Evaluation Of The Acid Mist Suppression Efficiency Of Polymer Microspheres

Research on generation of acid mist in metal-working processes and evaluation of the performance of different acid mist suppression techniques are significant for the workers' health and environmental protection.In this work,a bench-scale equipment which is capable to simulate the industrial acid mist generation in the process of electrolysis,electroplating and pickling was customized.The equipment is also able to evaluate the performance of acid mist suppression efficiency qualitatively.In this dissertation,polymer microspheres were employed as a type of suppressant to suppress the acid mist,and the device is used to evaluate the effectiveness of polymer microspheres in inhibiting acid mist.The thickness of the polymer microspheres layer,The effects of the thickness of microspheres,the size of microspheres,the particle size distribution,the density gradation and the hydrophilicity and hydrophobicity distribution on the reduction of acid mist were systematically studied.The mechanism of inhibiting acid mist by polymer microspheres was also investigated.The main conclusions reached are as follows:(1)By varying the operation parameters,bubbles with different number,size,velocity,the path of movement and energy can be produced underneath the working electrolyte or acid solution and then acid mist generation in different industrial metal-working process can be simulated by laboratory self-assembled acid mist generation simulation,testing and evaluation device in the laboratory.The concentration of the generated acid mist can be monitored qualitatively by using the decice to evalute the acid mist suppression efficiency.The device can also be used to explore the new acid mist suppression method.(2)The thickness of the sphere has a great effect on the reduction of polymer microspheres.With the increase of the thickness of the sphere,the effective coverage of the sphere increases,and the effect of inhibiting fogging is better.However,when the thickness of the sphere reaches 10 mm,the effect of fog suppression will not increase obviously when the thickness of the sphere will continue to increase.When the thickness of the ball reaches(20mm),the effect of fog suppression is reduced,excessive thickness of the ball layer leads to poor gas flow,which causes the bubbles to coalesce into large bubbles.When blasting,the energy is large and more acid mist is generated.(3)The combination of particle size and particle size of polymer microspheres is another important factor in reducing acid mist.In the case of a certain thickness of the sphere,As the particle size decreases,the bulk density increases,the porosity decreases,the better the effect of inhibiting acid mist.When the microspheres with different particle sizes are used in combination,The large particle size microspheres are in direct contact with the acid liquid,buffering the rising momentum of the bubbles,and the small particle size microspheres are distributed in the upper part of the sphere for trapping acid droplets,When the amount of small-sized microspheres(0.45 <d <0.9mm)is increased,the effect of suppressing fog is improved,When the amount is increased to 60wt%,the microspheres have a significant increase in their fog-inhibiting effect.(4)Density pairing of polymer microspheres is the third important factor affecting the reduction of acid mist.When the thickness of the layer is constant,with the increase of the volume ratio of the low-density microspheres,the inhibition effect of the sphere layer increases,the larger the volume ratio of low-density microspheres,the greater the effective layer thickness on the acid liquid surface,the path of trapping acid droplets increases and the fog suppression effect increases.The hydrophilic and hydrophobic gradation of microspheres has little effect on its fog inhibiting effect.With the increase of the amount of hydrophobic microspheres,the effect of fog inhibiting is slightly increased.(5)The mechanism by which polymeric microspheres inhibit the acid mist is to suppress the rising bubble to lower its energy,at the same time provide an effective barrier and tortuous path to capture film drops and jet drops to achieve the effect of inhibiting acid mist.Based on this mechanism of inhibiting fog,experimental verification has found that polymer microspheres cannot effectively suppress volatile acid mists.