Investigating the efficiency of fixed bed column containing Fe3O4-ZIF8@eggshell membrane matrix in concurrent adsorption of arsenic and nitrate from water

In the current work, the behavior of a fixed bed column (FBC) containing an innovative nanocomposite, Fe₃O₄-ZIF8@eggshell membrane matrix (F-ZIF8@EMM), was investigated in the concurrent elimination of arsenic and nitrate, as two potentially harmful elements (PHEs) in drinking water. Flow rate (6-10 mL/min), column height (10-20 cm), reaction time (30-180 min), pH (5-10), primary content of arsenic (25-100 µg/L), primary content of nitrate (100-200 mg/L), and nanocomposite dose (0.25-1 mg/L) were examined as different operational effects on the simultaneous uptake of arsenic and nitrate from actual water via the as-fabricated novel nanocomposite through various experiments. Characteristics of F-ZIF8@EMM were analyzed via X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and Brunauer-Emmett-Teller (BET) analyses. The consequences illustrated that the optimal parameters were: flow rate (6 mL/min), primary content of arsenic (100 µg/L), primary content of nitrate (150 mg/L), bed height (20 cm), and pH (7). The simultaneous elimination efficiency of nitrate and arsenic was 90 % under optimal conditions. The FBC fed with water containing arsenic and high nitrate could operate for 440 min with a q_m of 226 mg/g. After fitting, different models were identified, with the concurrent uptake of nitrate and arsenic was the optimum fit with the Thomas model (R² = 0.9998). Analysis of the cost of the process displayed that it should be estimated to be approximately 0.005$ per liter of safe drinking water. This study demonstrates the stability and high efficiency of the newly structured adsorbent after 10 consecutive adsorption cycles. It also validates the significant capacity of the as-made composite F-ZIF8@EMM in the concurrent uptake of nitrate and arsenic. Consequently, the application of FBC technology has shown promise in enhancing this process.