Innovative use of immobilized zinc oxide-impregnated activated carbon (ZnO@CB) for effective treatment of leachate: modeling and predictive assessment.

Abstract

This study examined the viability of column method utilizing the immobilized zinc oxide-loaded activated carbon obtained from corncob (ZnO@CB) to treat the landfill leachate. Instrumental techniques like BET, FTIR, SEM-EDX, and XRD were applied for the characterization of the adsorbents. The break through curve (BTC) was evaluated by altering the flow rate, bed height, and initial concentration of NH₃-N and COD. At 35 cm bed height with an initial level of 3264 mg-COD/L, the optimal adsorption capacity was observed to be 35.44 mg-COD/g. Meanwhile, the optimal NH₃-N adsorption capacity was 4.81 mg-NH₃-N/g at a flow @ 1 mL/min, with an initial concentration of 460 mg-NH₃-N/L, and a bed height of 35 cm. Both NH₃-N and COD adsorption exhibited a correlation coefficient higher than 0.98 as calculated by linear plots of bed depth service time (BDST) equations, indicating that the column structure model was appropriate. The results reveal that the performance of the adsorption process could be well predicted by artificial neural network (ANN) at 4, 7, and 1 neuron for input, middle, and output layers, with a mean absolute error of 0.0096 and 0.0093 for COD and NH₃-N reduction, respectively. In the RF model, higher values of R² (0.9876 for COD and 0.9874 for NH₃-N) indicate the model accuracy. The regenerated adsorbent achieved 54.2% and 54.1% removal of COD and NH₃-N and adsorbent usage was feasible for up to three cycles. Results of BDST, ANN, and RF models revealed that packed column with immobilized ZnO@CB adsorbent is an efficient method for treating landfill leachate, highlighting the potential of ZnO@CB for industrial applications.