Comparative Evaluation of Metal Organic Frameworks for Textile Wastewater Treatment

Abstract

Hazardous contaminants present in industrial wastewater are harmful for human health and environment. These carcinogenic materials cause various environmental health hazards. Dyes are the hazardous contaminants that are discharged from textile industries in liquid effluent. Dyes potentially cause skin damage and problems with the respiratory system and may increase the risk of cancer. To remove dyes various techniques such as oxidation, filtration, UV degradation, adsorption, solvent extraction are used. Adsorption is considered as a superior technique because of its numerous advantages such as low cost and environmentally friendly; operation at low temperature. However, low adsorption capacity of the adsorbents is a big problem to be addressed. Metal Organic Frameworks (MOFs) are the promising adsorbents which are explored to overcome this drawback because of their microporous structure which increases the capacity and efficiency of adsorption. MOFs have high gas sorption, excellent catalytic properties and high thermal and mechanical stability. Only few studies reported their capability to remove dyes from textile wastewater. Moreover, comparative evaluation of different MOFs for the elimination of dyes contaminants during textile wastewater treatment is required. This study aims to assess the performance of MOF-5 and MOF-74 on to the elimination of Congo red (CR) dye from aqueous solutions. Effect of different adsorption parameters such as; interaction time; temperature; dosage of adsorbent; concentration of dye and pH is on the adsorption capacity of MOFs and their dye removal efficiency was investigated. Results showed that the maximum adsorption capacity of MOF-5 and MOF-74 was 120 and 106mg/g respectively. The results were used to predict the applicability of kinetic models, isothermal models and thermodynamics models. Results showed that both MOF-5 and MOf-74 have followed pseudo 2nd order kinetics. In case of isothermal study, they have followed Langmuir models. At different temperatures, the adsorption efficiency suggested that the mechanism was a spontaneous and endothermic reaction of adsorption. MOF-5 is the more favorable adsorbent compared with the MOF-74 because of its high adsorption x capacity. The comparative evaluation of results with the previous published studies showed that MOF-5 and MOF-74 would be the potential MOFs for large scale removal of CR dye from wastewaters