Removal of Cr(III), Mn(II), Fe(III), Ni(II), Cu(II), Zn(II), and Pb(II) from water solutions using activated carbon based on cherry kernel shell powder

Abstract

In this work, a method for preparing activated carbon based on cherry kernel shell (AC-CKS) was investigated using two consecutive steps: chemical activation with H2SO4 agent and thermal activation in air. For the first time, AC-CKS product is used for the removal of numerous metal ions such Cr(III), Mn(II), Fe(III), Ni(II), Cu(II), Zn(II), and Pb(II) from water solutions. The AC-CKS was characterized using EA, FTIR, SEM, EDX, and XRF techniques. The AC-CKS obtained by heating at 600 °C showed product with higher iodine number and invariably micro-size pores compared to those obtained by heating at 55°C and 400°C. Adsorption capacity of AC-CKS600 was tested in removal of previously mentioned metal ions. The essential parameters affecting the removal of metal ions were studied. The results showed maximum adsorption of 99.0% for Cr(III), 91.7% for Fe(III), 62.0% for Cu(II), 59.3% for Pb(II), 42.0% for Zn(II), 28.0% for Ni(II), and 26.9% for Mn(II). The adsorption data of most metal ions fitted well with Langmuir model. The maximum adsorption capacity followed the sequence: Cr(10.75 mg/g)>Fe(10.15 mg/g)>Cu(7.58 mg/g)>Pb(7.36 mg/g)>Zn(6.08 mg/g)>Ni(2.83 mg/g)>Mn(2.29 mg/g). The adsorption kinetics was tested for the pseudo-first order and pseudo-second order. The rate constants of adsorption for all studied metal ions were calculated. Good correlation coefficients (R2>0.9972) were obtained for the pseudo-second order kinetic model showing that all metal ions uptake processes followed the pseudo-second order rate expression. Desorption studies showed the quantitative recovery of metal ions in the range from 89.4% for Pb(II) to 94% for Cr(III). According to the adsorption model applied in this work, AC-CKS600 product could be recommended for the removal of Cr(III), Fe(III), Cu(II), Pb(II), and Zn(II) from aqueous solutions.