  In this paper, we report herein, the conversion of waste prescription and
non-prescription pharmaceuticals into carbonaceous materials. The hydrothermal
carbonization (HTC) of the pharmaceuticals was carried out at temperatures of
180, 230 and 275 0C in closed reactors for 6, 12 and 24 hours, respectively.
The main products from the carbonization process were in the solids, liquids
and gas phases. The resulting hydrochars were shown to be very functionalized
with a high degree of aromaticity and high carbon content (between 55% to 65%).
The adsorptive capacity of the hydrochars to remove Pb2+ ions from an aqueous
system was evaluated and compared to that of analytical reagent activated
carbon (AR-AC) through batch adsorptive tests. The effect of contact time on
batch adsorption experiments with an initial Pb2+ concentration of 50 mg/L was
also evaluated. The results indicated that PH24_230 has a better adsorption
capacity when compared to AR-AC; achieving over 97% removal of Pb2+ after 60
minutes. The batch adsorption studies were best described by the pseudo-second
order kinetic model with coefficient of regression (R2) values above 0.99.
Also, slow pyrolysis experiments were carried out to evaluate the difference in
solid yields, char heating value and surface area. Pyrochar yields were
slightly higher, while heating values were one order of magnitude lower when
compared to hydrochars. The pyrolysis conducted at 700{\deg}C led to the
pyrochar with the highest value of the surface area (63.15 m2/g). The study
shows that valuable products can be generated successfully from the
hydrothermal carbonization of waste pharmaceuticals.
  KEYWORDS: waste pharmaceuticals; hydrothermal carbonization; hydrochars,
batch adsorption, adsorption capacity
