Characterization Of Biochars And Investigation Of Their Adsorption Performance For Heavy Metal Cadmium In Wastewater

The abuse of heavy metal cadmium leads to a large amount of heavy metal cadmium in water.In recent years,cadmium pollution in rivers and lakes has brought great environmental risks to environment and human health.How to effectively treat cadmium pollution in water becomes the focus of research on the management of water bodies.Adsorption is the most efficient method for removing metals in water,and biochar is a new type of adsorbent.In this paper,heavy metal cadmium was used as the research object,and the utilization modification of enteromorpha prolifera was studied.The modification ratio of KOH,different modification methods(potassium permanganate,zinc chloride,phosphoric acid)and hydrothermal carbonization of enteromorpha were studied,and the adsorption mechanism of heavy metal cadmium in water was studied.Thermogravimetric analysis,elemental analysis,scanning electron microscopy and Fourier transform infrared spectroscopy were used to analysis.The pyrolysis characteristics and the physicochemical properties of biochar were explored,and the adsorption process and adsorption performance of biochar on heavy metal cadmium were studied,which can provide data support for the development of biochar materials and technologies for efficient adsorption.The main findings are as follows:(1)EPB2 has higher adsorption capacity of Cd(II).EPB2 had a unique microporous structure.Electrostatic interaction might be the main mechanism,which indicated that the oxygen-containing functional group played an important role.(2)The adsorption capacity was related to the external surface area of biochar.The larger external surface area could increase the adsorption capacity of biochar.CB had the highest external surface area of 1022 m~2/g and higher Cd(II)adsorption capacity.(3)The maximum adsorption capacity of PBC was 368.31 mg/g.The adsorption rate of PBC was very fast,and the adsorption saturation was achieved within 1 h,which had industrial application value.(4)The adsorption was mainly affected by the specific surface area,and the main adsorption mechanism was physical adsorption.Intermittent adsorption experiments showed that the adsorption performance of HC and PHC on Cd(II)depended largely on p H,adsorbent dosage and heavy metal concentration.Kinetic studies showed that the experimental data could well fit the pseudo-second order kinetics equation.HC was suitable for the Freundlich model and PHC was suitable for the Langmuir model.