| With the rapid development of my country’s industry,the demand for mechanical lubricants has gradually increased,and a large amount of waste lubricants has caused serious pollution to the environment.As a recyclable resource,waste lubricating oil can be reused after purification and refining,which can effectively alleviate the shortage of petroleum resources and environmental pollution.As a kind of waste,fly ash is a new type of porous adsorption material,and has the advantages of low price and wide sources.It can be used as an adsorbent in waste oil regeneration treatment.At the same time,it has been that fly ash also has a unique hollow microbead structure.These microbeads can be separately extracted to make an adsorbent,which should effectively improve the adsorption efficiency.This paper is based on waste lubricating oil regeneration treatment technology,taking fly ash sedimentation/magnetic beads as the research object,the magnetic bead collection rate is an evaluation index,and single factor experiment is used to explore the influence of various factors on the separation effect of fly ash sedimentation/magnetic beads,use orthogonal optimization test to determine sorting conditions;microwave-assisted alkali is used as the modification method,and the acid value of waste oil is the evaluation index of regeneration.The influence of each factor on the modification effect of fly ash/magnetic beads is investigated through a single factor test,and the modification conditions are optimized through a response surface experiment;the adsorption kinetic/thermodynamic study of fly ash sediment/magnetic beads is carried out to explore the adsorption characteristics and adsorption mechanism of fly ash sediment/magnetic beads before and after modification.Finally,investigate the influence of fly ash sedimentation/magnetic bead modification on its contact angle.The sorting experiment shows:the collected amount of magnetic beads increases with the increase of stirring speed,stirring time and standing time,while the collected amount of sinking beads decreases.After reaching the plateau value,the collected amount of each bead tends to be stable;the orthogonal optimization experiment with the collected magnetic beads as the target value showed that the optimized separation process conditions are:solid-liquid ratio 1:4,stirring rate 600 r/min,stirring time 20min,and standing time 70min.Modification experiment shows:the factors affecting the modification effect of fly ash precipitation/magnetic beads are microwave power,modifier concentration,solid-to-liquid ratio,microwave time,stirring time.The acid value of the oil decreases to the optimized value with the increase of various factors,and then this increases the acid value and reduces the adsorption effect;the modified conditions were optimized through response surface design experiments:microwave power 500 W,microwave time 8 min,solid-liquid ratio 1:5,modifier concentration 0.75 mol/L,stirring time 85min,at this time the adsorption capacity could reach 4.667 mg/g.The adsorption kinetics experiment shows:the equilibrium time of fly ash sedimentation/magnetic beads adsorption equilibrium is 180 min.After modification,the equilibrium adsorption capacity of sedimentation beads increased from 3.88 mg/g to4.67 mg/g,and the equilibrium adsorption capacity of magnetic beads increased from4.14 mg/g to 5.09 mg/g.It can be seen that before and after modification,the equilibrium adsorption capacity of magnetic beads was always higher than that of sinking beads;the entire adsorption process can be described by a quasi-second-order kinetic equation,which is divided into two processes,fast external diffusion and slow internal diffusion,and the main control steps of the entire adsorption process are pore diffusion and adsorption reaction.Modification had a promoting effect on both stages,and the diffusion effect of adsorbate in the modified magnetic beads was better,and the adsorption performance was better.Adsorption thermodynamic experiment shows:the Langmuir adsorption isotherm equation can be used to describe the adsorption process,the adsorption capacity increases with the increase of temperature,and the equilibrium adsorption capacity of magnetic beads at each temperature is better than that of sink beads,and modification can further increase the adsorption capacity;it can be known from the Temkin equation that the adsorption of acid in waste oil by the sink/magnetic beads is a physical adsorption process,and the k _Tvalue decreases after modification;it can be known from the Freundlich equation that the adsorption of waste oil by sink/magnetic beads is an easy and preferential adsorption,and the value of n increases after modification;it can be seen from the Sips equation that the surface uniformity of fly ash/magnetic beads decreased after modification;according to the analysis of the adsorption thermodynamic function,the adsorption process is a spontaneous endothermic reaction,and the main force is van der Waals force.After modification,∣ΔG∣,ΔH andΔS increase,the degree of spontaneity was higher,and the driving force of the adsorption reaction was greater.The adsorption performance of magnetic beads was better.The contact angle experiment shows:the affinity of the modified fly ash/magnetic beads with liquid paraffin was increased,the relative contact angle was decreased,the surface free enthalpy was increased,and the surface activity of the beads was significantly enhanced. |
PDF Full Text Request