Enhanced Adsorption of Pb(II) on Chemically Treated Neem (Azadirachta indica) Leaf Powder Megat Ahmad Kamal Megat Hanafiah 1,a , Munirah Alias 2,b , Wan Khaima Azira Wan Mat Khalir 1,c , Haslizaidi Zakaria 1,d 1 Faculty of Applied Sciences, Universiti Teknologi MARA (Pahang), 26400, Jengka, Malaysia 2 Faculty of Applied Sciences, Universiti Teknologi MARA, 40450, Shah Alam, Malaysia a makmh@pahang.uitm.edu.my, b munirahalias07@gmail.com, c wkawmk_2505@yahoo.com, d haslizaidi@pahang.uitm.edu.my Keywords: Adsorption; Isotherm; Kinetic; Neem Leaf Powder Abstract. Neem (Azadirachta indica) leaf powder was treated with hydrogen peroxide followed by sodium hydroxide and its performance in Pb(II) removal was investigated. The characteristic of chemically treated neem leaf powder (CTNLP) was studied using Attenuated Total Reflectance Infra-red (ATR-IR) spectrometer and CHNOS Analyzer. The amount of Pb(II) adsorbed increased with increasing pH, concentration and contact time. The kinetic study indicated that adsorption equilibrium time was dependent on initial Pb(II) concentrations. The adsorption kinetic data fitted the pseudo-second-order model. The maximum adsorption capacity calculated from the Langmuir isotherm model was 227.3 mg/g. This study suggests suitable use of CTNLP as an adsorbent for treating wastewater containing Pb(II). Introduction Lead (Pb) has been grouped into one of the top three most toxic elements to humans. Pb tends to bioaccumulate in the food chain [1] and has a potentially damaging effect on human physiology and other biological systems if the tolerance level is exceeded [2]. The major sources of Pb in the environment come from various industrial activities such as paints, finishing tools, cathode ray tubes and ceramics. Pb is also able to bind strongly to particles such as oil, sediments and sewage sludge; therefore, Pb removal has become a great concern [3]. Biosorption is a promising alternative method due to its high selectivity, easy handling, lower operating costs, high efficiency in removing very low levels of heavy metals from dilute solutions, reduces quantity of chemicals or biological sludge, and satisfactory repeated use of biosorbents [4]. Different types of biosorbents derived from plant wastes have been used to adsorb Pb(II) [5]. This study investigated the behaviour of Pb(II) uptake by chemically modified neem leaf powder. The main focus of this study was to enhance the adsorption capacity of Pb(II) by reacting neem leaf powder with hydrogen peroxide (H 2 O 2 ) and sodium hydroxide (NaOH). The effect of parameters that influence Pb adsorption efficiency was also investigated. Materials and methods Adsorbent treatment and characterization. Required Pb(II) solutions were prepared by diluting a stock solution of 1000 mg/L Pb(NO 3 ) 2 , purchased from Merck (Germany). Neem trees are commonly planted along roads and they are called street tree. The fresh mature neem leaves were collected from streets in Shah Alam city. The neem leaves were washed, dried in an oven at 80 o C overnight before being ground and sieved to particle size of 150-200 µm. The neem leaf powder (NLP) was stored in a glass bottles. Five grams of NLP was weighed on a filter paper and was mixed with 100 mL (30%, v/v) H 2 O 2 in a 250 mL conical flask. This treatment oxidized the primary alcohol on the neem leaf surface to carboxylic acid [6]. The mixture was shaken at 200 rpm for 3 h at room temperature (24 ± 0.5 °C). Then, it was filtered using a vacuum pump and washed extensively with deionized water to remove excess H 2 O 2. The NLP was dried in an oven at 80 ° C Advanced Materials Research Vol. 856 (2014) pp 128-133 Online: 2013-12-06 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.856.128 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, www.ttp.net. (ID: 210.48.147.110, Universiti Teknologi Mara (UiTM), Shah Alam, Malaysia-08/09/15,07:38:46)