Enhanced lead(Ⅱ) binding properties of heat-treated cattle-manure-compost-activated carbons

摘要

Considerable concerns have been raised over the presence of lead(Ⅱ) in water bodies. In this work, the performance of heat-treated cattle-manure-compost-activated carbons were investigated to remove lead(Ⅱ) from aqueous solution. Activated carbons were prepared by one-step ZnCl_2 activation followed by heat treatment at different temperatures. They were characterized according to BET surface area, pore size distribution, elemental analysis, pH_(PZC) and Boehm's titration. It was found that the increase of treatment temperature resulted in a decrease in both the BET surface area as well as the concentration of phenolic groups. However, such decreases were compensated by an increase of lead(Ⅱ) by more than three times to a value of 0.110 mmol/g, and this was also true for commercial F400-activated carbon. Lead(Ⅱ) adsorption onto heat-treated activated carbons could be described by Langmuir isotherm with weaker interaction to active sites. Results also suggested that the increase in lead(Ⅱ) uptake was due to the rich electron clouds of the Cπ-system, regardless of the difference in the surface area upon heat treatment.