Journal of Hazardous Materials 170 (2009) 357–365 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Scavenging behaviour of meranti sawdust in the removal of methylene blue from aqueous solution A. Ahmad a,∗ , M. Rafatullah b , O. Sulaiman b , M.H. Ibrahim a , R. Hashim b a Environmental Technology Division, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia b Bio-resource, Paper and Coatings Technology Division, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia article info Article history: Received 6 February 2009 Received in revised form 8 April 2009 Accepted 21 April 2009 Available online 3 May 2009 Keywords: Meranti sawdust Adsorption Isotherm Methylene blue Kinetic abstract Meranti (Philippine mahogany) sawdust, an inexpensive material, showed strong scavenging behaviour through adsorption for the removal of methylene blue (MB) from aqueous solution. Batch studies were performed to evaluate and optimize the effects of various parameters such as contact time, pH, ini- tial dye concentrations and adsorbent dosage. Langmuir, Freundlich and Temkin isotherms were used to analyze the equilibrium data at different temperatures. The experimental data fitted well with the Langmuir adsorption isotherm, indicating thereby the mono layer adsorption of the dye. The monolayer sorption capacity of meranti sawdust for MB was found to be 120.48, 117.64, 149.25 and 158.73mg/g at 30, 40, 50 and 60 ◦ C, respectively. Thermodynamic calculations showed that the MB adsorption process is endothermic and spontaneous in nature. Kinetic studies showed that the adsorption followed a pseudo- second-order kinetic model. The results indicated that the meranti sawdust could be an alternative material in place of more costly adsorbents used for dye removal. © 2009 Elsevier B.V. All rights reserved. 1. Introduction The pollution caused by industrial wastewater has become a common problem for most of the countries. Wastewater from the textile, cosmetics, printing, dying, food coloring, and paper making etc., are polluted by dyes. The number of dyes presently used in tex- tile industry is about 10,000. The annual production of these dyes is over 7 × 10 5 tons [1]. Effluent discharged from dyeing industries is highly colored and not only is toxic to aquatic life in receiving water but also affects its aesthetic value. Color impedes light pene- tration affecting plants in the receiving streams, thereby seriously affects the ecosystem of the streams [2]. Dyes may also be prob- lematic if they are broken down anaerobically in the sediment, as toxic amines are often produced due to incomplete degradation by bacteria [3]. Many dyes and pigment have toxic as well as carcino- genic, mutagenic and teragenic effects on aquatic life and also on humans [4]. Methylene blue has wider application, which includes color- ing paper, temporary hair colorant, dyeing cottons, wools, coating for paper stock, etc. [5]. Though methylene blue is not strongly hazardous but on inhalation, it can show various harmful effects. It can give rise to short periods of rapid or difficult breathing while ingestion through the mouth produces a burning sen- sation and may cause nausea, vomiting, diarrhea, and gastric. ∗ Corresponding author. Tel.: +604 653 2214; fax: +604 657 3678. E-mail addresses: aneesahmad ana@yahoo.com, anees@usm.my (A. Ahmad). Accidental large dose creates abdominal and chest pain, severe headache, profuse sweating, mental confusion, painful micturation, and methemoglobinemia [6]. During the last few years new or tighter regulations coupled with increased enforcement concerning wastewater discharges have been established in many countries. There is an increased demand of cheaper methods of pollutant removal [7]. Thus, adsorp- tion process are being employed widely for large-scale biochemical, chemical and environmental recovery and purification applica- tions. The major advantages of a sorption system for water pollution control are less investment in terms of initial cost and land, sim- ple design and easy operation, no effect by toxic substances, and superior removal of organic waste constituents as compared to the conventional biological treatment processes [8]. Activated carbon as an adsorbent has been widely investigated for the adsorption of basic dyes [9–13], but its high-cost limits its commercial appli- cation. In recent years, extensive research has been undertaken to develop alternative and economic adsorbents. An economic sorbent is defined as one which is abundant in nature, or is a by-product or waste from industry and requires little processing [14]. Such alternatives include: chitosan bead [15], oil palm trunk fiber [16], fly ash [8], and dried biomass of Baker’s yeast [17], durian (Durio zibethinus Murray) peel [18], Guava (Psidium guajava) leaf powder [19], chitosan/oil palm ash composite [20], high lime Soma fly ash [21], almond shells [22], pomelo (Citrus grandis) peel [23], treated parthenium biomass [24] and broad bean peels [25]. Recently, an extensive list of sorbent literature for dye removal has been com- piled by Allen and Koumanova [26]. 0304-3894/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2009.04.087