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.