Nano‐water treatment residuals: Enhancing phosphorus kinetics and optimization in saline soils

Abstract

AbstractPhosphorus (P) use in agriculture has witnessed a global increase, leading to significant environmental problems. Nevertheless, the understanding of P kinetics in saline soils amended with nano‐water treatment residuals (nWTR) remains limited. This study aimed to (1) Investigate the impact of different nWTR addition rates (0%, 0.10%, 0.20%, and 0.50%) on the adsorption‐desorption kinetics of P applied to five soils with different salinity levels (1.47–58.50 dS m−1) using batch adsorption experiments. (2) Using different optimization models via Fit Quadratic Model and principal component analysis to predict the optimal utilization of nWTR. The X‐ray diffraction and Fourier transform infrared patterns proposed that the main mechanisms controlling the process are ligand exchange and precipitation. The results revealed that the adsorption level of P in amended soils was rapid, then decreased gradually until reaching equilibrium after 24 h/25°C. The kinetics data were well described by a pseudo‐second‐order model, suggesting a chemisorption‐dependent adsorption process. Increasing soil salinity and nWTR addition led to decline the phosphorus desorption. The application of 0.5% nWTR decreased P‐desorption from 33.95% to 16.22% in the non‐saline soil and from 18.43% to 10.63% in the highly saline soil. principal component analysis distinguished a positive association between P‐adsorbed and nWTR. The optimization models predicted that applying 0.5% nWTR for 965 min maximizes the P‐adsorption rate, reaching 1041 mg Kg−1 in highly saline‐soils. Therefore, nWTR can serve as a cost‐effective and efficient absorbent for mitigating P mobility and reducing its transport in saline soils.