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

The carbonaceous samples based on 3-aminophenol-formaldehyde polymer were prepared by pyrolysis at different temperatures (400-900 degrees C). The obtained trends for sorption of phenol (similar to 0.03-0.4 mmol g(-1)) and Cu(II) ions (similar to 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 similar to 7.3) was not changed; however, uptake of Cu(II) (pH similar to 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 degrees C). Sorption is also affected by positively charged surface at 800 degrees C and 900 degrees 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 degrees C. Only physisorption prevails for the samples pyrolysed at higher temperatures. (C) 2016 Elsevier B.V. All rights reserved.