Activated carbon from coconut shell waste is a porous solid that has a large surface area with high absorption capacity, making it an alternative for reducing levels of heavy metal ions in the air. Active carbon is made by carbonization and chemical activation, then SEM testing is carried out to see the morphology of the activated carbon and analyzed using ImageJ software. This research aims to determine the effect of chemical activation and no activation on the number of pores formed in activated carbon. From the results of research that has been carried out, there are more pores formed after carbon is activated compared to carbon without activation. This is because the carbon surface without activation is still covered by impurities. In addition, unactivated carbon and activated carbon from coconut shells have pore sizes that fall into the mesoporous category.

Padang Mulya Village, Koba District is part of the Koba Groundwater Basin area. This area has the potential of abundant aquifer layers. An aquifer is a layer of rock that can store water in large quantities. However, the continued increase in exploration of the aquifer layer will result in damage to the aquifer environment. In this case it is necessary to identify the aquifer layers to determine the depth and lithology of the constituent rocks. The resistivity geoelectric method of the dipole-dipole configuration is the most sensitive geophysical method for identifying aquifer layers. Measurements were made on six tracks to obtain data variations on current strength and potential difference. From these data variations in apparent resistivity values will be obtained. 2D modeling of the apparent resistivity value using the backward modeling method is carried out on each track in order to obtain a 2D cross-section of the subsurface structure. The 2D section of each track has an aquifer layer with a depth of 0 meters to 20 meters and is composed of clay, loamy sand, rather dense gravel sand and sandstone.