Functional polyacrylonitrile fiber waste: synthesis, characterization, and statistical optimization approach

This work focuses on surface modification of an innovative anionic chelating support derived from discarded polyacrylonitrile fiber (PANF) waste. The approach involves transforming nitrile groups into N,N-dicarboxymethyl amide groups through surface functionalization. Key operational parameters such as pH, temperature, chelating agent concentration, and reaction time were systematically optimized using JMP experimental design methodology. The study’s results affirm the success of the functionalization process, showcasing the efficient conversion of nitrile groups into iminodiacetic groups. Significantly, the findings underscore the economic feasibility of generating a novel chelating fiber through surface modification. The achieved optimal conversion rate for nitrile groups was approximately 81.4%, with pH, reaction temperature, and time identified as influential factors. The optimal conditions were determined as a pH of 10, a temperature of 70 °C, and a reaction time of 60 min. Additionally, comprehensive characterization revealed improved thermal stability resulting from the modification process utilizing the monochloroacetic acid (MCA) chelating agent. The study further explored the structural and thermal properties of the produced adsorbent. Measurements of ion exchange capacity confirmed the successful incorporation of additional carboxylic groups on the functionalized polyacrylonitrile fiber waste (PANF_F), reaching a maximum value of 7.55 meq/g. This is notably higher than the 0.89 meq/g observed for pure polyacrylonitrile fiber (PANF) waste.

Graphical Abstract