Cellulose-based microporous carbon fibers (CFs) were evaluated for the adsorption of 2-Chlorophenol (CP), 2,4-Dichlorophenol (DCP), and 2,4,6-Trichlorophenol (TCP), which are persistent organic pollutants in wastewater. CFs with different surface area values were prepared by using ZnCl2 as a chemical activator, and the samples were characterized by BET, FTIR, SEM, PALS, Zeta potential, and pH titration analysis. The point of zero charge values for CF-1, CF-2, and CF-3 were found as 8.14, 6.79, and 7.01, respectively. The surface area of CFs were determined as 454 m2/g (CF-1), 760 m2/g (CF-2), and 1217 m2/g (CF-3), and PALS measurements at ambient temperature and vacuum indicated the effective pore diameter of about 0.6 nm for all samples. The adsorption of chlorophenols was examined at different solution pH, temperature, and contact time. At the optimum pH of 6.0, the DCP adsorption capacities of CFs, namely, CF-1, CF-2, and CF-3 were calculated as 29.27, 229.81, and 244.09 mg/g, respectively. The adsorption capacity of the CF-3 sample was found to be an ideal adsorbent for CPs removal from aqueous solutions. A comparison of the adsorption kinetic data was best described by the pseudo second-order and particle diffusion models. For the CF-2 sample, the initial sorption rates of CP, DCP, and TCP were found in the increasing order as 2.084, 32.23, and 43.63 mg/g min. Similar order of the sorption rates were also observed for CF-1 and CF-3 samples. The obtained results demonstrated the fact that among the CP homologues, TCP showed both a higher affinity and a higher diffusion rate for all CFs. The adsorption process was found to be exothermic, and the entropy values were positive, depicting that CPs were randomly distributed at the solid/solution interface.
