Synthesis of coconut fiber activated carbon for chloramphenicol wastewater adsorption

A series of activated carbon (CFAC-n, n = 1,2,3,4) adsorbents of higher adsorption capacity were synthesized through coconut fiber carbon (CFAC-0) and KOH activator (CFAC-0:KOH = 1:1, 1:2, 1:3, 1:4), respectively, by the heating method for chloramphenicol (CHL) adsorption. The pore diameter, pore volume, specific surface area and surface functional groups of CFAC-n were determined by several characterizations such as BET, XRD, Raman, TEM, FTIR and XPS. The adsorption kinetics of CFAC-n for CHL removal were investigated and the kinetic parameters were also calculated. According to the results, the adsorption capacity onto CFAC-n was positively correlated to the specific surface area. CFAC-3 possessed the largest specific surface area (1755 m(2) g(-1)) and the best adsorption amount (523.0 mg g(-1)). The adsorption conditions (adsorbent dosage, antibiotic initial concentration, adsorption temperature and pH value) of CFAC-3 showed to be directly related to the adsorption effect. In addition, it was found that the CHL adsorption onto CFAC-n was well suitable for fitting with pseudo-second-order kinetic model and Elovich kinetics model. The adsorption isotherm was carried on and it was found that CHL adsorption onto CFAC best fitted to Freundlich and Temkin model. Those results revealed that the adsorption process was heterogeneous adsorption by main chemisorption. The adsorption capacity for CHL onto CHAC-3 was much higher than those of reported low-cost adsorbents. The adsorption included mainly hydrogen bond and pi-pi conjugation interactions, and electrostatic interaction.