Bambang Rusdiarso

Coating of magnetite with mercapto modified rice hull ash silica in a one-pot process

In this research, mercapto-silica coated magnetite (Fe3O4-SiO2-SH) has been prepared in aqueous solution through a simple approach so called a one-pot process. The Fe3O4-SiO2-SH was prepared in nitrogen condition by mixing magnetite, 3-mercaptopropyltrimethoxysilane (MPTMS), and sodium silicate (Na2SiO3) solution extracted from rice hull ash, and adjusting the pH of 7.0 using hydrochloric acid. The residue was washed with deionized water, dried at 150°C and separated with an external magnetic field. In that work, the volume of MPTMS and Na2SiO3 was varied and the total amount of Si represented as silica was kept constant. Characters of the material including the functional group presence, the structure, the porosity, the morphology and stability toward various solvents were identified and evaluated. Results of characterization indicated that mercapto-silica has been coated magnetite particle with a simple one-pot process. Coating mercapto-silica on magnetite increases particle size, surface area, and chemical stability. Additionally, Fe3O4-SiO2-SH also shows high stability toward various organic solvents. The magnetic property of magnetite does not change after coating and the addition of nonmagnetic material still gives high value of maximum saturation magnetization. The presence of mercapto groups effective for interaction with heavy metal ions, the high chemical stability without removing the magnetic property promises the prospective application of Fe3O4-SiO2-SH in the future such as for separation and removal of heavy metal ions from aquatic environments.

Degradation profile of azoxystrobin in Andisol soil: laboratory incubation

The fate of azoxystrobin in soil under the effect of different temperature is of interest because application directions specify soil-surface treatments for number of agricultural pests. Temperature is an important factor governing the rate of degradation in soil pore. The purpose of this investigation was to understand better the effect of temperature on the degradation of azoxystrobin in Japanese Andisol soil. This was done through laboratory incubation of soil at three different temperatures (5 °C, 20 °C, 35 °C). First-order kinetics could be used to describe degradation of azoxystrobin under controlled condition of temperature (r2 ˃ 94). The results showed that, during the 120-day incubation period for azoxystrobin, 64%, 70%, and 78% of applied azoxystrobin were degraded at 5 °C, 20 °C, and 35 °C, respectively. By using the Arrhenius equation, the activation energy of degradation of azoxystrobin fungicide was calculated (7.48 ± 1.74 kJ mol−1) in soils, which confirm that temperature had a significant influence on the degradation rate. Q10 value of 1.11, for azoxystrobin, indicated that the response of fungicide dissipation to temperature was large. For azoxystrobin, there was a much larger difference in dissipation rates at 5 °C and 35 °C, indicating that biological and/or chemical degradation of azoxystrobin may have nearly reached its optimum at 35 °C.

The novel kinetics expression of Cadmium (II) removal using green adsorbent horse dung humic acid (Hd-Ha)

Humic acid from dry horse dung powder has been prepared and this horse dung humic acid (HD-HA) was then applied as a sorbent to adsorb Cadmium(II) from a solution. Characterization of HD-HA was conducted by detection of its functional group, UV-Vis spectra, ash level, and total acidity. Result of the work showed that HD-HA had similar character compared with peat soil humic acid (PS-HA) and previous researchers. The adsorption study of this work was investigated by batch experiment in pH 5. The thermodynamics parameters in this work were determined by the Langmuir isotherm model for monolayer sorption and Freundlich isotherm model multilayer sorption. Monolayer sorption capacity (b) for HD-HA was 1.329 × 10-3 mol g−1, equilibrium constant (K) was 5.651 (mol/L)−1, and multilayer sorption capacity was 2.646 × 10−2 mol g−1. The kinetics parameters investigated in this work were determined by the novel kinetics expression resulted from the mathematical derivation the availability of binding sites of sorbent. ...

SYNTHESIS OF 1,9-BIS [1-PHENYL-3-METHYL-5-HYDROXY-4-PYRAZOLYL] 1,9 NONANEDIONE AND ITS APPLICATION FOR THE EXTRACTION OF COBALT ( II), NICKEL (II), AND CADMIUM (II)

Synthesis of 1,9-bis [1-phenyl-3-methyl-5-hydroxy-4- pyrazolol)-1,9-nonanedione (HL-7-LH) and its application for the extraction of cobalt (II), nickel (II), and cadmium (II) have been carried out. The HL-7-LH were prepared by treating a dioxane solution of 1-phenyl-3-methyl-5-pyrazolone (H2PMP) containing calcium hydroxide catalyst with azelaoyl dichloride [ClCO(CH2)7C0C1l Purification of the HL-7-LH obtained were done by mean recrystallization in etanoltoluena (9:1) at 70°C. Characterization of the HL-7-LH were done by infrared and nuclear magnetic resonance spectroscopic techniques. The application of the HL-7-LH as extractant in the extraction of cobalt, nickel, and cadmium were performed in chloroform and dichloromethane. It was observed that the effectivity of the extraction increases as the extractant concentration and pH increases. Results show that cobalt, nickel, and cadmium extraction in chloroform wereobtained with the extraction constants (log Keks) = -5,37, -5,44, -5,22 and at dichloromethane were -5,19, - 5,24, and -5,08.Key Word : Synthesis, effectivity of the extraction, the extraction constants