Adsorption Of Indoor Formaldehyde By Different Modified Sludge Ceramsites

In recent years,with the rapid development and popularization of the interior decoration industry,indoor formaldehyde pollution has become increasingly serious and has become the focus of attention.Activated carbon adsorption is a widely used method for removing formaldehyde,but it is more expensive due to its higher price and difficulty in regeneration.Therefore,this paper takes the sludge from municipal sewage treatment plant and the sludge ceramsite fired from clay as the research object.The adsorption mechanism of sludge ceramsite to formaldehyde is studied by static adsorption method and fixed bed dynamic adsorption method.At the same time,the sludge ceramsite was subjected to acid immersion modification,zeolitic modification and heavy metal loading modification,and the adsorption effect of the modified sludge ceramsite on formaldehyde was studied,in order to obtain a cheap and high adsorption effect material.Provide reference for the study of indoor formaldehyde removal.The results obtained by the Institute are as follows:1.The characterization of sludge ceramsiteTaking the clay and the undigested dewatered sludge of the urban sewage treatment plant as the raw materials,sludge ceramsite was obtained by roasting at1250?.And the sludge ceramsite was porous inside.The heavy metal content of sludge ceramsite leaching meets the standard limit of GB 5085.3-2007"Hazardous Waste Identification Standard-Leaching Toxicity Identification".2.Adsorption capacity of sludge ceramsite for formaldehydeUsing sludge ceramsite as adsorbent and formaldehyde gas as adsorbent adsorbate,the equilibrium adsorption capacity of formaldehyde-by sludge ceramsite under static adsorption conditions was determined,and through the pseudo first-order kinetic model,pseudo second-order kinetic model and the internal diffusion model of particles explored,the adsorption mechanism of sludge ceramsite to formaldehyde was explored.The results were showed as follows:?1?The adsorption capacity of sludge ceramsite to formaldehyde increases with the decrease of particle size.The adsorption capacity of formaldehyde by the<2 mm particle size sludge ceramsite to formaldehyde was 0.00620 mg�g^-11 and the purification efficiency was 8.01%.?2?The kinetic fitting found that the adsorption of formaldehyde by the sludge ceramsite accords with the pseudo first-order kinetics and is the physical adsorption process.?3?The intraparticle diffusion model was used to fit the data of the adsorption amount over time,and found that the whole adsorption process was divided into three stages:extra-diffusion,internal diffusion and multi-layer adsorption.The three-stage rate was affected by specific surface area,micropore and mesopores,respectively.3.Acid impregnation modification,zeolitic modification and heavy metal loading modification on sludge ceramsiteThe adsorption effect of formaldehyde by sludge ceramsite was not ideal.The acid immersion modification,zeolitic modification and heavy metal loading modification of sludge ceramsite were carried out.The equilibrium adsorption capacity formaldehyde by modified ceramsite was determined by static adsorption method.The adsorption mechanism of formaldehyde by modified sludge ceramsite was explored by pseudo first-order kinetic model,pseudo second-order kinetic model and intraparticle diffusion model.The results show:?1?The sludge ceramsite is acid-modified by hydrochloric acid and phosphoric acid impregnation.In the immersion modification of sulfuric acid,with the increase of acid concentration,the adsorption capacity of formaldehyde by modified sludge ceramsite first decreased and then increased.In the 1 mol�L^-11 sulfuric acid immersion modification,the adsorption capacity of formaldehyde by sludge ceramsite was0.00838 mg�g^-1,while the adsorption efficiency was 10.8%,which was 34.83%higher than that of unmodified ceramsite.In the phosphoric acid impregnation modification,with the increase of acid concentration,the adsorption quantity of formaldehyde on the modified ceramsite decreases,and in the 1 mol�L^-11 phosphoric acid immersion modification,the adsorption capacity of formaldehyde by sludge ceramsite was0.00537 mg�g^-1.The adsorption efficiency is 6.97%,which is 12.98%lower than that of unmodified ceramsite.?2?The sludge ceramsite is subjected to zeolitic treatment by an alkali hydrothermal reaction.The results show that with the higher the temperature of the alkaline water thermal reaction,the adsorption of formaldehyde by ceramsite was more effective,and the higher the alkali concentration,the better the adsorption of ceramsite on formaldehyde after zeolitic modification.At 160?,the adsorption capacity of formaldehyde by 5 mol�L^-11 sodium hydroxide zeolitic modified ceramsite was 0.0224 mg�g^-1,the adsorption efficiency was 28.83%,which was 3.60 times than that of unmodified ceramsite.And the adsorption capacity of formaldehyde by 5mol�L^-11 potassium hydroxide zeolitic modified ceramsite was 0.0226 mg�g^-1,the adsorption efficiency was 29.04%,which was 3.63 times than that of unmodified ceramsite.Kinetic fitting revealed that the adsorption process of zeolitic modified ceramsite to formaldehyde was mainly a physical adsorption process.Using the intraparticle diffusion model fitting,it was found that the zeolitic modification mainly improved the adsorption effect on formaldehyde by changing the pore volume content in the ceramsite.?3?Modification of magnetic Fe₃O₄,TiO₂ and MnO₂ supported on sludge ceramsite.Studies have shown that the simple iron loading modification does not increase the adsorption capacity of the sludge ceramsite on formaldehyde,but when it is modified with a molar ratio of 6:1 to aluminum and manganese,The adsorption capacity of the sludge ceramsite on formaldehyde was significantly increased after modification.Fe-Mn modified ceramsite had the best purification effect on formaldehyde,and the purification efficiency was 86.93%,which was 10.7 times that of unmodified.In the photocatalytic modification,the efficiency of photocatalytic modification of formaldehyde on formaldehyde was increased by 23.78%under 365nm UV irradiation under 365 nm UV irradiation,and the addition of heavy metal iron reduced TiO₂.The photocatalytic degradation of formaldehyde,and the addition of copper and manganese heavy metals increased the photocatalytic degradation of formaldehyde by TiO₂.In the manganese loading modification,with the increase of the concentration of potassium permanganate in the immersion liquid,the adsorption capacity of manganese loaded modified ceramsite to formaldehyde also increased,and 20 g�L^-11 of potassium permanganate impregnated with manganese The ceramsite has the best purification effect on formaldehyde,and the adsorption efficiency is77.99%,which is 9.74 times that of unmodified.Kinetic fitting found that the adsorption process of formaldehyde by heavy metal loaded modified ceramsite was mainly physical adsorption process.Using the intraparticle diffusion model fitting,it was found that the heavy metal modification was mainly to increase the adsorption effect of formaldehyde by changing the content of pores and large pores in the ceramsite.