化学工学およびプロセス技術ジャーナル
オープンアクセス

概要

Fixed-Bed Column Adsorption of PFOA and PFOS from Aqueous Solution Using Maize Tassel Pellets

Pinky Mokwena, OJ Okonkwo

This study was conducted with the primary aim of assessing the efficiency and practicality of the adsorption of PFOA and PFOS onto fixed-bed column through maize tassel pellets. The effects of bed height (0.5 g -1.5 g), flow rate (0.5 L min-1-2.5 L min-1 x 10-3L min-1) and initial concentration (5 mg L-1-20 mg L-1) were investigated and three models were employed to evaluate the performance of the adsorption experiment. The Thomas, Adams-Bohart and Yoon-Nelson models were selected for this purpose. The adsorption rate constants and their respective correlation coefficients were also determined. It was found that an increase in initial concentration of both PFOA and PFOS from 5 mg L-1 to 20 mg L-1 resulted in higher uptakes at average bed loading. Additionally, it was noted that an increase in bed height for adsorption had a threshold for highest uptake with increase from 0.5 g to 1 g showing an increase in removal. However, desorption pattern was observed when bed height was increased from 1 g to 1.5 g. The removal of both PFOA and PFOS fitted Thomas model, but did not conform satisfactorily to the Adams-Bohart and Yoon-Nelson. It was also observed that there was an increase in KTH values from 7.311 L min-1 mg x 10-4 L min-1 mg to 7.532 L min-1 mg x 10-4 L min-1 mg and 6.831 L min-1 mg x 10-4 L min-1 mg and 7.722 L min-1 mg x 10-4 L min-1 mg for PFOA and PFOS respectively as the flow rate increased from 0.5 10-3L min-1 to 1.5 10-3 L min-1. Moreover, the behaviour of MT pellets for the removal of PFOA and PFOS from surface water indicated that the adsorption was based on a high driving force that was influenced by the increase in initial PFASs concentration. The concentrations of PFOA and PFOS prior to all treatment were calculated at 195 ng mL-1 and 120 ng mL-1 respectively after the SPE extraction and LCMSMS analysis, and the column study treatment resulted in final concentrations of 31.25 ng mL-1 and 29.4 ng mL-1 for PFOA and PFOS respectively after removal, which is indicative of a 83.9 % removal of PFOA and more than 75.5 % of PFOS removal