Green Synthesis of Iron Nanoparticles-Modified Biochar For Efficient Adsorption of Cd(II) From Aqueous Solution

In recent years, the technology of producing zero-valent iron nanoparticles from extracts of natural products has attracted more and more attention due to its advantages of green and environmental protection. In this study, green iron nanoparticles-modified biochar materials (BC-FeNPs) were prepared using a simple method of biochar, FeSO₄ and banana peel extract. The characterization results showed that Fe²⁺ was reduced to Fe⁰ by banana peel extract, which proved the successful synthesis of BC-FeNPs. Biochar loaded with iron nanoparticles (BC-FeNPs) is more conducive to the removal of Cd(II). The effect of varying the dosage of BC-FeNPs and the initial pH value on the removal of Cd(II) was found to be significant. The maximum adsorption of Cd(II) by BC-FeNPs was 51.6 mg/g when the BC-FeNPs dosage was 0.05 g and the temperature was 323.15 K. The adsorption process of Cd(II) by BC-FeNPs can be accurately described by the Langmuir isotherm model and pseudo-second-order model. The adsorption mechanism of Cd(II) on BC-FeNPs mainly involves complexation and precipitation. This study demonstrated that BC-FeNPs prepared from FeSO_4, banana peel extract and biochar with a facile and non-toxic approach, can be used as a new green material for the treatment of Cd(II) polluted wastewater.