Insights into the pyrolysis behavior and adsorption properties of activated carbon from waste cotton textiles by FeCl3-activation

Activated carbon derived from waste cotton textiles (WCT) was synthesized using FeCl3 as an activating agent. The influence of pyrolysis temperature on the physiochemical properties of activated carbon were examined by XRD and XPS analysis. The carbonaceous materials participated in the transformation of Fe species by carbothermal reduction. Abundant acidic surface functional groups appeared during pyrolysis of WCT in the presence of FeCl3. According to the TG-FTIR-GC–MS technique, FeCl3 significantly influenced the pyrolysis behavior of WCT. The major carbonization temperature was reduced from 350 to 163 °C due to the catalytic cleavage of glycosidic bonds and cellulose chains over FeCl3. In addition, the release of CO2 and H2O(g) via decarboxylation, carbonyl group cracking and cross-linking reactions contributed to the pore development. Furthermore, the maximum adsorption capacity of Cr(VI) for the prepared adsorbent was 267.12 mg/g and the adsorption was fitted with the pseudo-second-order model and the Langmuir isotherm model. The adsorption mechanism was mainly driven by electrostatic attraction, reduction, and complexation.