Reclamation is an effort to repair the damaged mining sector to provide optimal benefits. This review article aims to propose a natural product technology approach to the reclamation of post-coal mining land by increasing the content of soil organic matter so that the post-mining land becomes fertile and can be used for agricultural land. The method used is an observation and literature study. Literature searches were using them ScienceDirect, Scopus, PubMed, and Google Scholar databases. Land-use change of post-mining site to agricultural land provides prospective economic value to the community. However, the land quality of the post-mining area should be improved before food crop production. Tephrosia vogelii is a member of the Papilionoideae subfamily is important for land revegetation. They can fertilize the soil because of mutualistic symbiosis with the bacteria Rhizobium sp. which is capable to fix nitrogen in the soil and hence provide available nitrogen. Thus, the use of post-mining land as agriculture can improve the economy and sustainability as well as protect life and the environment with natural product technology.
This research aims to make a polypyrrole (PPy) membrane and crude extract of polyphenol oxidase (PPO) as a membrane of mPPy/PPO apple extracts. The membrane of PPy/PPO-apple extract has been synthesized by the electrodeposition method. The electrolyte composition consists of a mixture of 0.10-0.20 M pyrrole (Py) and 50-100% PPO apple extract, which is stable using 50 mM of phosphate buffer solution at pH 6.80-7.00 and room temperature. The electrodeposition process is used 400 mesh steel gauze anode ST-304 and carbon plate cathode. Electrodeposition is carried out at potential = 5.00-6.00 V; current = 0.02-0.25 A; the distance from both electrodes = 1.00-2.00 cm for 300-500 seconds. The results from the deposition of PPy/PPO apple extract of the anode are a membrane of mPPy/PPO-apple extract, with total enzyme activity (U) = (957,1441, 2287 and 1754) using 2.00-5.00 mM phenol as a substrate which is measured based on the UV-visible spectrophotometric method. PPy and mPPy/PPO-apple extracts were characterized by SEM and SEM-EDS. The membrane of mPPy/PPO-apple extract can be used to remove phenol in industrial wastewater samples is 50-65% with a filtration capacity of 500 mL for 2 hours.
Surface area has significant impact on the photocatalytic activity of semiconductor material. It was found that templates as structure directing agent played a role in regulating the surface area of materials. The most widely used as template is cetyltrimethylammonium bromide (CTAB) surfactant. In this research, TiO2 was prepared by solvothermal method used temperature variations of 150, 175, 200, and 225 ºC. The X-ray powder diffraction (XRD) data indicated that anatase phase of TiO2 was successfully obtained with I41/amd space group and as the synthesis temperature was increased, the crystallinity increases. The spectra infrared spectroscopy (IR) showed the broad peak situated at wavenumber 400-800 cm−1 which was assigned to the stretching Ti-O vibration. Raman spectra showed peaks at wavenumber 145, 197, 397, 516, and 639 cm−1 which were attributed to vibration modes of anatase. The scanning electron microscopy (SEM) image demonstrated the morphology particle has homogeneous distribution and irregular shape. Furthermore, Brunauer-Emmett-Teller (BET) specific surface area showed the CTAB-assisted TiO2 which was synthesized at 175 ºC has the highest surface area of 227.043 m2/g in this research among the others.
(YSZ). LSO-YSZ composite synthesis was carried out by combining LSO with commercial YSZ (9:1, 8:2, 7:3) using hydrothermal method. In order to get dense pellet, all of the product were sintered at 1450 °C for 3 hours. X-ray diffraction pattern of the entire pellets show typical both of LSO and YSZ pattern which indicate that the composite was succesfully formed. The highest conductivity was detected in YSZ-7LSO (YSZ:LSO = 7: 3), i.e 1.72 x 10 -4 Scm -1 at 700 ○ C and also has low activation energy (0.88 eV). This result suggests that the LSO-YSZ composite materials are good oxide ion conductor and potential to be used as an alternative solid electrolyte in IT-SOFC technology.
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