Efficient and selective adsorption of dye in aqueous environment employing a functional Zn(Ⅱ)-based metal organic framework

Adsorption is considered as one of the eco-friendly methods to effectively remove pollutants from water environment. 1 , namely ([Zn 3 (dpcp) 2 (1,4′-bmib) 2 ] n , dpcp ​= ​3-(3,5-dicarboxylphenoxy)-5-carboxylpyridine and 1,4′-bmib = 1,4-bis(2-methylimidazol-1-yl) butane), was synthesized under simple solvothermal method and characterized by XRD , PXRD , TGA , FTIR, BET and Zeta potential . The influence of temperature and pH of the solution and the dye initial concentration on the adsorption process of 1 was investigated using Congo red (CR) as the adsorption object. Pseudo second-order kinetics and Langmuir isotherms more accurately described the adsorption process of 1 . The maximum adsorption capacity measured in the adsorption experiment was about 262.2 ​mg ​g -1 . Thermodynamic studies showed that the entire adsorption process was spontaneous. In addition, 1 released the CR dye by a simple organic solvent (ethanol solution of NaOH) and exhibited stable and high adsorption performance over 5 cycles. The subtle hydrogen bond between 1 and the dye promotes its selective adsorption of CR.