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Removal of heavy metals from aqueous system using plant-based sorbents
Author
Chew, Chai Hung
Supervisor
Wong, Ka Lun
Tan, Swee Ngin
Abstract
Anthropogenic activities have contributed to elevated heavy metal concentrations in the environment. Heavy metals such as lead and cadmium are not biodegradable and thus they have a tendency to remain in environment leading to accumulation in the food chain. Hence, removal of heavy metal from the environment is of paramount importance to minimize public health risk. In this study, leaves of five local tropical plant materials including Bambusa vulgaris, Schizostachyum brachycladum, Scirpus grossus, Pennisetum purpureum and Cymbopogon citrates were screened for their efficiency for the removal of Pb and Cd. The removal efficiency for Pb and Cd ranged from 47 to 70% and 44 to 67%, respectively. Based on the preliminary screening results, the leaves of Bambusa vulgaris (BV) and Schizostachyum brachycladum (SB) were selected for further detailed investigation. BV in Pb solution achieved maximum sorption capacity, 4.4 mg g-1 at an initial concentration of 50 ppm while SB in Cd solution achieved maximum sorption capacity, 5 mg g-1 at an initial concentration of 300 ppm. FTIR spectra revealed that major functional groups, such as carboxyl and hydroxyl groups present in the leaves may act as active sites on the sorbent surface during the metal ion uptake process. The isotherm study revealed that only Cd sorption onto SB leaves fitted well with Freundlich model. Based on kinetic and isotherm results, Cd sorption onto SB leaves could be due to multi-layer sorption which involved both chemisorption and physisorption. However Pb sorption onto BV leaves followed pseudo-second order kinetics which involved chemisorption process. BV and SB which are inexpensive source of readily available natural material could be recommended for use as an environment-friendly sorbent for the removal of Pb and Cd.
Date Issued
2016
Call Number
TD475 Che
Date Submitted
2016