In general, basic activated carbon itself has some catalytic activity due to the presence of a small number of chemical functionalities present on the corners of its graphitic basal plane. To enhance the catalytic activity of carbon, the surface is modified by a chemical process in which the electronic structure of the carbon is altered in such a manner that the resulting carbon offers enhanced catalytic capability.
As a result, the catalytic carbon produced by this method is not only rich in chemisorption, but also physisorption capacity.
Measuring Catalytic Activity
The catalytic activity of carbon may be measured by the rate at which a carbon decomposes hydrogen peroxide. In general, the peroxide number is represented in terms of the time, in minutes, required to decompose a fixed amount of peroxide. The peroxide number also can be represented in terms of capacity to decompose peroxide in a fixed time.
It is important to measure how fast the peroxide decomposition occurs. For comparison purposes, 1 gram of regular coconut shell-based activated carbon powder (100x325 mesh) shows approximately 20% capacity to decompose peroxide (from 30,000 ppm influent concentration), compared to more than 95% by corresponding catalytic carbon under an identical contact time of 10 minutes. Furthermore, it can be seen in Table 1 that the peroxide decomposition capacity increases significantly as the carbon particle size is decreased.
Comparative Performance
For comparing the chloramine reduction capacity of GAC, a column adsorption test method was used, wherein 10 grams of carbon were packed and an input of 3-ppm chloramine solution was passed through the column at a constant flow rate of 50 cu cm per minute.
Breakthrough for standard GAC was observed within 10 minutes, whereas the breakthrough for the catalytic carbon occured at 50 minutes. This increase in the chloramine reduction capacity is in line with the increase in the peroxide decomposition capacity from less than 5% to more than 50%.
Powder activated carbon, both standard and catalytic, were used to make standard 10-in. blocks for the comparison of chloramine reduction capacity. Like the column performance data, the performance of catalytic carbon block was superior to standard carbon block. The chloramine reduction capacity of the catalytic carbon block increased in proportion to the peroxide decomposition of the corresponding carbon.
Benefits and Importance of a Upflow System:
UNIT INCLUDES:
Catalytic Carbon 1.5 Cu Ft
Upflow Valve
MINERAL TANK (Tank color varies) 1054
DISTRIBUTOR ASSEMBLY