Effects of chemical aging on the properties of Zn-modified biochars and the adsorption properties of Pb2+
In this paper,ZnSO4-impregnated biochar(PRZn)was subjected to high temperature(60℃ and 90℃)abiotic aging for six months.The characteristics of biochar properties after aging were determined by elemental analyzer,specific surface area analyzer,X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy.The effect of aging on the adsorption performance of Pb2+was comparatively studied with aged biochars and pristine biochars.The results indicated the free radicals(methyl radicals)generated by high temperature aging process led to the increasing of oxygen-containing functional groups content on the surface of biochars.The specific surface area of biochars pyrolyzed under 500℃ was greatly increased after aging(from 24.67m2/g to 85.51m2/g),while Zn oxides introduced from modification process were transformed from crystal structures to organic bound forms.The adsorption capacity of Pb2+was increased from 31.18mg/g to 47.70mg/g because of aging processes.However,a slight decrease of oxygen functional groups and Pb2+adsorption capacity(36.05mg/g decreased to 31.92mg/g)was observed for biochars pyrolyzed under 700℃ after ageing at high temperature(90℃),mainly because a self-quenching effect of reactive substances at high ageing temperature and a stable structure for biochar pyrolyzed at 700℃.Findings of this study can provide new insights to the long-term utilization of modified biochar in lead-contaminated soil.
Zn modified biocharsadsorption of Pb2+abiotic aginglong-term utilizationfree radicals
万方数据
