Dewi Tristantini

Removal of Heavy Metals from Aqueous Solution by Hydroxyapatite/Chitosan Composite

Hydroxyapatite/chitosan (HApC) composite has been prepared by precipitation method and used for removal of heavy metals (Cr6+, Zn2+ and Cd2+) from aqueous solution. The HAp and 3H7C composite with HAp:chitosan ratio of 3:7 (wt%) were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy-energy dispersive X-ray spectroscopy. The SEM results showed that HAp is spherical-shaped and crystalline, while chitosan has a flat structure. SEM micrograph of 3H7C composite reveals crystalline of HAp uniformly spread over the surface of chitosan. The crystal structure of HAp is maintained in 3H7C composite. Chitosan affects the adsorption capacity of HAp for heavy metal ions; it binds the metal ions as well as HAp. The kinetic data was best described by the pseudo-second order. Surface adsorption and intraparticle diffusion take place in the mechanism of adsorption process. The binding of HAp powder with chitosan made the capability of composite to removal of Cr6+, Zn2+ and Cd2+ from aqueous solution effective. The order of removal efficiency (Cr6+ > Cd2+ > Zn2+) was observed.

Evaluation of Separate and Simultaneous Kinetic Parameters for Levulinic Acid and Furfural Production from Pretreated Palm Oil Empty Fruit Bunches

Palm oil empty fruit bunches (POEFBs) can be converted into levulinic acid (LA) and furfural, which are among the top building-block chemicals. The purpose of this study was to investigate separate and simultaneous kinetic model parameters for LA and furfural production from POEFBs, which were pretreated by soaking in aqueous ammonia (SAA). The highest LA yield, which was obtained at a reaction temperature of 170°C after 90 min in an acidic solution with a concentration of 1 M, was 52.1 mol%. The highest furfural yield was 27.94 mol%, which was obtained at a reaction temperature of 170°C after 20 min in an acidic solution with a concentration of 0.5 M. SAA pretreatment affected activation energy in glucose degradation reactions and favoured direct conversion of hemicellulose to furfural. The activation energy of LA production (EakHMF) increases with higher acid catalyst concentration, and the activation energy of furfural production (EakXYN) decreases with higher acid concentration. These trends in the activation energy occurred in both separate and simultaneous kinetic models. Simultaneous kinetic model is better to calculate kinetic parameters of LA and furfural production than separate kinetic models because the simultaneous kinetic model had a lower sum of square error (SSE) when estimating kinetic parameters.

Anti-cholesterol activity test of tanjung (Mimusops elengi L.) leaf extract in the water using in vivo method in mice (Mus musculus L.) DDY-strain

High cholesterol level in blood is one of deadly cardiovascular disease’s causes which is triggered by accumulation of cholesterol patching in blood vessels through heart and using synthetic medicine has several side effect. However, tanjung (M. elengi) which abundant in Indonesia is believed that it can strengthen and clean plaque in blood vessels wall. In this study, anti-cholesterol activity of tanjung (M. elengi) leaf extract in the water will be tested by in vivo method to 6 group of mice (Mus musculus) DDY-strain. The result showed that tanjung (M. elengi) leaf extract has significant effect to decrease total cholesterol level of mice, more extract given to mice, it will give higher cholesterol decreasing. TE 3 can decrease cholesterol level as much as 36%. In this study, it can be concluded that tanjung (M. elengi) leaf extract can be used as cholesterol decreasing medicine.