The influence of pyrolytic temperature on sorption ability of carbon xerogel based on 3-aminophenol-formaldehyde polymer for Cu(II) ions and phenol

- 3-Aminophenol-formaldehyde based polymer was pyrolysed at different temperatures.
- The influence of pyrolytic temperature on material properties was studied.
- Pyrolytic temperature was related to sorption ability for Cu(II) and phenol.
- Sorption mechanism was explained by the changes during pyrolysis.

The carbonaceous samples based on 3-aminophenol-formaldehyde polymer were prepared by pyrolysis at different temperatures (400-900 °C). The obtained trends for sorption of phenol (∼0.03-0.4 mmol g−1) and Cu(II) ions (∼0.03-0.2 mmol g−1) were explained by a detailed study of pyrolysis and surface characteristics. The surface charge of the samples during phenol sorption (pH ∼7.3) was not changed; however, uptake of Cu(II) (pH ∼5.7) is partially reflected by the different surface charge of the samples. The changes in surface functionalities (obtained by TGA-MS, XPS, FTIR and elemental analysis) and also trend in microporosity during pyrolysis can also explain sorption behaviour of phenol and Cu(II). Based on the results, the following sorption mechanisms were postulated. Sorption of Cu(II) ions is complex and can be explained by complexation of Cu(II) with pyridinic and pyridonic nitrogen together with physical sorption in micropores (up 700 °C). Sorption is also affected by positively charged surface at 800 °C and 900 °C. Precipitation of Cu(II) is minor mechanism. For sorption of phenol, the combination of chemisorption on surface groups and physical sorption in micropores seems reasonable for the samples pyrolysed at 400-600 °C. Only physisorption prevails for the samples pyrolysed at higher temperatures.