Remediation of Zn, Pb and Cd in Leachate Using Carbonized Water Hyacinth Stem

In recent years, tropical fresh water lake basins are continuously being infested by Water Hyacinth (Eichhorniae crassipes) weed. This has led to fish decline, impede boat and ferry navigation, and blocked water supply to both rural and urban population. Currently, the use of herbicides to control the weed has led to water pollution, the mechanical and biological method have proven to be expensive and unsustainable. Alternatively, due to its high lignocellulose content, it offers a sustainable solution. In this study, heavy metal adsorption capacity of carbonized water hyacinth stem was investigated. Carbon was produced with yield of about 50%. Preliminary data on adsorption with synthetic wastewater identified pH 5, temperature 30°C, adsorbent dosage 1 g/100 ml and contact time 1 hr as the optimal operating conditions for Pb (1.982 mg/L), Zn (1.284 mg/L) and Cd (1.32 mg/L) removal from leachate. The results revealed that the experimental data fitted well with Langmuir and Freundlich isotherm, and also First order Kinetic model. Maximum removal rate of near 100% was attained with leachate. This was attributed to high surface area 327.9 m2/g, total pore volume 0.06 cc/g and pore size 7.257 A, and main functional group OH 3429.08 cm-1. Desorption with 0.6 M HCl gave a maximum recovery yield of 96%.