Study On Treatment Of Organic Dye Wastewater With Modified Biochar

Among the various methods for dye wastewater treatment,the adsorption method has been studied more because of its excellent adsorption effect,simple operation,and reusable adsorbent.In this paper,magnetic biochar materials were prepared by magnetic modification method using sunflower seed shells as raw materials.Using durian shell as raw material,durian shell biochar modified with active agent was prepared.The properties of the two modified materials were analyzed,and the adsorption properties of Congo red dye were studied.The specific research contents are as follows.（1）The magnetically modified sunflower seed husk biochar material was prepared by hydrothermal method,and the morphology and microstructure of the prepared biochar material were analyzed by SEM,XRD,XPS,FTIR and BET and other characterization methods.The adsorption performance was tested with Congo red solution as the simulated organic dye wastewater.First,a single factor experiment was designed to determine the specific role and influence of each factor in the overall experiment.The single factor included contact reaction time,initial concentration of Congo red solution,dosage of adsorbent,reaction temperature,and initial p H value of Congo red solution.The results showed that the adsorption equilibrium was reached when the time was 240 min.When the concentration of Congo red dye was 70 mg/L,p H was 6,the dosage of adsorbent was 0.6g/L,and the temperature of the reaction system was 45°C,the adsorption was successful.The adsorption sites on the agent can be fully utilized,and the saturated adsorption capacity of the modified material reaches 259.54 mg/g,which is much higher than the adsorption capacity of pure sunflower seed husk biochar under this condition.This is due to the presence of Fe₃O₄ particles in the modified material,which increases the specific surface area of the material by 1.68 times.At the same time,the separation of the magnetic biochar composite material from the Congo red solution is easier to achieve using the action of an external magnetic field.Secondly,the adsorption kinetics fit fits the pseudo-second-order kinetic model,indicating that the dye molecules are mainly physically adsorbed on the adsorbent surface.The adsorption isotherm fitting fits the Langmuir isotherm adsorption model,indicating that monolayer adsorption occurs.The desorption experiment results show that the desorption effect is good,and the adsorption efficiency is still high after 5 cycles of adsorption experiments,indicating that its performance is relatively stable and reusable.（2）The active agent-modified durian shell biochar was prepared by hydrothermal method,and the morphology and microstructure of the prepared modified biochar were analyzed by SEM,XRD,FTIR and BET.Similarly,using Congo red solution as the simulated organic dye wastewater,single-factor experiments were firstly carried out,including contact reaction time,initial concentration of Congo red solution,dosage of adsorbent,reaction temperature,and initial p H value of Congo red solution.The results showed that the adsorption equilibrium was reached when the time was 240 min.When the concentration of Congo red dye was 150 mg/L,p H was 6,the dosage of adsorbent was 0.8g/L,and the temperature of the reaction system was 45°C,the change was The saturated adsorption capacity of the biochar material reaches the highest of 641.5 mg/g,which is much higher than that of the pure durian shell biochar material under this condition.This is because the presence of the active agent in the modification process can expand the pores,so that the specific surface area of the modified material is increased by 2.12 times compared with the pure biochar material,providing more adsorption sites.Second,the adsorption kinetic model fits the pseudo-second-order kinetic model,and chemisorption mainly occurs.The adsorption isotherm model conforms to the Freundlich isotherm adsorption model and follows the principle of surface coverage.The desorption experiments show that the desorption effect is good,and the adsorption efficiency is still high after 5 cycles of adsorption experiments.This study shows that the preparation of biochar adsorbents from nutshell biomass can effectively remove organic dye molecules in sewage,and at the same time realize the recycling of biomass resources.