Study On Adsorption And Anti-interference Properties Ofpalladium And Lead Imprinted Polymers Modified By Broomlike Polymer Brushes

Recently,heavy metal pollution in water resource has brought serious influence on human production and life.The removal and resource recycling of heavy metal lead and noble metal palladium have gained widespread attention.Imprinted polymers can selectively adsorb specific heavy metals then remove and recycle them from wastewater.In real complex wastewater,the imprinted holes will be blocked easily by solid particles and floccule.To remedy the defect,we designed and synthesized palladium and lead ion-imprinted polymers with broomlike polymer brushes,and studied their performance by removing palladium and lead ions in complex water.1.The palladium ion-imprinted/non-imprinted polymers grafted with different polymerization degree of hydrophilic polymer brushes?PHEMA?were synthesized by reversibleaddition-fragmentationchaintransferpolymerization?RAFTPP?precipitation polymerization.The palladium ion-imprinted/non-imprinted materials?grafted-IIPs/NIPs?with five polymerization degrees of broom-like hydrophilic polymerbrushes?IIP-1/NIP-1,IIP-2/NIP-2,IIP-3/NIP-3,IIP-4/NIP-4,and IIP-5/NIP-5?were confirmed to be synthesized successfully by gel permeation chromatography?GPC?.The isothermal adsorption and kinetic assays showed that the data was consistent with Freundlich model and Pseudo-second-order model respectively,which indicated multi-layer chemical adsorption behavior of the materials.The analysis of XPS spectrum and the concentration change of Cl ions in fixed bed experiments proved that palladium existed as cation and was adsorbed on the S site of S=C in 3-allyl thiourea.In real wastewater,the adsorption capacity of imprinted polymer?IIP-3?with broom-like hydrophilic polymer brush in Ningbo wastewater was as high as 96.2%of that in pure water.2.By comparing isothermal adsorption performance and adsorption kinetics behavior of grafted-IIPs/NIPs with different polymerization degrees,it was carried that the broom-like polymer brushes grafted on the surface did not change the imprinted effect and only led to reduction of amount of the effective holes.The polymerization degree of the grafted broom-like hydrophilic polymer brush was greater,the rate constant K₂ was higher with maximum adsorption rate constant at IIP-4.In simulated wastewater with three different sizes of solid particles,the interference intensity??Q?order was 40 nm SiO₂>100 nm Si O₂>4 nm SiO₂ at the polymerization degree of 43.28?IIP-1?,49.35?IIP-2?and 72.90?IIP-3?,while the interference intensity??Q?order was 4 nm SiO₂>100 nm Si O₂>40 nm SiO₂ at the polymerization degree of 121.76?IIP-4?and 293.57?IIP-5?.The optimum anti-interference strength was at the polymerization degree of 72.90?IIP-3?in the simulated floccule wastewater.Comparing the three different methods of ion imprinting surface grafting,we can see that ion imprinting grafted with broom-like two component?hydrophilic and rigid?polymer brushes on the surface can achieve the maximum anti-interference strength in the wastewater containing solid particles and floccule.3.Pb?II?imprinted polymer grafted with broomlike two components?PHEMA and PS?polymer brushes on the surface was synthesized by RAFT.Isotherm adsorption and kinetic assays by ion imprinted before and after grafting?RAFT-IIP/NIP and grafted-IIP/NIP?conformed to Langmuir model?R²>0.98?and Pseudo-second-order model?R²>0.91?respectively,proving that the adsorption of Pb?II?was monolayer chemical adsorption.The selective adsorption experiments showed that the relative selectivity coefficient?of all the materials was higher than1.2.The Pb?II?ion-imprinted polymers with broom-like polymer brushes showed the best anti-jamming performance in the simulated wastewater containing 400 nm solid particles,and the order of anti-jamming intensity was PAC>PAM>CMC in the wastewater containing flocculent pollutant.The analysis of XPS and SEM-EDS indicated that broo-mlike bi-component brushes played an indispensable role for anti-interference ability by Al-O coordination bond,hydrogen bond,or hydrophobic interactions.