Optimization of Alkali catalyzed hydrothermal carbonization of Prosopis juliflora woody biomass to biochar for copper and zinc adsorption and its application in supercapacitor
Mothil Sengottian, Chitra Devi Venkatachalam, Sathish Raam Ravichandran
Abstract
Although there are many possible routes for the desorption of pollutants, reuse and regeneration of the used adsorbents, the performance and the adsorption capacity is not restored fully and after several cycles again the adsorbent becomes a waste and finally an environmental concern. Thus an alternative route to handle this problem of disposal of used adsorbents, especially for heavy metal adsorption is needed. An attempt is made to use the biochar obtained from hydrothermal carbonization of Prosopis juliflora woody biomass using 5 wt% KOH alkali catalyst. Response surface methodology was used to obtain the optimum conditions for the hydrothermal carbonization process by changing the process parameters such as temperature (200-300°C), reaction time (15-45 min), and water loading in biomass (4-8 mL g -1 ) to maximize mass yield and carbonization ratio. This biochar produced had good adsorption behaviour for Cu(II) and Zn(II) ions from its aqueous solutions with adsorption capacity of 217.39 mg g -1 and 149.25 mg g -1 respectively. The Copper and Zinc adsorbed hydrothermal carbonized biochar were further used as an active material for the supercapacitor and it was observed to possess good specific capacitance of 144.48 F g -1 and 104.56 F g -1 respectively. This study suggests a possible route to utilize the spent adsorbent as an energy storage material.