The raw materials for the preparation of activated carbon are very wide. The carbon-containing substances can be used as raw materials for the preparation of activated carbon. These raw materials can also be applied to the preparation of granular activated carbon, which is mainly divided into two categories: coal raw materials and wood raw materials.
Coal raw materials mainly include anthracite ", slime P, lignite 3, petroleum coke and coal-based LS, etc.
Wooden raw materials mainly include walnut shell 6.7, wood I8]I9], fruit shell [10.11], bamboo [213], crop straw 14.15], carbon containing waste residue 16][I7, etc. In addition, good quality granular activated carbon can also be prepared by separating charcoal powder 8 with dust removal ash and waste polystyrene foam ['.
Preparation method of granular activated carbon is mainly physical activation method [12 and chemical activation method [3.821]. Physical activation method is to dry, carbonized materials will be first, and then carbonized material crushing, then add to the crushing carbonized material, the binder and its mixing, forming and drying grain charcoal, then the granular activated carbon under a certain temperature, the final results of dry granular activated carbon products. The method commonly used activation main gas water vapor and carbon dioxide [20] [l ⒂ 5]. The physical activation methchina activated carbon supplieris characterized by high activation temperature (generally at about 900 ℃), the equipment investment is large, step trival,
But the pollution to the environment is relatively small.
Chemical activation method is to mix raw materials with chemicals in a certain proportion, impregnation for a period of time, kneading and plasticizing at an appropriate temperature, and then carbonization and activation are completed in one step.
The chemicals commonly used are ZNC12, H5PO and KOH.
At present, more research is done on H;
PO4 activation method, the technological process is shown in Figure 1-2.
Chemical activation process is characterized by low activation temperature (generally 400-600℃), easy to adjust the pore structure of the product.coconut shell based activated carbon
However, there are also some disadvantages 1) it is highly corrosive to equipment; (2) it pollutes the environment, etc., which makes the chemical method limited to a certain extent.
There are many researches on activation by adding H3P04 at home and abroad. In China, the development and research work of preparing activated carbon by using phosphoric acid method with wood chips as raw material has been carried out since the end of 1980s，It has been successfully put into industrial application in the 1990s，The mesopore (transition pore) structure of products produced by phosphoric acid activation method is well developed and has wide application fields.