Fabrication of Zinc MOFs Using Room Temperature and Hydrothermal Approaches for Removal of Anionic Diazo Dye from Wastewater

Abstract The production of dyes with strong, sustainable colours produces a large amount of dye discharge in water, which is unfavourable for human and biological life. In this report, Zn-MOFs were prepared using room temperature and hydrothermal approaches for efficient removal of anionic diazo dye from wastewater. Our results confirm the significant crystalline and uniform structure morphology of the designed room temperature Zn-MOFs (RZM) and hydrothermal Zn-MOFs (HZM) adsorbents. To evaluate the ability of RZM and HZM adsorbents to adsorb Congo red (CR) from an aqueous solution, numerous adsorption parameters have been studied, such as adsorbent dose, temperature, pH, contact time, and initial concentration. RZM and HZM adsorbents have been employed to assess the kinetic, thermodynamic, and isotherm models for the adsorption of CR dye under optimum removal conditions. The RZM and HZM adsorbents exhibited fast adsorption rates towards CR at pH 7, and maximal adsorption capacity according to the Langmuir model reached 200 mg g –1 much higher value than that of other adsorbents that have been reported. The adsorption mechanisms of RZM and HZM adsorbents are based on π–π stacking and electrostatic interactions with multiple reusability. Our Zn-MOFs are synthesized using an easy, low-cost process enabling the use of affordable and easily accessible precursors. This renders the procedure cost feasible for extensive implementations. Zn-MOFs show excellent stability, with constant adsorption capabilities observed in several trials. Thorough evaluation in a range of environmental conditions has validated the repeatability of our results, assuring consistent performance. The RZM and HZM adsorbents provide an easy-to-use and efficient method for water purification as well as controlling industrial wastewater.