Thiol -functionalized activated carbon fibers as efficient adsorbents for Pb2

In this study, thiol functionalized activated carbon fibers (ACF-SH) are employed to improve adsorption performances of heavy metals, resulting high density of sulfur-containing and nitrogen-containing groups (6.64 atom % S, 4.49 atom % N confirmed by X-ray Photoelectron Spectroscopy, XPS) and high binding affinity towards Pb2+. We find that time, pH, initial ion concentration and adsorbent dosage are important factors affecting the adsorption capacity of modified activated carbon fibers for Pb2+. The kinetics and isotherm studies show that the pseudo-second-order model and Langmuir isotherm model can more reasonably explain the adsorption mechanism. Excitingly, the qmax obtained through Langmuir isotherm model reaches 700.77 mg g−1, which significantly surpassed most fiber-based adsorbents. Thermodynamic results significantly exhibit positive ΔHθ and ΔSθ indicating the endothermic property during Pb2+ adsorption onto ACF-SH with an increase, and a negative ΔGθ reveals its spontaneous at the same time. Moreover, the adsorption mechanism is revealed by diversified analysis. The outcomes from this work indicate that the activated carbon fibers are promising as an adsorbent for effectively repairing Pb2+ ions in effluent. [Display omitted] •High density of S-containing and N-containing groups grafting result were achieved.•Modified activated carbon fiber had excellent performance in adsorbing Pb2+ with biggish adsorption rate and high capacity.•Remarkable adsorption performance exceeded that of many similar adsorbents.•The adsorption process better conformed to the Pseudo-second-order model and the Langmuir isotherm model.•The mechanism of enhanced adsorption capacity was revealed by quantitative analysis.