spent coffee grounds (SCG) oil extracted using n-hexane as a non-polar solvent, and acetone and 1-butanol as polar solvents, in order to simultaneously obtain SCG oil and antioxidant component. Moreover, oxidation stability and antioxidant capacity of SCG oil and their biodiesel production process were evaluated using the Rancimat method and oxygen radical absorbance capacity (ORAC) method, respectively. ORAC values of SCG oil from polar solvents and a non-polar solvent were 97–98 and 93–386 μmol-TE/g, respectively. Antioxidant activities of SCG oils from polar solvents were higher than those of SCG oil from non-polar solvent. However, these ORAC values were decreased by one third on raw oils during biodiesel production model experimental. These characteristics were utilized to develop an improved method of producing waste rapeseed biodiesel: (1) blending the SCG oil with rapeseed oil; (2) soaking powdered SCG in the reaction mixture during biodiesel production; and (3) adding active components extracted using methanol. In method (1), oxidation stability was improved such that 10 wt% of polar solvent extracted SCG oils increased the stability from 1 to 3 h. Also, oxidation stabilities in methods (2) and (3) were improved by soaking 40 wt% SCG and adding 1 wt% SCG extract, respectively.

Thermal Behavior of Used Alkaline Primary Button Batteries Disposed as General Waste

The thermal behavior of new (1.5 V) and used (0 V) primary LR1130 alkaline button batteries was investigated by thermogravimetric differential thermal analysis (TG/DTA). The anode (MnO2) and cathode (Zn) from the batteries were mixed with paper or plastic (1:1). Cellulose and polyethylene were used to represent paper and plastic, respectively. The thermal behavior of MnO2, Zn and the separator from both new and used batteries was comparable by TG/DTA using. There was no exo- or endothermic decomposition of Zn and minor exothermic decomposition of MnO2 from new and used batteries. MnO2 and Zn were markedly affected by the thermal decomposition of cellulose. However, cellulose mixed with MnO2 was more of a thermal hazard than when mixed with Zn. Moreover, MnO2 and Zn from both new and used batteries were also affected considerably by the thermal behavior of polyethylene. Therefore, the accidental disposal of used alkaline button batteries shows high potential to lead to an accident.

Reduction of the Cloud Point of Biodiesel by Combination of Various Factors

Optimization to reduce the cloud point of biodiesel fuel (BDF) was investigated by considering the combination of different kinds of alcohols for transesterification, catalyst type, and blending with castor BDF. Rapeseed oil (R), spent coffee oil (S), and jatropha oil (J) were used as raw materials. The cloud point of BDFs prepared with 1-butanol was found to be lower than that of those using methanol. H2SO4 was a more effective catalyst to reduce cloud point than NaOH. As for blending with castor BDF, the cloud point was decreased from −7 to −7.5 °C for a 25 wt% blend of castor BDF with R-BDF, from 10.2 to 8.0 ° C with S-BDF, and from 8.2 to 2.8 ° C with J-BDF with permissible increases of kinetic viscosities. From the above results, the optimized conditions of 1-butanol, H2SO4 and 25 wt% castor BDF were determined. Under these conditions, the cloud points were −7.5, 2.8 and −3.5 °C for R., S. and J. BDFs, respectively. This paper that the blend ratio of castor BDF was at 25 wt% or less, it was possible to suppress the increase in kinetic viscosity.