The adsorptions of lead from aqueous solution by pineapple and paper waste sludges are studied through equilibrium isotherm. Langmuir and Freundlich adsorption models are applied in order to describe the Langmuir coefficient (  ), Langmuir constant (  ), separation factor (), Freundlich constant (  ), intensity of Fruendlich adsorption (   ). The Gibb free energy (°), enthalpy (°), and entropy (°) are calculated for thermodynamic parameters. The adsorption of rate constant (  ) are determined with from kinetics studies; zero"order, first"order, and second"order adsorption. The activation energy (  ) of adsorption is applied with Arrhenius equation. Langmuir adsorption model presents better fit with experimental data. The   from first" and second"order adsorption have the high correlation coefficient (R 2 ) with concentration 100"250 ppm, temperature 30"50 °C, and pH 6. Equilibrium isotherm, Thermodynamic, Kinetic, Lead adsorption. INTRODUCTION Many industries, especially plating facilities and electronic manufacturing often lead to the containing of heavy metals in the effluent of wastewater which is the serious environmental problems. All heavy metals are toxic and non"biodegradable and should be separated from wastewater. There are several ways for separation heavy metals from wastewater such as chemical separation, filtration, membrane separation, electrochemical treatment, ion exchange, and adsorption [1"5]. All these methods, with the exception of adsorption are costly, have low output and are incapable of removing trace level of heavy metals from wastewater. Adsorption has been shown to be a feasible alternative method for removing heavy metals from wastewater. Several natural and synthetic hydrous solids have been investigated as adsorbent of heavy metals. Among these, metal oxides [6"8] and activated carbon [9"10] are the most extensively employed, but the high cost of these materials limits their large"scale use for removal of metals [11]. Adsorbents can be used for water and wastewater treatment and indeed they are widely used due to their higher output and low costs [12"16]. Among current adsorbents, activated carbon is used in different industries, but it is not a selective adsorbent. Recently, a number of studies were carried out on low cost adsorbents from natural resources. The use of low cost adsorbent for heavy metals derived from natural resources has been reviewed by Baily, Olin, Bricka, and Adrian [17] and Babel and Kurniawan [18]. Such the low cost adsorbents are pineapple and paper waste sludges which are the biodegradable. Lead (Pb) is a highly toxic metal that is very poisonous for neurobehavioral development [19] and brain cell function [20] even in trace concentration (ppm) and therefore, before the disposal of lead containing industrial wastes their lead content should be eliminated. Many researches were published on removing of lead ions by different adsorbents such as natural and industrial materials, granular activated carbon, char, and chitosan. [21"23] In the present research, the pineapple and paper waste sludges as adsorbents to remove lead from wastewater treatment, the equilibrium and kinetic sorptions and thermodynamic studies have been studied. MATERIAL    Pineapple waste sludge was obtained from the solid waste of filtration process in the pineapple juice manufacturing located in Prajuabkirikhun (southern of Thailand). Paper waste sludge was obtained from the final recycle paper process of the paper processing factory located in Samutpragran (Thailand). The pineapple and paper waste sludges were washed with distilled water to remove easily suspension materials many times and dried in oven at 105 °C for 48 h. The dried sludges were sieved into particle size of 2 mm and kept in desiccator. The structures of pineapple and paper waste sludges are the cellulose as shown in Fig. 1. Fig. 1 Cellulose structure of pineapple and paper waste sludges The specific surface area (BET) of pineapple and paper waste sludges measured by Micromeritic Chemisorb 2750 automated system are 45x10 2 cm 2 ⋅g "1 , and 205x10 2 cm 2 ⋅g "1 , respectively. Scanning electron micrographs (SEM) of pineapple and paper waste sludges at magnification 500 m are shown in Figs. 2"3. The functional group of materials is hydroxyl (R" OH) group, which can serve as coordination and electrostatic interaction sites to adsorb heavy metals. The adsorption mechanism can be expressed as R"OH + Pb 2+ R"O"Pb + + H + (1) Equilibrium Isotherm, Thermodynamic and Kinetic Studies of Lead adsorption onto pineapple and paper waste sludges Panida Sampranpiboon, and Pisit Charnkeitkong Issue 3, Volume 4, 2010 88 INTERNATIONAL JOURNAL of ENERGY and ENVIRONMENT