Assessment of lead desorption from pomelo peel biosorbent after water treatment

Abstract

Biosorption, using fruit peel, can now provide an efficient process for toxic lead removal from wastewater treatment. However, the lead adsorbed on the biomass surface could potentially desorb back into solution and re-contaminate water systems. This current work evaluated the amounts of lead desorption from pomelo peel based on two widely used techniques: chemical extraction and column leaching. The efficiency of lead adsorption from solution treated by pomelo peel was 8.80 ± 0.27 g Pb/kg biomass (approximately 94.7% removal). Lead desorption was evaluated using two common eluents: 0.01 M Ca(NO₃)₂ and 0.04 M EDTA (a chelating agent) solutions. Under batch kinetic chemical extraction, the amounts of lead desorption were 0.17 ± 0.01 g Pb/kg obtained using Ca(NO₃)₂ and 10.16 ± 0.55 g Pb/kg obtained using EDTA (1.80% and 115.0%, respectively, desorption of the adsorbed Pb) with up to 3 d equilibration. For the column leaching study, the amounts of lead desorption were 6.60 ± 0.56 g Pb/kg obtained with Ca(NO₃)₂ and 9.42 ± 0.24 g Pb/kg obtained with EDTA (75.0% and 107.1% desorption, respectively). The relative advantages and disadvantages of the two types of assessment were considered. The results indicated that the disposal of contaminated solid waste resulting from water treatment is a serious issue in waste management. Such disposal represents a potential risk for lead metal mobilization and transfer to other compartments of the environment such as soil, plants or underground water.