Saltbush biomass and biochar loaded magnesium oxide nanoparticles for sustainable phosphate removal and recovery from poultry wastewater

Abstract

Biochar is a cost-effective, porous material with a high carbon content, making it an excellent candidate for adsorption applications. However, its adsorption performance can be further enhanced by incorporating metal oxide nanoparticles. Magnesium oxide (MgO) nanoparticles possess a highly porous structure, providing numerous active sites for adsorption. When loaded into biochar, they disperse more effectively, reducing the risk of particle clumping and enhancing the overall adsorption performance. In this work, a widely distributed Mediterranean saltbush plant, Atriplex hamilus, biomass has been used for the first time to fabricate three composites; MgO@biochar-A(BCC-1), MgO@biochar-B(BCC-2) and MgO@biomass. A one-step,cost-effective pyrolysis process was adopted for the PO43− removal from synthetic- and poultry wastewater. The as prepared composites were verified using different characterization techniques. Transmission electron microscopy(TEM) and Scanning electron microscopy(SEM) analysis revealed the formation of rod, rhomboid and spherical shapes of BCC-1, BCC-2 and MgO@biomass. X-Ray Diffraction(XRD) results confirmed the crystalline nature of MgO@biochar. Thus, emphasize that MgO-NPs were successfully loaded on biochar via surface complexation and ion exchange mechanisms. Batch adsorption experiments demonstrated maximum PO43− uptake capacities;qm of 129.80, 74.79, and 18.40 mg g⁻1 for BCC-1, BCC-2, and MgO@biomass, respectively, at a dose of 0.2 g L⁻1 and time of 60 min. Moreover, the removal efficiency of PO43− reached a maximum of 84% using BCC-1 from real poultry wastewater. The reusability of MgO@biochar proved their effectiveness in PO43− removal up to 4 consecutive cycles. The kinetic, isothermal models and contour plots for interactive factor effects were provided. Based on data collected, BCC-1 acquired the maximum adsorption capacity. Accordingly, this nanocomposite could be considered as a good candidate for PO43− removal and recovery from wastewater.