[Adsorption Characteristics of Pb(â ¡) on Eucalyptus Biochar Modified by Potassium Permanganate].

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.

Efficient performance of magnesium oxide loaded biochar for the significant removal of Pb2+ and Cd2+ from aqueous solution.

Lead (Pb) and cadmium (Cd) are considered as a typical heavy metals in aqueous solution, which may pose adverse health effects on human beings. For the removal of these two pollutants, magnesium oxide (MgO) was successfully immobilized onto eucalyptus biochar (BC) matrix via simple and cost-effective pyrolysis process of MgCl2-pretreated eucalyptus biomass under high temperature (500 °C). Synthesized MgO nanoparticles-biochar composites (MBC) exhibited superior removal performance for target pollutants, and achieve 99.9% removal efficiency for Pb(II) and Cd(II) at optimum conditions (0.02 g, pH in range of 4-7, and reaction time 120, 240 min). Furthermore, the maximum theoretical adsorbing amount of MBC was 829.11 mg/g for Pb(II) and 515.17 mg/g for Cd(II). Pseudo-second-order model and Langmuir models were well-determined for isotherm and adsorption kinetics. FTIR, XRD, and XPS analysis revealed that precipitation and ion exchange was of great importance for the removal of contaminants. Besides, cation-π interaction and complexation from the carbon-containing functional groups should not be neglected. Considering the advantage of low-cost, facile preparation, and brilliant adsorption capacity, it is anticipated that MBC has a promising prospect for the broad application in Pb(II)/Cd(II)-containing wastewater treatment.