DPF soot as an adsorbent for Cu(II), Cd(II), and Cr(VI) compared with commercial activated carbon.

The use of carbon soot recovered from diesel particulate filters (DPF) has been investigated as a potential adsorbent for heavy metals including cadmium, chromium, and copper from wastewater. Results were compared with the adsorption performance of powder activated carbon (PAC). The uptake capacity of heavy metals for soot was found to be higher than PAC. And the thermodynamic study result for both soot and PAC indicated the adsorption procedures are exothermic. The adsorption studies were carried out for both single and binary systems. The data are best modeled by the monolayer model and Langmuir isotherm model for single systems. The adsorption mechanisms are more complex for binary systems. The kinetic studies indicated the adsorption happens rapidly within the first 1 h, and the results can be best modeled by pseudo-second-order model. The SEM-EDS analysis revealed the soot possesses higher porosity and surface area. Carboxylic and hydroxyl functional groups are the predominant surface functional group on both soot and PAC as revealed by FTIR and IEP values. The adsorption can be explained by both Van Der Waals force and electrostatic force. Graphical abstract ᅟ.