China Nonferrous Metallurgy

The magnetic walnut shell biochar was prepared by using walnut shell powder as biomass raw material and H₂O₂ and FeCl₃ as modifiers in turn under oxygen-limited conditions, and then the chitosan/magnetic walnut shell biochar composite (CS/MWSB) was prepared by using chitosan as modifier and polyethylene glycol as cross linking agent, and SEM, FT-IR, N₂ desorption, XRD, XPS, and VSM techniques were used to characterize the morphological and physicochemical properties, and the adsorption performance of CS/MWSB on Pb(Ⅱ) in simulated wastewater was investigated by static tests. The results showed that: the surface of CS/MWSB had a large number of microporous structures, and the active groups and the aromatic group of CS/MWSB increased when the surface was loaded with spherical Fe3O4 particles and chitosan; the CS/MWSB with 30% chitosan loading had the strongest adsorption capacity for Pb(Ⅱ); for the Pb(Ⅱ) solution with the initial concentration of 400mg/L, when the adsorbent was dosed at 4g/L, the adsorption capacity of CS/MWSB was increased by the adsorption of Pb(Ⅱ). The adsorption rate of CS/MWSB for Pb(Ⅱ) was 90.86% and the adsorption capacity was 89.86mg/g at pH 5.0 and temperature 40℃ for 3h. The adsorption of Pb(Ⅱ) by CS/MWSB was in accordance with the quasi-secondary kinetic equation and the adsorption process was mainly chemisorption.