Synthesis of magnetic activated carbon from Citrus hystrix (Kaffir lime or Kolumichai) leaves with excellent Pb(II) adsorption performance towards electroplating wastewater

Abstract

The adsorption behaviour of Pb(II) ions from aqueous solution has been successfully tested by magnetic activated carbon prepared from novel adsorbent such as Citrus hystrix leaves (MCHLAC) by co-precipitation method and followed by thermal activation. The optimum contact time for the removal Pb(II) ions onto MCHLAC is found to be 90 min, and the optimum pH ranged from 5.0–7.0 respectively. The functionality, surface morphology and elemental composition of MCHLAC have been explored by FTIR, SEM and EDX analysis. The equilibrium data agree well with Langmuir model, which confirm the monolayer coverage of Pb(II) ions onto MCHLAC and the maximum monolayer adsorption capacity is 345.65 mg g^-1.  The kinetic data follow by pseudo-second order model with film diffusion process. Thermodynamic studies indicate that the process of uptake of lead(II) ions is spontaneous and exothermic. A single –stage batch adsorber is designed using the Langmuir adsorption isotherm equation. The regeneration study show that MCHLAC could be effectively utilized for the removal of Pb(II) ions for seven cycles of operation.