Synthesis of low-cost hydrochar using agro-industrial residues for the removal of pharmaceutical drug chloroquine

The aim of this work was to synthesize a low-cost hydrochar via hydrothermal route using two residues from the sugar-energy industries: sugarcane bagasse and the high-pressure boiler water discharge. The applicability of the hydrochar in water treatment process was tested in the biosorp-tion of chloroquine from water in a discontinuous process. The synthesized hydrochar exhibited a high specific surface area (similar to 188 mg g(-1)) with average pore diameter <2.0 nm. The biosorption results showed a fast biosorption kinetic in the initial 10 min and an equilibrium time of similar to 60 min. Acidic properties of both contaminant and HC-T resulted in repulsive forces, therefore, basic conditions would represent the optimum condition for the highest chloroquine biosorption, but that is not interesting for a water treatment plant due to chemicals consumption for pH correction, costs and salinity problems. The pseudo-second-order kinetic and Sips isotherm models were the best models fitted to experimental data. The thermodynamic parameters indicated an endothermic and spon-taneous biosorption. The maximum experimental biosorption capacity was 73.34 mgg(-1) at 45 degrees C. In conclusion, hydrothermal-activated carbon (HC-T) is a promising biosorbent, synthesized with an ecofriendly process, for the removal of chloroquine from contaminated waters due to the great availability, quantity and low-cost of sugarcane bagasse in the Brazilian territory, allied with the reusability of high-pressure boiler water.