چكيده لاتين
In this research, in order to adsorb the Methylene blue from water, the composite of metal-organic framework (ZIF-8) and carbon nanotubes functionalized with COOH functional group were used and the effect of different parameters were investigated in batch and continuous systems by coating on the slag in a fixed bed absorption column. ZIF-8 was synthesized by the solvothermal method. The synthesized adsorbent was characterized by FTIR, XRD, BET and FE-SEM analyses. The effect of factors such as pH in the range of 3,5,7 and 9, temperatures of 25,35 and 450C, isotherm and kinetic models of the adsorbent were investigated in the batch system. The concentration of the pollutant after the absorption process was measured by a spectrophotometer. The obtained results indicated that at pH= 7, due to the increase of electrostatic interaction between the adsorbent and the adsorbate, the amount of absorption increased. Moreover, the increase in temperature leads to an increase in the amount of absorption due to more molecular collisions. Experiments related to adsorption kinetics showed that the adsorbent reaches equilibrium after 60 minutes and the results were fitted with the pseudo-second-order model. The adsorption isotherm experiments showed the highest adsorption capacity 433.9 mg/g of ZIF-8/CNT-COOH, and the experimental data fitted by the Langmuir isotherm model, representing monolayer adsorption. In the continuous system in the packed column, the effect of pH 5,7 and 9, initial concentrations of methylene blue 25, 50 and 100 mg/L, the column bed height 1,2 and 0.5 cm and flow rate of 0.6, 0.8 and 1.2 ml/min were investigated and the breakthrough curves were drawn and absorption efficiency was calculated. The results showed that by reducing the flow rate and the concentration of the input pollutant, and also increasing the height of the absorption bed, the absorption efficiency increases. Also, pH = 7 has the best efficiency for the column. Moreover, the reusability of the adsorbent in the adsorption column was investigated. Results showed that the reusability of adsorbent reached 60% initial value after 3 times.
