Original Paper

Chemical Papers

, Volume 67, Issue 5, pp 497-508

First online:

Removal of heavy metal ions from aqueous solutions using low-cost sorbents obtained from ash

  • Maria HarjaAffiliated withDepartment of Chemical Engineering, “Gheorghe Asachi” Technical University of Iasi
  • , Gabriela BuemaAffiliated withDepartment of Chemical Engineering, “Gheorghe Asachi” Technical University of Iasi
  • , Daniel Mircea SutimanAffiliated withDepartment of Chemical Engineering, “Gheorghe Asachi” Technical University of Iasi
  • , Igor CretescuAffiliated withDepartment of Environmental Engineering and Management, Faculty of Chemical Engineering and Environmental Protection, “Gheorghe Asachi” Technical University of Iasi Email author 

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This study’s main objective was the development of effective low-cost sorbents for the removal of heavy metal ions from aqueous solutions. The influence of different factors on the sorption capacity of ash and modified ash as low-cost sorbents obtained by different methods was investigated. The synthesis of new ash-based materials was carried out at ambient temperature (20°C), 70°C, and 90°C, respectively, in an alkaline medium with NaOH concentrations of 2 M and 5 M, respectively, corresponding to a mixture with solid/liquid ratios of 1: 3 and 1: 5, respectively. The prepared materials (sorbents) were characterised by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), X-ray diffraction, and BET surface measurement. Adsorption isotherms were determined using the batch equilibrium method. The results showed that these types of new materials displayed a good capacity to remove copper, nickel, and lead ions (29.97 mg of Cu2+ per g of sorbent, 303 mg of Ni2+ per g of sorbent, and 1111 mg of Pb2+ per g of sorbent) from aqueous solutions. The modified materials were prepared using an alkaline attack (a recognised method used in previous studies), but Romanian ash from a thermal power plant was studied for the above purpose for the first time. Hence, the factors which affect the sorption capacity of the prepared low-cost sorbents were determined and their behaviour was explained, taking into account the composition and structure of the new materials.


ash characterisation heavy metal low-cost sorbent sorbent synthesis