The purpose of this study was to find out the carbon influence of rice husks and wood grain as electrolyte absorbers on large voltage and battery life. The battery fabrication procedure is as follows: (1) Preparing sixteen used batteries with a 1.5 Volt voltage, (2) Making NaCl solution with percentages of 10, 20, 30, and 40%, (3) Drying rice husks and wood grain until drying, (4) Carbonizing rice husks and wood grain, (5) Smoothing rice husks and carbonated wood grain, (6) Mixing rice husk, wood grain, and electrolyte solution, (7) Remove the contents of the used battery and wash it thoroughly, (8) Insert carbon from rice husks and wood grain. (9) Perform the process of closing the battery with the battery cover, (10) Measuring the battery voltage using an Avometer. This research shows that carbon derived from rice husks and wood grain can generate electrical voltage, but the resulting voltage is still low compared to commercial batteries. In addition, batteries with electrolyte solutions that have a salt percentage of 10% provide the most voltage.

The purpose of this study was to find out the carbon influence of rice husks and wood grain as electrolyte absorbers on large voltage and battery life. The battery fabrication procedure is as follows: (1) Preparing sixteen used batteries with a 1.5 Volt voltage, (2) Making NaCl solution with percentages of 10; 20; 30; and 40%, (3) Drying rice husks and wood grain until drying, (4) Carbonizing rice husks and wood grain, (5) Smoothing rice husks and carbonated wood grain, (6) Mixing rice husk, wood grain, and electrolyte solution, (7) Remove the contents of the used battery and wash it thoroughly, (8) Insert carbon from rice husks and wood grain. (9) Perform the process of closing the battery with the battery cover, (10) Measuring the battery voltage using an avometer. This research shows that carbon derived from rice husks and wood grain can generate electrical voltage, but the resulting voltage is still low compared to commercial batteries. In addition, batteries with electrolyte solutions that have a salt percentage of 10% provide the most voltage.

The purpose of this study was to determine the effect of video learning on the coagulation process using a mango peel-based bio-coagulant on cement wastewater for vocational school students. The bio-coagulant fabrication is done by drying the mango peel in an oven at 60 degrees Celsius, mashing it in a blender, then uniforming the powder particle size using a 200 mesh sieve. The mango peel bio-coagulant powder was then applied to cement wastewater that had been conditioned to an acidic atmosphere with variations of 100, 150, 200, 250, and 300 mg/L. Cement wastewater was tested through pH, temperature, and total dissolved solids (TDS) tests before and after adding the bio-coagulant powder to determine the effect of the bio-coagulant application. This research was also conducted by providing pretest questions, learning videos, and posttest questions to vocational students. The results showed that giving bio-coagulants to cement wastewater could increase the pH value, had no effect on temperature changes, and could decrease the TDS value. Then, the learning outcomes for vocational students show that the use of video learning media has a low effect on students' understanding of the coagulation process. Keywords: bio-coagulant, coagulation, mango peel, teaching, students