Efficient removal and recovery of Cd^(2+)from aqueous solutions by capacitive deionization(CDI)method using biochars

Biochars are low-cost and sustainable materials for environmental technologies.In this work,we pre-pared three biochars using pomelo peel(P-BC),algae(A-BC),and corncob(C-BC)to recover Cd^(2+)from wastewater via capacitive deionisation(CDI).A-BC possesses the highest amount of mesopores and nitro-gen functionality and attains the highest removal of Cd^(2+)via physical adsorption.For the electro-sorption capacity,C-BC and A-BC perform better capacitive removal of Cd^(2+)than P-BC due to the smaller charge-transfer and mass-transfer resistances.Also,this work investigated the impacts of surface morphology,cell voltage,NaCl,initial pH,and Cd^(2+)concentrations on Cd^(2+)capacitive removal and electrode regen-eration performances.The results indicated that A-BC and C-BC may be prospective materials for Cd^(2+)removal from wastewater by CDI.However,the presence of competing cations at high concentrations may influence the removal of Cd^(2+)at a low level,requiring the modification of A-BC and C-BC in future work.