Cadmium ion removal from aqueous media using banana peel biochar/FeO/ZIF-67.

In the present study, banana peel waste was used as a suitable source for biochar production. The banana peel biochar (BPB) was modified using FeO magnetic and ZIF-67 nanoparticles. The modification of the BPB surface (4.70 m/g) with FeO and FeO/ZIF-67 significantly increased the specific surface of the nanocomposites (BPB/FeO: 78.83 m/g, and BPB/FeO/ZIF-67: 1212.40 m/g). The effect of pH, temperature, contact time, adsorbent dose, and concentration of Cd on the efficiency of the Cd adsorption was explored. Maximum adsorption efficiencies for BPB (97.76%), BPB/FeO (97.52%), and BPB/FeO/ZIF-67 (99.14%) were obtained at pH 6, Cd concentration of 10 mg/L, times of 80 min, 50 min, and 40 min, and adsorbent doses of 2 g/L, 1.5 g/L, and 1 g/L, respectively. Thermodynamic measurements indicated that the process is spontaneous and exothermic. The maximum capacity of Cd adsorption using BPB, BPB/FeO, and BPB/FeO/ZIF-67 were obtained 20.63 mg/g, 30.33 mg/g, and 50.78 mg/g, respectively. The Cd adsorption using magnetic nanocomposites followed the pseudo-first-order kinetic model. The results showed that studied adsorbents especially BPB/FeO/ZIF-67 have a good ability to adsorb-desorb Cd and clean an effluent containing pollutants.