(ii) The carbonization was impregnated into a phosphoric acid solution with the quantity ratio of 1/2, and then transferred to
a carbide furnace to be carbonized at 600 ◦C for 2 h with the heating ramp of 10 ◦C/min. After cooled to room temperature,
the activated carbons were washed with the alkali solution to neutrality, and then dried in a furnace at 105 ◦C for 24 h, yielding the modified activated carbon (signed as P-AC).