ABSTRACT
In water, synthetic dyes undergo chemical degradation to form highly toxic and carcinogenic products. The first publication on the adsorption of organic dyes from solution on a metal-organic framework (MOF) was published in 2004 in Nature. Adsorption was performed on MOF-177 from saturated solutions of the dyes in dichloromethane (CH2Cl2). The adsorbed amount of the dye decreased when the pH of the dye solution was increased. This observation suggests that ionic interactions might take place between the dye molecule and the structural unit in the MOF. The adsorption of uranine dye on MIL-101(Cr) (F) was found to be a spontaneous endothermic process, as determined by the van't Hoff equation. MOFs, including mesoporous MOFs, contain two main structural units: positively charged metal cations and, usually, negatively charged organic linker units. The majority of organic dyes can be classified into two major groups: cationic dyes and anionic dyes.
