Efficiency Recycling and Utilization of Phosphate from Wastewater Using LDHs-Modified Biochar

Abstract

The excessive application of phosphate fertilizers easily causes water eutrophication. Phosphorus recovery by adsorption is regarded as an effective and simple intervention to control water bodies’ eutrophication. In this work, a series of new adsorbents, layered double hydroxides (LDHs)-modified biochar (BC) with different molar ratios of Mg2+ and Fe3+, were synthesized based on waste jute stalk and used for recycling phosphate from wastewater. The prepared LDHs-BC4 (the molar ratio of Mg/Fe is 4:1) has significantly high adsorption performance, and the recovery rate of phosphate is about 10 times higher than that of the pristine jute stalk BC. The maximum adsorption capacity of LDHs-BC4 for phosphate was 10.64 mg-P/g. The main mechanism of phosphate adsorption mainly includes electrostatic attraction, ion exchange, ligand exchange, and intragranular diffusion. Moreover, the phosphate-adsorbed LDHs-BC4 could promote mung bean growth, which indicated the recovery phosphate from wastewater could be used as a fertilizer.

The Phosphorus Adsorption and Recovery of Mg/Fe-LDHs Mulberry Rod Biochar Composite

“…Figure 1 shows the nitrogen adsorption-desorption isotherms and pore size distribution of MFBCs and MBC. According to the Brunauer-Emmet-Teller theory, MFBCs exhibit type IV isotherms in the relative pressure range of 0.1-0.9, indicating that MFBCs are mesoporous [13]. The results showed that the adsorption capacity of MFBCs and MBC gradually increased with the increase in relative pressure, and the adsorption/desorption curve of the MBC in the low-pressure region (0.15-0.40 relative pressure (P/P 0 )) showed a significant increase, indicating that MBC contains more abundant mesoporous and microporous structures than MFBCs [14].…”