Biosorptive removal of lead from aqueous solutions onto Taro (Colocasiaesculenta(L.) Schott) as a low cost bioadsorbent: Characterization, equilibria, kinetics and biosorption-mechanism studies

• Published in: Journal of environmental chemical engineering 2017-06, Vol.5 (3), p.2151-2162
• Main Authors: Saha, Ganesh Chandra, Hoque, Md. Ikram Ul, Miah, Mohammad Al Mamun, Holze, Rudolf, Chowdhury, Didarul Alam, Khandaker, Shahjalal, Chowdhury, Shahriar
• Format: Article
• Language: English
• Subjects: Biosorption; Biosorption mechanism; Isotherms; Kinetics; Regeneration; Taro
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2017.04.013

[Display omitted] •Taro shows excellent biosorption capacity for removal of Pb(II) from water.•Taro provides huge surface area, high porosity and sufficient active sites.•The biosorption process was primarily accompanied by ion exchange mechanism.•Isotherm studies suggest a complex sorption process for Pb(II).•Adsorption follows fast kinetics with low cost involvement.•Taro retains its Pb(II) removal capacity even after five regenerations. Taro (Colocasiaesculenta(L.) Schott) was studied as a biosorbent to remove lead(II) from water. The biosorbent was characterized with scanning electron microscopy (SEM), energy dispersive X-ray measurements (EDX), Fourier transformation infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) technique. Its structural and morphological characterizations indicate that it has potent adsorptive functional groups, high surface area (20.8m2·g−1), flaky stratified structure and huge porosity (pore size: 0.80nm, pore volume: 0.006cm3·g−1). Optimum biosorption occurred at pH 5.5–7.00 with a particle size of 0.150mm and the maximum adsorption capacity of Pb(II) was 291.56mg·g−1. The effective biosorption dose was estimated to be 0.9g·L−1. The ion exchange mechanism is primarily a biosorption process. The biosorption exhibited a high tolerance towards various other ions. The study of Langmuir, Freundlich and Tempkin isotherms implied the involvement of a complex biosorption process. The biosorption followed a pseudo-second-order kinetic model with significantly fast rate and the intra-particle-diffusion-process was the prime rate-controlling factor. For 100mg Taro, the regeneration was carried out using 5mL of 0.1M nitric acid as an eluent and five times regenerated Taro could be efficiently reused. The biosorbent along with developed biosorption procedure was successfully applied to remove Pb(II) from river water.