锌锰铁改性生物炭去除废水中镉的性能及作用机制OA

Heavy metal pollution is widespread and increasingly severe,cadmium(Cd)in water is potentially toxic,and can be transferred and enriched into the human body through the food chain and other ways,endangering human health.Adsorption method has garnered significant attention in the treatment of heavy metal pollution,and different biomass materials can affect the adsorption effect of biochar on heavy metals in water to a certain extent.In this study,magnetic pomelo peel biochar(ZMF@BC)was prepared from agricultural waste pomelo peel as raw material via zinc-manganese-iron impregnation modification to investigate the removal effect and mechanism of biochar on Cd(Ⅱ)in water under different conditions.The adsorption performance of ZMF@BC on Cd(Ⅱ)was analyzed by coexisting ion competition adsorption,adsorption-desorption,etc.The adsorption mechanism was also explored using batch adsorption experiments,Fourier Transform Infrared Spectroscopy(FT-IR),and X-ray Diffraction Analysis(XRD).The results showed that at pH 6.0,the biochar adsorbed Cd(Ⅱ)with a maximum adsorption capacity of 26.3 mg/g due to the reduced ionic competitiveness,and the competitive adsorption of Cd(Ⅱ)by common cations coexisting in the water was in the following order:Na+>Mg2+>Ca2+>K+.The adsorption of Cd(Ⅱ)by ZMF@BC was in accordance with Langmuir and quasi-secondary kinetic models,suggesting monolayer chemical adsorption.The thermodynamic results showed that the adsorption process was spontaneous,and the adsorption-desorption could maintain 85.1%of the initial adsorption amount after five adsorption-desorption cycles.ZMF@BC can absorb Cd(Ⅱ)through ion exchange by using the Zn,Fe,and Mn in the metal oxides on its surface,and also be immobilized through the complexation mechanism specific to the iron oxides.