Fabrication Of Macroscale Porous Polymer And Their Interaction With Metal Contaminants

The development of industrial technology is accompanied by serious metal pollution,among which toxic heavy metal pollutants will not only break the ecological balance,affect the environment,but also endanger the safety of human life,while rare precious metals will lead to waste of resources due to the lack of reasonable separation and recovery.In this thesis the research content of metal pollutants is divided into the adsorption of environmental pollution-type heavy metals and the recovery of resource recovery-type high-value precious metals for the convenience of research.The research objects of environmental pollution heavy metals are common heavy metals(lead,copper,cadmium and manganese,etc.)and arsenic pollution,and the research objects of resource recovery type high-value precious metals are gold and platinum.As a widely studied treatment technology,adsorption method has the advantages of simple operation,fast treatment rate,wide application range and cost saving.However,the current adsorbent has many problems,such as high production cost,low adsorption performance,not easy to recycle powder,secondary pollution and so on.Moreover,large-scale industrialization cannot be achieved in the practical application.Therefore,it is necessary to rationally design novel adsorbents with macroscale,three-dimensional porous channels,abundant active sites,high specific surface area,low cost,green environmental protection and scalability.It is expected to provide reliable scientific basis and innovative solutions for the treatment of toxic heavy metals and the recovery of precious metals by investigating the removal of toxic heavy metals and the separation and recovery performance of high-value precious metals,exploring the selective interaction mechanism between it and target metals,and evaluating the treatment efficiency in the actual pollution system.The main research contents of this thesis include:1.Cheap,green,efficient and renewable adsorbent is the key to solve the problem of heavy metal pollution for common environmental pollution heavy metals.Herein,poly amidoxime/bacterial cellulose(PAO/BC)composite aerogel with macroscale three-dimensional network hierarchical pore structure was designed and prepared by self-assembly and in situ oxime transformation crosslinking method to achieve efficient removal of heavy metals.Not only the hierarchical pore structure was obtained but the modification of amination also brought functional active sites(amidoxime functional groups)after complex cross-linking of long-chain polyamidoximes with biocompatible bacterial cellulose.The saturated adsorption capacities of PAO/BC aerogels for common heavy metal ions such as Pb2+,Cu2+,Zn2+,Mn2+,and Cd2+are 571.5 mg g-1,509.2 mg g-1,494 mg g-1,457.2 mg g-1,and 382.3 mg g-1,respectively.PAO/BC aerogels have excellent broad-spectrum adsorption properties,which is much higher than other adsorbents reported in the literature.PAO/BC aerogels achieve nearly 100%of target heavy metal ion removal in a short period of time(25 min)and multiple recycling due to their unique three-dimensional network and hierarchical porous structure,high mechanical properties and high stability.PAO/BC aerogel can continuously treat 19.3 L of actual wastewater under the drinking water effluent standard stipulated by the World Health Organization(WHO),indicating its efficient treatment capacity in the actual environment.2.For arsenic contaminants,an ultra-fast aqueous phase synthesis strategy was developed to successfully prepare macroscale Iron base organogel/bacterial cellulose(Fe-MOG/BC)composites at room temperature,which are characterized by ultra-light,hydrophilic,hierarchical porous structure and high mechanical properties in this chapter.Both the adsorption performance(495 mg g-1)and the adsorption rate of arsenate were improved due to the abundant functional groups and hierarchical porous structure facilitating the mass transfer of arsenate.In addition,Fe-MOG/BC has ultra-high As(Ⅴ)wastewater treatment capacity in actual water treatment due to its high selectivity and excellent recycling of As(Ⅴ).It shows that the material has a broad application prospect in the actual arsenic-containing wastewater treatment because of its simple preparation conditions,low production cost,mass production and other advantages.3.The adsorption and recovery of high-value precious metals in e-waste is also particularly important except for heavy metals of environmental pollution.Herein,a water-phase self-assembly strategy with rapid synthesis and easy scale was designed to prepare three-dimensional hierarchical porous polyimide dioxime(PIDO)membrane,and its performance for the separation and recovery of gold from e-waste was investigated.The results showed that the saturated adsorption capacity of Au(Ⅲ)on PIDO membrane reached the highest record of 9250 mg g-1.PIDO membrane can achieve adsorption equilibrium in 8 min when the concentration of Au(Ⅲ)is 100 mg L-1,showing ultra-high adsorption recovery performance.The PIDO membrane can efficiently and selectively enrich Au(Ⅲ)and reduce it to Au(0)in the actual CPU leaching solution,and the purity of gold foil after pyrolysis can reach 23.6 K.PIDO membrane shows a great industrial application prospect in the field of precious metals recovery in electronic waste due to its simple preparation,low cost,mass production.4.In addition to the precious metal gold,precious metal platinum(Pt)is widely used in automobile and jewelry industry,indicating its important economic value.On the basis of the above work,a composite polymer coating pyrolysis method was proposed to prepare hierarchical porous PIDO/PEI films in one step.The adsorption capacity of PIDO/PEI to Pt is up to 4185 mg g-1 through the reduction trap mechanism,99%of Pt can be recovered within 9 min and exhibit ultra-high selectivity for Pt in practical noble metal catalysts.PIDO/PEI composite membrane is expected to play an important role in the recovery of precious metals in industrial catalysts due to its simple preparation,low production cost,high adsorption performance,mass production,strong structural stability and recyclable use.