Adsorption of Pb(II) in aqueous solutions by bamboo charcoal modified with KMnO4 via microwave irradiation

A novel KMnO4 modified bamboo charcoal (Mn-BC) was prepared with microwave irradiation. The surface characteristics of the adsorbent were measured by means of N2 adsorption, XRD, FTIR, SEM, EDS and pHzpc, respectively. The composite exhibited higher surface area of 172.3 m2/g for Mn-BC than that of unmodified bamboo charcoal (BC) (15.5 m2/g). The adsorption behavior of Pb(II) by Mn-BC was studied as a function of contact time, pH, ionic strength and temperature under ambient conditions. The results showed that the kinetic adsorption could be described by a pseudo-second order model very well. The Langmuir model fitted the adsorption isotherms of Pb(II) better than the Freundlich model and the maximum adsorption capacities at 298 K of Pb(II) were 25.03 and 55.56 mg/g for BC and Mn-BC, respectively. The thermodynamic parameters indicated that the adsorption was spontaneous and exothermic. The spent Mn-BC could be readily regenerated for reuse. The results show that Mn-BC is a promising material for the preconcentration and separation of heavy metals from large volumes of aqueous solutions.

The results suggested that KMnO4 treatment could improve the porosity of bamboo charcoal based material under a short time microwave heating, as its oxidation process could enlarge the pores and consequently form mesopores.Figure optionsDownload as PowerPoint slideHighlights
► A novel KMnO4 modified bamboo charcoal (Mn-BC) is prepared with microwave irradiation.
► The binary oxidation process of KMnO4 and HNO3 can improve the porosity of bamboo charcoal.
► Mn-BC has a higher adsorption capacity for Pb(II) than that of BC.
► The spent Mn-BC can be readily regenerated for reuse by dilute H2SO4 solution.