ORIGINAL ARTICLE Removal behavior of peat collected from Brunei Darussalam for Pb(II) ions from aqueous solution: equilibrium isotherm, thermodynamics, kinetics and regeneration studies Tasneem Zehra 1 • Linda B. L. Lim 1 • Namal Priyantha 2,3 Received: 7 November 2014 / Accepted: 3 March 2015 Ó Springer-Verlag Berlin Heidelberg 2015 Abstract Peat collected from Brunei Darussalam shows a remarkable affinity toward Pb(II). Under optimized condi- tions of shaking time, settling time, pH and ionic strength, more than 95 % can be removed from a 10.0 mg L -1 Pb(II) solution using 0.050 g of peat at ambient temperature of 25 ± 1 °C. Scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray fluorescence spectroscopy performed on peat samples before and after interaction with Pb(II) solution conclusively demonstrate the transfer of Pb(II) ions from the solution phase to the solid peat phase. Interaction of Pb(II) solution and peat follows pseudo-second-order ki- netics and adsorption best fitted the Redlich–Peterson iso- therm model. The maximum adsorption capacity (q max ) was found to be 15 mg g -1 . Thermodynamic parameters evaluated for the Pb(II)—peat system indicate that the above adsorption reaction is spontaneous and endothermic. Regeneration of Pb(II)-loaded peat is effective with HCl solution and the re- generated peat can be reused for adsorption of peat. Keywords Peat  Adsorption  Isotherm  Thermodynamics  Kinetics  Regeneration Introduction The presence of heavy metals in wastewater contributed by industries, such as electroplating, battery manufacturing, mining operations, pulp and paper industries, is a major concern because of their toxicity and threat to human life and environment. As heavy metal ions are non- biodegradable, it is important to treat industrial effluents containing such ions before discharging them into water streams. Various methods including ion-exchange, chemi- cal precipitation, ultrafiltration, oxidation and ozonation have been used. In recent years, adsorption techniques have become attractive, due to their advantages over the other processes, such as cost-effectiveness and ability to produce high-quality treated effluents. Different low-cost adsor- bents, such as clay (Kim et al. 2013; Gil et al. 2011), peat (Chieng et al. 2014), shells of various nuts (Dahri et al. 2014; Pehlivan et al. 2009) and fruit wastes (Annadural et al. 2002; Lim et al. 2013a, 2014) have been successfully employed to remove industrial pollutants, especially dyes and metal ions from wastewater. Studies show have shown that adsorption of Pb(II) on various biosorbents is feasible and spontaneous (Kamaraj et al. 2013; Rashidi et al. 2010; Saroj et al. 2014). Pb(II) removal increases with increase in temperature. The adsorp- tion process follows pseudo-second-order mechanism with formation of monolayer based on the Langmuir isotherm which provides the best fit to the experimental data (Liao et al. 2010; Salim and Munekage 2009; Okoye et al. 2010). Peat is a kind of soil, rich in organic materials, which has a porous structure. It has been used as an effective adsorbent for the removal of oil, organic matter and other pollutants present in water (Ringqvist and Oborn 2002; Zehra et al. 2014). Brunei Darussalam is blessed with large areas of peat lands which are still unexplored. The present & Linda B. L. Lim linda.lim@ubd.edu.bn Tasneem Zehra if_tz@hotmail.com Namal Priyantha namal.priyantha@yahoo.com 1 Department of Chemistry, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong, Brunei Darussalam 2 Department of Chemistry, Faculty of Science, University of Peradeniya, Peradeniya, Sri Lanka 3 Postgraduate Institute of Studies, University of Peradeniya, Peradeniya, Sri Lanka 123 Environ Earth Sci DOI 10.1007/s12665-015-4273-2