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