Adsorption Characteristics of Pb(Ⅱ) on Eucalyptus Biochar Modified by Potassium Permanganate

Abstract

Eucalyptus biochar(BC) was prepared and potassium permanganate was used to modify the biochar(KBC). Static adsorption experiments on Pb(Ⅱ) in aqueous solution were carried out to investigate the effects of pH, adsorbent dosing, adsorption time, temperature, and initial concentration on the adsorption of Pb(Ⅱ). The results showed that the optimum pH was 5 while the adsorption reached saturation after 6 h. When the temperature was 25℃, the initial concentration of Pb(Ⅱ) was 100 mg·L-1 with an adsorbent dosage of 0.06 g; the maximum adsorption of Pb(Ⅱ) by KBC was 83.059 mg·g-1, with a removal rate of 99.67%. The adsorption of Pb(Ⅱ) by KBC followed the pseudo-second-order kinetic model and the Langmuir isothermal adsorption model, which is a monolayer adsorption occurring on a homogeneous surface. The adsorbents were characterized using the BET method, scanning electron microscopy and energy dispersive spectroscopy(SEM-EDS), X-ray diffraction(XRD), Fourier transformed infrared(FT-IR) and X-ray photoelectron spectroscopy(XPS). The adsorption mechanism of Pb(Ⅱ) by KBC oxygen-containing and manganese-containing groups was through complexation and precipitation, and the formation of -O-Pb-O- bidentate complexes on the surface of the biochar. Therefore, potassium permanganate-modified BC can be used as a good Pb(Ⅱ) adsorbent.