Hydrothermal Method Was Used To Prepare Biomass Adsorption Material And Explore Its Adsorption Performance For Congo Red Dye

Today,with the rapid development of industry,dyes have been widely used in all walks of life,which bring us convenience while also bringing great challenges to the environment.Dyes are extremely difficult to degrade naturally in water,and their composition is complex,which often causes greater harm to the water.In the process of wastewater treatment,the adsorption method has received more attention because of its low cost and environmental friendliness.In recent years,among the many adsorbents,biomass adsorbents have been studied in many ways.The raw materials of biomass adsorbents are easy to obtain and are often crops or plant by-products.Pomelo peel and shiitake mushroom root waste as agricultural by-products are often discarded because they have no useful value,but they contain rich functional groups,which will become potential adsorption sites after modification.Therefore,this experiment explored the modification method of pomelo peel and shiitake mushroom waste,and conducted a batch study on its adsorption performance in Congo red dye wastewater.In this study,potassium hydroxide solution was used for activation treatment.During the activation process,the pigments and impurities of pomelo peel and shiitake mushroom waste were removed,and more functional groups were exposed.Subsequently,the activated waste is put into the reactor for hydrothermal treatment at200?.Hydrothermal treatment can not only change the structure of pomelo peel and mushroom root waste,but also not damage the integrity of raw materials,which is beneficial to the recovery and reuse after adsorption.In order to explore the effect of drying methods on the adsorption performance,the materials after hydrothermal treatment were freeze-dried and naturally air-dried.The results showed that the freeze-dried adsorbent had better adsorption effect.FTIR characterization of pomelo peel and shiitake mushroom waste revealed that the characteristic peaks of the carboxyl and hydroxyl groups of these two biomass materials shifted after the completion of the adsorption,indicating that these two functional groups played a role in the adsorption process.Through SEM and BET tests,it can be found that after modification,the pore structure and porosity increases of the material changes,and the specific surface area increases.These structural changes are more conducive to the adsorption process.In order to explore the specific adsorption performance of modified pomelo peel and shiitake root waste to Congo red,batch experiments on temperature,time,dosage and pH were carried out.The results showed that with the increase of temperature,the adsorption capacity of biomass adsorbents decreased,and the same trend appeared in the experiment of p H.The results showed that the modified pomelo peel and shiitake mushroom wastes conformed to the Langmuir model,and the maximum adsorption amounts(q_max)were 144.93 mg/g and 217.86 mg/g,respectively.The study of adsorption kinetics shows that the adsorption process of modified pomelo peel conforms to the pseudo-second-order model,and the adsorption process of modified shiitake mushroom root waste conforms to the pseudo-first-order model.The analysis and calculation of the intraparticle diffusio model show that the adsorption process of the two biomass adsorbents is affected by the boundary layer of the adsorbent and the internal diffusion of the particles.The thermodynamic parameters of biomass adsorbents were-31.43 and-18.78?kJ/mol?,respectively,so they were exothermic reactions.