High efficacy on diclofenac removal by activated carbon produced from potato peel waste

In the present study, a novel porous carbon obtained by K₂CO₃ activation of potato peel waste under optimized conditions was applied for the first time as liquid-phase adsorbent of sodium diclofenac in parallel with a commercial activated carbon. The biomass-activated carbon presented an apparent surface area of 866 m² g^-1 and well-developed microporous structure with a large amount of ultramicropores. The obtained carbon presented leaching and ecotoxicological properties compatible with its safe application to aqueous medium. Kinetic data of laboratorymade and commercial sample were best fitted by the pseudo-second-order model. The commercial carbon presented higher uptake of diclofenac, but the biomass carbon presented the higher adsorption rate which was associated with its higher hydrophilic nature which favoured external mass transfer. Both adsorbents presented adsorption isotherms that were best fitted by Langmuir model. The biomass carbon and the commercial carbon presented adsorption monolayer capacities of 69 and 146 mg g^-1, and Langmuir constants of 0.38 and 1.02 L mg^-1, respectively. The better performance of the commercial sample was related to its slightly higher micropore volume, but the most remarkable effect was the competition of water molecules in the biomass carbon.