Elimination of Cu2+ ions from aqueous solutions utilizing a walnut shell biochar/CoFe2O4/ZIF-7 nanocomposite adsorbent

Abstract

In the present study, a pyrolysis method used a walnut shell as a natural source to synthesize biochar (WSB). WSB was doped with CoFe2O4 and ZIF-7 nanoparticles to remove copper ions from the water media. BET surface area for WSB, WSB/CoFe2O4, and WSB/CoFe2O4/ZIF-7 was computed to be 123.47, 146, and 256.67 m2/g showing the effectiveness of CoFe2O4 and ZIF-7 nanoparticles in enchantment of WSB surface area. The maximum removal performance for WSB/CoFe2O4/ZIF-7 adsorbent was obtained at 99.05 % under optimum conditions of pH 6, adsorbent dosage 1 g/L, initial Cu2+ ions concentration 15 mg/L, sorption time 80 min, and temperature 25 ◦C. Isotherm study findings demonstrated an excellent fitting with the Langmuir model having a monolayer adsorption capacity value of 31.65, 40.34, and 48.39 mg/g for WSB, WSB/CoFe2O4, and WSB/CoFe2O4/ZIF-7, respectively. Thermodynamic outcomes illustrated that the sorption of Cu2+ ions onto prepared adsorbents occurs spontaneously and exothermically. The reusability study showed that WSB/CoFe2O4/ZIF-7 could be used in five successive cycles with a high removal performance (>90 %). Finally, it could be inferred that WSB/CoFe2O4/ZIF-7 is a promising adsorbent with high potential in wastewater treatment applications.