CO₂-Responsive Microgels With Recyclable Adsorption For Wasterwate

Nowadays,water pollutant resulting from discharge of industrial effluents has become a global concern.For example,huge amount wastewaters were generated by from paper,leather,textile,plastics,cosmetic and electroplating industry.The main pollutants in wastewater include organic dyes?especially anion dyes?and heavy metal ions,such as Cr?VI?and As?V?.It was revealed that the presence of organic dyes and heavy metal ions lead to numerous physical and mental diseases,such as cancer,tumour,anemia,and psychosis Therefore,the removal of these dyes and heavy metal ions from wastewater before discharge is an essential issue in view of environmental protection.However,most of the adsorbents mentioned above more or less have some shortcomings,such as low adsorption capacity,separation inconvenience,poor selectivity or difficult to regenerate and recycle.Therefore,it is still desirable to search for adsorbent with excellent adsorption capacity,facile separation and eco-friendly regeneration.The main works of this paper are as follows:?1?A series of giant microgels were synthesized through one-step inverse-suspension polymerization of hydrophilic PAM and hydrophobic DEA,it can be realized under CO₂ control The microgels with high DEA content can undergo switchable collapse-expansion transition upon alternative stimuli of CO₂ and N₂.Based on the CO₂-induced protonation-deprotonation and collapse-expansion transition,the microgels exhibited on-off,selective,and recyclable adsorption for anionic dye,the microgels have a high maximum adsorption capacity of 821 mg g^-1 and the adsorption isotherms and kinetics obeyed Langmuir isotherm and the pseudo-second-order kinetics models,respectively.Moreover,the microgels were fabricated as a column of a wastewater treatment prototype with a continuous flowing stream manner,and the dye was removed and recovered by alternative bubbling CO₂ and flushing with aqueous alkali?p H 12?.?2?A series of degradable CO₂-responsive microgels were designed and prepared.The as-prepared microgels underwent switchable collapse-expansion and protonation-deprotonation transition upon alternative stimulus of CO₂and N₂.Based on these smart properties,the microgels exhibited an on-off,selective,and recyclable adsorption for anionic dyes and heavy metal ions.The kinetics and isothermal adsorption data were well-fitted by pseudo-second-order kinetic model and Langmuir model,and the maximum adsorption capacity are as high as1537 mg g^-1 and 423 mg g^-1 for MY and Cr?VI?,respectively.The competitive adsorption revealed that dyes were adsorbed preferentially compared to heavy metal irons in metal ion-dye binary systems.Besides,they could be separated from the water by a simple filtration process,and the adsorbates could be readily desorbed by flushing with alkaline solution?p H12?.Macrogels regenerated with CO₂ stimulus exhibited high adsorption ability after ten consecutive recycling trials,and could be applied to fixed-bed adsorption system.Moreover,macrogels could be degrade after treating with DTT.Thus,this type of degradable microgels have potential applications in the treatment of complex industrial wastewater streams and avoid the secondary pollution caused by the accumulation of nondegradable adsorbents.?3?Rigid monomers were polymerized by emulsion polymerization and functionalized by tertiary amines.The microgel can be used for the adsorption of anion dyes,and the adsorption capacity of MY is up to 2814 mg g^-1.After the alkali solution treatment of p H 12,the microgel can be completely desorbed.After 15 sorbtion-desorption cycles,the microgel can still maintain the adsorption efficiency of 85%.In addition,an artificial intelligence?AI?model for dye concentration recognition is designed.