Sequestration of toxic Pb(II) ions by chemically treated rubber(Hevea brasiliensis) leaf powder
Megat Hanafiah Megat Ahmad Kamal , Wan Mat Khalir Wan Khaima Azira , Mohamed Kasmawati , Zakaria Haslizaidi , Wan Ngah Wan Saime
DOI:
Received April 14, 2009,Revised July 06, 2009, Accepted , Available online
Volume 22,2010,Pages 248-256
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Rubber leaf powder (an agricultural waste) was treated with potassium permanganate followed by sodium carbonate and its
performance in the removal of Pb(II) ions from aqueous solution was evaluated. The interactions between Pb(II) ions and functional
groups on the adsorbent surface were confirmed by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy
(SEM) coupled with X-ray energy dispersive spectroscopy (EDX). The effects of several important parameters which can affect
adsorption capacity such as pH, adsorbent dosage, initial lead concentration and contact time were studied. The optimum pH range
for lead adsorption was 4–5. Even at very low adsorbent dosage of 0.02 g, almost 100% of Pb(II) ions (23 mg/L) could be removed.
The adsorption capacity was also dependent on lead concentration and contact time, and relatively a short period of time (60–90
min) was required to reach equilibrium. The equilibrium data were analyzed with Langmuir, Freundlich and Dubinin-Radushkevich
isotherms. Based on Langmuir model, the maximum adsorption capacity of lead was 95.3 mg/g. Three kinetic models including pseudo
first-order, pseudo second-order and Boyd were used to analyze the lead adsorption process, and the results showed that the pseudo
second-order fitted well with correlation coefficients greater than 0.99.
