Nano activated carbon is activated carbon with nano-sized carbon particles and can be synthesized from cellulose-containing materials such as the Annatto peels. In this study, the synthesis of nano activated carbon of the Annatto peels was carried out in terms of activation temperature variations and the carbon impregnation ratio of 50% H3PO4 acid and determining the characteristics of nano activated carbon from Annatto peels (NAPAC). The activation method used is the impregnation of carbon in 50% H3PO4 with a ratio of 1: 3; 1: 4; 1: 5; 1: 6; and 1: 7 (w/w) for 24 hours and heating at 400; 500; 600; 700; and 800 °C for one hour. Nano activated carbon from Annatto peels (NAPAC) was characterized by Infrared Spectrophotometer (FTIR), X-ray Diffractometer (XRD), and Transmission Electron Microscope (TEM). The results of the study showed that the NAPAC can be synthesized from Annatto peels with activation by 50% H3PO4 at the temperature of 500°C and the impregnation ratio of 1:5 (w/w).

Heavy metal waste can endanger human health and can accumulate in rivers or land. Heavy metals such as Co(II) can be removed or minimized using adsorbents such as activated carbon. The use of activated carbon from water hyacinth leaves (Eichhornia crassipes) has the potential to reduce the concentration of heavy metals in the environment as water hyacinth leaves (WHL) have the ability to adsorp both organic and inorganic compounds. This study aims to determine the appropriate adsorption kinetics and isotherm models in the process of Co(II) adsorption using activated carbon from water hyacinth leaves (ACWHL). The ACWHL can be produced from the carbonization process at 400°C for an hour and two-stage activation process (physical and chemical activation) with 30% H3PO4 as an activator and the impregnation ratio of 1:4 (w/w) for 24 hours and then activated at 600°C for 60 minutes. The analytical method used in this study was using a UV-Vis spectrophotometer. The results of the study showed that the ability of ACWHL to adsorp Co(II) followed the pseudo second-order kinetic model with R2 = 0.3086 and the Elovich isotherm with R2 = 0.664 with a maximum adsorption capacity of 140.725 mg/g. Fulfillment of this model can be assumed if the adsorption process of Co(II) on the surface of ACWHL occurs in multilayer.

No abstract

This study develops a subsurface detection system based on a photoacoustic effect. The main parts of the system are a laser diode as an exciter, a standard microphone as an acoustic detector, and a software-based phase sensitive detection (PSD) method. Artificial defects of various depths were made inside an alumunium plate as the object which was painted with acrylic paint to cover the defects. The difference in the thermal diffusivity of alumunium and acrylic paint will cause different amplitudes of photoacoustic so they can be used to detect the subsurface defects. Photoacoustic signal amplitudes used in this study as measured by a microphone have an average amplitude of −57 dB with an SNR of 11.2. High noise level was found below 2.153 Hz, so that the photoacoustic signal amplitude cannot be detected. The accuracy of PSD method was tested by measuring amplitude of 400-600 Hz sinusoidal voltages from a signal generator. The range of the amplitudes was 0.73-6.27 µV with a resulting maximum error of 9%. The PSD method was succesfully implemented to detect the subsurface defects of a 300 µm thick alumunium plate at depths of 215 µm, 241 µm, and 254 µm with a resulting maximum error of 5.83%.

Waste of tea is still limited in terms of utilization, potentially to be made into nanocarbon. In this research, nanocarbon synthesis from the waste of tea through carbonation method using furnace and purification with HNO 3 with activator substance used is H 3 PO 4 . The specific objective of this study was to determine the optimal levels and ratios of ortho-phosphoric acid and to determine the properties and characteristics of nanocarbon from tea waste. Based on the Fourier-Transform Infra-Red (FT-IR) spectra, the best ortho-phosphate acid levels and ratios are 50% and 1:2 (w/w) H 3 PO 4 . The x-ray diffraction (XRD) analysis showed that the activated carbon dregs obtained were C graphite which was characterized by the diffraction peak at 2theta: 26.2°; 26.5°; 42.2°; 42.4°; and 44.3°. Based on the Transmission Electron Microscope (TEM) image obtained shows that the activated carbon of the resulting tea waste has a particle size of 20-40 nm.

No abstract

No abstract

The impacts of strengthening magnetic field exposure on combustion performance of low-octane fuel have been examined experimentally. The combustion test was carried out using a 2-stroke 49 cc engine where the fuel was magnetized using a low magnetic field (<2 kG). Moreover, the molecular behavior of magnetized fuel was also characterized through spectrum tests using NIR and UV-Vis spectrophotometers. The result of this study indicates an exponential decrease of magnetized fuel consumption against the strengthening of magnetic field exposure. This exponential decrease of consumption can be related to the Arrhenius principle. In addition, the decrease of oxygen in the exhaust gas along with the strengthening of the magnetic field also confirms the increase of combustion reactions. Meanwhile, the increase of magnetized fuel absorption against ultraviolet and near-infrared lights along with the increase of the magnetic field intensity indicates a bond weakening, accompanied by the increase of molecular vibrational energy.