Heavy Metals Adsorption on Cellulosic Materials from Agricultural Waste

Abstract

Adsorption technique has been known to be a very effective method for treatment of heavy metals polluted wastewater, with the advantages of specific affinity, simple design and being user-friendly. However, the high cost of activated carbon commonly used as the adsorbent makes it necessary to explore the use of cheap cellulosic adsorbents. In this study, the adsorptive property of sugarcane bagasse (SB) and orange mesocarp (OM) was investigated. The cellulosic adsorbents were used for the sorption of lead and zinc ions from aqueous solutions. The effects of varying adsorbent dose, varying contact time and initial metal ion concentration on adsorption process of the metals were studied. The results show that both adsorbents (though waste materials) are viable for removal of metals from wastewater. Moreover, SB had higher sorption capacity for zinc (12.95 for SB and 12.68 for OM) while OM had higher sorption capacity for lead (9.90 for OM and 9.48 for SB) at optimum dosage. The isothermal studies shows that for lead adsorption, experimental data best fitted the Langmuir isotherm for both adsorbents (R² of 0.9574 for OM and 0.98 for SB) while the data for zinc adsorption best fitted into Freundlich isotherm with SB (R2 of 0.9565) and Langmuir isotherm for OM (R2 of 0.814).