Indonesia is the world’s second largest producer of coconut. This at the same time resulted in huge generation of coconut shell waste that need to be properly managed to prevent environmental contamination such as water, air and soil pollution. Current techniques of physical and thermal processing are time and energy consuming. This study reports on the conversion of coconut shell biomass into biochar using microwave-assisted pyrolysis (MAP). The MAP processes were carried out at different microwave power (550-650W) and residence time (15-25 minutes). Two of the highest biochar yields were obtained at 550W with the residence times of 15 minutes (91.31 wt%, termed as S1) and 20 minutes (83.88 wt%, termed as S2), respectively. Both values were higher than biochar yield obtained using conventional pyrolysis process i.e. 30.10 wt%. Both S1 and S2 showed considerable capacity to remove 0.6875 mg.g-1 and 0.5165 mg.g-1 methylene blue which had the initial concentration of 25 mg.L-1. The adsorption efficiencies of S1 and S2 biochars were 55.00% and 41.32%, respectively. Results obtained from the FTIR, FESEM and BET analysis also supported the methylene blue removal properties of both S1 and S2, respectively. As a conclusion, coconut shell showed potential as a useful raw material to produce biochar that can be used for methylene blue removal from solution. Nevertheless, more investigation need to be carried out prior to commercialization venture of the coconut-shell based biochar.
Microstrip slotted meander line antenna with diverse number of meander slots is presented for 2.4 Wireless Local Area Network (WLAN) application. The proposed antenna comprises a rectangular microstrip patch element embedded with several numbers of meander slots in many positions. The parametric study is performed to investigate the characteristic of these microstrip patch antennas with different numbers of meandered slots. Many designs of slotted meander line antenna are produced and they are analyzed based on the number of slotted meander line used. Antenna wit slotted meander lines has the most size reduction of approximately 23% of the original size. This study is an early investigation in designing the RF energy harvesting to support green technology and sustainable development particularly for Wireless Sensor Network (WSN) as well as Radio Frequency Identification (RFID) applications.
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