Adsorption and desorption of phenols and dyes on microporous and mesoporous activated carbons

The adsorption capacities of coconut shells-based microporous and mesoporous activated carbons were examined by uptake of phenol, 4-Cholophenol (4-CP), 4-nitrophenol (4-NP), methylene blue and erythrosine red from aqueous or ethanol solution, The results showed that the uptake of phenol and substituted phenols depends on the microporosity of the adsorbent and the hydrophobicity of the adsorbate. The higher the hydrophbicity and the micropore volume, the larger the uptake capacity. The adsorption is in the order of phenol < 4-CP < 4-NP. The adsorption of dyes depends on the mesoporosity of the adsorbent. The desorption of phenol was studied by boiling water washing and subsequently thermal treating phenol-saturated activated carbon in nitrogen at temperatures from 300 to 700 degreesC. The adsorption capacity could be recovered by about 90-110%.