Removal of copper(II) in aqueous solution using pyrolytic biochars derived from red macroalga Porphyra tenera

Steam activation enhanced the copper removal performance of Porphyra tenera-derived biochar significantly by increasing the quantity of exchangeable cations, whereas KOH activation reduced the copper removal performance of the biochar, despite the huge increase in specific surface area and pore volume, by washing out the exchangeable cations into the basic KOH solution. Both ion exchange and adsorption appeared to be important mechanisms for copper removal by P. tenera-derived biochar but ion exchange may be a more important mechanism. The pseudo-2nd order kinetic model and the Langmuir's isotherm model provided a good interpretation of the kinetics and equilibrium of copper removal.