Effect of ZnCl2 addition to sunflower husk’s hydrothermal carbonization process: hydrochar yield, fuel properties and methylene blue removal

The lack of optimal and environmentally friendly treatment of agricultural solid waste and textural wastewater are thought to be critical environmental issues. Processes such as adsorption, chemical oxidation, photocatalytic degradation, advanced oxidation, and electrochemical methods have been implemented to deals with these issues. An experimental design approach was employed in this study, to clarify the impact of ZnCl 2 addition during hydrothermal carbonization (HTC) of sunflower husk (SF) at various temperatures and reaction times. The impact of process parameters on hydrochar yield, high heating value (HHV) of HC and methylene blue adsorption capacity were studied. The maximum attained methylene blue adsorption capacities at optimum conditions were 278.4 and 195 mg/g for ZnCl 2 -assisted hydrochar (at 171 ℃ and 7.48 h) and no-ZnCl 2 -assisted hydrochar (at 169 ℃ and 7.78 h), respectively. Moreover, the mean adsorption capacity increased by 51% due to ZnCl 2 addition during the HTC process. At 220℃ and 7.5 h, about 60% and 36% improvement in HHV of HC compared to SF were attained in the presence and absence of ZnCl 2 addition, respectively. Moreover, ZnCl 2 addition caused a 7% increase in the mean HC’s HHV.