Journal of Hazardous Materials 170 (2009) 969–977 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Adsorption of copper (II), chromium (III), nickel (II) and lead (II) ions from aqueous solutions by meranti sawdust M. Rafatullah a,∗ , O. Sulaiman a , R. Hashim a , A. Ahmad b a Division of Bio-resource, Paper and Coatings Technology, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia b Division of Environmental Technology, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia article info Article history: Received 30 December 2008 Received in revised form 13 May 2009 Accepted 15 May 2009 Available online 21 May 2009 Keywords: Toxic metal Adsorption Isotherm Kinetic Intraparticle diffusion abstract The present study proposed the use of meranti sawdust in the removal of Cu(II), Cr(III), Ni(II) and Pb(II) ions from synthetic aqueous solutions. Batch adsorption studies showed that meranti sawdust was able to adsorb Cu(II), Cr(III), Ni(II) and Pb(II) ions from aqueous solutions in the concentration range 1–200 mg/L. The adsorption was favoured with maximum adsorption at pH 6, whereas the adsorp- tion starts at pH 1 for all metal ions. The effects of contact time, initial concentration of metal ions, adsorbent dosage and temperature have been reported. The applicability of Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) isotherm was tried for the system to completely understand the adsorp- tion isotherm processes. The adsorption kinetics tested with pseudo-first-order and pseudo-second-order models yielded high R 2 values from 0.850 to 0.932 and from 0.991 to 0.999, respectively. The meranti saw- dust was found to be cost effective and has good efficiency to remove these toxic metal ions from aqueous solution. © 2009 Elsevier B.V. All rights reserved. 1. Introduction The presence of toxic heavy metals in industrial effluents has become a matter of environmental concern. Mining, tannery, jew- elry, chemical, metallurgical, electrical and electronics large scale industries in industrial nations, and also arts and crafts in devel- oping countries [1] are the main source for metal containing waste pollution. The effect of waste as sludge deposition and wastew- ater on flora, on marine life and on public health has invited numerous research activities. Increasingly strict discharge limits on heavy metals and their widespread uses, threatening pres- ence at hazardous waste sites have accelerated the search for advanced and economically attractive treatment technologies for their removal. Heavy metals removal from aqueous solution has been commonly carried out by several process, chemical pre- cipitation, solvent extraction, ion exchange, reverse osmosis or adsorption [2,3]. Chemical precipitation, in particular, is the most prevalent method but not suitable for removing low concentra- tion of heavy metal ions. Adsorption processes are promising in this regard as opposed to more conventional chemical precipita- tion in that, it achieve higher level removal over a wider range of solution conditions. The adsorption, with the selection of suitable ∗ Corresponding author. Tel.: +60 4 653 2241; fax: +60 4 657 3678. E-mail address: mohd rafatullah@yahoo.co.in (M. Rafatullah). adsorbents, can be an effective technique for the removal of heavy metals from wastewater [4]. Some of the suggested adsorbents are moss peat [5], fly ash [6,7], activated carbon [8–10], zeolite [11], chitosan [12], lignin [13], clay [14], biomass [15,16], xanthate [17] and cactus material [18]. All the adsorbents are not economically suitable enough for wastewater treatment. Though they generally have high metal adsorption capacity but are expensive and diffi- cult to be separated from the wastewater after use. Therefore, a growing research interest has been developed in search of low cost alternatives to these adsorbents. Sawdust has received particular attention as an economical adsorbent for removing heavy metals from wastewater due to its abundance, easily available and low cost. Further it will be a step ahead towards exploring the possibility on the use of waste biomass for industrial wastewater pollution man- agement. The studies on the use of meranti sawdust as adsorbent are limited. It is a common tree present in all tropical countries such as Malaysia and Indonesia. Meranti tree is widely used for fur- niture making and the waste sawdust produced is generally used for heating in the boiler. The aim of this paper is to assess the ability of meranti sawdust to adsorb Cu(II), Cr(III), Ni(II) and Pb(II) ions from aqueous solu- tions. The effect of the solution pH, temperature, contact time and adsorbent dosage on the removal of Cu(II), Cr(III), Ni(II) and Pb(II) ions was studied. The adsorption isotherm and probable mecha- nism are explained and also tried to find out the kinetics and order of reaction at the surface of the adsorbent. 0304-3894/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2009.05.066