In this study, a carbon nanocolloid based on water was produced by an electrochemical method that is relatively simple and cheap. Then, the removal efficiency assessment of formaldehyde, which is an indoor air pollutant, was studied through filter tests using a chamber.
Three kinds of carbon nanocolloids produced in this study were treated on medium filters made of nonwoven fabric. After the treated filter was fixed in the middle of the chamber (made of stainless use steel), 5 ppm of formaldehyde standard gas and zero gas (9:1) flow into the chamber. Gas penetrated through the filter was collected, and its formaldehyde concentration was analyzed by high performance liquid chromatography. In addition, field applicability was evaluated through a comparison study using a normal carbon filter.
Distilled water was used as an electrolyte, and the density of graphite used for the electrodes was 1.65 g/cm3. The carbon nanocolloids were produced through electrolysis under 15–30 V. Resulting from transmission electron microscopy analysis, sonication-treated carbon nanocolloids showed the clearest images. Through filter tests using a chamber, which is made of stainless use steel, filters damped in carbon nanocolloids treated by sonication indicated the best formaldehyde removal efficiency, 44.47 μg of HCHO removed/g of carbon and 19.28 μg of HCHO removed/g of carbon, compared to the control experiment using a normal carbon filter, 1.45 μg of HCHO removed/g of carbon.
In conclusion, carbon nanocolloids were applicable in the removal of formaldehyde, one of the most harmful substances indoors, which means carbon nanocolloids can be used for the removal of other indoor air pollutants, such as radon, Volatile organic compounds, or odors.