iron terephthalate metal–organic framework (mof-235) as an efficient adsorbent for removal of toluidine blue dye from aqueous solution using box–behnken design as multivariate optimization approach

In this work, iron terephthalate metal–organic framework (mof-235) as an efficient adsorbent has been synthesized and employed for toluidine blue (tb) removal in a batch system. the adsorbent was characterized by fourier-transform infrared, scanning electron microscopy, and powder x-ray diffraction. the effects of operational parameters including ph, initial dye concentration (cd), and the adsorbent dosage (m) on the tb adsorption were studied. a box–behnken design (bbd) was applied to identify the effective factors on the removal efficiency (r%) of toluidine blue. the optimal conditions were as follows: m = 0.02 g, cd = 100 mg l−1, and ph = 4.5. the equilibrium adsorption isotherms and kinetic models were also studied. since the results of the langmuir model fitted well to all the experimental data (r2 = 0.9972), the maximum monolayer adsorption of tb was 180.4 mg g−1. furthermore, the pseudo-second-order model describes well the process. iron terephthalate metal–organic framework (mof-235) shows a great potential to remove tb from aqueous solution.