Tenfold increase in adsorption capacity of HKUST-1 toward Congo red by producing defective MOF under controlled thermal treatment

The effort to achieve an optimal toxic dye removal adsorbent from wastewater has led to the design of new structures or the modification of existing materials. A practical method to improve the efficacy of current effective adsorbents is to create controlled structural defects to increase effective adsorption sites. Here, Quasi-HKUST, which is prepared by a thermally controlled method from HKUST-1 and has structural defects and more free open metal sites, was used as an absorbent of concord toxic dye. The findings demonstrate that Quasi-HKUST was able to achieve an adsorption capacity of 715 mg.g−1, which is about tenfold more than the original structure. The experimental results demonstrated an exothermic spontaneous mechanism for the dye adsorption process that fit the pseudo-second-order and Langmuir isotherm models. Converting MOFs to quasi-MOFs, especially in materials that are desirable adsorbents for removing pollutants, can be a turning point in improving the absorption capacity and achieving dream absorbents.