Synthesis Of Sodium Polyacrylate Intercalated Hydrotalcite Composites And Study On The Adsorption Properties Towards Dyes And Heavy Metals

Dye wastewater with heavy metal wastewater treatment has been a hot topic in the scientific research,adsorption method due to its characteristics of simple operation and low cost has been widely attention,hydrotalcite compounds for anionic layered nanometer materials,with interlayer anionic exchangeability,in such aspects as fire protection,environment,health has a potential application value.In this study,sodium polyacrylate(PAAS)with different molecular weights was used to modify hydrotalcite,and a series of polyacrylate intercalated hydrotalcite composites(PAAS/LDHS)with different molecular weights were prepared,which were applied to the removal of methylene blue(MB),Pb²⁺and Hg²⁺in aqueous solution.The PAAS/LDHS was characterized by XRD,FTIR,SEM,Zeta potential,BET and contact Angle.he adsorption isotherm,adsorption kinetics,adsorption activation energy and adsorption thermodynamics in the adsorption process of MB,Pb²⁺and Hg²⁺by PAAS/LDHS were investigated.The effects of the amount of adsorbent and the initial pH of solution on the adsorption process were investigated.The competitive adsorption of MB,Pb²⁺ and Hg²⁺ on PAAS/LDHS and the effects of the ionic strength of Na+and Ca²⁺ on the adsorption process of MB,Pb²⁺ and Hg²⁺ on PAAS/LDHS were studied.The recycling performance of PAAS/LDHS and the adsorption mechanism were discussed.The specific experimental results are as follows:PAAS has successfully entered the interlayer of hydrotalcite,and the modified hydrotalcite still maintains the unique layered structure of hydrotalcite;Langmuir type adsorption isotherm and quasi-second-order kinetics can better describe the adsorption behavior of MB,Pb²⁺and Hg²⁺on PAAS/LDHS.The maximum adsorption capacity of MB,Pb²⁺and Hg²⁺on PAAS/LDHS is 242.8 mg/g,429.1 mg/g and 218.1 mg/g,respectively;The increase of initial pH could promote the adsorption of MB,Pb²⁺and Hg²⁺,With the increase of the amount of adsorbents,the removal rate of the three increased,but the equilibrium adsorption capacity decreased;The adsorption activation energies of PAAS/LDHS for MB,Pb²⁺ and Hg²⁺were 20.8 k J/mol?29.5k J/mol and 21.3k J/mol,respectively.The adsorption processes of PAAS/LDHS for MB,Pb²⁺and Hg²⁺were spontaneous endothermic processes;The competitive adsorption capacity of MB,Pb²⁺and Hg²⁺was Pb²⁺>Hg²⁺>MB;The effect of the ionic strength of Na⁺on the adsorption process is less than that of the ionic strength of Ca²⁺;PAAS/LDHs still maintained excellent adsorption performance for three kinds of cationic pollutants after four cycles;Through the influence of infrared,XPS and initial pH of solution before and after adsorption on the adsorption process,it is concluded that the adsorption of PAAS/LDHS on MB is mainly the effect of electrostatic attraction,while the adsorption of Pb²⁺and Hg²⁺is the result of the combined action of electrostatic attraction and carboxyl chelation.