Removal of Cu (II) and Zn (II) ions from wastewater by cassava (Manihot esculenta Cranz) waste biomass

Abstract

The ability of cassava waste biomass (untreated and acid treated) to remove heavy metals (Cu(II) and 
Zn(II) ) from single-ion solution and wastewater was investigated. All experiments were conducted 
using 10mM solutions of mixed metal ions of CuSO4.5H2O and ZnCl2. The uptake capacities of the two 
metal ions tested on the untreated and acid treated cassava waste biomass were 71.3 and 85.2 mg/g for 
Cu(II), and 43.4 and 58.1 mg/g for Zn(II) in single-ion solution. For wastewater, the uptake capacities of 
untreated and acid treated biomass was found to be 40.1 and 59.7 mg/g for Cu(II), and 38.6 and 38.7 
mg/g for Zn(II), respectively. Metal ion uptake capacities in wastewater were lower than in single-ion 
solution probably due to competition of metal ions of different sizes on available binding sites. Uptake 
capacities of these metal ions on the biomass surface increased with acid treatment. Equilibrium 
sorption studies showed that the extent of metal uptake was enhanced by chemically modifying the 
cassava waste biomass by thiolation. Cassava waste biomass saturated with metal ions shows 
remarkable ability for metal recovery by dilute acid treatment, and can be used repeatedly for removal 
of heavy metals in single-ion solution and in wastewater effluents.