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Terracotta as a natural adsorbent for nutrient recovery from agricultural effluents
Proceedings of the 2022 Mississippi Water Resources Conference
Year: 2022 Authors: Sauers J., Gude V.G.
Nutrients released through agricultural effluents cause eutrophication of receiving water bodies. In this research, the adsorption capacity of terracotta clay was evaluated due to its promising benefits in nutrient and water retention. The efficacy of terracotta clay to act as a solid-phase sorbent was studied for two main nutrients, nitrogen and phosphorus. The phosphate solutions were prepared at three difference concentrations (20 mg/L, 35 mg/L, and 50 mg/L). The phosphate solutions were mixed with the terracotta clay in a mixer at 8 different time intervals of 0, 5, 10, 20, 40, 60, 300, and 1440 minutes at 25℃ and 50℃. Samples were collected at the aforementioned predetermined intervals. The ammonium nitrogen solution was prepared in a similar manner to the phosphate solution, but only tested at a concentration of 50 mg/L at 25℃.
The kinetics of nutrient absorbance by the terracotta clay was studied by fitting the Pseudo-first-order, pseudo-second-order models. The adsorption capacity for the phosphate was similar at both temperatures for ammonium. The terracotta clay absorbed the phosphate for the first 20 minutes followed by desorption at the 40-minute interval. The phosphate absorbance capacity was better at 25℃ than 50℃. The pseudo-second order model fitted the adsorption kinetic data with high correlations. The R2 values for the three concentrations range from 0.9765 to 0.9977 at 25℃, while the confidence intervals for the three concentrations at 50℃ ranged from 0.9672 to 0.9952. The phosphate adsorption capacity at a temperature of 50℃ but the capacity varied at each time interval. This presentation will also include thermodynamic analysis of the adsorption studies.