Eco-friendly synthesis of self-existed magnesium oxide supported nanorod-like palygorskite for enhanced and simultaneous recovery of nutrients from simulated wastewater through adsorption and in-situ struvite formation

In this study, a novel adsorbent, MgO supported palygorskite, was synthesized by co-precipitation method and applied for simultaneous recovery of nutrients from wastewater. The synthesis parameters including MgO load ratio, calcination temperature, and calcination time were established and investigated. Several techniques, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Field-emission scanning electron microscope (FE-SEM) were employed to characterize the products at various synthesis conditions. A known concentration of simulated nutrients wastewater was used to optimize synthesis condition. The effects of adsorbent dosage, solution pH, and contact time on simultaneous recovery of nutrients were investigated under optimal condition (load ratio of 30%, calcination temperature of 400°C, and calcination time of 4h). 30%-MgO-PAL exhibited a strong removal capacities of ammonia nitrogen and phosphate in a wide pH range of 3–9, and the highest removal capacities of ammonia nitrogen and phosphate separately reached at 42.6mg/g and 69.8mg/g at pH of 9, dosage of 0.6g/L, and contact time of 3h. Both kinetics of ammonia nitrogen and phosphate followed the pseudo-second-order kinetic model. The mechanisms of nutrients recovery by MgO-PAL were extensively investigated.