Preparation Of Poly (Phenol-Amine) Composites And Adsorption Properties For Heavy Metal Ions

With the improvement of modern life,the problem of heavy metal ion pollution caused by the discharge of domestic and industrial wastewater is becoming more and more serious,directly or indirectly causing harm to human health.At present,the treatment of heavy metal ion wastewater is mainly adsorption method,and macromolecule composites have become the focus of research due to their large surface functional groups and strong adsorption capacity.Polydopamine?PDA?has excellent application prospects in the fields of energy,catalyst,biomedicine and surface modification due to its good adhesion and excellent physical and chemical properties.However,due to the high price of PDA,its application in other fields and mass production are greatly limited.Thus,by studying the autoxidation polymerization mechanism of PDA,a polymer containing a catechol group and a polyamine was designed instead of PDA.The material price is reduced while having similar physical and chemical properties.In this paper,two polyphenolamine composites were designed and their adsorption properties for Cr?VI?were studied.The specific research contents are as follows:?1?A novel poly?tannic acid-tetraethylenepentamine?-polyacrylamide-reduced graphene oxide?P?TA-TEPA?-PAM-RGO?ternary composite adsorbent was prepared by a simple one-step method.For the adsorption reduction of Cr?VI?.The morphology,chemical composition and thermal stability of the prepared composites were analyzed by scanning electron microscopy,infrared spectroscopy and thermogravimetric analysis.Adsorption studies have shown that there is a synergistic effect between the adsorbent component P?TA-TEPA?rich in phenolic hydroxyl groups and amine groups and the supporting components PAM and RGO.At 308 K,the maximum adsorption capacity is397.52 mg/g,which is higher than most graphene oxide and tannic acid based materials.The material not only exhibits good Cr?VI?removal ability,but also has a high reduction effect on Cr?VI?.The prepared composites have a highly competitive competitive adsorption capacity for other metal ions such as Cu²⁺,Zn²⁺,and Cd²⁺and anions such as NO^3-and SO₄^2-.After the adsorption-desorption cycle,the maximum adsorption capacity of the material can reach more than 300 mg/g,indicating that the adsorbent has good adsorption stability.?2?The new Pre-AM-P?TA-TEPA?and AM-P?TA-TEPA?absorbents were prepared by inexpensive herbs and the above phenolic amine polymers?polyphenolamines?,which were effectively removed by a simple method.Cr?VI?.The adsorbent showed a high efficiency Cr?VI?removal rate?555.56 mg/g?at pH 2 and 298K,which is higher than most biomass based adsorbents.Adsorption kinetics,isotherm andthermodynamicfittingindicatethattheadsorptionprocessfollows pseudo-secondary kinetics and Langmuir adsorption isotherms,demonstrating that the adsorption process is a chemosorption process of spontaneously endothermic monolayers.In addition,the prepared adsorbent showed good adsorption stability by adsorption-desorption cycle and ion influence.Rapid adsorption of the adsorbent at low concentrations can be achieved using a simple filtration device,and pure Cr₂O₃ can be collected by calcining the Cr?VI?-loaded adsorbent.This paper provides a new idea for polyphenolamine instead of PDA,not only provides a new method for heavy metal ion adsorbents,but also hopes to broaden other applications of polyphenolamine.