Publications

The surge in nano/microplastics (NPs/MPs) through myriad daily products released in the aqueous environment highlights the importance of the urgent development of mitigation techniques. The study has assessed the performance of iron-modified biochar pyrolysed at two different temperatures, i.e., 550°C (FB-550) and 850°C (FB-850), with magnetic extractability for the easy and prompt removal of NPs of varying size and surface functionality. NP1 (1000 nm, carboxyl), NP2 (1000 nm, amine), and NP3 (30 nm, carboxyl) were subjected to batch experiments with the composites. Rapid elimination of all the NPs (<10 min) from the water system using robust magnetic composites was observed. A higher order of reaction kinetics (n > 2) was found through the general order model, and a good fit for the Sips isotherm suggests ultrafast NPs removal and the heterogeneous nature of the composite surface. Maximum removal capacities for NP1 (225.11 mg/g) and NP3 (206.46 mg/g) were obtained using FB-850, whereas FB-550 showed higher removal of NP2 (290.20 mg/g). The influence of solution pH on the sorption of NPs was limited with significant variation in zeta potential, suggesting the probability of surface complexation of NPs. The spectroscopic analysis of the reaction mixture showed the disappearance of the COO− peak, the generation of FeOOH stretching, and the shift in the Fe-O band, confirming the involvement of surface complexation in the sorption process. Minimal impact of environmental parameters, reaction spontaneity, and efficient removal of NPs in complex aqueous matrices justifies the composites’ environmental applicability. No-iron release and excellent reusability of the utilised adsorbents support the large-scale applicability of the composites.