Preparation Of Fe₃O₄/Biomass Carbon Composite And It’s Adsorption Properties For Tetrabromobisphenol A

Tetrabromobisphenol A(TBBPA)is a widely used brominated flame retardant.Although it has low water solubility,exposed TBBPA can induce cytotoxicity,immun-otoxicity and biological toxicity,which have adverse effects on humans and ecology due to its strong lipophilicity,low volatility and chemical stability.As an adsorbent,biomass carbon is widely used in the repair and treatment of various pollutants in water bodies because of its simple preparation process,low cost and rich pore structure.However,biomass carbon is usually a small,powdery solid,so separation from water is very difficult.In order to improve the separation ability of the powdered biomass carbon,the biomass carbon is "magnetized",and the biomass carbon can be quickly separated from the water body by an external magnetic field.In this thesis,biomass carbon materials were prepared from bamboo,orange powder and pine cone.On this basis,Fe3O4/biomass carbon composites were prepared by "chemical precipitation method".The surface morphology and structure of the composites were characterized by SEM,XRD,FTIR and nitrogen adsorption desorption tests.The adsorption capacity of the adsorbent,the adsorption equilibrium time,the initial concentration of the adsorption solution and the initial pH were investigated.The adsorption mechanism of Fe3O4/biomass carbon composites adsorbing TBBPA was also discussed.Firstly,the optimal synthesis process of composites was discussed.The experimental results show that when the carbonization temperature is 500℃ and the Fe/C mass ratio is 1:2,the adsorption performance of the composites is the best.Different carbonization temperatures affect the morphology and surface functional groups of biomass carbon.SEM analysis showed that Fe3O4 could be uniformly distributed on the surface of biomass carbon to form composite materials.Compared to biomass carbon materials,the adsorption properties of composites after"magnetization" are improved.Then,the effects of adsorption amount,equilibrium time,initial solution concentration and pH on the adsorption performance of TBBPA were investigated.The results show that when the optimum adsorbent dosage is 15 mg,the adsorption equilibrium time of the pine cone biomass carbon composite material MPC,the bamboo biomass carbon composite material MBC and the orange powder biomass carbon composite material MOC is 200 min and 400 min,respectively.The adsorption kinetics of TBBPA on the pine cone biomass carbon composites accords with the quasi-first-order kinetic model.The adsorption kinetics of the bamboo powder and the orange powder bio-carbon composites accords with the quasi-second-order kinetic model.The isothermal adsorption curves of the three composites are consistent with the Langmuir model.When the initial pH of the solution is 6～7,the composite has the best performance for adsorbing TBBPA.Based on the experimental results and related research reports,it is concluded that the adsorption mechanism of TBBPA on biochar includes:hydrophobic effect,electron action,hydrogen bonding and pore filling.