Biomass-based perovskite/graphene oxide composite for the removal of organic pollutants from wastewater

Water pollution is a critical issue that affects both human health and the environment. Biomass-based LaFeO₃ is prepared by the microwave-assisted method using rice straw as a cellulose source. Then LaFeO₃/graphene oxide (GO) composite is prepared by ultrasonication to facilitate the perovskite-GO binding. Raman and FTIR spectra of the prepared composite identify the presence of the perovskite, biochar, cellulose and GO oxide phases and proves the surface functional groups interactions. Transmission electron microscope image shows that the GO sheets are homogeneous covered with the perovskite nanoparticles. The adsorption performance of the LaFeO₃/GO composite for the removal of methylene blue (MB) and congo red (CR) dyes from aqueous solution is optimized. Adsorption follows pseudo 2nd order kinetic model and Freundlich isotherm, with maximum adsorption capacities of 319.5 and 416.7 mg/g for MB and CR, respectively. These values are higher than those reported for magnetic GO composites, indicating the excellent adsorption ability of the proposed perovskite/GO composite. A thermodynamic study shows that the adsorption of MB is exothermic, while it is endothermic for CR and combines physisorption and chemisorption characteristics for both dyes. The proposed adsorbent shows a good performance in the presence of NaCl interferent, with the possibility of regeneration and efficient successive reuse.