Study On Preparation Of Activated Carbon Based On Municipal Sludge Doped Waste Foam Plastic And Its Adsorption Performance

Sludge is a product generated in sewage treatment process,is a harmful substance,if the sludge can not be properly disposed,not only a waste of resources,and will lead to serious environmental pollution.The general disposal methods include:landfill,high-temperature incineration,farmland utilization,etc.These methods can not fundamentally solve the harm caused by sludge,and easy to have a negative impact on the surrounding environment,there are great drawbacks.In recent years,the research on reducing the yield of sludge,eliminating the potential harm of sludge to the environment,and recycling the sludge has become the focus of attention in the field of environmental protection.In this paper,municipal sludge and waste foam board were doped together to prepare biomass activated carbon by chemical activation.It not only reuses and effectively disposes of sewage sludge and waste foamed plastics,but also transforms the waste into porous adsorbents,which embodies the value of secondary utilization.In this study,ZnCl₂and FeCl₃were used as active agents to analyze the influencing factors.ZnCl₂was used as active agent,the activated carbon prepared by sludge and foam was denoted as ZAC₁,and the activated carbon prepared by sludge was denoted as ZAC₂.When FeCl₃is used as active agent,the activated carbon prepared by mixing sludge and foam is denoted by FAC1,and the activated carbon prepared by single sludge is denoted by FAC₂.The influences of active agent concentration,pyrolysis temperature,holding time and material ratio on the iodine adsorption values of the four activated carbons were discussed.The results showed that under the same conditions,the iodine adsorption values of the four activated carbons were sorted as follows:ZAC₁>FAC₁>ZAC₂>FAC₂,orthogonal experiments were designed on the basis of experimental parameters of ZAC₁,the preparation conditions were further optimized,and the influence degree of various factors on iodine adsorption value was determined.The optimal working conditions are:The material ratio is 1:1,the concentration of ZnCl₂is 40wt%,the pyrolysis temperature is550℃,the holding time is 90min,and the maximum iodine adsorption value is 762.57mg/g.The characterization results of ZAC₁show that the material has a relatively developed pore structure,and the S_BETis 671.63 m²/g.The total volume of BJH is 0.4943 cm³/g,and the average pore diameter of BJH is 2.94 nm.Methylene blue（MB）and 4-chlorophenol（4-CP）were selected as the target pollutants,and the prepared ZAC₁was used as the adsorbent to simulate the adsorption of the two pollutants.The effects of solution concentration,adsorption time,adsorbent dosage and solution p H value on the removal rate were discussed.The results show that the concentration of pollutants in the solution is inversely proportional to the removal rate.Adsorbent dosage is directly proportional to the removal rate.The p H value of the solution is positively proportional to the removal rate,which is more conducive to the occurrence of adsorption reaction when the solution is alkaline.Adsorption time is also positively proportional to the removal rate.When the adsorption process lasts for a certain period of time,the adsorption equilibrium can be reached eventually.When the adsorption process lasts for 120 min,the removal rate will not fluctuate dramatically again and basically reaches the state of adsorption saturation.Langmuir isotherm model can be used to fit the experimental data well（R²>0.99）.The results of Langmuir isotherm calculation show that the monolith saturated adsorption capacity of ZAC₁for MB is 111.11 mg/g,and that for4-CP is 18.66 mg/g.It is basically consistent with the experimental results.According to the adsorption kinetics fitting results,the adsorption kinetics of ZAC₁for MB and4-CP was more consistent with the Mc Kay equation（R²>0.999）.The experiment shows that ZAC₁has good adsorption performance for both MB and 4-CP,so it is feasible to prepare activated carbon with municipal sludge and waste foam plastic board as raw material,which can realize the reuse of waste.