Study Of The Removal Of Heavy Metal Pb(?)/Zn(?)Pollution By Aqueous Foam Based On Green Surfactant

With the rapid development of industry,the heavy metal pollution has become more and more severe all over the world.Because it cannot be biodegradable,and would cause serious damage to water and soil,there is extremely urgent requirement to develop effective technology to control heavy metal pollution.In recent years,utilizing green surfactant to treat heavy metal contaminants in water and soil is considered to be a highly efficient method,and foam fraction has been recognized as one of the potential approach to treat heavy metal pollution.It is worth to study that the microscopic mechanism in the removal of heavy metals by aqueous foams,as well as its application performance in treating industrial wastewater and contaminated soils.In this dissertation,the interactions between heavy metal ions and surfactants were quantitatively analyzed by quantum chemistry calculations.which would be very helpful to guide the determination of surfactant,and the mechanism of the enhancement of the foam properties in the presence of heavy metals was explored.The aqueous foam generated by solution of green surfactants was used to efficiently remove the lead and the zinc ions from simulated wastewater and battery factories wastewater.respectively.And silica particles were used to construct porous media,by which the performance of aqueous foam for removal of heavy metal ions trapped in the porous media was explored.This work provided theoretical support for the application of foam fractionation in the treatment of heavy metal contaminated water and soil.revealed the advantages and bright application prospects of aqueous foam in the heavy metal pollution management.This paper is mainly divided into three parts:The first part is about the design of foam system and the study of its foam properties.The interaction between surfactants and heavy metal ions was confirmed through quantum cheimistry calculation,and the green surfactant alkyl ethoxy carboxylate(C13EC)was determined as the foaming agent in the foam fractionation.The foam properties were characterized with or without heavy metal ions,including static stability,dynamic stability,viscoelasticity and microhardness of the foam liquid film,and so on.It was found that the performance of C13EC foam was more stable in the presence of heavy metal ions than that of the pure surfactant system.because of the dense adsorption of C13EC in gas-liquid interface through the interaction between C13EC and heavy metals,which makes the strength of the liquid film enhanced.The second part is about the exploration of the efficiency of aqueous foam being used in the treatment of lead and zinc ion polluted wastewater,including simulated wastewater,diluted battery factory wastewater and real battery factory wastewater.In this process,the effects of surfactant concentration,the type of heavy metal ions,the pH of the solution,and the dilution ratio of the wastewater on the removal efficiency of foam fractionation were investigated.It was found that lead and zinc ions in water could be removed effectively by foam fractionation,the removal efficiency could reach over 99%.In addition,the application scope of the original system was broadened through the synergistic combination of surfactants.The removal efficiency of lead and zinc ions in industrial wastewater from battery factories can also reach over 99%by the precipitation-foam combination method.Besides,the recycling of the collected lead ions after foam fractionation was achieved through formation of the lead sulfide nanoparticle using the foam films as template,which provided a feasible solution for the recycling of heavy metal ions.The third part mainly focused on the investigation of the performance of aqueous foams treating heavy metal ions trapped in solid porous media.The silica particles were used to construct pore media,and a foam generation device was designed to explore the performance of the foam in the coexistence of gas,liquid and solid.The efficiency and influencing factors of C13EC aqueous foam in the treatment of heavy metal pollution in solid porous media was investigated,including the size of solid particles,gas velocity,and packing height.It was found that the aqueous foam has a significant effect on the removal of heavy metals from solid porous media in suitable conditions.This method provides theoretical support for the treatment of heavy metal pollutions in soil by aqueous foams,and demonstrates the advantages and good application prospects of aqueous foams in the treatment of soil pollution.