Activated carbon can be produced from many carbon-containing materials, with the most common including coal, wood and coconut shell. The source material can greatly impact the properties of the resulting activated carbons.
For example, activated carbons from different source materials will not have the same range of pore sizes.
Micropores: Less than 2 nanometers in diameter. For comparison, one nanometer is about 100,000 times thinner than a sheet of paper.
Mesopores: 2 to 50 nanometers in diameter
Macropores: Over 50 nanometers in diameter
For water filtration, a broad range of pore sizes is desired, as the pores can filter out differently sized contaminants as water moves through them.
Coal based activated carbons contain a good mix of mesopores and micropores, which make them an effective general-purpose solution for many applications, including surface water treatment, wastewater treatment, sludge removal, and odor control.
Wood based activated carbons like the ones produced by Tongke contain more mesopores and macropores, which make them ideal for removing large molecular compounds. This may be the case for food decolorization, odor control, and groundwater, wastewater, and municipal water treatment. Unlike coal-based carbons, wood-based carbons can be sustainably sourced.
According to a review on using wood based activated carbons for bioremediation, wood-based biochar is also “more recommended than other synthetic materials like granular activated carbon and carbon nanotubes” for treating wastewater contaminated with potentially toxic elements. In one study, granular wood-based carbons demonstrated a greater adsorption capacity than granular activated carbon at high initial concentrations of chemical oxygen demand, phosphate, and ammonium. This performance may be attributed to macropores in wood-based carbon, which prevent the system from clogging and enable better access to the material’s micropores, which filter out smaller contaminants.